TEDSgrad

iTrader: (4)

I've been reading about KPI/SAI & Caster split as a starting point for alignments.
KPI/SAI for our cars is pretty much fixed. Camber bolts maybe, but doesn't excite me. How can extending the a-arms help (adj a-arms)?
It would be nice to get a favorable caster split between the two, but it's not going to happen for us. Our KPI/SAI is too large and most are struggling to get more caster (>5-5.5). Does anyone know the KPI/SAI for the stock spindle?


Here's a quote from Ron Sutton on the split:
So … caster helps both the inside & outside wheel & tire.
Here’s the most important piece of info to know at this point. It is the first & most important key to getting the front tires to use their full contract patch when cornering … increasing front end grip & turning speed. Drum roll please …
Caster offsets KPI/SAI on the wheel & tire on the outside corner … and compounds (adds to) KPI/SAI on the wheel & tire on the inside corner.
Read that again. It’s very important.
The greater the split is favoring the KPI, the worse the problem. On the other hand if the KPI/Caster split favors the caster … meaning the caster is slightly greater than the KPI, the outside wheel is going to gain camber as the steering is turned, creating a flatter, better tire contact patch. The inside wheel also gets cambered the correct direction (for the inside wheel) and both front tires stay flatter to the road, have more grip, better turning & higher corner speeds.**P.S. I like to end up “around” 1.5-3 degrees more dynamic camber on the outside tire, since the outside tire is loaded so much more. This varies with tire grip (think TW200 versus Slicks) and with sidewall height, design and rim width.
The best way I have found to work out a front end setting is to start with KPI/SAI & caster … then bring in camber gain … and finally static camber … to achieve the optimum dynamic camber for BOTH tires. Regardless of how you get there ... all of these geometry pieces need to work together in harmony to achieve full, optimum contact patches for both front tires in hard cornering situations … for optimum cornering grip & speed.
Remember the KPI/Caster Split concept ... if the caster is slightly greater than the KPI, the outside wheel is going to gain camber as the steering is turned, creating a flatter, better tire contact patch. The inside wheel also gets cambered the correct direction (for the inside wheel) and both front tires have more grip, better turning & higher corner speeds.

TEDSgrad

iTrader: (4)

And here's his process for optimum alignment:
I have a step-by-step process I follow ...
with the goal being optimizing the contact patch of both tires, while turning hard on tight corners of AutoX tracks or Road Courses .
A. I have to work out the Spindle KPI/SAI with the length of the A-arms, tire width & wheel backspacing ... to end up with a desirable scrub radius.
B. Once I know the spindle KPI/SAI, that guides me on how much “static” caster I need to build in to achieve a KPI/Caster Split favoring the caster.
C. I need to work out if we want caster gain, or for the caster to stay the same, as the front suspension compresses fully under braking & turning (Term = "Dive") Think of this as “dynamic” caster, because it only happens when the suspension is compressed.
D. If I can get the caster I want ... statically and/or with gain ... so the KPI/Caster Split favors the caster 1.0+ ... I can run less Camber, which is the goal. We're always going to run SOME static camber (negative) … say –0.5 at a MINIMUM … and we always want SOME Camber gain … but if we don’t end up with a KPI/Caster Split favoring the Caster by 1.0+ degrees … then we need to make the difference with Static Camber & Camber Gain.
This is NOT ideal, because Camber by itself helps the angle of the outer tire achieve optimum contact patch … and hurts the angle of the inner tire, preventing optimum contact patch. The more static camber & dynamic camber we have to run … to make the outer tire work best … the more it hurts the contact patch of the inner tire.
If we can get to the optimum angle with a KPI/Caster split favoring the caster by 1.0+ degrees … either statically or in dive … we will run smaller amounts of static camber & camber gain. This is optimum. But if we don’t … we’ll run all the camber we need to … to make that outer tire WORK.
E. Once I know how much camber I need for that combo, I work out how much of it is going to be static camber & how much is going to be camber gain.
We always want some static camber. -0.5 is like the minimum. I like -1.0 to -2.0 … IF everything above falls into place.
F. How we get the camber gain, & how much, affects the car's static & dynamic roll center ... so they have to work as a team too.
Our desired roll center plays a role in this decision, because all the A-Arm angles creating Instant Centers determines where the static Roll Center is ... and where it goes dynamically in dive.
It should be clear now why I don't start with Camber.
*Caster gain is achieved when the front A-arm geometry is set for anti-dive. Zero caster loss or gain is achieved with zero anti-dive. Caster loss is achieved when the front A-arm geometry is set for the opposite of anti-dive … called “pro-dive.”
** The more static camber you have to run to optimize the outside tire, the more you’re hurting the inside tire. I like to get 50%-60% of the total camber desired … through camber gain. Here is why: The suspension on the inside of the corner is not compressed as far as the suspension on the outside corner. So effectively … the inside tire is not getting as much negative camber gain to fight & overcome.
*** Don’t get greedy with static camber. Yes it improves initial turn-in steering response, which is good. But two things:
1. Camber helps the outside tire & hurts the inside tire. If you run too much static camber, you can’t get the inside tire to work optimum.

TEDSgrad

iTrader: (4)

To sum all that up, we need to decrease KPI/SAI & increase caster (generally, increasing one, decreases the other[xcept below]). Once that is accomplished as best we can, then concentrate on camber with an eye towards dynamic caster (caster in dive).

Also to think about: lowering our cars tends to increase negative camber & increase positive caster, and increasing negative camber increases SAI (McStrut cars).

Lonnie P

Excellent info.

Wondered about the camber effect, but no one would ever explain why we use so much camber when caster seems like the best way to get contact patch.

tvc 15

I would like to reduce the SAI on my car but the other side effect is "if you have wide rims" is it will increase scrub. I don't know the lesser of both evils. I'm under the impression that our cars have more SAI than the modern sports cars do.

TEDSgrad

iTrader: (4)

Yes, you mention the two evils of our suspension - SAI and scrub. We can't get a favorable SAI to caster split, so camber is where we have to go, which hurts inside tire.
Improving the split by an means should be the primary focus.
Increased width usually pays dividends even with the scrub penalty - to a degree of course. But it's not the whole picture and brings with it more rolling resistance, more unsprung weight, more uneven tire wear.

Also, we have very low RC's and high CG's. Moving both of these will also help.


