Do Caster Shims Help or Hurt when Autocrossing?

[Ozzie]

They increase caster. They increase steering effort, thus slowing steering. What is your experience or what do you think?

[Ghia Nut]

I know that they are severely stressing out the connection/coupling between the steering box and steering rod on my ghia. This a bad thing???

[Southernbug]

Hey Oz!

Here is a great link describing the effects of caster angle on a race suspension:

http://www.240edge.com/performance/tuning-caster.html

I agree with you that increased caster angle has no real benifit on an autocross car because of the relatively low speeds. Usually caster angle increases are to help improve high speed stability.

However on a VW front suspension that has been lowered with "Adjusters" I believe that the caster shims on the lower torsion tubes helps maintain proper geometry. On VW front suspension that have been lowered using dropped spindles the caster shims truly add positive caster and can cause heavier steering feel.

Thanks the way I think about it.

Rock on!
Shane

[Marc]

The VW front suspension undergoes ZERO camber change due to wheel travel - If you want the outside tire to stay flat on the ground under a mere 2° of body roll, it'll have to have 2° of negative camber statically.
Caster induces camber as the wheels are turned, however (this is explained in the article Shane cited), and you'd want as much as you had the physical strength to manage. Obviously if you put in so much that the driver can't handle it overall performance is going to suffer, but otherwise it WILL improve cornering.

[gcorrado]

that was a great article and this is a great point.
i, for one, had been confused about this before and now it's crystal clear.

increased caster improves high speed stability
AND corning at all speeds

it does so only at the cost steering effort
and tire wear (if you go to far).

for my money that's a GREAT trade.

[Ozzie]

The VW front suspension undergoes ZERO camber change due to wheel travel.

Good to know.

Caster induces camber as the wheels are turned.

Also good to know. Easy to see once you look at it analytically. A little explanation helps too.
Nice link Shane. Things were explained in a way even I could understand.
I'll keep the shims in.
Does this mean you are building a 240 also? AX or drift?

[Theo]

I found that the dynamic camber changes due to the increased caster really helped for slow tight autocross corners. I'm also running a 'quick steering' kit. It takes some work to turn but it does turn fast.

Once I get up to speed, say over 35 mph, it isn't so hard to crank the wheel.

T