Horrible understeer

[Scootsmcgreggor]

I get it "the nut behind the wheel".

I'm a very smooth driver was pro back in the late 1970's to early 80's. I'm sure I could learn tons more but at the edge this car understeers badly. I like a neutral car. At the edge I like all 4 tires sliding. I do know braking or throttle will upset this. I have the understeer with maintenance throttle.

The stiffer rear bar is what I was thinking about doing but everything I read says people increase the front. So I am ????

As far as body roll I think it is fine

In my experience these cars don’t like maintenance throttle. Avoid it at all costs.

Also just added a note about camber to my post above. Take a look. Don’t know how camber would be fine with your setup if you’re driving the car near the limit.

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[AvalancheSVT]

sway bar end links can increase the "spring rate" of a sway bar (which is just a big long spring connecting each wheel). that said, have you adjusted the end links to decrease tension?

this could be as simple as decreasing tension in the front end links or adding some to the rear.

 

[K4fxd]

And even with that much spring camber should be in the 3-4* range.

Yes the outside is wearing, I figured I'd need to add more front camber.

So I guess I need to get tire wear even, then re-visit? Maybe reduce rear camber? Again this is not a competition car, just against me, lap to lap.

It is mostly a street car so coil overs are out, I like my kidneys to not hurt, the bilsteins and 200/800 are about the limit for me and street.

In my experience these cars don’t like maintenance throttle. Avoid it at all costs.

That will take some driver habit change. So a drag racer gives good advice to a road racer. @WildHorse

 

[AvalancheSVT]

if it was me i'd adjust the sway bar endlinks to be max loose in front, drive it, then start stiffening the rear sway bar accordingly if that didn't do the trick.

im not familiar with the springs but i guess if you're wearing the outside of your tires its possible you might be driving hard enough to warrant more negative camber.

 

[K4fxd]

if it was me i'd adjust the sway bar endlinks to be max loose in front, drive it, then start stiffening the rear sway bar accordingly if that didn't do the trick.

You are over my head here. How do I adjust for max loose? or how to stiffen the rear. Currently the bar is adjusted to be level when at rest.

I do know on tracks with mostly right turns the bar can be biased for right hand turns.

 

[Scootsmcgreggor]

Yes the outside is wearing, I figured I'd need to add more front camber.

So I guess I need to get tire wear even, then re-visit? Maybe reduce rear camber?

Yeah def increase front camber to -3.5 and see how wear and grip are. I’d bet money they both improve measurably.

Rear camber at 2* should be about perfect.

Front camber and be more patient mid corner waiting to apply throttle and I bet it’s a lot closer to what you are hoping from the car.

Let us know how it goes!

 

[paulm1]

Just a thought, disconnect front swaybar end links and try out a few controlled spirited turns around town to see if she goes way loose on you. if so then you know you need a stiffer rear bar. I don't think a half degree of camber up front is going to fix the front tight condition you're describing. And if there's enough realestate on the sway bar you might try drilling another hole out closer to the end of the rear bar and or in closer to the round section of the front bar to make your own adj bars. I know I've seen guys do this on E36's.

 

[Dana Pants]

To echo others, you need more front camber. I’m at -4, which is awesome for turning but with noticeable reduction in braking traction and inside tire wear is dominant. I might try -3.5 the next time I have a reason to adjust.

For rear camber I’m at like -2.7 which is measurably faster than -2.

 

[kz]

Few comments to some of the posts above - GT PP bar is stiffer (than base) and has bonded bushings providing additional (unknown) stiffness than just its cross section.

Bar links should be adjusted to at ride height you're not preloading the bar.

I'm far from being suspension tuning expert but - would do what Nightmaremoon recommended - replace both bars and fine tune it - you have stiffer springs at this point and more damping. Especially rear is way stiffer than stock.
More camber will help but I wouldn't expect super dramatic change if you're already at -2.5 degrees.

 

[Skye]

Is there a shop in the area which specializes in suspension mods, adjustments, track setups and the like? Reads like you've done all the heavy lifting. But with so many variables which have changed, maybe do a sit-down with a shop, discuss your goals and see what they think. They could give fresh pair of eyes to what's been done so far, put it up on their machines for baselining, etc. Maybe you need one last bit installed. Maybe you just need the new setup tuned towards what you're working to accomplish. Might be worth a chat, remove a lot of frustration and leverage the insight being offered here.

 

[shogun32]

Where's @TeeLew when you need him... Are you sure you're not using up all your suspension travel? If you no longer have suspension all you have left is sidewall and depending on tires that can easily let go.

Put a thin zip tie semi tight on the shock shaft and see where it ends up after a lap. I would do the lap focusing on corner entry speeds and take it real easy on the straights so you don't have the zip tie move in response to heavy braking.

Granted that won't put heat in the tires... Maybe buy a pair of supercar 3r and try that for comparison

 

[AvalancheSVT]

You are over my head here. How do I adjust for max loose? or how to stiffen the rear. Currently the bar is adjusted to be level when at rest.

I do know on tracks with mostly right turns the bar can be biased for right hand turns.

a sway bar can add spring tension to the front end, its just a big long spring, and since you've got too much understeer we know the problem is your front tires don't grab as much as the back.

my theory is you don't have enough body roll in the front to allow for the tires to load up in the way they used to.

since the swaybar is a big long spring its part of the equation somehow and since its the only adjustable thing you have that's why i would start there.

 

[Dana Pants]

my theory is you don't have enough body roll in the front to allow for the tires to load up in the way they used to.

200 lb/in front springs are Charmin Ultra Soft. I’m certain there is plenty of body roll.

This is 250 lb/in and a 35mm front bar on full stiff:

The car is floppy.

 

[shogun32]

my theory is you don't have enough body roll in the front to allow for the tires to load up

or he has too much. ie. mid-corner the inside tire is too light and so the outside is taking all the lateral AND steering loads and is giving up.

1) are the tires even at their optimum temp
2) put your phone on a stable/solid mount and do some logging on left-right tilt.

I don't think anyone has ever run a 200 front spring up front at any kind of serious pace.
@K4fxd if you feel like driving up here (NoVA/DC) you can borrow a pair of Steeda adjustable fronts with their dual-rate 220/350 springs.

I also have the Steeda front bar and the front-end seemed to dig in nicely.
When I switched to 250 straight rate it seemed to me I lost some of that dig.

I'm looking into stacking 2 springs, say 250+450 where the 250 goes into coil bind after an inch or so of travel.

 

[AvalancheSVT]

200 lb/in front springs are Charmin Ultra Soft. I’m certain there is plenty of body roll.

This is 250 lb/in and a 35mm front bar on full stiff:

The car is floppy.

okay, i had no idea (in new to these cars) so if that's the case then its probably the alignment like others have mentioned. its gotta be something simple since its not very modified.

man that car is gorgeous.

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