today i did an allignment to my '77 (fully modded as you might know..and now with tubular a-arms and hoosier tires) giving:

6 grades positive caster...(this high caster seems to give a pretty firm drive around bends, even if i didnt go that fast on a short and twisty road yet)...toe front is at 1 grade neg and camber at 1/8 positive.

do you have comments?

 

I just picked my new VB tubular upper arms off the front door step. I have the mono spring all ready installed just need to bolt on the uppers and head for the alignment shop. I was just reading you want a minimum of 4 degrees and 6 degrees is better yet. I'll shoot for 6 and see what happens. Have you road tested yours yet? I'm curious to hear what yours is like.

 

caster provides straight line stability and better wheel straightening (return to center). it also affects camber gain.

I would set the camber slightly negative, why do you have it positive?

 

sorry t/t, i meant to say camber 1/8 negative...

 

Caster is good.......

Toe is out? 1 degree (silly American asking here)? How stiff are your front springs?

Positive camber in front? Why? You said Hoosier tires, which ones (bias, radial)? You should go for about 1.2-1.5 negative camber in front with bias ply tires. I'm thinking your camber may have been sacrificed for that high caster value. I myself would rather have the camber and sacrifice some caster.

 

gordomn, with the tubular a-arms you'll get 6 degrees pretty easy...i thought it was too much but i've also red somewhere that 6 would be better then 3 or 4 degrees, if you could get there...and the a-arm make it posible. so i went for 6, you'll need to start with quite a few shims on the front side of the arm and one for the rear, and from there see what happen.
the front wheels seem to be well anchored on the tarmac...

 

nop, camber is neg, hoosiers are the sports car dot bias, the front is veeery hard (front transverse monospring at its hardest position and QA1 shocks at 90% hardest position), caster is 6 degrees. the car rides firm like a rock.

 

Gordonm and Panic,

Check out a couple of Corvette alignment specs for racing.

The following suggestions are for race day (assuming you drive your car to the event) and not for every day driving.

First off, I don't understand alignment figures given in grades, maybe that is just a Eureopen system but in the US we work in Degrees. So you'll have to do the conversions!

Camber
Shoot for about 1.5 degrees NEGATIVE camber on the front tires (tire leans out at the bottom and in at the top).

Rear camber should be around .75 - 1 degree NEGATIVE.

Caster:
If you have power steering, you can set the front caster toward the max factory setting as this will allow the front wheels to self-center when you let go of the steering wheel. Good for short courses with tight turns.

With manual steering, you have to balance excessive caster with steering effort. The more self-centering you put in (caster), the harder it is to turn the wheel.

Toe:

Front toe can be from 1/16 inch to 1/8 inch toe-IN. The more toe-IN, the more straight line stability. (You hit a bump and the car returns to a straight line by itself). The closer you can run to zero the better off you are as your tire has less slip angle in a turn and provides more grip. On my SCCA racer, I actually ran toe-OUT to reduce the slip angle of the front tires.

Rear toe: You are best off starting at 1/8th inch toe-IN. The rear tires will want to toe-OUT under acceleration so more here is better.

See what you think about that and don't be afraid to modify your settings. Camber gauges are relatively inexpensive (look at the Mitchell gauge) and you can use the string method to set toe.

Good luck.

Bob

 

Without a tire temp gauge the camber setting is guess work. If you have all new bushing and ball joints, also depending on how the tire rolls under I have found the .64 degrees negative works fine on my Vette.

Toe - I have set to zero. Since I drive my car on the street, i never liked the feel of even 1/8th inch toe out

 

bob, thanks for the input.
camber front well negative, i have mine at 1 degree.
caster positive to 6 degrees, the get well planted on the tarmec, you're right harder to turn but i dont mind, it's a sweet sacrifice (specially with PS.. )
front toe, i have it at 0.14 neg.

 

i'd go to 1 or 2 degree negative, if you really want it to handle.

 

sorry turtle, i made a mistake, i intended to say negative...

 

This is all great info but I can't go to the alignment rack every time I want to make a change. I understand how to set the toe and can set the camber with a gauge but how would you set the castor without an alignment machine?

 

You could probably set the caster once and be done with it. Camber and toe changes would be independent of caster, as long as the camber changes are with an equal number and thickness of shims on both control arm studs.

 

So castor should be set on an alignment machine. Yes I understand the camber being equal number of shims on both studs.

 

One question here. You say put more shims on the front side of the A arm. This will pull the ball joint towards the front which gives you less positive Castor. To me I would think more shims on the rear stud which will pull the ball joint to the rear of the car giving more positive Castor. Am I right?

 

... . actually it worked the other way round...i checked it with a very sofisticated electronic sistem and a guy who knew this job and he confirmed me that was the way...adding shims at the front end of the arm will give you more caster.

maybe T/T wants to chime in and explain? i'm not an expert here, i'm only good to try the results on the tarmac..

 

Shims should be added to the rear stud for positive caster.

 

That is what I thought also.

 

i have to re-check on this tomorrow, i have to be frank, i'm pretty confused right now...