GMan 3MT

iTrader: (4)

Guys, need some advice here. I'm in no way trying to hide what I previously wrote in my first post, I don't do stealth edits. I stated WHEN I edited that first post, and even do *edit* so people know what's been changed. Brian has what I originally had quoted, so it's there for everyone to see.
I can't tell the tone of "I said what needed to be corrected and you obviously went up top and edited your opening post stating you in short terms "misspoke on the topic" ". Is that a compliment for admitting I was misleading, or saying I'm trying to be sly and hide what I said?

Do I put it back the way it was, which could possibly lead to some future reader assuming these parts are what is required when lowering?

Do I need to add a an depth explanation of what everything does and what it affects and why someone may or may not want to make that modification depending on their car?

I hate the fact that caved into it in the first place to edit it. Rereading these, they are not WRONG from a pure physical geometry standpoint. They state facts about what physically happens when these parts are installed. No, they do not go into why, or what happens to RC or handling, but damnit, which of these is not true and warrant the wrath of god?

3/4" extended ball joints - brings the front control arms back 'down'
They sure as hell don't bring the control arms up.

raised bearing strut mounts - adds back some strut travel
They sure as hell doesn't reduce strut travel.

"shorter" rear shock - avoid bottoming out
They sure as hell doesn't increase possibility of bottoming the shock out.

adjustable panhard bar - re-centers rearend
It sure as hell isn't used to make the rear off-center

rear lower control arm brackets - brings LCA back level or slight pointing downhill or uphill
They sure as hell don't increase the LCA angle up towards the rear

'tall' rear sway bar axle mount - brings rear sway bar closer to being flat
They sure as hell don't make the sway bar leg at an increased angle.

axle side panhard bar lowering mount - brings the panhard bar to level -
This one, as discussed with Brian, depends on the starting angle. I assumed, after lowering, the axle side would be higher. They sure as hell wouldn't make the phb more unlevel.

bump steer kit - bring tie rods back level
They sure as hell doesn't increase the angle of the tie rod to the spindle.

skinny z

From a personal standpoint I don't edit an original post in the original text. I will go back to said post and add an edit at the bottom (posting an EDIT note as you've described) because I've seen before where changing even a single word after someone has replied really messes up the whole context. True the original has been copied in a quoted reply but it does cause some confusion. And in some cases, hard feelings.
I'm not above editing someone else's reply and putting into wording which reflects how I've interpreted it. It often provides some insight into how I'm thinking about that particular reply and may solicit another response which will clarify things. There are a few examples in this thread where I've culled quotes from here and there and assembled them in such a way that my uncertainty and where that comes from is evident. I was actually sort of called out on that however I think eventually my intent came through. And has been pointed out, you can't read tone or intent in a text message.
Anyway, you asked....

yevgenievich

iTrader: (4)

coming in and reading from beginning I was confused due to edits at first. I have somewhat similar of apart list on my 3rd gen, but it is also not lowered as drastically. I am interested in the topic to get a better handling vehicle. I believe I am close to where it needs to be for the street. I have stock 89 ws6 sway bars, 900lb front, 300lb rear springs. Weight jacks on top of front springs, regular ball joint, rear adjustable PHB, tubular rear lca, rear lca relocation brackets and stock torque arm

skinny z

For what it's worth, having read countless threads and with relatable experiences with 3rd gen Camaros and Firebirds I can see the following changes being effective. Keep in mind that this is from my own personal perspective and my own objectives as for the ultimate use of the car. Namely, street use with plenty of long distance driving, weekend drag racing and the potential to try out the local road course. The latter which undoubtedly prompt improvements in other directions.
I will state that compared to what I know about the other contributors in this thread, their experiences and efforts certainly outweigh mine in regards to a road racing orientated approach to these cars.