More quoted text:
The forces that act on the car to make it roll … when a car is cornering … … act upon the car’s Center of Gravity (CG). With typical production cars & “most” race cars, the CG is above the roll center … acting like a lever. The distance between the height of the CG & the height of each Roll Center is called the “Moment Arm.” Think of it a lever. The farther apart the CG & roll center are … the more leverage the CG has over the roll center to make the car roll. Excessive chassis roll angle is your enemy, because it is over working the outside tires & under utilizing the inside tires.
Now I’ll throw you a curve ball. The static RC at ride height doesn’t mean much. It is the dynamic roll center “in dive” that really matters. “In dive” means when the front suspension is compressed & the car is in roll. So in the corner … when you have the front suspension compressed & the car is rolled over … all those angles change … and therefore the roll center moves. It typically goes down … and may migrate to the left or right of center. In the drawing below, the car is making a right hand corner … compressing the suspension 2” in the center and rolling over at a 3 degree angle.
What are (or can be) your tuning tools to change angles:
1. Spindle heights and/or distances from spindle pin to ball joint surfaces
2. Ball joint pin heights
3. Control arm length*
4. Adjustable control arm mounts on the chassis.
5. Also, obviously, any changes in ride height.

Direction:
a. Raising the RC, places it closer to the CG, reducing the CG leverage, reducing roll angle … and working the front tires less.
b. Lowering the RC, places it farther from the CG, increasing the CG leverage, increasing roll angle … and working the front tires more.
c. For faster corners found at big road courses I’ve found the happy window to be 1” to 2.5” … and -0.5 to 1.0” for tight AutoX events.
d. If the RC migrates to the inside of the corner under dive … it will work the front tires more … but roll more if not controlled by the suspension.
e. If the RC migrates to the outside of the corner under dive … it will roll less work the front tires & roll less.
A lot of stock production cars have the swing arms so far out … there is little to no camber gain … often camber loss. Plus, in many stock production cars the A-arm angles put the roll center so low it is below ground ... and the CG is high … giving it a ton of leverage to roll the car … which is part of why many stock production cars roll so much.


That last sentence describes our cars!

TEDSgrad

iTrader: (4)

In order to turn the car, the IR (inside rear) needs to disengage to a degree to allow the car to rotate, while working both fronts as best as possible (managing that camber gain, suspension travel changes). When exiting the corner, you need to re-engage the IR for exit grip.
Cars use roll movement (side-to-side) OR pitch movement (front-to-back) for cornering grip. Using both causes a very unstable car.
The modern method (double control arms & custom spindles for favorable SAI/castor splits) uses lots of suspension travel (4-6”), large sway bars, and milder springs. They control roll movement (side-to-side) with the large bars, let the car pitch (front to back) with milder springs, and have more tools to tune with (double CA’s, moveable BJ’s, etc.). You have to brake earlier, but can carry more speed through the corners with increased grip.
The conventional method uses little suspension travel (1-3”), moderate bars, and heavy springs. They let the car roll, but do not let it pitch as much due to restricted suspension travel. You can brake later and under more control, but sacrifice mid-corner grip (don’t have all the tune-able tools for optimum camber gain) and the heavy springs hurt. Conventional set-ups can be used with success.
Modern set-ups do not use RC as a primary tuning tool – they have more tuning tools to use. Our McStrut cars can benefit from improved RC, and we don’t have all the tuning tools available.

TEDSgrad

iTrader: (4)

One way to help reduce scrub radius is to run wheels with more backspacing - that gets the KPI/SAI closer to the center of the tire.
Our 16x8" 0mm offset front rims would have 4.25" of backspacing. The positive 16mm rear rims (16mm/25.4 = 0.63") have about 4.9" of backspacing. You can fit rims with a maximum of 5" front and 5.85" rear backspacing.

tvc 15

If I would have done more research on the front suspensions of the third gens I'm not sure I would have chose one for a project. Wide wheels and struts are not a good match. Either you have a high degree of SAI or a lot of scrub. My car has 18"x10" with 6 1/8" backspace and I still have close to 2" of scrub.

TEDSgrad

iTrader: (4)

Absolutely!
In The Grip, I debated the 245 vs 275 tires, and what would produce the best results. Since I've already gone the 2" spindle route, I have to be careful that I'm not debating to justify the position I've already taken (easy to do), or if I am letting the facts lead to the correct decision. For the average person who just wants a larger tire, take it in for alignment, and has spirited street driving, the 275 can be a good decision.
With the limitations of our set-up, I believe that concentrating on using all of the tire patch for a 245 is better (many will disagree). Dean said this: Most people with larger tires do not always have favorable geometry to use a larger foorprint. Often they have a smaller contact patch through articulation without realizing it. Sometimes, just by usaing all of a smaller tire contact patch will be better than a heavier whell/tire combo. Just adds unnecessary unsprung weight and alot of times more scrub radius and poor lateral track front to rear.
Now if we're talking 295 or above, that's a different story, and I'm not convinced that would be comfortable for street - there's always someone who says their 415's are comfortable! But a dedicated track car is a different discussion.
Using a 17X8 with 245/45/17 with just a little more backspacing as mentioned, adj the a-arms a little (improve SAI/caster split); raise front RC (drop spindles no longer a choice), use lighter springs with the lighter un-sprung wheel assembly (allows dive to return RC to 2" or so); and a quality 13" rotor assembly would outperform. I believe this is the better grip scenario.

Lonnie P

How much more backspace can you get before the wheel hits the strut?
I wanted to do 18"x10" wheels, but need one to test fit to determine how far in I can get it before contact.

paul_huryk

I'm not going to disagree with you, but when you think about options out there for better handling, it puts many who won't go buck wild changing things into a bind.

Now I for one would love some easy and streetable items to make 3rd gens handle better on 245 tires, but as you mention - parts are scarce to cover those bases. When a potential customer calls up looking for better handling, I automatically refer them to a 275 width tire, a set of Konis, and (if they are wiling to spend), a 13" brake kit. Most just want to use off the shelf items (exception is weld in subframes) and get their handling and looks that way.

That being said, I wanted to talk about one item that I know for a fact works to make a 3rd gen handle on 245 width tires - increased wheel width using light wheels. One of my chumpcar racers picked up a set of (our) CTW Wheels in 17" x 9.5" to replace his 8" wide Cragar Soft 8's and the same 245-45-17 Dunlop tires. Long story short, the car dropped 55lbs of unsprung (and rotating) weight and ended up lapping several seconds (I believe it was 2.8s per lap average for 7 hours) quicker than the old wheels. Now part of that was the reduction in rotating unsprung weight - he mentioned the car felt like it picked up 25hp; another part was the dampers being able to control the suspension better, and the final reason is that the sidewalls were solid due to the increased wheel width.

As most of us run factory 16" wheels that are not that heavy, I focused on the last reason - wider wheel width and the effect it gives. I know BMW uses 8" wheels to mount 225 tires and a 9" wheel for 255 tires, yet GM used a 8" wheel for a 245 tire. If you were to say, use a lightweight 9" wide wheel to mount a 245-45-17 tire, that would improve handling right there - no questions asked. Couple that with a few things to keep suspension geometry good (at least not to ruin it), and you can get to what TEDSgrad is aiming for.

