R Mackow

I've got 1.5 deg front and 1 deg rear negative camber.

I want a toe setting that will be easy to drive on the street but help w/auotx or track days. i've done a slight toe out front and toe in rear. What are the limits I should stay within and avoid rapid tire wear. I also see that some shops set toe in inches and other in degrees...how do I compare one to the other? I can do the trigonometry on my TI calculator if it's just that easy to convert degrees to inches, but at what point from the horizontal center line of the hub is the toe/offset measured?

What caster setting is Ok. Do I go with a 6-7 degrees and right side about ahalf degree more to offset road crown? Right now I have about 6.0 deg caster and the car feels "nervous". It tracks OK on a smooth road but wants to go left or right if I hit a small bump or rut.

I also just put Z51 sway bars on, but have a standard base suspension spring...wasn''t sure if a stiffer sway bar would make a difference in the feel of the wheel.

thehammer69

I set my car up based on Sam Strano's recommendation. He basically said not to worry about Castor as the Corvette has plenty as is. The nervousnous you are feeling is most likely from the "toe out" you have up front. Just toe it in a hair until you have dialed out however much nervousness you want to lose.

Hammer

TedDBere

There really is no compromise for toe. Any toe will wear tires on the street. Camber and caster have little effect on wear, particularly if you drive "spiritedly" on the street.

Front bar will improve power-down on corner exit and have no effect on "feel of the wheel".

Increased positive caster will make the car want to go straight and make the wheel harder to turn, but will increase camber in turns which is a good thing.

Good luck and have fun.

VetteDrmr

I don't have enough time on the street to comment on tire wear, but I recently changed my alignment to go with 0.1" toe out front, 0.1" toe in rear. Old alignment was basically 0 toe front and rear.

Our first autocross I found the car better in the slalom, less understeer (wasn't bad before, but it's noticeably better), and throttle oversteer seemed less than before (but it's just one event).

I also got my first FTD ever at that event! So, I'm a happy camper so far!

HTH, and have a good one,
Mike

TommyBoy72

I've been running 0 toe in the front with good results. Yes I wear out the inner tire edge due to the front camber but its not as dramatic. Also, I run more rear toe in but stock bars (Z06). I did run a larger front bar but found I prefer the car without it. The car is prep'd for SS.

To convert toe from inches to degrees:

http://www.smartracingproducts.com/p...conversion.pdf

http://www.smartracingproducts.com/p...e_settings.pdf

MungoZ06

Rich ...
You'll want = caster for autox ... just gotta deal with the road twitches ...
Talked to Jack P at Summit last Sat. He has a 0 toe but his shop marked his right tie rod and showed him how much to turn it to set some toe out for autox (or track).

Dave W of CVCC does this as well.
I haven't collaborated on settings for mine "yet" ... thinking about it.

DennyM

gkmccready

How does increasing roll stiffness, removing front grip, help get power-down on corner exit? I'm not trying to be rude, just trying to understand.

JaGsC5

I'm just here to see what the competition is doing. Just leave it stock, you'll be fine.

TedDBere

Increasing the stiffness of a sway bar will reduce grip at the end of the car you have added it to and will increase grip at the other end of the car.

While I'm not an engineer, it was explained to me that the stiffer sway bar will result in faster weight transfer at the end of the car that the bar is on, while reducing body roll. Some reduced body roll also occurs at the other end of the car, without the faster weight transfer. Allowing for better contact patches with slower weight transfer. I believe this is what is refered to as uncoupling the weight transfer.

Stiffening the front bar sticks the rear. If you want to play with the effects of different suspension changes buy Forza2 for X-Box 360 and have at it. You'll learn a ton by playing with the suspension settings of different cars.

Here's a good tuning guide to help with your suspension: http://www.wtrscca.org/tech.htm

gkmccready

I had known about the decreased grip with a stiffer sway bar, but I have never heard of that increasing grip at the other end.

I always thought that was in the drivers head because they simply got braver because jumping in to the gas harder, earlier now got them understeer rather than oversteer.

If stiffening the front gave grip to the rear and vice versa wouldn't we all run crazy stiff swaybars? What you're describing as uncoupling the weight transfer sounds like you could achieve the same thing by reducing the amount of rear bar, and keeping the front bar. There-by creating the same relative differential of roll stiffness, but without taking the grip away from the front?

I understand that's not an option for stock class autox cars...

TommyBoy72

The larger front bar will lift the inside front as the outside front is compressed thus lowering the inside rear (think about how corner balancing works). This gives more weight on the inside rear and the ability for it to provide more traction. Compared to most of you, I race at 5000ft to 7500ft above sea level in most of our venues and the power/traction isn't an issue. Not using the larger front bar prevents the balance (turn-in and steady state) issues you have to over come while not having to run crazy rear toe-in to be able to get on the gas early. Those at sea level would probably not run my setup as successfully.

gkmccready

So, right turn. Weight to LF, bar tries to keep weight on RF. Weight wants to go to LR, too. So what does the front bar do? I guess it keeps some weight on the RF, which puts less weight on the LR which means the RR keeps more weight and therefore more traction?

Still seems like a smaller rear bar that doesn't try to lift the RR when the weight shifts to the LR would be more effective without doinking with the weight transfer and ultimate grip up front?

TedDBere

Ever see T1 bars? They are crazy big!

When you stiffen the bar at one end it loosens that end...to a point. It also reduces camber changes caused by roll and increases grip too, by keeping the contact patch optimal. If you can make other changes in the suspension to counter the faster weight shift then you get a net gain in traction, ie sticker tires, wider tires, more camber for better contact patches in the turns, and shock changes. Less roll maintains a more stable, low, CG too.

The game is to get the most grip you can get with the most stable and balanced car. Go with as big a bar you can use without over loosening that end by overcoming the other grip variables.

In stock class autox no one has ever been able to get the T1 front bars to work because the car will push too much. You have to heavy trail brake to get a T1 bar car to rotate and not push since you can't use the rear T1 bars to improve the traction on the front. FWIW.

It's a game.

TommyBoy72

Somewhat wrong and somewhat right.

Right Turn:

LF gets loaded. RR gets light.

Think of your washing machine trying to level the legs. If you shorten one corner the opposite corner is light and it will see-saw between them right?

Bar dynamically shortens the RF. This adds more weight to LF and RR.

This makes the washing machine not see-saw anymore.

You are correct that rear bar lifts the RR as the LR takes some load. No bar would be better I would think but I'm not that knowledgeable to make that statement and understand what no bar at all would do.


I should add I used the T1 bars for awhile and yes they are huge. I never believe I could make the front with a stock rear though the sizes are not that dramatically different.

TedDBere

Remember the opposite applies too.

If you soften the rear bar, the back gets tighter...and the front becomes looser!

Donn Malwick

I ran -1.0 neg camber on all four wheels with +8.0 caster on both fronts & ZERO toe in front with .06 toe in on each side which is .12 total toe in on rear.
This was on my 01 Vert with F55 & the Kumho MX wore even across & the car handled much better in Autocross than with the -0.20 it had from the factory.

fatbillybob

by chance did someone lower the car and adjust the rear camber without readjusting the rear toe? Those two common adjustments result in toe out on the rear and that makes for a really nervous car which I think gets worse as you put the power down exiting a corner.