SlickTrackGod

WHen you have massive caster build like it did, you have to have limited travel or the car will definately go into bumpsteer from the whole assembly coming up AND back in a-arm curve in relation to the tierod paths of the outer tierod connections. I set mine up with toe gain 1/32 on each side with 1" wheel travel. Both combined would gain 1/16" toe out at 1" dynamic suspension travel lower than static ride height.

Alice89

iTrader: (6)

At a 25" front fender height with ext bj's & 900lb front springs; I was having to use a lot of static negative camber to compensate for my poor camber gain (i was over -1 before the car felt like it was turning well on a tight corner). I feel using too much static camber is a bandaid fix for poor A-arm geometry. It leads to masive inside tire wear in the straights. My temperary fix was to lighten the front of the car as much as possible to limit my camber loss in cornering roll.

To fix the issue out right I recently installed drop spindles. With only -.7 static camber and better a-arm geometry; the car felt way better in the corners with the same 900lb springs.

I cant remember my measurements off the top of my head; but I believe my A-arm mount was 7.5" off the ground, and my ball joint was 6.5" off the ground. My Ball joint was 1" lower than my a-arm mount giving me a decent camber gain. Before the drop spindles were installed my a-arm mount was level with my ball joint resulting in horrible geometry & a poor camber gain.

Again sorry if my terminology is poor. I need to read up on suspension terminology so I can use better wording.

SlickTrackGod

Now to the V8 cars, you will never be able to drop the polar weight unless you move the entire drivetrain rearward, so wheat you have to do on the V8 cars is fiberglass hood, alum heads, alum bumpers, drop A/C weight etc etc. in order to get weight off the front nose of the car in bump travel momentum.

You then need to focus on the suspension and wheel assemblies (this is what cost big bucks) and reduce weight via exotic metals and narrower wheels and tires with best quality rubber in that size. most people do not use all of there 9.5" wider wheel footprints anyways because of poor geometry and lack of decent footprint when hard pressed in corners. I pulled 1.07g's on 8" wheels and 220tw street tires, but my car was light and my unsprung weight was very light. This is what the key is to a good ride and good handling. Sprung to unsprung weight ratio is everything...overall vehicle wheight is everything, weight bias is everything....and lastly a reduction of polar weight (weight that is farthest from the center of the car/ weight outside the wheelbase) is everything.

You focus on this and you develop one evil machine.

SlickTrackGod

The only ill effect you have to watch for is the incrased scrub radius the drop spindles yeild. They put the dstribution force pivot far inward of tread on the front tire contact patch . What this can do is cause a handful of car upon hard braking loads. You may develop wandering in steering under hard braking corner setup. Large static camber as well as large dynamic camber actually help reduce this in straight line braking- however the reduced ininward overall footprint lessens the braking friction footprint also.

Alice89

iTrader: (6)

Wow, that's excellent! I hope to achieve 2" of travel with my ls swap; I wish I could get 1 1/2 inches of travel like you did but I just don't see it happening. I had 2 1/2" of travel with a full iron sbc minus 40lbs of emissions crap. I don't think I'll achieve less than 2" inches of travel with just an ls swap & aluminum bumper support; as I'll only be dropping roughly 130lbs off the front of my car. That's no where near as light as a 6 cylinder. Congrats on those figures btw; 1.07 g's on street tires is no easy feat to say the least.

I will have to keep an eye out for this once I get the car back on the road. I will say it felt really good after the bell tech DS's were installed even with the heavy all iron sbc. I cant wait to feel the difference with the ls1 installed.

Alice89

iTrader: (6)

Edit to add: Will I basically be sawing at the wheel under extremely hard braking?

Colt

I didnt know if he was gaining (more negative camber) or actually having his wheels go toward positive. I've never had any problems with this, but im running the founders upper mounts and have it pushed to maximum camber.. around 3° or so static. I even took out the springs and put the suspension though its entire range, when the tire hit the fender well, it must have had over 5 degrees. I'm running 200lbs rear springs and the car has never had any understeer, quite the opposite actually. I think i will be lowering the panhard bar whenever i can, which should help plant the rear. I like the idea of watts linkage even better, but they want a lot of money for it.

In my experience, the killer for this car is how low the roll centers get when you lower the car, which induces body roll. Brake dive is also a huge problem. I've never checked, but these cars must not have any anti-dive in the geometry, and it doesnt help that i run so much caster. Yes, removing front end weight is one way to combat the problem, but theres no denying the **** poor geometry to begin with.

My car has 56% of its weight in the front. Here it is in action recently.

SlickTrackGod

With very grippy race tires on wider wheels? It is a slim possibility that can start to happen and make corner setup placement a little bit of a fight.

Watching Colts video -that car is staying very well planted coming off corners- good throttle modulation. I can tell you are fighting the notorious understeer/snap oversteer 3rd gens are known for. You are handling it surprisingly well considering there is no panhard lowering as you say. I can see the car is stripped of weight so yes that does aid in handling, and I am sure you are on race rubber, never the less you are not sawing at the wheel at all and are very much in control of it. When you can get the rear RC down a little you will find a little heavier wheel that will be easier to simply one hand pull the wheel down turning into a corner (not having to two hand stabilize it like you are.) The car ins NOT wander at all though, very nice.

Autobahn is a great track. I have not been there yet but was invited this year by A few very good acquintances of mine for the past Katech event- Andy Pilgram (Factory Caddy Andy), Jim P, and Tommy M) I was going to ride out with Tommy, but he sold his Katech Vette 3 months ago. Gorgeous track- it would be nice to own a lot there and build a garage.