FYI - I had a set of 295-35-18 BFG KDWs in the shop (on a 10.5" wheel) and they had the same exact measured treadwidth as a set of 275-40-17 Falken 615Ks mounted on a 9.5" wheel - the section width was wider though. BFG almost always measure wider than other brands.

tvc 15

Here's what mine look like.

SlickTrackGod

Hi guys (Hey Lonnie, been a long time- hope all is well)-

Brian, what Ron Sutton is talking about in caster split is a difference in caster setting from left side to right side of the car. he is talking steering angle inclination /or King pin inclination of circle track cars that only go left.

He is NOT refering to difference of SAI to Caster. SAI is around 10-14*, and caster of course is around 5*. You do NOT want to reduce your SAI down to 6*, you want to increase it up to the 14* range based on scrub radius. This can be done via fudging the struit bolt holes slightly elongated and tightened while being forced into increase SAI (not decreased. Most people accidently increase one side and decrease the other in toruing the bolts on the car since one side torques up and the other down.)

Let me just give you a quick conclusion. All of this is just notepad racing. You need to put a pyro on your tires and see what they are actually yeilding in tire temps across the contact patch. Simply run a car on a skidpad only in a turning sequence about 10 hard loops and get tire temps and you will see how the car generating grip- then run it a few laps on a track with straights and turns and compare the temp readings (percentage wise in relation to all four corners) and see just how much you are changing footprints of tread widths being actually used in cornering only compared to straights and corners.

You can try and calculate this all you want, but you are wasting time without a pyro...why?....because all cars roll differently based on weights and roll axis. I have done extensive posts on here as to my car weghing the inside tires much mnore that anyones here and the reduction of positive roll weight (my RC's were closer to my CG's) My footprints stayed constant. I increased my SAI so I had almost zero scrub...I had no wandering on hard braking corner setup, I had great inside contact patch grip with overall longevity of tire wear eveness. The 245 can and did do wonders when the chassis weights all four tires in a corner instead of just the two outside ones. (as well as weighting those two outside ones more efficiantly.)

get a pyro and see what you are workjing wioth before you go changing things.

I will also note: you simply change a brand or style of tire and you have just thrown everything right back out the window and need to change the setup.

Dean

SlickTrackGod

More on caster split:

It is used in circle track to get the car to turn into the corner easier. Too much caster split will make it real work going down the straights because you have to steer the car towards the wall just to track straight...then bobble the steering a little with corrections in the "no mans land" of slop momentarily going from straight to corner entrance unless you have sufficiant front swaybar preload. All of this has NOTHING to do with road racing setups.

You do not want any caster split left to right on a roads race car.


A typical street car will used up to +0.5 more caster on the right side to keep a car tracking straight on a crowned road. Roads will usually dive down on the right sides for water drainage (U.S. roads that is...left for you Aussies). Circle track cars will sometimes run as much as 2* caster split if the cars are running on a very circular course...and about 1* for more of an oval or long oval. Caster split in laymans terms would be an example of 4* Front Left wheel and 5* front right wheel (that is a 1* split)

Now when you increase that to lets say 2* and you have 3* LF and 5* RF... then at about 20* steering angle and 3* body roll you are starting to drag the LF contact patch because it is over leaning as the body rolls off it and it extends.

I will just simply say again- This topic has nothing to do with road race setups and your interpetation is off a bit in understanding what Ron Sutton is writing.

SlickTrackGod

When I help the local guys at the small local tracks, I will set their tire PSI's iindividually based solely on the pyro readings. I will initially lets say for examplke set someones fronts at 40 and rears at 37 cold, but then after each run sequence I will pyro them and set each tire individually as to what the pyro is telling me the patch needs. It will tell me if the tire is cambered correctly, etc. I may end up putting some camber into the lf and taking some out of the rf, I may end up with tire temps like 39 (hot) LF, 34 RF. 35 LR, and 32 RR. You just never know. You give them what the pyro tells you the car needs for that driver ad that track on that particular day and track surface condition.

Ive posted this pic a few times in the past but will put it up again showing me helping Val and a few others at AMP (Adam's Motorsports Park) in So Cal with pyrometer readings.

TEDSgrad

iTrader: (4)

Dean - my interpretation might be off. I'm here to put my assumptions/opinions on the table for discussion and learning. I'm trying to glean/boil down what he's saying and bring it over here for McStrut discussion. It's more likely that it doesn't translate over.
However, he's writing a book and using the forum to clarify/refine things in a PT context (Pro Touring), and he does mention Road Racing quite a bit. He wants to help PT track cars (with some street) and dedicated track cars. He explicitly states that he starts with the SAI vs caster split - and wants a +1 caster number vs SAI. He will even design a spindle with that in mind. But that is double control arm set-ups. Nowhere do I see that he was talking about L/R splits. He wasn't willing to help me unless I was willing to put a $6k front clip on - nah. But I try to learn from those who know more than me. I've got thick skin - not an invitation. If I'm wrong let me know. The truth is more important than my ego!
Agree this is all desktop racing. But some software can help get you in the ballpark, so when you go out, you're closer to your goals. Like this software(plus version $129): http://performancetrends.com/rc.htm
If it saves me from buying a wrong spring or bar, helps me understand, or helps me communicate hard data to others, I think it's worth the price.
Here's a screenshot of Stan'sIROC from frrax. He was lowered at 15.7* SAI then added the 1" ext BJ, now he has this 15*, and scrub went from 2.33 to 2.7
Yes, SAI is high on our cars, and no way could we get it to 6* That's the limitations of our set-up. Improving the split is a good idea, but even at this we're limited.
In using 4 IROC rears, you helped scrub with the additional backspacing I mentioned. I'm on the fence concerning the camber bolts - difficult to do right and little gain, but maybe.
Pyrometer: http://www.longacreracing.com/catalo...id=188&catid=7
Thanks for your input, Dean. Always appreciated.

Lonnie P

Hey man... been a while. Glad to see you still participating here.

Based on what you are saying, we could elongate the upper strut mount hole & pull out on the top of the spindle while tightening... then adjust the strut inward to reset the camber. This would increase the SAI & reduce scrub correct?

Even with all the suspension limitations of our cars, I still really like them.
Plus improving on the original design is a fun challenge.

Looks like you have a lot of room for more backspacing.
Have you ever measured the distance between the strut & the wheel at the top?

I have a 17" wheel with 5.95" BS & aftermarket brakes. I am dangerously close to the tie rod. I was hoping for a 10" wheel with about 1" more backspace.

I need someone that can lend me an 18" wheel locally for a test fit.

