Caster and wheel clearence

[409novaman]

I'm in the market for tubular control arms for the front of my 1973 Nova. My question revolves around the caster choices offered by the manufacturers.
I notice that some of the manufactures offer caster increase only in the upper control arms, some only on the lower arm and others split the caster increase between both.
Does this make a difference to me and will the wheel stay centered in the wheel well for tire clearance with one system over another? Should I mix and match the arms?
My intention with the car is for modern handling, not competition.

[68Formula]

Caster can definitely impact clearances and centering of wheel in the wheel well, which is why some split the difference between the upper and lower arms. In some applications, it could actually cause contact between the tire and the rear edge of the fender when the wheels is turned. Depends on how much caster, tire diameter, subframe alignment, resting height and suspension travel, etc.

[Chad-1stGen]

Caster is the angle of the upper ball join in relation to the lower ball joint. On a your Nova caster is obtained by shimming the upper control arm to angle the upper ball joint back (aka adding shims to the rear upper control arm bolt between the frame and cross shaft). Buying upper control arms with "built in caster" reduces the amount of shims needed and/or increases the amount of obtainable caster.

If you are looking to go over 5* of caster then having a lower arm with built in caster (aka lower ball joint positioned further forward) can be helpful to keep the wheel centered in the wheel well.

It's usually best to stay with matched parts but yes you could theoretically use different brand upper and lower arms.

[Beantown]

I have a 74, lowered 3 inches, stock lower arms, Global west uppers, 18x8.5 wheels with 225/40 tires. The alignment is set at 6 degrees positive caster, 1.5 negative camber and I have zero clearance issues. The arms were the last thing I did and what a difference it made. At high speed it was very twitchy and would wander out of the lane pretty quick. It's straight as an arrow now and way better when pushing it into a turn. On a windy road at a decent speed i did not have confidence in the car, now I can push it much harder with more confidence in the handling. Hope this helps

[409novaman]

Caster can definitely impact clearances and centering of wheel in the wheel well, which is why some split the difference between the upper and lower arms. In some applications, it could actually cause contact between the tire and the rear edge of the fender when the wheels is turned. Depends on how much caster, tire diameter, subframe alignment, resting height and suspension travel, etc.
Thank you for your answer.

- - - Updated - - -


Caster is the angle of the upper ball join in relation to the lower ball joint. On a your Nova caster is obtained by shimming the upper control arm to angle the upper ball joint back (aka adding shims to the rear upper control arm bolt between the frame and cross shaft). Buying upper control arms with "built in caster" reduces the amount of shims needed and/or increases the amount of obtainable caster.

If you are looking to go over 5* of caster then having a lower arm with built in caster (aka lower ball joint positioned further forward) can be helpful to keep the wheel centered in the wheel well.

It's usually best to stay with matched parts but yes you could theoretically use different brand upper and lower arms.
Thank you for the answer.

[409novaman]

I have a 74, lowered 3 inches, stock lower arms, Global west uppers, 18x8.5 wheels with 225/40 tires. The alignment is set at 6 degrees positive caster, 1.5 negative camber and I have zero clearance issues. The arms were the last thing I did and what a difference it made. At high speed it was very twitchy and would wander out of the lane pretty quick. It's straight as an arrow now and way better when pushing it into a turn. On a windy road at a decent speed i did not have confidence in the car, now I can push it much harder with more confidence in the handling. Hope this helps
So the difference of the wheel/tire position in the wheel-well must be very small, if you can fit that size tire. I had no idea how much the actual position of the wheel/tire would change front to back.
Thank you.

[Beantown]

My pleasure. Glad I could help. I was worried when I put the control arms on and thought I'd have to at least remove an inner fender bolt or 2, glad I didn't have to.