Mythbuster: continuing project thread of my 1303 '75

[evilC]

Originally Posted by Wally

I hear you Rich; I run the 21mm spacers up front as well, but more because I couldn't fit the high ET wheels; this was before I ran the slimmer AVO struts. Now the spacers help to have full steering without hitting the inner fenders...

My theory is that the 944 spindles are bad for scrub radius. I think their tie rod ends are located further outwards then the originel VW 2-bolt spindles, which curve more towards the inner side of the car? Not sure though. Whats your take on my theory?

Wally, you are right that the tie rod ends are further out and this is because the steering arm is straighter i.e. more parallel than the 1303 (2 bolt one) I took off. This obviously affects the ackermann but I don't see the corrolation with the scrub radius? The bottom pivot of the 944 strut/stub axle also appears further outboard as my fabricated TCAs, although they match the 1303 pressed steel ones, had to use all the camber adjustment at the base of the strut and the inner bush to get a maximum -1.5* camber. If that is the case then it should move the point at which the kingpin angle i.e. the line through the top mount and the bottom ball joint strikes the ground plane than the VW stub axle.
I found that with 30mm spacers on the front, to fill the arches, the steering became very heavy (+ve scrub radius) and I now run without spacers for easier steering. I also now have inner wheel arch scrubbing with the 6" teledials with 195/65 tyres so I am going to try fitting those tyres to the 7" teledials that will increase the scrub radius but it might provide the compromise between the rubbing and heavy steering as well as stiffening the tyre sidewall.

Clive

[Wally]

Originally Posted by evilC

Wally, you are right that the tie rod ends are further out and this is because the steering arm is straighter i.e. more parallel than the 1303 (2 bolt one) I took off. This obviously affects the ackermann but I don't see the corrolation with the scrub radius?

Nah, that was my faulty take on what KPI angle was.. Your right that it doesn't matter for scrub, but will for ackermann principle (if I understand that correctly). Maybe the straighter steering arms on the 944 spindles are a more modern take on suspension geometry?

Anyways, do you think the stance of my front wheel is ok in the turn, or can it have some more negative camber in the corner under stress?
It just may be so that the tca presses the (topline) semi-urethane joint enough inbound that it reduces camber too much? If so, Lee's rose joint solution for the tca may help out?
In the picture, my front camber was -2 degrees in rest!