Street, Track and Autox Alignments

Lest anyone is interested, following is an e-mail I just sent to the fellow with whom I'll be corner balancing/aligning and indexing my camber plates Thursday AM.

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Ed -

Looking forward to setting-up car with you Thursday AM.

I'll be looking to set things up so I can change alignment for 3 different wheel/tire combinations:

Street: 245/40-17 front -- 265/40-17 rear
(rear PS2s taller by 0.65")

Track: 255/40-17 front -- 275/40-17 rear
(rear RA-1s taller by 0.66")

Autox: 245/35-18 front -- 285/30-18 rear
(rear V710s shorter by 0.05")

Since a bit (~ 1/16") of toe-in OK for street, 0 toe right for track and a bit of toe-out OK for autox (~ 1/16") -- and increased negative camber results in more toe-out -- would be great if we could index camber plates so won't require me to wrench on tie rods to adjust toe.

Thinking 'bout 2.5 to 2.75 camber for street, 3.0 to 3.25 for track and 3.5 to 3.75 for autox.

Other issue relates to different size tires.

Since height difference between street and track tires almost same (+ 0.65" v. + 0.66"), changing wheels/tires should have little effect on corner balance. (I could, however, lower car by approx. 0.15" at each corner which would slightly increase camber and decrease toe-in.)

Change to autox tires will, however, change things alot since the rear tires are so much shorter. To maintain balance, I could either raise rear by 0.35" (reducing rear camber), lower front 0.35" (increasing negative camber and adding toe-out) or do some combination of raising rear/lowering front.

BTW, I removed the TCK VVS springs at rear and re-installed the GC coilovers with Eibach springs. So height once again adjustable at each corner.

Also, Brian Downey slotted the rear subframe last week. Right now I have 2.1/2.2 negative camber and 1/16" total toe-in. Figure that anything between 2.2 degrees and 2.5 degrees should be fine. Brian tells me that it's mighty tight back there and than an unusually short 18mm open wrench is needed for rear alignment.

See you Thursday 8 AM.

Neil

Reply » Street, Track and Autox Alignments

Changing rear ride height by changing tire sidewall height doesn't change camber. Camber is changed when ride height is changed at the spring, changing the angle of the trailing arms.

Reply » Street, Track and Autox Alignments

Terry -

I understand that, but I will be needing to change spring height to maintain corner balance when changing from street or track tires to the V710s.

Neil

Reply » Street, Track and Autox Alignments

Looks good to me.

How are you going to get to -3.75 for auto-x? Offset control arm bushings and/or shim washers on the lower strut bolts? Or are you just going to slam the ride height for auto-x? With my ride height just under 23" in the front (bottom of rim to lip of fender), stock centered control arm bushings and the TC Kline plates at max negative camber and max caster, I'm just shy of -3.5 camber in the front.

I finished installing the TCK camber plates on Sunday, just in time to get 7" of snow on Monday. New street tires haven't even turned one revolution yet. I've got the springtime itch something fierce, and am counting the days 'til the first week of events. Car was on jackstands for 4 weeks; it's itching as much as I am.

Reply » Street, Track and Autox Alignments

Daniel -

Don't in fact know whether I can get 3.75 degrees, but will find out on Thursday. But by setting my Ground Control plates for max camber and lowering the car, I may get close.

I hear you about the itch. I get to scratch mine this weekend running the Grand Course (4.2 miles) at VIR with the Tarheel Chapter. Can't wait!

Neil

Reply » Street, Track and Autox Alignments

Once you start changing any spring heights you pretty much need to re corner balance. In that case, I would corner balance for the thing you do most, and live with it for other uses.

I wonder though how much difference even the amount of gas in the tank will make versus just changing things. Would be interesting to play with things with a set of scales.

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