SlickTrackGod

What you are showing me with Stan's graph shows a massive scrub radius. Take into account for static camber, he would be fine under smooth road braking...actually perfect when you take into account the contact patch center is sitting inward a few inches on those wide 10.5" front tires. He is using about half that width if he's running about -2.5" front camber and is under nose dive load of braking compression of the suspension. Problem here lays bigtime if he encounters any significant road imperfections- that car will wander like a redheaded stepchild in the mall. Once those outside edges of the tire tread meeat bumps independantly on one side of the car it will rip the car in that direction.

So much to try and say here-

the biggest problem facing Ron Suttons definition is you lack the geometry of the suspension links. His +1" senerio you state will not work in a all application world- it is taylored to a specific suspension platform (meaning track width, link arm radius', body roll, etc) they all have to be married to that specific need to work. You have to basically build a suspension platform from scratch to try and hit that tolerance.

We have something already built that we are altering. Putting wider front wheels on a third gen only creates more of a problem. Wider meats will work fine at low speed autox stuff on smooth courses, but encounter any high speed modulation of the chassis and those wider front footprints will play all sorts of havoc as well as premature tire wear. Not to mention the Ackerman taboo these cars face with worsening via a wider track width.

Conclusion? keeping the front wheels to spec like the suspension was (somewhat) enginnered for will help maintain less static camber and more dynamic camber via utilizing more SAI in steer geometry. Also the extended mall joints play right into keeping that RC higher to the CG as weel as the less neg camber keeping the RC up as well. Keeping the car more towards netral roll will help the lack of camber curve (negative camber gain in roll) as the footprint sets- also larger spring rates help limit both roll and compression which would both hurt the footprint in straight ANd corner contact.

To go back to the caster slpit- I still stand by my words. It always makes me laugh when a so called pro will only help you if you give him money. I try and help everyone regardless. His caster split still pertains to circle track. WHen you increase caster split on an unsymetrical fornt suspension (mean for example an 8" RF upper control arm and a 9" left front upper control arm...then also induce lets say 2" caster split.....when you turn the wheel left to 20* the inside footprint will not get to the outside edge like needed in banked compression body roll of about 3*. (this all gets very technical to follow unless you really have an understanding of circle track setups- so sorry to comfuse but I have to try and explain what he talks about. His spindle setup you speak of can only pertain to PT as you state if the SAI is fitted to a unique overall chassis suspension platform. Long and short of it, you are not going to be able to retrofit his secret suspension platform into your 3rd gen.

TEDSgrad

iTrader: (4)

Yes, he was saying that I would have to get that platform, then he would help me. I don't want to characterize him as saying I had to pay him, then he would help me. Buying my way into that platform isn't cheap or necessary. These cars can be made to perform well - better than my driving ability.
Readily agree with camber goals, just uncertain with regard to "SAI in steer geometry."
With regard to larger spring rates - is that larger than stock, or larger in relation to moderate bars. Improving RC helps. Do you have a set "in dive"/dynamic RC that you're shooting for? With my 2" drop spindles, I guess my RC to be close to 5" RC static. If my spring choice is shooting for 3" dive/compression, than I have a 2" dynamic RC - good for high speed RR. AX might want close to 0" for dynamic RC. My thinking is that one starts with known RC, and chooses spring rate to get there + bar. It's not static RC that is important, but dynamic/"dive" RC. Is 3" dive too much?
We have that conventional set-up with: let it roll, control with springs, and little suspension travel. If we have improved RC with BJ or drops, can we lighten springs if maintaining light wheel assemblies? BUT then you increase travel which goes against the conventional set-up. I wish there was a bigger bar than the 36 front.
Maybe, I'm just frustrating myself by trying to come up with a "tweener" set-up, but then making things more unstable by introduces more pitch while having a conventional roll set-up.

Lonnie - yeah, love these cars. Thankful we have forums like this to argue/debate (in the classic sense of the words) to improve them.

SlickTrackGod

What I did was focus on geometry in changing setting points to my favor (in other words moving the fixed suspension mount points) To start off, I want to make sure we are all clear that in the illistration of Stan above it shows a change of SAI from the addition of drop spindles. The spindles themselves do NOT change SAI, how they were bolted to the strut is what change specs from 15 to 15.7 or vica versa.

Lets note this impoirtant fact- running lets say -1* camber with 12* SAI(Edit Correction- I should have listed IA, not SAI- IA is Included Angle) is like running +1* camber with 14* SAI(Edit-again, should be IA). You loose camber when you gain SAI...Sooooo...you need to increase the neg camber at the strut mount. THis now moves the suspension point inward up top (good for favorable RC height gain.

Also, note that I ran a very lightweight nosed car. I was the only person I have ever seen to get away with 24 3/4" front fender heights on a 3rd gen for daily street use and NEVER rub. I had a 1" normal travel and never more than 1 1/2" max front suspension travel. I also had very light unsprung weight so my wheel/suspension assemblies did not thurst upward as hard as the average 3rd gen. I did not have the positive roll weight up front either than most 3rd gens have...all of this has to be taken into account when I discuss what I built and why...and also explains why it worked so well. Now I had slightly heightened aftermarket strt mounts, but overall, the distance of my balljoint to strut mount pivot was less that anyone and most importantly it stayed very consistant (not changing dramatically in dynamic form). This shorter distance also accounted for raised RC...and then lastly I had the extended ball joints.

With all of that said, I had a lower cg, a RC that was high considering I did not have driop spindles so my roll couple was about that of guys with drop spindles, YET, I did not have the issue of massive scrub radius or poor camber adjustment, nor did I have as much positive roll weight so I did not need the massive front bar everone runs. I ran a 34 front/25 rear bar setup(yes a 25 rear and I was nice and tight coming off corners- but so much more attributed to all this like rear wheel steer and progressive rear springs)

Now- when the body does not roll as much, yet the inside wheel trys to lift the car as it steers, the inside wheel is weighted and does more work to aid in conrnering traction. Now if the swaybar was bigger, the bigger bar would lift the outside of the car not set it (thus a bigger bar is bad- now you see the catcher). If the roll weight of the car is more positive AND the swaybar is big, then more SAI will throw the car into roll. More SAI is more inside chassis lift, and thus also more outside chassis droop- so you can not have massive positive chassis roll in using more SAI. The massive weight I got on my inside front tire is why my car reacted and steered like a jetfighter. The inside wheel is what turns the car.

I stop for now to see if you have questions.

ps remember that SAI aacts just like caster.

Lonnie P

True... I have a 4th gen but my 3rd gen is still my favorite car to go around corners in.

I do want to make it better even though the average person is amazed how it already handles.

SlickTrackGod

Sorry also- to answer you question of "in dive RC" or dynamic RC I would shoot for? Keep in mind that the strut front end does not have dive/antidive settings like a double wishbone has. My car did not "dive" so to speak for two reasons

1) as stated I was very light weight nosed with the little V6 powerplant and on fairly massive 825lb springs and koni yellows considering that nose weight..

