Bump steer question
The term is literally "near zero bump steer". For most applications less than .030" is acceptable, for racing applications it's usually under .010". But neither of those are actually "0". Or 0.000”, because that’s what that would mean. Like when Ehrenberg talked about measuring bump steer with a piece of plywood and a piano hinge for the Green Brick article. Must be fancy plywood to be true within .010”.
And of course the application matters. Reducing the bump steer is a lot harder if you have more suspension travel like with a street car. And there are always trade offs. Like running 0° camber with radial tires on the street is dumb. I'd rather have .030" of bump steer with -.5° camber than "0" bump steer with 0° camber, because if you have to go around corners you want your tire patch to stay parallel to the ground on the outside where the weight is, and 0° camber doesn't do that.
Caster for narrow front tires like used in drag racing is different too. A couple degrees positive is all you need to keep you from feeling like you're driving a shopping cart. Put 275's up front and it's not enough, adding positive caster improves stability. Just look at the alignment specs for a modern car. A Challenger SRT8 calls for -.5° to -1.6° camber, and between +8° to +10° caster. Yeah, +10° caster. Yes, I understand that is not the same suspension design and it is designed to have those numbers. But the wide front tires are why those numbers are that high (they aren't specific to the Challenger, look at a modern mustang, or any other RWD modern car for that matter).
So no, your drag set up is not ideal for the street. Not enough negative camber. Barely enough positive caster, dependent on what your tires are. And who knows what your ride height looks like, or if your torsion bars can keep your suspension off the bump stops with your average pot hole. If you're driving to Dairy Queen maybe that works, if you're going for a rip up the mountain in the twisty's it's piss poor.
Regardless, bump steer is a moving target. Just saying "the caster is too high" is silly. Yes, caster changes the bump steer. So does the ride height. So does the camber setting. So can things like adjustable strut rods, repaired LCA's and K-frames, aftermarket UCA's, etc, etc, etc. The OP has made a lot of changes to his car from stock, and that's fine. He doesn't have to set the stock alignment to get his bump steer under control, he needs to investigate further, make sure nothing is broken/cracked/binding or installed incorrectly, and go from there.
The term is literally "near zero bump steer". For most applications less than .030" is acceptable, for racing applications it's usually under .010". But neither of those are actually "0". Or 0.000”, because that’s what that would mean. Like when Ehrenberg talked about measuring bump steer with a piece of plywood and a piano hinge for the Green Brick article. Must be fancy plywood to be true within .010”.
And of course the application matters. Reducing the bump steer is a lot harder if you have more suspension travel like with a street car. And there are always trade offs. Like running 0° camber with radial tires on the street is dumb. I'd rather have .030" of bump steer with -.5° camber than "0" bump steer with 0° camber, because if you have to go around corners you want your tire patch to stay parallel to the ground on the outside where the weight is, and 0° camber doesn't do that.
Caster for narrow front tires like used in drag racing is different too. A couple degrees positive is all you need to keep you from feeling like you're driving a shopping cart. Put 275's up front and it's not enough, adding positive caster improves stability. Just look at the alignment specs for a modern car. A Challenger SRT8 calls for -.5° to -1.6° camber, and between +8° to +10° caster. Yeah, +10° caster. Yes, I understand that is not the same suspension design and it is designed to have those numbers. But the wide front tires are why those numbers are that high (they aren't specific to the Challenger, look at a modern mustang, or any other RWD modern car for that matter).
So no, your drag set up is not ideal for the street. Not enough negative camber. Barely enough positive caster, dependent on what your tires are. And who knows what your ride height looks like, or if your torsion bars can keep your suspension off the bump stops with your average pot hole. If you're driving to Dairy Queen maybe that works, if you're going for a rip up the mountain in the twisty's it's piss poor.
Regardless, bump steer is a moving target. Just saying "the caster is too high" is silly. Yes, caster changes the bump steer. So does the ride height. So does the camber setting. So can things like adjustable strut rods, repaired LCA's and K-frames, aftermarket UCA's, etc, etc, etc. The OP has made a lot of changes to his car from stock, and that's fine. He doesn't have to set the stock alignment to get his bump steer under control, he needs to investigate further, make sure nothing is broken/cracked/binding or installed incorrectly, and go from there.
