Segond56

Hi, over the winter I just bought my first corvette, which is a C5 Z06 race car. I wanted to know what would be a good starting point for alignment for the car. Typically in the past I have run 3 degs. of neg. camber, as much caster as possible up front and a little toe out up front. Rear was say around 2 deg. neg camber and some toe in. (This was on another race car, just as an example) Any thoughts and feedback would help, I will be running 295's up front and 315's in the rear hoosier R6's and the car has coilovers. Thanks.

Sam

froggy47

Seems good place to start, take tire temps & go from there.

Bills Z06

Take a look at these numbers:

http://www.pfadtracing.com/blog/wp-c...-9.12.2011.pdf

Good luck!

Bill

geerookie

What kind of bushings do you have in the upper and lower control arms?
That will determine the best starting place.

FYI, Corvettes have enough over heating issues on power steering fluid so running high caster will only help that get worse.

justkickin

Not to thread jack, but can you explain how high caster leads to more overheating of PS fluid? I run a lot of caster and this might explain why my PS fluid doesn't last long. Should caster be reduced then? Or just replace fluid more often?

geerookie

The higher the caster the more the wheels try to center themselves and the faster you go the more the affect. This makes it harder to turn thus the PS pump has to work harder.

There are 3 things you can do to a stock system to help cool it down and make it last.
1st - Synthetic PS fluid, this is a must.
2nd - BIG cooler. mines 13"x8" never had an issue with over heating and I run Hoosier A 18x315's on the front with original '99 rack and pump.
3rd - better flow restrictor tuned to your needs. See Turn One

SoDiezl350

The recommended alignment specs by PFADT call out mild toe in on both front and rear. Searching the forums though reveals quite a few people prefer a little toe out on the front. There are also those who advocate no toe in the front. Would be nice to hear some insight.

Segond56

I have a turn one power steering pump plus a cooler for the power steering system installed, so I would imagine I would be ok. The Pfadt specs look good, the only thing I might change from their listing is a little toe out in the front. Toe out helps turn in at the begining of the turn. You don't need much, usually from 1/16th to 1/8th toe out is where I have run in the past.

Also the bushings are solid all the way around.

geerookie

As long as you are using synthetic fluid I wouldn't worry about cooling with that setup.

What does solid bushings mean?

Delrin, Poly, blocks of aluminum, steel, spherical bearings, T1 rubber?

Segond56

bushings are derlin and running Royal purple for all fluids.

geerookie

Delrin doesn't give near as much as poly or rubber.

Depending on whether you are running slicks or DOT tires will determine the proper starting place for camber.

DOT's will require about 1/2* more IMHO.

Slicks, good starting place -2* camber +/- .5* I run about -1.5* on sphericals.

DOT I find that -2.5* works well at most tracks but some -2* works better. Mostly depends on how much banking there is in particular corners.

If you have Poly bushings add -1* to those numbers and if you are on stock or T1 then add 1.5* - 2*

1/8" total toe in on rear and 1/8" total toe out on front.

About 3* - 4* caster max. This will make the steering feel pretty light but that is because GM's pump and rack are WAY OVER assisted! A little tweaking on the Magnasteer can take most of that away and the Turn One pump and restrictor are a big help.

taken19

Geerookie, can you clarify something?

Are your baseline recommended camber settings (-2 degrees) with delrin bushings on slicks? Then add another one degree with poly bushings (-3 degrees)?

geerookie

Correct. With Full slicks. Hoosier R's and A's are not full slicks.

This is assuming you have stock travel of your suspension and you have minimized bump steer front and rear.

RogerT

Some toe-out on the front tires is helpful for low speed turn-in on tight courses. However, toe-out on the front will lean toward high speed instability. Something most people forget about or do not know about is Ackerman steering geometry is built into the front steering through the design of the steering arms and provides built-in toe-out on turns. Use discretion when adding more toe-out to the front steering geometry.

Under no circumstance do you ever dial in any toe-out on the rear wheels.
This creates high-speed instability.

This is an area of our sport where a little knowledge can be dangerous. Consult with someone who is knowledgeable and listen to them.

Hope this helps.

Roger T

froggy47

The only time I ever use front toe out is for autox never track and then it's very little. It will eat up your front tires if street driven (not to mention tram lining/ trolly tracking).

taken19

Thank you for the info.

davidfarmer

I don't think you can get "excessive" castor to the point of causing PS issues...or at least I've never seen it. I think a lot of steering issues come down to driving style. If you tend to constantly make corrections, or "saw" at the wheel, you will over-work the system. As you improve, and consistently go straight to your ideal steering input, you take a lot of pressure off of the system.

keep it simple, slow/simple hand movements, remember "slow is fast"

Anywhere from 2-3deg front camber, 1.25-2.0 rear camber, and you are fine for both wear and grip. Further dialing in should be done based on tire temps and wear (depending on your goals). A setup for fastest times will not yield longest lift, and vice versa.

Today's A6 tires love excessive camber and really low pressures, but they will not survive forever under those conditions.