With respect to a lowered chassis (by whatever means and some means are better than others) some of things that keep coming to the forefront are:

Extended ball joints.
Relocated panhard bar mount axle side (possibly chassis side as well).
Adjustable panhard bar and torque arm.
Lower rear control arm brackets.
Add to that a set of Koni yellow struts and shocks.
Keep the OEM 16" wheel and tire sizes.
At one point I was certain that a raised strut mount would restore the requisite strut travel with the OEM spec strut however it has since been pointed that this may impair performance on some levels. It is certain however that a move from the rubber style mount to a bearing type is required.
Adjustable lower control arms are a consideration (although personally I don't see the effectiveness unless other changes in the chassis necessitate the relocation of the rear axle for and aft).
The idea of weight jacks never seems to be a bad idea.
Sway bar sizes have to be determined by experimentation. Once changes are made the via the lowering, extended ball joints and panhard relocation, sway bar requirements will change. The thinking is that a smaller bar is more effective.
Just an assessment from another enthusiast. I am open to critique.

SlickTrackGod

It was an acknowledgement that the topic was cleared up and covered. All is good. I thought your edit was appropriate.

TEDSgrad

iTrader: (4)

To get back to the title: correcting geometry for lowered cars.
This is just for conceptual understanding: Pink is regular ride height, yellow is lowered ride height, dots are CG.






You can see that the new yellow line has a steeper angle of inclination. The rear RC dropped a little with lowering, and the front RC dropped much more (probably 1:1 with the lowering amount). This steeper angle of inclination can make brake hop much more difficult to control and other handling issues (weight transfer affected, spring rates off, etc). What is needed is to raise the front RC and drop the rear RC to lessen this angle of inclination. For what is available today, ext BJ's and the PHBB help to correct this steeper roll axis inclination. Chassis side PHBB not needed for vast majority, but is an option.
By raising the front RC, you can use a little softer spring (keeping the largest bar possible). For the rear, lowering the RC means a stiffer rear spring and a corresponding smaller bar. General guidelines - real world experimentation needed. OP's #850 fr and #200 rear are in the ballpark for starters though rear probably needs to be bumped.

Once lowered, getting the stance just right (and hopefully you might want to corner weight some day), front weight jacks are a must. Koni yellows are the best bang for the buck right now (JRi's are the unobtainium choice, or you get a DSE sponsorship-BADNBLCK envy). For the rear, I believe the new coilover technology exceeds the old rear shock choices, and eliminates the need for rear WJ's (I have RideTech HQ 6110, 14" range, 11.34 collapsed, 16.5 extended, #250).
Spohn strut mounts secure the bearing the best, DSE's are excellent and I'll switch one day (the are not as tall, either, but their positioning ability is killer). DSE nailed the strut mounts.

Eventually, you'll have to move off 16" wheels for the sake of good rubber options. I don't like larger than 17" for unsprung weight reasons and because I drive 120+ and want sidewall. I know options are limited, and I am waiting myself (and a quality 12 bolt killed my bank). For just the ext BJ crowd, you can go as wide as 275, but it does kill scrub radius. Search for "The Grip" threads for discussion (three of them). My drop spindles limit me to 8" wheel - maybe a custom 8.5" max. I'm fine with my better RC and 245 width. And you don't need more than a 13" rotor with a 4 piston caliper (I have FSL 6pot 2 pc rotors with alum hubs).

LS2 motor, alum radiator saved front weight, but added Raamat on floor and the 12 bolt out back - probably a wash but better distributed. I have seats I can sit in for 14 hours(getting older, once drove Key West to Mpls in 35 hrs elapsed alone!), AC, Bluetooth, and Cruise control with DBW (have parts but not hooked up, yet). It's not a track car, but it ain't a ******!

TEDSgrad

iTrader: (4)

Stan over on frrax posted some figures from the aforementioned software. It's just a ballpark look at changes from the ext BJ - figures will not totally relate to anyone else's car, but it gives an idea.

SlickTrackGod

Lets go over a few things and I will debate why I say your thought process is wrong with softer front springs and larger bar. I will then go over this "stan chart" and point out how these Frrax so called engineers that all think they are big shot racers can plot geometry but can't figure out the holes in it- typical paper pushers- worst click of people on a forum and all are monkey see monkey do which is oh so typical in series racing.

