I totally agree. I thought I would have had to Machine the rack down at atleast within 5mm of the LCA bush.... it's no where near parallel to the tie rod end. The tie rods don't even sit parallel to the rack.
The rack is exactly 85mm from the centre of the centre of the LCA bushings. NOTE: I had a AE86 crossmember in my garage, and these had the rack about 115mm behind, not 85mm. I chose 85mm for a few reasons, one being it suited what I wanted for ackerman better, and secondly the KE20 steering knuckles (108mm modified) are considerably shorter than AE86 (132.5mm) and AE86 p/s ones (115, 120mmish- can't remember exactly. Also, this way it doesn't put too much strain on the KE20 knuckles and rack ends when turning with lots of lock.
The Rack is 6mm ABOVE the LCA inner pivot point. Saying that another way is the centre of the rack ends are 6mm higher from the ground than the centre of the LCA inner pivot points.
AE86 racks are 7mm higher. So very similar. In my 1/2 scale drawings, this measurement seemed to make the biggest difference to any bump steer.
Quote from Rob ( Successful KE20 R&P conversion )
"Did 2 attempts. first one I shortened the rack by how much closer the LCA inner pivot points are in my design, but it didn't work. A lot of bump steer, possibly more than a standard AE86. But it was toe in on compression, not toe out. Yuck.
Fitted a spare rack bar I had (standard length) and brilliant! No bumpsteer at all in compression and the in the first 25mm of droop. Then slight toe out with more droop. "
NOTE: Without the 40mm RCA's it would still have no bump steer in compression at all, nor at least for the first 65mm in droop. But this isn't much good for roll centres, and understeer would result in hard cornering (due to tire scrub, not bump steer obviously). Besides, a bit of extra ackerman on the inside wheel in turns never hurt... check out the competitive IP cars like the front line escorts
It does have 0 bump steer. It does need a 40mm RCA though and I need to wind more camber in by making a set of custom struts.... Have to remove the Cast hub with stub and reset the strut tube with more King pin inclination angle............![]()