If anything a psrs will prevent toe out under suspension loading, which may or may not counteract all that toe in. Additionally, a stock or poly front LCA bushing will exacerbate the toe in condition. Leading to a net toe in condition by preventing a stock rear lca bushing from squishing inwards to counteract some of this toe in.

The only other effect of the PSRS is that by pushing the wheel forward, you're moving the tie rod pickup point forward as well. Since the rack cannot move forward by the same amount, you are essentially (and ever so slightly) changing the toe in condition by forcing the tie rod to travel in a tighter arc. In a case of rear steer, it could force toe out as the arc shortens faster.




This is all assuming there is zero caster. Since we have plenty of positive caster (7.5 with psrs + vorslag plates) The hub will move rearwards during compression, essentially straightening out the arc of the tie rod. And in a rear steer hub (that's what we have), it will actually force a toe in condition. I don't know what the relationship is between the two, but i think there is honestly a NET tradeoff for the worse by adding caster (in regards to toe). Atleast that's what my hunch is telling me without measuring it.

The only way to tell for sure is to measure it. Good thing i have fully adjustable LCA's that i can measure this on in the coming weeks

 

Edited the post with the graphs to provide more info.

Also added two graphs with stock camber/steering axis inclination for refference.

 

picture of the setup i used to measure for those asking me questions. I think its pretty self explanitory

 

welded rear evo IX diff. lol

that is ultimate

 

For a rally car maybe

 

not even lol

 

Moving to suspension section. Also subscribed to learn more

 

Here's some parts **** for you guys.

Taking measurements tonight.

 

Race Fab?

 

Nope. Hispanic Fab.

These are longer than the racefab units.

 

Interested in where this goes. I had some interesting moments at my last track event (minus blowing up my engine) where the car felt great overall but some random moments where understeer came out of nowhere.

It was easily driven out by lifting a little to get the back end to rotate, little bit of counter steer and then throttle on, but that was slowing me down.

 

Well, the first prototypes didn't fit up like i wanted them to. I took measurements from a whiteline balljoint, and now it seems i should have just taken measurements from the upright in the first place :/

Hopefully i can get another set made within a week and take more measurements.

On a related note, anyone with an 8/9 that is converting to X arms, let me know. I have a tie rod adapter/sleeve that you'll need to finish a swap like that.

 

Seems like good info in here,I'm gonna sub so my noob *** can learn something.

 

Very nice info there , but I don't understand how, with this setup, you account for track width variations ?
See how a Longacre bump steer kit is made, it follows the front of the plate fixed at the hub, thus measuring only toe variations.

 

It doesn't matter what the track width is really. You establish a baseline at full droop, and meassure the change as you enter full compression. Then when you graph the toe chanve vs compression, you just choose the middle of the compression as your zero.