1st, roll centers have "technically " nothing to do with fore aft weight transfer in straight line, spring rates and shock dampers do. The inclination angle of the roll axis only comes into play in diagonal transfer of weight (which can play a little part in straight line braking) as forces transfer from LF-to-RR and RF-to-LR tires and back as tires hit road imperfection. Just want to clear this up for anyone confused as to this angle causing nose dive. A rake angle of the car body has nothing to do with roll axis angle-the two are separate and unrelated for most part other then both drop together but not in same ratios in dynamic movement.

Now Brian it you take a good long look at that stan graph you will see the plotted green line where he show he calculated instant center changes based on dynamic suspension heights. You can clearly see as the nose dives under brake compression the IC will go into the dirt and thus bringing the RC down as well (note the rear stays up because of braking weight transfer of the chassis unsprung weight. So why would you go to a softer front spring ? Makes no sense to leave a large sway bar that locks up independent wheel travel and go to a softer front spring that causes more brake dive. You cause more potential of bumpsteer and change of tire footprint with chassis movement and the end product of the suspension mount points on the chassis changing attitude.

Now here is the funny part this Frrax guy didn't seen to figure out (nor anyone for that matter and is one of the reason my car was so deadly precise like a jet fighter "years ago" Look at his inclination angle- it changed. This loss of inclination angle is the added distance of the ext ball joint added to the strut length to the strut mount. Hence you can see two things here if you put enough time to study it which I doubt they have the capacity or he would have worked on this and had yet another paper pusher chart to impress his click of friends. You "fudge" the bolt holes in the spindle to strut mount and increase the inclination angle (you loose ability for negative camber setting, but if smart enough you realize the increased SAI [steering angle inclination] equates to caster gains and thus dynamic negative camber gains which is a win win- but I digress...lol) You also keep the strut mount distance close as you can in limiting add height for this very reason it aids in what negative camber setting you can obtain since it is overall reduced from the added SAI and thus the IA [included angle]. Now the second and equally important thing he lost was where he ran the IC out to laterally due to the IA and its height combined. Both angle (when you go 90* off it) and the height it sits at makes the IC connect to the a-arm line much further out and as a result a lower front RC.

I give away my secrets, but you see why no one could touch me in my car apples to apples.I have yet to see anyone understand this and duplicate it. I did this 15 years ago and have explained this a few times on here but goes over everyone's heads.

Lastly by using a smaller front bar and keeping heavier front springs you reduce nose dive and keep the front RC more stable, and thus the entire car's platform more stable with a result of better consistent contact patches. You reduce unsprung weight and this provides confort and minimizes uplift of wheel travel over bumps thrusting the chassis into unwanted movement. Big swaybars hold a car flat in a corner, but toss the car over bumps.

SlickTrackGod

Probably the best thing I can teach anyone is there are certain things you can do to a car when you -what we call- BASELINE as car build. These are things you do to take most advantage of chassis geometry before you start accounting for spring rates, sway bars, and shock values to control and balance it all. Things such as what I described about, other things like wheel base, ride heights pretaining to suspesion aids like roll understeer of the the rear suspension, reducing jacking effects, tq arm length and how you taylor in eliminating wheel brake hop afte rshortening it via spring choices and shock values as well as keeping the rear down using smaller front leverage angles- in other words, you don't lift and you don;t suck up wheels either. Its fine tunes to stay where it is and weighted. Most lift the chassis and then suck up the rear wheels- I see this time and time again. THis is where I tested years ago rear spring/bar/shock combos with my slightly shorter tq arm adn came up with proigressive spring rates that build enough in squat to hold the wheels from pulsing under brake grip...and I had a lot of rear brake as well as front. Might I remind everyone I recorded a 60-0 in 102 feet on an 8" wheel and 245 street tires (Factory IROC did it in 147ft. That is 3 cars lengths difference.)

When you baseline a car after modifications are bought and made, you are changing the characteristics of the car and will have to start over.