2) and mainly what these cars suffer from is not nose dive, but "rear jacking effect". THis is multiplied forward through the strut mount (very tall spindle so to speak) as the body weight motions through it when the brakes are applied. Take note by lessening this distance (balljoint to strut mount pivot) like I described I had in the above post, I lessened my rear jacking effect and thus less weight came off the rear tires so I never encountered rear wheel brake hop either. The car's platform stayed very neutral in retrospect to other 3rd gens. The weight was controlled so the platform did not change attitude and thus is what changes suspension link angles and footprints.

Lonnie P

I'm trying to read minds here... Would this make sense for a good initial approach?

1. Minimize wheel offset by keeping wheels as inboard as possible

2. Increase SAI until scrub radius is near zero (or as close as reasonably possible)?

3. Minimize front suspension travel with moderate rate springs (guessing 800-1000# depending on engine weight) to prevent roll center migration. Brian & I are both running LS engines.

4. Maintain lower control arm angle with extended ball joints etc. to keep roll center as high as possible. (already knowing it will never be too high with our suspension design)

5. To combat the "Jacking Effect" (rear to front weight transfer) could we run a stiffer rear spring & the corresponding lowered rear roll center from a relocated panhard bar?

Does this make sense?

TEDSgrad

iTrader: (4)

I think you misunderstood about Stan's - but it's not a big deal. I posted the pic as an example of that software, and how SAI & scrub changed when he added an extended BJ. He doesn't have drop spindles with those wheels and his RC would have raised more significantly. Look at the static RC changes and you'll see. Here's the before and after to see. Just for clarity.

TEDSgrad

iTrader: (4)

WOW, that is the definition of conventional set-up: moderate bar, stiff springs, minimal suspension travel, and RC tuning!
If I remember, you had 800# springs (OK 825#)? With the lightweight V6, I can understand. Like Lonnie just stated, we would have to go much stiffer springs with more weight - and ride suffers with all that weight and little travel - more jarring. I believe Lonnie's at 800# and I'm at 850#. Also, a little more compression helps my RC get to a desired dynamic RC position. I may not be getting 3", though. I'm sure we could benefit from a little more, though. The drawback of the V8 weight means a little more suspension travel for comfort and helps my dynamic RC. BUT THERE IS A PULLFORWARD And my backyard track needs speed, whereas most tracks do not approach that.
Yes, lowering rear and PHB lowering would require stiffer springs & bar, both. If using the Jegster axle side only, it will not be too bad (I'm 200# rear coilover), but Lonnie's got the Watt's so you should consider upping the ante. How is that working out for you? Been wondering...

Changing the fixed mount suspension points...hmmm. Elongating the strut mount holes like Lonnie mentioned earlier is easy. I understand the camber bolts, but still on the fence. I would need to find an educated person with good equipment to attempt it. Been thinking about adj the Spohn arms, too. SAI does improve with 2" drop spindles as the shorter length would lessen the angle.

Forgot about light wheel assembly not slamming back down as hard as heavier allowing for stiffer springs. Knew that, just sometimes fail to add in all these parameters. Lots going on.

TEDSgrad

iTrader: (4)

OK, so you minimize weight/force xfer front to back (dive, pitch, etc), and maintain force on front wheels by the stiffer springs. Also, minimal suspension compression controls camber gain, so that grip is maintained.
Question - with so little "attitude change," how are you disengaging and re-engaging (to a degree, of course) the inside rear tire if you are increasing the rear sway bar (25 on a V6!)?

Lonnie P

Great discussion here...

Brian,
Do you still have the drop spindles? I thought you broke one for some reason.

I have 800#F & 150#R springs.
Running 1/2" extended ball joints & 36/24 sway bars.
Fender height is now 26-1/4" if I remember correctly.

The rear felt too soft to me, so I tried a spring rubber in the rear coil to stiffen it up a bit. It improved things, but I haven't driven it enough to get into tuning the Watts link further. I was limited to the highest roll center height adjustment before, so I'm anxious to see what I can do with a stiffer spring. I'll eventually buy another set of rear springs after I see how these work out.

TEDSgrad

iTrader: (4)

Never had a problem. I thought I had ordered road-race spindles, but found out that I did not get them. Had to send them back in, they took them completely apart, re-welded them, and strengthened them to the road race version. Cost me additional time and money. Besides that added hassle, I have had no problems. They are no longer offered, so future customers are out of luck. Ext BJ are you're only option at this point, and you're right, they don't quite get you to favorable RC. But you can run a larger wheel. The grip discussion between the two is how these threads go started.
Since I'll go custom 17's, I may have enough room to go 8.5", but will probably just get 17x8 with 245/45 because I'm not moving off of my unsprung weight build theme. This discussion helps to reassure that decision. And gives rise to urgency of using all the tread width to its full potential.
For the average, street only guy reading this, Paul makes a decent case for his wheels. For guys who push the limits a little more at higher speed (AX & tight circuits are different), I think this route is the correct one. My local track is a 4 mile lap with three sections of above 130mph. I like debate, though, as I can always learn.

TEDSgrad

iTrader: (4)

You definitely need stronger rear springs! And we might need a little higher front - maybe to the 1,000# limit or slightly under.
I think I'm at 26.5 fr 27.5 rr, but I know I've played with them a lot. Here's my recent pics

SlickTrackGod

Sorry, my mis-quote. I did list drop spindle when you showed he put extended ball joints...

However- With either change of drop spindles OR extended lower ball joints the SAI does not change. I will repeat: The SAI does NOT change(EDIT: OOPS Sorry, I meant the IA does not change, the SAI can and generally will. IA is Included angle). The change he has is from unbolting the strut from the spindle and then retightening it back together will simple change the reading due to tolerances slop between the two componants. SAI is plain and simple the angle of the spindle shaft in relation to the angle of the imaginary line from balljoint to strut pivot(Edit: THIS IS WHERE I MISLABELED IA TO SAI...SORRY). This for the most part is a "fixed" (or non adjustable) setting on third gens- however as stated there is slop in that componant connection thjat will slightly vary that reading each time you unbolt and rebolt it toghether unless care is taken.

Lonnie P

Dean,
I believe the SAI change on Stans picture is due to the fact that after the extended ball joint was added the spring was lengthened/shimmed to regain the previous ride height. This lowered the outer pivot point (ball joint) effectively lengthening the overall height of the strut/spindle assembly by 1". This reduced the SAI angle. If he added an extended ball joint & let the car drop 1", then the SAI would stay the same due to the same overall strut/spindle height. ...not including any alignment changes needed.

