Alignment settings & tires for racing

[VetteMed]

25' probably = 25 minutes, or 0.25 degree?

[lbszr]

Originally Posted by VetteMed

25' probably = 25 minutes, or 0.25 degree?

You got it, I forgot I had a calculator to that, it comes out to .41666667 degrees, and .1666666667 degrees on the front. Now we need somebody to figure that out to inches.

I don't have tools to measure toe in angle.

[jrtoffroad]

Thanks for the math Dynomite.

You're assuming it's 10' & 25' between the tire and the vehicles centerline. I thought it would be the angle between the two wheels, thus giving you 1/2 your calculation or a total toe-in of ~ 1/32 and 1/16 when measuring tire to tire.

Thoughts?

[lbszr]

[QUOTE=Dynomite;111767]Excellent point..I made some assumptions
That I am not sure about......normal Toe In is comparing distance between Front of tires (right and left tire) to distance between Rear of tires (right and left tire) on same axle.

It appears however since angles are used it is for the individual tire angle around vertical (Toe In) and the individual tire angle around longitudinal (Camber).

If you are correct (you prolly are) we end up with a Toe In Rear of 1/8 inch and Toe in Front of 1/16 inch (called a Racetrack Setup)
http://www.guldstrand.com/alignment.asp

lbszr did you buy these adjustable control arms and install them on a ZR1? It appears to me these would fit on my 91' ZR1 as well as my 91' Corvette with L98
http://www.guldstrand.com/scripts/pr...?idCategory=42

/QUOTE]

Thanks for figuring all that out, that makes my brain hurt.

I have not bought those control arms, just wish I would of when I had the front end apart. -2.5 Camber is all I can get, even with the offset bushings on the lower control arm. I believe the control arms would fit on both your 91's. It looks like any C4 88-96 would use the same one.

That confuses things with VBP measureing wheel to wheel, and GM's track specs measureing from the wheel to the centerline of the car for base settings. It looks like they both agree on the same measurement for the rear toe in, which is where I have mine set. The front toe in might give it a sluggish feeling on the turn in's, but make it stable on the straights. At 0.0 front toe in, mine is still good on the straights.

[VetteMed]

Those of you who are doing your own alignments, what equipment are you using to do so?

[batchman]

Just a note as it took many tries to get my wife's 88 Z51 car to behave. We wound up rear at -3 deg camber and 1/4" total toe-in on the rear end, a recipe passed down from a couple nat champ c4 autoxers. The car looks broken but the thing finally hooks - no more oversteer. It has to do with bump steer ie when the outside is under compression the toe changes dyamically. The 1/4" total toe-in sets it up to be correct for the max load in the corner, which in autox is an awful lot of your lap.

I backed away some from those settings due to much wider tire - 335 vs 295, ironically I've wound up using the same spring as her car but lighter sway bar. I still need to dial this in a little further but it's looking like -2.6 or so and maybe 3/16ths total toe in for rear traction in corner slightly prioritized over launch.

HTH,
- Jeff

[jrtoffroad]

Originally Posted by VetteMed

Those of you who are doing your own alignments, what equipment are you using to do so?

I'd also be curious to hear what everyone is using. I did see this article on completing an autocross alignment for a C4 corvette:

http://www.flintcorvetteclub.com/ima...0%28Web%29.pdf

[lbszr]

Originally Posted by VetteMed

Those of you who are doing your own alignments, what equipment are you using to do so?

I've seen brackets online for under 200$.

Or you can do a set up like this, http://wiki.seloc.org/a/Geo_Alignment_Rig_(Home_Made) (I don't know how to fix it, but add a parenthesis to the end of the address) I use pvc pipes with fishing string and bungee cord it to the tail pipes and lower front spoiler. Laser level for toe, and no calculations since I set it to 0.0. Harbor Freight digital angle measure was 20 or 30$, and it's been checked to +-.15 degree. I put it on four wheel dollys for easy settling, or it could be rolled, or grease plates. Setting up the strings takes the longest. Probably 12 hours to get it the first time. About 3 hours now. The castor can be checked with string also, but wasn't easy.

[lbszr]

Originally Posted by jrtoffroad

I'd also be curious to hear what everyone is using. I did see this article on completing an autocross alignment for a C4 corvette:

http://www.flintcorvetteclub.com/ima...0%28Web%29.pdf

Looks like a good article. If the string setup is not secured to the car though. It would not be centered anymore when the car is moved or needs jacked up and resettled to adjust the rear toe, and double check after tightening toe rods.

[jrtoffroad]

Alright, got the car aligned yesterday:

FRONT
Camber: -1.5 -1.6
Caster: 5.5 5.6
Toe in: 0 0


REAR
Camber: -1.2 -1.2
Toe in: 1/8 total (1/16 per wheel)

We noticed a fair difference with me in or out of the car, so these settings were achieved with me in the car. Not as much front camber as I was hoping for, but I may try grinding down the spacers, should get me pretty close to 2 deg.

Another Autocross this weekend, can't wait to see how it feels!

QUESTION:
I played around with the rear bolts to level the rear. My car does NOT have a noticeable lean, but I was trying to get it perfect and now have 1 bolt set maybe 1 inch shorter than the other (really didn't make much of a difference in the suspension height). Is there any issue with this? Is this the proper way to dial in the rear suspension, or should I just set both bolts the same?

Thanks!
Jordan