cumbercr

I just finished rebuilding the front suspension and steering rack on my 85. I did the rebuild because the car wandered and pulled on uneven surfaces. Over the last 5 years my tires had worn perfectly. I installed new poly bushings, ball joints, tie rods and had the steering rack rebuilt by Turn One. I did not replace the upper control arm bushings. They looked to be OK and I didn't want to deal with pressing new bushings in.

I had a local shop do the alignment. The Tech checked caster and camber and left them as is. He adjusted the toe.

Actual LF Camber -0.1 Factory +0.3 to +1.3
Actual RF Camber -0.2

Actual LF Caster +4.9 Factory +2.3 to +3.8
Actual RF Caster +4.7

Actual LF Toe -0.01 Factory -0.10 to +0.10
Actual RF Toe +0.01

I'm curious what others are setting caster and camber to. Should I go with positive camber like the factory specs? And do I need to reduce caster? By the way, this is a street car that I may do some autocross with.

DanielRicany

Hi, the caster and camber numbers here look like they are designed for performance. These will give you better stability going straight and around corners. Excellent for racing. But, the camber may wear your tires a little faster than it would if it was factory. Your toe is good, and this should be a stiffer ride, and have more stable handling. If you would like to have them to factory go back and make him do it. But these are the specs that I would prefer.

Good luck!

Forgot to mention, what happened with the rear toe and camber results? Did he not do the rear? You always do the rear FIRST in an alignment. The rear alignment specs, if off, can cause a pull too.

cumbercr

Thanks for the reply. The Tech also felt the caster and camber would be better for performance. So I had him leave them as is. He did check the rear. The numbers are below. I had him leave the rear alone because I plan on doing a complete rebuild of the rear very soon.

Actual LR Camber +0.20 Factory -0.10 to +0.90
Actual RR Camber -0.30

Actual LR Toe +0.09 Factory -0.10 to +0.10
Actual RR Toe -0.04

JackDidley

Those numbers look good. I like 6* caster, to make it go very straight at high speed.

383vett

Your target camber numbers are wack. There hasn't been a Corvette built that asks for positive camber settings front or rear.

cumbercr

Those numbers came right out of my FSM. They also came up on the alignment shop's computer. The Tech said he didn't understand why they would specify positive camber. That's why I'm asking the question.

DanielRicany

Okay looks good for handling and corners. It will give your better performance than from the factory, although the ride will be much stiffer and you will definitely feel the bumps more. Tires may have camber wear a little, but that's the price you pay. Other than that, feel free to drive like a maniac, because this car will take it.

cumbercr

With the poly bushings it does feel a little stiffer. The car is a Z51, so it has stiffer springs, 30mm front sway bar and closer ratio steering. I'm looking forward to trying it on autocross. The car will do fine, it's the driver that worries me.

383vett

Something is not right. Check out these numbers...

http://tech.corvettecentral.com/2011...ignment-specs/

DanielRicany

It's the alignment that will make it feel stiffer. Your caster angles will add better stability, tighter steering, and a stiffer ride. This is because the shock is now more towards the passenger compartment, and with every bump, because of positive caster, is aimed towards the passenger compartment. Negative caster will add looser steering, better steering wheel return-ability, and softer ride because the shock is directed towards the engine bay.

cumbercr

I like these targets better. I'm holding on to this. I don't know what to say about the factory specs. Just cause something's written down don't make it right.

I think for my use, advanced street may be the best specs.

383vett

If you go with positive camber, your car will look like a 70s VW bug and squeal around corners.

cumbercr

Thanks for explaining caster. I was having trouble understanding what effect the geometry has on handling. It's not intuitive!

Midnight 85

I'm guessing 383vette gave you the advanced street specs from VB&P's catalog. I had the shop use those specs on my car and I really like the difference it made. One thing to keep in mind and I know this is going to stir the pot but NEVER and I mean NEVER believe all you read in the fsm! I just got done straightening out a wiring issue because the '85 fsm was wrong in at least a dozen different areas. Gordon Killebrew told GM the book was wrong many times and GM ignored him.

vader86

I used the advanced street specs from VBP on the 86. It didn't make a huge difference but I did like the change. Without checking, the specs 383vette gave look the same.

cumbercr

Thanks all for the replies. I feel enlightened on the subject. My next step is to completely rebuild the rear suspension with poly bushings, replace the half shaft u-joints and service the differential. I'm looking for a reputable shop to adjust the ring and pinion gear lash.

Once I've finished the rear, I'll have the front and rear aligned to the advanced street specs 383Vette provided. This has been educational.

Vader,
Did you put the engine Jim built into the 88?

PLRX

Give this to your alignment shop.

84wannabezo6

Dick Guldstrand also has a spec sheet you might want to check out

pkincy

Can we get 3 deg negative with our stock suspension geometry? I forget as my only real autox Corvette was a 94 Coupe that I ran for about a year. I do remember more negative than I could get on a stock height F Body, but I don't remember 3 degree's negative. That would be wonderful at an autox and would quickly kill your tires on the street.

I don't remember ever running more than 2 deg negative on my race car and that could have gotten more and that had zero street miles.

BTW, I like the specs you have now. A good mix of performance and OK for street use.

Hot Rod Roy

Sorry, Daniel, but I can't agree with this analysis. Changing the caster in a Corvette won't affect the angle of the shock. Negative caster will cause the car to wander, and the steering wheel won't return to center on its own. The +5 degrees caster recommended by several people is an excellent suggestion.

If you want to test this negative caster idea, try backing up fast, turn the steering wheel a bit, then take your hands off the wheel! (Be ready to step on the brakes!!)