rear suspension pick up point

[puma]

i tried to adjust the coilover on the car and realised that as soon as you lower the rear a little, the angle of the arms quickly becomes off compared to how level they were stock. I am afraid to throw the handling off with this bad geometry

Has anyone tried to modify the pick up points on the subframe to put the geometry back to where it was before?

any tips on doing this? I am no expert in calculating the roll center but it seems like it is going to be way off compared to stock which seems pretty good.

In front with a roll center corrrection ball joint it is pretty easy to correct but in the rear, the arms are way more complex.

[Turdinator]

Calculating and correcting the rear roll center is not straight forward from all reports. You can however get adjustable upper or lower control arms to correct your static camber and possibly improve the camber gain for your new height fairly easily.

[puma]

yeah camber and toe is not a problem, arm angle is though.

[dradernh]

Originally Posted by puma

Has anyone tried to modify the pick up points on the subframe to put the geometry back to where it was before?

any tips on doing this? I am no expert in calculating the roll center but it seems like it is going to be way off compared to stock which seems pretty good.

Because I don't know much about this sort of thing, I'm wondering if it's possible that you need a custom subframe designed to your specifications to solve this problem?

[wparsons]

You could modify the knuckle to lower the bottom pivot point, but the UCA would require moving the inner pivot higher which I believe would need a custom sub frame.

How much are you lowering it? Look for threads by RobiSpec (they'll be a bit older, he's been absent or banned for a while), he had a really low car (~3" lower IIRC) with good suspension geometry. He was making custom front LCA's but I can't remember what he was doing in the back.

[puma]

yeah i guess i wasn't clear enough, yeah i was talking about modifying the subframe. From what i can see, raising the toe arm point is pretty easy, the LCA is going to be a little harder since there would be some welding and grinding involved because of the curves but the hardest would be the UCA since if i move the pick up point higher, the UCA will now hit the frame of the car.

Unless someone has designed a UCA with a bigger curve than maybe it could work.

[puma]

Originally Posted by wparsons

You could modify the knuckle to lower the bottom pivot point, but the UCA would require moving the inner pivot higher which I believe would need a custom sub frame.

How much are you lowering it? Look for threads by RobiSpec (they'll be a bit older, he's been absent or banned for a while), he had a really low car (~3" lower IIRC) with good suspension geometry. He was making custom front LCA's but I can't remember what he was doing in the back.

yeah i have the racerx front lower control arm which are pretty much like the Robispec with an adjustable roll center ball joint.

I'll try to tsee if he talks about the rear.

[JDKane527]

Originally Posted by puma

yeah i have the racerx front lower control arm which are pretty much like the Robispec with an adjustable roll center ball joint.

I'll try to tsee if he talks about the rear.

IIRC, Robispec also has a solution for adjusting the roll center with his front lca.