SlickTrackGod

As for me dealing with only race car stuff? that is about as far from the truth. The most basic street car benefits for exceptional geometry. I will use a perfect example... I have an S10 truck I daily drive in (Not Vetruck, I have two trucks). This truck rides like crap. I just picked it up a few years ago and I hate the way it rides comfort wise. I will never drive this truck fast on a race track nor will I race around the street in it. It just does not go downt he road confortably because the front RC is in the dirt from the factory and every little bump you get tossed side to side you damn near hit your head on the side windows. It is not just this one, every one Ive rode in or drove are like this...they suck. I am merely adding parts to it for provisions to attain comfort and stability for safety in emergency situations. Every vehicle can benefit for proper geometry and adjustment setups- you just need to understand it is not a race car thing but if done correctly it benefits ride quality.

Just an ordinary truck and daily driver. Chassis dynamics is an art and is not a "race car only" thing.

SlickTrackGod

Then there is Vetruck I bought new in 1989 and a decade ago cut the entire suspension off the front of it and hand built my own suspension from scratch. This truck will run circles on the S10 and still will probably ride better in comfort. This is something I still drive often, but is a toy as well as my grocery getter Brabus Mercedes which is built on Konis and custom suspension parts I made but is just a purpose built street car and not a track car. I have other vehicles but those 3 are my street cars and all three are not stock because of things I corrected for what ever reason I felt necessary. Vetruck carries 4000lbs in the bed. I use to be a construction/tile contractor and would carry heavy payloads in it to clients houses. It is amazing on race tracks for its size and weight. My point? There was discussion on this post that I only deal with race cars. Nothing further from the truth. I can make anything ride exceptional as well as handle exceptional. It not just what you buy but more importantly how you do the setup/adjustments that make or break what you do. Understanding adjustments and fine tuning modifications to work is 90% of the game.






you can see the upper arms onthe left side. I cut everything off the frame and made my own pick up points on the entire front end. I run 8 shocks as well, 2 on each wheel.

With all that said, the Ex wife's Camaro turned circles on any one of these cars, as well as my race cars and pretty much anything Ive ever come across. The 3rd gen platform can be amazing if done correctly. I do miss that car but already built one in life. I just help others with theirs now.

TEDSgrad

iTrader: (4)

I think I said, slightly softer spring, but OK. I have 2" drop spindles and 3/4" ext BJ's - possibly the highest front RC on the board (one never knows). Add to that the LS, alum rad, and my light wheel assemblies...Oh, and in relation I have lowered rear RC. I do believe this gives me an opportunity to travel the front suspension more. Both are valid strategies if properly executed (travel more with less roll or travel less with more roll). Historically, we've only had one choice because of front RC. I do think #850 is slightly lesser than what most run (you had #825 with V6), but I also would not call it soft. Maybe, we're debating a distinction within a distinction - softER, I am not old, just oldER.
I also believe that with a V8 (LS or not), use the largest bar. Combo is everything and light wheel assemblies help tremendously. I have committed to be ruled by low unsprung weight considerations, and sometimes it hurts, but I will stay committed. That's why I critiqued the OP's choice of wheels. But I understand the dilemma in wheel choice.
Yes, roll axis is diagonal. I should have been clearer on that.

As for Stan's graph, I was not putting that out to propose it. There is a lot wrong going on, but you do get to see # differences/changes in the ext BJ. Yes, IA is bad, scrub is bad. I would not want to tour this car anywhere. AND YES, I did hope you'd notice and goad you into commenting on IA. My intuition is that your new product will address this, AND it will help me travel the front a little more (little, not lots).

Dealing with only race car stuff? - I don't know where that came from. I actually think we are of the same mind/philosophy in this area. Unless, you're responding to someone else.

