98_TA_EMLC

So this is my first year autox'ing my 98 TA and it's been an absolute blast! I can control the car very well, but occasionally I still have a bad understeer problem. Yes I could just slow down, but at some of the sweeps I'm understeering at, with the speed I'm going I feel that I should be gripping with the front more. I have some ideas as to what I can do, but wanted to hit you guys up and ask for your help.

Currently the car has Strano Springs on Bilstein HD Shocks, 35mm Front Sway Bar with poly end links, PHB, STB, and LCAs'. My tires are Kuhmo Ecsta XS 285/40/17 on all 4 corners with C4 ZR1 (grand sport actually) 17x9.5's. The tires are new this year and have 5 events on them....so they're fine.

Below are some thoughts I've had, let me know if I'm on the right track.

1. Air pressure. I kept dropping air pressure at my last event and ended up at 32 front, 34 rear. I usually start at 35 all around. Am I way off here?

2. Camber. Adjustable lower a arms??? Still needs to be streetable though so how much camber do you suggest? Any reason I can't get an alignment squared up, and then extend the arms out for an event?...then put them back to the square mark to save my tires on the street?

3. Weight. Specifically the battery is the only thing I can think of that needs to be moved. I already have the bracket for the spare tire spot...I just need the cable. I already have EGR , AIR, and winsheild fluid resevore gone. I'm a very budget minded person so a chromoly k-member isn't in the cards yet.

4. Rear Sway???? I wouldn't think this would help with understeer at all, although since I don't have one I wanted to ask if you'd feel a difference in the front with the rear sway?

5. ??? I'm out of ideas.

If I ever get to a place financially where I could...I'd go 315's on all 4 corners...but just for autox events. Otherwise I'm kinda lost what else I can do here.....other than slow down


On a completely different topic....I have adjustable LCA's and PHB. I adjusted the PHB to center the rear....but what about the LCAs? I just put those wherever I needed to get the bolt through.....should I measure my wheelbase and make sure it's square? Also is there any advantages to making the LCA's shorter as opposed to longer? I know pinion angle is set by the torque arm...but I was wondering if I'm missing something. Also, would LCA reloc brackets make a big difference in the twisties? The rear feels very planted as is, but was just wondering if they would have a good application for me even though I don't launch at the 1/4 mile...just coming out of the start gate.

SIK02SS

iTrader: (11)

To decrease understeer: lower front tire pressures, raise rear pressures, more negative front camber, more positive rear camber, more front toe out, more rear toe in, more front wheel caster, softer front springs, harder rear springs, soften front sway bar, harden rear sway bar, use larger front tire section, use smaller rear tire section. If you have balast in the car move it rearward.

Don't do all at once though

98_TA_EMLC

Thanks for the response SIK02SS

Ok...tire pressures I can play with...what's funny is all the BMW guys are yelling at me saying I'm doing it backwards and should have more pressure in the front and less in the rear...but I know what I'm feeling and dropping the front more than the rear helped out. So I'll keep my train of thought there.

I pretty much don't have a choice on caster/camber/toe for the rear being solid axle...so I'll just exclude that and talk about the front.

I never understood caster until just now...basically it's the imaginary line between the top and bottom of the spindle. And you suggest more positive camber....I'm going off memory here from when I did my shocks/springs/uppermounts/swaybar....and i'm not sure how I can get more positive caster? I'll have to research how to get that on a F-body.

More negative front camber, yeah I kinda knew that...just wondering how I could achieve it? Can I get enough camber out of stock suspension other than what I've noted, or do I need adjustable lower a-arms?

More front toe out....never thought of it, but it makes sense. How much should I be looking for to balance with street driving?

Harden rear sway? So I should get a bigger rear sway bar then..good to know. Didn't know if it'd make a difference for the front.

Tires I'm stuck with for now.

Balast...not sure what that is...but I presume it's just weight distribution....i'll consider my battery that as that's what I want to move all the way back! haha.

cookba

iTrader: (10)

Hey Ken about time you came over here.

I think 32 front PSI is kinda high. I would imagine 25-28 to be ideal. And the LCA should be adjusted so the wheels sit perfectly centered between the fender front and back.

wrencher

iTrader: (2)

I had a similar problem that was somewhat present & couldn't really get rid of with tires or alignment.
So I started modify the suspension more.
I relocating the rear pan hard. Bring the roll center down, it helped .
I run my F-car on road courses though a little faster than auto-x but I still ran into that problem.
Seems like every time the panhard jacked the rear of the car it really liked to push.
The relocation worked some to prevent the jacking effect.