Also- yes there is no antidive in the chassis to adjust. There is anti jacking of the rear via a shorter leverage of the strut length (as I described in my above posts) the motion of the chassis weight under braking will leverage through the strut mount and use the lever of the strut as a lifting point to rotate the rear of the chassis upward. Lower control arm angle is flat enough to not cause chassis dive there, nor antidive (which of course is more pronouced through upper control arms of SLA suspensions but) does come into play a little with a-arm mount ear heights. Side note: I just proved this by changing adjustments on my little Brabus Mecerdes showing a friend how to clock KMAC eccentric bushings on the cars to aid in antidive- all by just setting lower A-arms.

Edit to add: here's a pic of Andy and I earlier this year and a live conversation with Jim and Tommy on FB about Autobaun and cutting grass I blocked my name on FB so I protect my privacy. They love that track and always rant and rave about living there or owning a shop trackside there to keep toys.

Alice89

iTrader: (6)

Thanks for sharing that video colt. It makes me want to get my car back together more than ever now. I need to get some videos of my car on the track once I get the new engine in.

I was losing camber gain in corner roll. My 900lb springs were not cutting it with ext. ball joints alone. The 900lb springs caused way too much travel and my car had noticeable under-steer when pushed hard; I assume that its camber loss due to poor geometry & a-arm inversion in travel. You seem to have found your sweet spot with those 1300lb springs.

Lowering my panhard bar & installing the drop spindles really made a profound difference on the car. It has damn near neutral steer.

Agreed. Getting weight off the front wont make a massive difference, but every little bit helps. It all adds up in the end.

edit: I meant negative camber loss.

Colt

My car weighs 3290 with a full tank of gas. I have had to add a lot of weight to it in the form of tubular torque arm and heavy old spohn LCA's. I'm currently running NT05 tires, not race rubber. I'm not competing for money or anything so there's no justification to run expensive race tires. I'm impressed with the NT05 though.

The car does not look like it, but it still has a lot of body roll with the 1300lbs springs and ws6 sway bar. Again, the front roll center must be so low that it's overcoming all of this spring rate.

SlickTrackGod

In comparison, My car was 53/47, I weighed 3100lbs Without driver and 5/8th tank fuel load, had more anti jacking to reduce rear jacking effect, less front travel for reduced nose dive and RC did not go into the dirt, extended ball joints for higher front RC, Jegs PH relocator for lower rear RC (overall more level roll axis even in dynamic form, A yawed roll axis with progressive spring rate build on outer side of car(equals more leverage to hold down the inside rear) ...thus the car did not lift the inside rear and canter the weight thrown up over and onto the outside front wheel in body roll like 3rd gens notoriously do. The geometry is very correctable as well as weight if you get rid of the nose weight and move it backwards and have the proper marriage of spring types rates and RC's. I also only ran a 34 mm front bar and I massive 25 mm rear bar. Chassis ride height was 24 3/4" fronts and 26" rears fender lips. I did a lot of work and spent a lot of money on the car to keep things very very light weight and most importantly had weight in the proper positions (I have and can again write a novel on all the little tricks I did in weight advantages in POLAR, Bias, Roll, and fore/aft diagonal leverage. Brake bias, tqarm, and chassis bracing all play a huge part in that marriage. I have always preached the importance of my progressive rate rear springs in my particular setup. It was unique.

It's your rear jacking AND roll axis diagonal canter when the car leans over onto the outside nose lifting the inside rear chassis is what is hurting you. Drop the rear RC with a jegs unit first and foremost, then worry about what to do next. The kit is about $80 and worth it's weight in gold. Trust me you'll thank me later. Best investment you can do right now.

Colt

Is this the jegs relocation kit?
http://www.jegs.com/i/Jegster/550/41...oductId=754011

This has a lot nicer price than the Unbalanced one...

Did you also lower the axle mount side?

SlickTrackGod

That's the hot ticket. Don;t worry about the tube bracket either that comes with the kit now. Ive installed several of them for people and as long as you grind the paint and weld it all around the OEM axle fitment you will be very strong without that unnecessary tube brace.

This is only the axle side. you do not need the chassis side on a car that is lowered. The fourth gens larger overall diameter wheels/tires and stock ride height need the chassis side UE thing a ma bobbers. THis is all you need. Put this on and drop it to one hole from bottom for the initial track setup. You may need to go 2mm larger on the swaybar it the car is tight going in and through corners. Give it a try first with the current setup you have. You might be good to go as is.

Your steering effort will get a little heavier (it will be noticible) but you will be able to steer the car with one hand without stabilizing the wheel with both hands for track placement of the car.

Colt

So, I have a 4th gen 10 bolt 6.725 rear end and am running 4th gen wheels all the way around... 275-40r17 on all corners. I may need the UE thing, but ill probably fab my own.

SlickTrackGod

Those parts are irrelevant. I am talking about ride height due ti wheel diameter. The 4th gens commonly ran/run the vette wheels of that era which are 1" taller overall (275-40-18's). The higher limited chassis height and the heavier car weight causes higher static ride heights compared to 3rd gen track cars. The ride height requires a drop on the chassis side only in order to level the ph rod. You don't need it.

As for the wider wheels you are runnibg on a 3rd gen, the wider track width and control arm leverage reduces the effectiveness of spring rates.

Colt

Ordered the lowering brackets last night. I have been eyeing the unbalanced ones for some time but felt it was a ripoff at 160 bucks. I still think its a rip off at 80, but oh well.

SlickTrackGod

The jegs unit really has a lot to it that is unseen. Its a very nice engineered piece. Yoy will like it when you go to fit it- you'll see what I mean in due time