Off Topic: Lat G just featured a 3rd Gen! I love those wheels (different size and color, though). #1000 fronts and #400 rear!
http://lateral-g.net/car-feature-val...r-88-trans-am/

yevgenievich

iTrader: (4)

Too bad I have just replaced the ball joints couple of months ago before this discussion really brought up the extended ball joints up to me. with currently set at 300 lb springs in the back, I feel a 350lb or 400lb might fit the car better. I am wondering if someone can help get a feel for a bit of unwanted behavior that my vehicle currently experiencing. At the turn in it feels like it sways a bit for a second and then suddenly bites and follows a corner. It essentially feels like it will barely make it when just starting a turn and then more or less suddenly like I just found tons more turn in radius and grip. It used to be worse before I redid the front suspension. Now it is subtle but noticeable.
I posted it earlier, but here is the current suspension set up.
3rd gen with ls1/t56
About 1.5"-2" drop from factory ride height
1" taller strut mount, -1* camber, 4.5* caster, 1/16 toe in
900 lb front springs
weight jacks(top of spring)
ws6 sway bar
poly a arm bushing
stock new ball joints
basic kyb gr2 struts
new tie rods, drag link, etc..
on the rear 300lb springs
blistein shocks
tubular lca
adjustable phb
lca lowering brackets
4th gen rear which causes me to run c5 wheels all the way around, huge compromise due to 2" front spacers.
front tires 265 wide, rear 285
I do have the basics supports in terms of wonder bar, three point strut mount brace and weld in subframe connectors

TEDSgrad

iTrader: (4)

Start a new thread, and we'll assist. No rear sway bar?
Going by just your description, first thought is bushing as you say it sways a bit then bites.

yevgenievich

iTrader: (4)

Will change to new thread then. Stock rear sway bar. All bushings have been replaced that I can think of. I though it was the a arm bushings and failing ball joints, but after replacing them the behavior lessened a lot but still a bit noticeable.

SlickTrackGod

Brian, That view of me only dealing with extreme race car stuff was from Gman in a post up higher in the thread. I clarified that proper geometry is important is all cars and that close is never good enough. It should be best it can be otherwise what is the purpose of buy adjustment settings? No need to answer however he probably will. I like my tires lasting and my balance safe.

The last byproduct I did not give is the fudge of SAI gives better scrub as well.

I want to just give you food for thought, Why travel a car when you do not have to? (suspension wise) All motion have a reaction. This takes time and alters parameters.Limiting too much can make loss of comfort and control, but why put in more travel then you need? 825 is extremely rigid on a V6. I ran a smaller 34mm bar, not a 36, and I would say with my extended ball joints, short strut mounts, light weight nose, and tweaked SAI I would dare to say your dynamic RC goes lower then mine and started a from my experience a bit higher hence why you need softer front spring to rotate the car. 850 is about as low as I would run for a confortable street car with average unsprung weight. Most race 3rd gens are 900-1100 range. I would put my 825 V6 equivilant to about 1000-1050 range if it were a V8

My Koni struts up front were just a tad too high compression rebound for my liking because the car was too light for that valving. I would speculate (because koni does not list valving figures on OEM applications) that the fronts are valved a 7 of 12 (fixed valve) and I would have liked more like a 5 (1-12). There was an occasional scenario where I would spontaneously overload the front upon a hard brake stab where I was in straightline compression coming down hill and needing to yank he car left or right. It would skip a few inches over then bit. It was almost there but just a tad bit high I could feel it walk for a split second.

SlickTrackGod

What tires are you running? Also are you fighting the wheel under hard braking and jiggling it trying to stay on line- then when you release the brake you have steering grip? Ill bet this is what you are feeling is steering feedback, not grip concerns.

yevgenievich

iTrader: (4)

Tires are Toyo Proxes T1. The situation described does not involve braking on corner entry. Relatively constant speed prior and through corner(medium sweep 90*). I need to verify hard braking condition. It has been a while last time I have been to autox and wheel/tire combo was different at that time.

TEDSgrad

iTrader: (4)

Yeah, I guess I'm not really going totally in the other direction, more of a "tweener" set-up where I am moving in that direction, a little. But like you said, #50 increments can make all the difference in optimal set-up. And a street touring set-up, I want that comfort! I want more travel than is common, but very little travel is common, so it's not like I'm looking for a lot. It's relative. So when I type softer spring, I hope people really hear ER - softer.
I'm impressed with my stock '12 Infinity G37XS. It travels some, but stiffer than regular G37's and is very predictable. It's nothing more than a good driver that doesn't disappoint for what it is - a good buy at a good price point.
Formula braking is excellent, but I have no experiential relationship to compare. This is the best braking I have experienced - FSL 6pot, 2 pc 13" curved vane rotors. What I am looking for is to carry more speed through. Now, I am more than willing to admit driver needs much more experience! And my hard street tires are no help.