I now run a Fays watts link that pretty much took car of that problem.
+ helped out more because my car is low.
I know a watts is expensive, but it did the trick in being able to adjust the rear's roll center. The car plants & transitions so much better.

98_TA_EMLC

Adam???

I've been on here for a while...I use ls1tech for research and don't post much unless I need some help from the masses. I'm always looking at stuff here though and hideout is my everyday posting place.

98_TA_EMLC

Fays watts link...? I'm looking up what that is now.


--just looked it up----HOLY CRAP! That thing looks BEAST! $650 is way up there, but I'll def keep that in mind as something to build toward. I never thought a PHB relocation kit would help with suspension, I just thought it helped with clearance for the exhaust. Now I know...makes sense. So PHB reloc kit is worth it....but will that help with front understeer???

cookba

iTrader: (10)

Ya man. Strano sells the Fays and has a ton of info on it. You should definitely get Sam's rear sway bar, i think UMI sells swaybars as renamed Strano ones.

cookba

iTrader: (10)

just looked and UMI sells solid sway bars, where as Strano's are hollow.

98_TA_EMLC

Eric offered me his since he upgraded to the drag bar...but I'm strapped for cash as you know right now. I'm still in planning stages trying to figure out the effective way to go ya go.

cookba

iTrader: (10)

What bar is he offering? Ya im broke for a while too. sucks.

98_TA_EMLC

Spohn 1" rear sway.

wrencher

iTrader: (2)

You have to modify the relocation to make it adjustable in most cases.
You drill holes in them for adjustment. You have to move the brace tube from the inside of the bracket to the forward outside edge, but a small piece of 1/4" scrap plate and you're in business. But it's not that difficult to mod.

SIK02SS

iTrader: (11)

Correct, you want the brackets to make them level to the ground, but none of the brackets on the market do that unless you mod them or build them yourself. Otherwise best left stock angle.


Keep lowering your tire pressures and check your front alignment.

This was my last alignment on my 02 camaro:

Front:
Strano springs (550)
Koni SA- set 4.5 sweeps from full hard
Strano front sway bar

Rear:
Strano springs (150)
Koni SA- set ~1/8" turn from full soft
Strano rear bar


Camber: -1 L/R
Caster: +4.5 L/R
Toe: 1/32" In

After more seat time with that I was getting a little under-steer at turn in. Dropped tire pressures a pound or two, worked great. I can't remember on the Camaro, but on my Corvette you want as much caster as you can possibly get, which is right around 6

98_TA_EMLC

I'm still not finding a way to adjust the camber....

Andy1

Some good advice posted above. Careful of multiple changes all at once would be my input. If you have a test day, then map out your changes based on results and do it methodically, otherwise you won't learn much about what helps to resolve your problem. To me, it's a fundamental process that all chassis setup should follow. Now if I were to take a stab at what you might do next, I would probably add the rear sway bar, toe out the front, then mess with tire pressures. Personally I tend to not throw too much money at something until I identify a need or see a trend. That said however, the guys with Fbody specific AX experience are a good resource.

Andy1

98_TA_EMLC

Yeah I'm def with ya......right now I'm still trying to understand all of it...but when I get down to implementing changes, they will be one at a time...trying to feel what works and what doesn't.

SIK02SS

iTrader: (11)

Do you know what your alignment is now and how much camber you have? -1* camber is about maxed out for stock suspension fbody's, some people can get a little more, others can't quite get there. But for a dual purpose (street/track) car, -1 is plenty and if you drive on the streets a lot you may find you want less, or you'll be rotating tires more frequently

98_TA_EMLC

yeah sorry...I'm an idiot...I meant to type caster not camber....camber I understand.....

I haven't been able to find how to adjust caster...

SIK02SS

iTrader: (11)

Ohh, I should've figured that out

There are two adjustable bolts that hold the lower A-arm to the K-member, one vertical and one horizontal. you loosen the rear lower control arm bolt and slide it in, for lower caster, or out for higher caster. Caster can be a pain to align only because it consumes time. Reason being is that to measure caster, you have to do a caster sweep. This involves turning the wheels to the left 10degrees (i believe it's 10degrees anyways), then to the right 10degrees, then straight forward. So every time you do any adjustment to caster, you have to do another caster sweep to get the correct caster measurement.

Make sure to re-check your toe and camber as adjusting one thing usually screws the rest up Oh how I love alignments :o