SlickTrackGod

Sometimes I make a bonehead mistake. Let me please explain. I do not deal with technical specs all the time like an alingnment technician reading charts, I am a backyard guru that does things as I see them. I keep refering to SAI when I should be refering to IA (Included Angle.) What I am refering to this whole time is: the angle of the imaginary line between the ball joint and the strut mount pivot- and the relation of the wheel at 0* camber. I need to clarify since I have stated what I am changing but keep using the wrong term to label it. Its like a golf club face, the club face can not be changed from the shaft, however the angle of the face can be changed if you change the angle of the shaft. (I am talking about changing hte shaft angle without changing the face angle--my bad, it is IA)

Yes of course the SAI will change. the IA will not. To correct the scrub radius without any changes to balljoints or drop spindles, you need to change the IA (relation between the spindle and strut. I am sorry for the confusion, but my text above is still accurate by simply changing SAI to IA.

SlickTrackGod

1) Keep the wheels as close to the OEM centerline as factory- which of course is as inboard as possible. Moving an 8" wheel any more inboard will hamper turing radius.

2) In the old days engineers utilized large scrub radius' so that a car would steer easier at a stand still (without power steering) as years went, engineers reduced this but not enough yet as they were learning. Modern cars generally have 0 scrub or just slightly positive becuase the advancement of progressive ratio steering systems, etc. We are not worried about a 100 lb lady making a parking lot manuever so we want it hard to move. I have a radical steering setup on Vetruck with very wide tires (wide track with long wheelbase so you can assume the strain stagnant sttering imputs with very wide front tires) but I still move a little as I steer it. I never crank the wheel at standstill because it strains all the tierods, bushings etc in in bind. I have completely reengineered the entire front suspension on that truck to zero scrub and actualluy run -2.6* camber on it as a somewhat daily driver (becuase it is HEAVY,lol) ---just a little lesson on zero scrub.

give me a minute to finsh the next 3

SlickTrackGod

3)Yes you want to minimise the front suspension travel because the nose RC dives very rapidly compared to the rear of the car if not then your roll axis changes drastically- regardless of engine weight, you want to limit movement of what weight you do have- tht's were of course proper spring rate choice comes into play based on your chassis weights. We have nice long A-arms on these cars, but poor frame mount geometry. The frame mounts should be higher to reduce roll movements especially when lowered to the 25" fender range. Staying at 26 is not as bad but you sacrific Cg height, yet gain the advantage of less positive roll force- most things are a give and take unless you reengineer it.

Back wheels should for the most part stay in track line with the fronts to lessen any bandaisd effect of loose in /tight off or tight in/ loose off from different forces on CG while sitting in lateral grip under braking and accelerating.


4) What is too high? If it is lower then the CG then you are not too high. You can reduce sway bar size which is great. Get that RC out of the dirt in dynamic motion. Free up the independant front wheel movement. Weight the insid wheel more. Win, win, win.

Balance everything with spring rates, shcok valving and fine tune with swaybars to get the car to turn..old school racing style with lots of R&D testing. It will eventually work and it will work very very well.

5) Yes. I have seen it proven on a 3rd gen buy drasticallu dropping the rear RC and upping the rear spring rate to 300 (no front RC correction work done though) that the car did not jackl as bad as stock even though it had massive stored energy of the 300 lbs springs in release over an OEM aprox 130? spring. The car also had a factory TQ arm geometry. The fact is (an I proved this myself on my car) by simply lowering the rear RC the car ewven has better braking bias and kept the rears planted. most braking is done not entirely on a straight line. The less of a diagonal transfer of rear to front weighted footprints is lessened so the inside rear brake works better- that wheel stays more weighted of course due to lesser diagonal canter of the roll axis.

TO add to #5- what causes rear wheel brake hop? A shorter Tqarm yanking up on the axle as the "rear jacking effect lifts the rear chassis and reduces weight on the rear contact patches. Shorter Tqarms require stiffer springs. A stiuffer spring on a factory torquearm will still harm in high speed stuff because it will aloow time for the srping energy to jack the cars rear under long raking zones. Increase rear spring rate? then shorten the Tqarm...or as I did I increase my rear swaybar and used progressive rear springs- but I could get away with the massive rear bar becasue I has a very lighteight nose. A win win for me. You'll have to experiment to get it right.

SlickTrackGod

I answer that with a question-

What steers a gokart> How does it disengage and reengage? How do you tighten or loosen one>

now Ill answer those- A kart disengages momentarily and steers via caster. As I stated above, (but used SAI instead of IA) IA is like caster. I plant the inside front wheel (which is the wheel that turns the car- more on this in a minute below) and as it does the inside rear will lift.

the rear of a kart is tightened by decreasing axle width, and loosened by increasing axle width. On my car I play a little trick with the rear spring rates to migrate the rear RC to the outside rapidly with the onset of the outside wheel rapidly loading- with progressive rear springs. The swaybar will momentarily flex as the outside rear increases rate. that imbalance of increase ouside wheel spring rate will 'Yaw" the roll axis ands weight the inside rear chassis from lifting becuase the RC moves rapidly towards the dominate spring rate. This is what keeps the balance of the inside rear of my car flat from jacking but yet it would lift momentarily enough to disengage adn the inside front would yank the car that wway like a jetfighter.Note the yawed RC moves the folcrum away from the inside rear of the car thus cause more weight to lift like a teeter tooter folcrum being moved to one side move weighting the other side.

Once initiated then chassis contral keep it all flat and the wheels all weighted for lateral grip. Note also that the massive onset of rear roll steer kep the *** end form getting violently out of shape as it did it's rapid change.

Sound like alot of smoke and mirrors? what it for your own eyse in this video footage. I thow it into this caorner @ 1:06 on the video (just fast forward to about 1:00, the first haldf is boring since shot from a distance. You literally can see the rear wheels steer and it snaps right into place and tigtens the car right off the corner.

As for the front inside wheel steering> it's like grabbing a pole with your left hand to turn left. It yanks you left. If the right wheel steered you left then it would be like running at a brick wall and usung your right hand to puch off the wall to go left- nope. Righ hand is for grip to keep from going into it, but left hand grabbing the pole is what takes you left. Right just keeps you from going right (IE tire grip)

SlickTrackGod

I want to also note that video of the car was in about 2004 when I was still in the testing stage of the car. I finally had enough seat time and componant additions to it in 2006 that it would beat the snot out of the car you see in the video. I had not done the extended ball joints, nor the front brakes, lighter unsprung weight, nor the rear panhard setup yet in this video. later the *** end of the car stayed much more planted- much more that you even see here. I still beat the pants off the other 10 local guys there that day in that grudge match. The closest one was 4 seconds slower up to 11 seconds slower with the last of 10 others here on TGO. I was on 245-50-16 street tires and 8" factory IROC's.