And, what we have not discussed, is shock valving/slower release to hold the front down a little longer - but, I'm waiting for the market (C'mon RideTech) to produce a better front strut that doesn't kill the bank like JRi. I'll wait before I try this, but I can learn while waiting. This is easier to do, if you are travelling the suspension a little moreER. It's the little bits we're after.

SlickTrackGod

Do me a favor and measure your panhard bolts off the ground to the center of the bolts on both the chassis and the axle sides and get back to me with those.

yevgenievich

iTrader: (4)

I probably need to lower the axle side. Axle side mounting bolt currently 30cm and the body side is 27cm. Braking is actually straight, but front left wheel locks up first. I can let go of the steering wheel and the vehicle will brake straight until front wheel locks up. Looked a bit closer at the geometry of the corner today and it might also be that I am experiencing bump steer mid corner due to changing banking, and I think the front a arms are hitting the bump stops(they are actually trimmed about 7mm from factory height). I have also only ever drove the car with sticky tires on level concrete surface before, and that was 5 or more years ago. Just put a set of fresh tires on it again, so I might just be fully misunderstanding the feedback that I am receiving.

SlickTrackGod

I was fishing for info and I will tell you why. I work with a lot of drivers and I often find they will tell me one thing and I am seeing and getting data from something else. I learn real quick which drivers to listen to and who not to when I see something totally different on the track. with that said I was wondering if maybe it was something going on here but I really need to get more feedback in order to see if there is a problem.

What I speculated is you had the panhard so low with the massive rear spring rate you had a push due to the roll axis and then went into grip once it finally clocked over into set. Your panhard measurement on the axle side is higher then I expected.

SlickTrackGod

Now when you say change bank...are you talking going into a banked corner and what speed?( Are we talking high banked oval) or are we talking changing from off camber into a normal sloped somewhat flat corner?? When you say no grip, then say grip comes in are we talking front of car, rear of car, or both?

My thought was the front had no grip then came alive, but now I am wondering based on your panhard settings you have a loose in condition until it compresses into a bank and kind of stuffs its self into the corner and banked compression of the chassis grabs the rear again.

Is your steering wheel heavy or are you fighting/jiggling it to keep the car on line?

yevgenievich

iTrader: (4)

Edit:
I think I was chasing some suspension feedback without correct understanding. Thank you for your input.

skinny z

Anything new?
I find any and all of this information useful, helpful and informative.

Except maybe this picture.



[/QUOTE]
!
There are so many things wrong with that I don't know where to begin...!
I do however respect the posters opinion on the 3rd gen platform. If I were closer, I'd solicit his services.

SlickTrackGod

!
There are so many things wrong with that I don't know where to begin...!
I do however respect the posters opinion on the 3rd gen platform. If I were closer, I'd solicit his services.[/QUOTE]

I never elaborated on that car but the poiint of that post was about how suspension geometry is not just about race cars. It is about ride quality and that a built suspension can even be comfortable in performance. That Brabus of mine is extreme lowers and I had to press offset camber bushing into the front as well as make my own custom rear links and chassis braces because the car breeched the capability of the subframe in grip. It rides better then OEM and is obviously a luxury box yet it too corners on rails compared to factory Mercedes. When I lowered it, as good as Mercedes geometry is it breeched the travel range of the suspension and when it did it all went to hell. This car now sets on massive rod ends and Koni Yellows and rides beautiful when the wife and I take friends out to dinner in the back seat- as well as I could toss it around a race course instructing passengers in the back on driving lines. It sits on Michelin Pilot Sport Cups.

Even a luxoBox can benefit from the right combination of parts even being a high end car known for precision engineering. This is why understanding geometry and getting things right, not just "close enough"- makes all the difference in the world otherwise a car generally performs worse, not better.