I did however have the progressive rear springs, 25mm rear bar, Koni yellows on #2 setting (fronts maxxed), Wilwood rear brakes (had just put them one- it was the 1st time out on them), LCA's shorted as much as I could pushing the driveshaft into the tailshft as far as possible (shortened my wheelbase as increased the rear steer effect of roll induced understeer). It was the start of my experimenting with the roll centers on the car. The *** end was responding so well to what I had tried and in this video was where I searched for corrections to get the rear RC down a little. I also played with a 23 mm bar, but once I got the extended ball joints uo front I went back to the 25 rear bar in about 2006

SlickTrackGod

(Temporary personal info I wanted to delete).

Reid Fleming

iTrader: (2)

I'd never considered this before. But does weight play much of a role in deciding on a camber spec? Take a lightweight V6, a medium weight IROC-Z, and a heavy GTA, would you choose different camber specs or the same? (Assuming you were doing the same type of driving in all 3 vehicles)

TEDSgrad

iTrader: (4)

Roll induced understeer is intriguing, and I've learned a lot from you describing it.
I have big fast sweepers and a WOT "kink". I prefer my rear planted. For tight circuits and AX, it sounds sweet, though.

SlickTrackGod

Yes weight makes a difference on both camber AND tire PSI. That is the sole reason why front tires take more pressure then rears (when the same size tire is used on all 4 corners.

I pyrometer is an invaluable tool for tuning. It will differentiate the need for camber and tire psi of the same tires on 2 different 3rd gens.

A pyro will also help assess (emphysis on 'help') what the roll center are doing. Even if it is a road race car, roll center setupo is best done by going in one direction like on a skidpad so you can see how the inner wheels are being weighted. By running both ways will equally like a zigzag slalom will not tell you inside weights because both siode will read pretty much close to idential (if nothing is bent and driver weight on the left side is not to an extreme).

Now once you have good R&D reading on a pyro through skidpad testing to see how the chassis is reacting along the roll axis and overall roll couple (this shows just how much positive roll you are getting at max grip- example the outsides could read 240* and the insides read 150*, or the outsides could read 240 and the insides could read 205* if the car is weighted better with a more neutral roll rate), you can then take a car out on a course with lets say 14 rights and 5 lefts (19 total corners) and it may read somthing like LF:

LF- 232* 228* 233* / 201* 212* 197*-RF
LR- 195* 195* 201*/ 189* 187* 179* -RR

Lets disect these pyro reading. When can first and formost see the left side is hotter then the right side- obvious because the car is turning more rights then lefts- so this is OK.

next thing we want to look at is diagonals. LF + RR averages are at about 230+ 185= 414 aprox. RF + LR averages are at about 204+ 197= 401. Very very close telling you your cross weights are good and there is no real imbalance in the left and right 50/50 in handling. You are at 49.2% cross weight. You can correct this by taking about a half turn out of the RR coilover, or slightly shimming the LR conventional spring. However. I personally would NOT touch this YET. I would focus on getting my footprints flat first to get rid of any possible unsolicited croass via under or over pressurized tires.

So lets look at tire PSI/At the same time lets also disect Camber
LF for starters: 232 218 233. Tells us the camber is perfect or close enough for now, but the tire is concaved in the center tread so it needs about 1psi. Add exactly 1 psi to it right now. Does not matter what it was cold or hot, just gauge it carfully right now and add 1 psi...period. In a perfect world, you want the inside tread heat to be close to 10% hoptter then the middle or outside- car rides mostly on inside edges and you want sidewall heat to escapoe down straights for temp recovery- get off the outside edges and bleed heat for the next corner- plus it helps a little with drag as long as traction is not an issue.

RF is at 201 212 197. Tire has way too much PSI and is crowning in center tread. Camber looks great so leave this alone. If a tiee were at lets say 215 205 195 then psi is great (even between all three nubers) but the camber is too far negative and it is riding on the inside edge more. This tire probable nneds about a 1/2* of neg camber taken out of it in the second example. Back to the 201 212 197- camber is fine, leave it alone for now.

LR you can't touch camber nor do you want to. Camber and the PSI are perfect!

RR might be about 1/2 psi high. I would pesonally bleed it since its a rear to gain a little grip and heat.

Lastly we look at front to rear heat ranges. Notice obviously the fronts have more heat then the rear tires. There is about a 30* difference on the dominate lefts. Tells me the car is cantering over onto the nose and the roll axis is too steep favoring the fronts. Knock down the rear panhard rod (rear RC) one notch which is on a JEGS adjuster 1" (this equals a 1/2" rear RC drop. This is a significant change and may be too much. Next go around you may want to increase some rear bar by widening the mounts on the axle- or go to the next larger bar and narrow the mounts.

Time for the next set of laps.

SlickTrackGod

If a car gets bent out of shape at high speed? trust me roll induce understeer is your best friend. Roll induce oversteer will kill you.

SlickTrackGod

(Temporary personal info I wanted to delete).

SlickTrackGod

I went back and re-read your initial post seeing where I went wrong labeling the SAI. (Smiles) I see where I went wrong labeling it becasue you actually started out doing the same asking wht the SAI was for a stock spindle. I was trying figure how I could have explained everything better and why I refered to the SAI and not IA. when you take into account for you saking the SAI of the spindlle it is in fact the same as IA. You actually state in the quote above you know it can't change.

I then started eloborating on that and you guys took it into mounted angle in the chassis rather than the initial talk of fixed spindle angle (where we all just obviously agree the spindle is parallel to the ground for angle sake.)that is where this talk made me look wrong- I was scratching my head as to what happened in this discussion and now I see how it happened. When you draw a vertical perpendicular to this and then measure the strut pivot from the ball joint pivot, this angle will change based on the length of the strut ahft pivot point. But for the most part, the angle is around 11-14* range.

Lets look how we can gauge this assembly at home (backyard mechanic abilities) without a professional alignment rack. The bast way to bolt both the left side and the right side spindle/strut housing assembies identical is to take them off the car and lay them (somewhat) flat on the floor with a rotor attached to them. You will need to prop the assembly up with whatever you can find to get the rotor face vertical 0* and the strut shaft horizantal at 90* or parallel to the ground. You need to place this assembly over some kind of graph or jig that you can reciprocate and gauge the other side to match when you compare it. This is where you have to be creative to gauge that angle. You will no way be able to do this 100% accurate, but it will save you hundreds on algnment rack costs with testing and testing each time you take it back home and try to fudge them more to get them the right angle for srcub AND most importatly equal +/- 0.50 each side in SAI with identical camber specs.

You basically try to tighten the two large strut to spindle bolts while the assembly is being forced with the spindle down the the strut inward (towards the center of the car if you consider how its mounted in the vehicle.) I am sorry to say I have not had my initial alignment specs Jon and I did on his rack at AccurateAlignment years ago when he let me play on it for a few hours, but that is how I initially set mine. Not everyone has this luxury I know (nor do I anymore- he retired to LaPaz Mexico a few years ago).

The reason this Ron Sutton discussion does not carry over to a strut assembly is becasue the strut assembly will not fit inside the cavity of a wheel backspace in diameter like a small spindle does. A strut assembly does however have the advantage of stabilty with length and the effect of a tall spindle on linear braking effects of the chassis. In order to get a strut suspension setup inside a wheel with very little SAI of the overall strut length the wheel would have to be 30" in diameter- it is not.

Companies like Toyota and Mercedes have been making tall spindles for years that loop around the top back side of the wheel and tire and attach to the upper control arm balljoint just above the tire tread- making for a very tal spindle. This feat is basically impossible (or unreasonably possible and heavy) for a strut assembly to be attached as the upper link. This is why strut cars have large SAI in static form of the strut/spindle angle. The strut has limitation in adjustment range (hence the strut mount adjustment range. It is favorable to neg camber max specs the shorter the overall strut distance is when mounted). A double wishbone will always have greater abilty for camber gains, but lack stabitly in short spindle and suffer from change in braking angle. The advancement in metalology in the last few decades has made short spindle setups more feasable so that is what you see in top level racecars like F1, etc with exotic strong and lightweight componants.

Getting the RC's up heigher to the Cg (or more favorably getting the CG down and leaving the RC where it is naturally (via drop spindles- wink wink), there is less roll and less suspension change form side to side. The lack of camber gain is also lessened in ill effect by limiting roll and inversion of A-arms loosing camber. The sway bar is reduced allowing for better independant wheel movement and thus more mechanical grip.

Conclusion- if you put a jack under the car and lifted it 1" while the car is on an alignment rack, you would see the SAI readings change even though the SAI of the spindle/strut do not change. On the car the spindle/strut angle is considered IA or Included Angle.

TEDSgrad

iTrader: (4)

Excellent! I knew you were wrong (misunderstanding, misinterpreting, etc.), and I did not know how to express it without a bomb going off. I held my tongue (fingers), and you corrected it yourself!
I applaud your emotional control as well as your explanations of car control.

Very good discussion, here....

Brian

TEDSgrad

iTrader: (4)

Here is a pic showing the spindle bolts (original drop spindle), and a pic of the De-assembled, re-welded road race spindle (which is no longer offered, though if you have the originals they will upgrade them)

SlickTrackGod

I only go off on someone if they are sarcartic to me.

Seeing the word "Caster Split" really is the wrong word for him to be using to describe a relation between steering angle and caster. This is not a common setup used at the track for setup like caster split is used (very very frequently I might asdd) in setting caster different one side to the other. I have never seen the use of the word Split describing the difference between two different settings. Split is obviously the difference in one setting, it is split into two different ones. This is also where this whole topic went off into left feild. You can split caster, you can split SAI, you can;t split two different things- it's not the correct terminolgy when especially when the words caster split already apply to something else.

I see the article is apparently trying to discuss the relation of Caster to the relation of SAI of a chassis. As Ron states, he also checks the camber gain and the overall relation between the three to judge the footprint. Caster split in relalation to SAI is a whole different setting used in circle track to get the left from dragging and keeping the right in grip by using a little bit more toe. I use a dynamic toe increase up to about 1/4" gain on the left- this gets very complicated to explain. You'll have to build a jig and rotate it to understand probably. Again, Pyros are invaluable.

On a 3rd gen sith struts- the MAIN thing you need to realize when dealing with SAI and relation to Caster is that Caster builds quicker the SAI in wheel travel. In fact, SAI stays about the same because of the geometry of the A-arm swing and lack of camber gain (lack compared to double arm that is). Now on a car like mine that was extremely low static ride height, I had a shorter assembly and 5.5* caster that will dynamically build to about 8-9* in corner set since the geometry changes rapidly when short and arched over already. The A-arm geometry archs forward and the camber gain is minimal so the SAI realy stay close to stagnant through travel(in relation to caster change). You also do not turn the wheel as much on a car that does not lean becasue the inside rear lifts (as decribed in eariler post) pressure initially like a gokart does. When a car leans or rolls alot then this effect is not present- has to be a firm springed and soild bushing chassis to feel this as well and / A car will not roll with quick slow speed imputs, it will simply lift a little and yank inside. I also had a little less front track width then the factory 1LE cars and ran 4 "Rears" 8" Irocs with my own custom made front hubcentric wheel spacers slightly keeping the wheel off the brake caliper (My custom Wilwood setup, not OEM) I had to do very little to get just shy of center tread with SAI, not like you guys needing massive SAI to get close to center tread on a 9.5" wheel that also sets a tad more outbound. Even though the average 9.5" front wheel should set outward 3/4" from mine, it actually sets outward more like 2" front mine. The centerline tread on most people cars using wider front sis way out there in comparison. This is why I preach an 8" wide wheel for the front of a 3rd gen- it keeps to factory engineering of geometry....AND is closer to try and perfect what they erred from the factory.

The last thing I had to watch for was bumpsteer with the massive caster increase. I set my toe dynamically to gain 1/16 on both sides through 1" travel (total 1/* out gain). I did not run massive static camber AND had no scrub radius problems to deal with yanking a car side to side wandering under hard braking. It was a whole package thing that was tested with the use of a pyro and the car was tested on a skid pad many times over a few years. I took it to an official skid pad up in Devore Ca and ran a 1.07g on the skidpad on 8" wheels and 245/50-16 220tw street tires

SlickTrackGod

The chassis SAI does change, but initially Brian asked (and I quote)
"Does anyone know the KPI/SAI for the stock spindle?"

I stand by my post that SAI does not change when in content of answering his question. No Brian I was not wrong, you were in changing the context on me.

Lonnie, Yes in your veiw I can see how I was wrong when you read my response and attach it to chassis SAI, not spindle?

I was not "WRONG" to you- I answered your post very accurately and once Lonnie questioned my post pertaining SAI I had to go back and figure out for everone why this went off context. YOU were wrong and misunderstanding I cleared this up for everyone.

As I appreciate you thanking me and trying to look polite, I do not appreciate blame being placed on me trying to help and it being taken off context. I know this was an accident with multiple people questioning the same thing, but my appology was not to you for me being wrong. Nor do I have a short fuse when it comes to civil conversation. I would kindly appreciate you refrain from "annoying me with suggestions I am a loose cannon" when I have always been civil to people like you unless sh*tty remarks like this are made to me- then yes I will just be an **** to you also if you'd like.

Lets get your facts straight.
Thank you.

JamesC

iTrader: (5)

Let's not allow rhetoric to close an interesting/beneficial thread.

JamesC

TEDSgrad

iTrader: (4)

Dean,
Please forgive me. I am not perfect. I agree we need to get facts straight. Please accept my apology.

Brian