Increase caster ... how?
Thread Starter
Drifting
Joined: Dec 2015
Posts: 1,319
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From: Dalton, Ma
Increase caster ... how?
I don't have the specs in front of me but if I remember correctly my front guy could only squeeze 2 degrees of caster last time I had the front end aligned. [after I added Borgenson Power Steering]
Recently there have been threads on how to increase road feel with the new Borgenson set up.
On my car I've decided to try to add caster first as a remedy.
Question, Can anybody tell me how much caster they were able to add with the Moog offset upper control arm shafts? I've read you will only gain a degree or so and I have to wonder if that is enough. I've read where you want to have 4-6 degrees. Is there a way to add even MORE caster?
If I am visualizing this correctly in my minds eye, You need to ADD shims correct? And you are limited by how long the studs [bolts] are where the shims go...Can to swap out those bolts for longer ones allowing more shims?
As always, Thanks for the anticipated advice.
Recently there have been threads on how to increase road feel with the new Borgenson set up.
On my car I've decided to try to add caster first as a remedy.
Question, Can anybody tell me how much caster they were able to add with the Moog offset upper control arm shafts? I've read you will only gain a degree or so and I have to wonder if that is enough. I've read where you want to have 4-6 degrees. Is there a way to add even MORE caster?
If I am visualizing this correctly in my minds eye, You need to ADD shims correct? And you are limited by how long the studs [bolts] are where the shims go...Can to swap out those bolts for longer ones allowing more shims?
As always, Thanks for the anticipated advice.
Drifting<br><img src="/forums/images/ranks/2k-3k.gif" border="0">
Joined: Aug 2016
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From: Grosse Pointe, MI
I slotted the holes in the cross bar the upper a-arm attaches to. That allows it to slide rearward which yields more caster. Can't remember how much I gained, but it was easy to do.
Patrick
Patrick
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Generally the offset shafts are used to assist with camber issues. The frames tend to flex inward and the camber ends up being negative. That said....using the offset shafts will allow you to start putting some shims back in there so you can at least get things headed the right direction.
Caster comes from tilting the top of the spindle rearward. So after setting camber, you can shuffle shims between the two studs to increase caster while maintaining camber.
But as you mentioned...you can only go so far. To increase it substantially you'll need to either modify the shafts or change upper arms. Some folks will slot the stud holes so the arm can be pushed backwards. That actually works well. Some leave it like that...others make little spacers to fill in the slotted area after the arm is positioned rearward.
I took the easier way out and just replaced the upped arms. It allowed me to get 6.5* positive caster and they came with offset shafts to assist with camber.
JIM
Caster comes from tilting the top of the spindle rearward. So after setting camber, you can shuffle shims between the two studs to increase caster while maintaining camber.
But as you mentioned...you can only go so far. To increase it substantially you'll need to either modify the shafts or change upper arms. Some folks will slot the stud holes so the arm can be pushed backwards. That actually works well. Some leave it like that...others make little spacers to fill in the slotted area after the arm is positioned rearward.
I took the easier way out and just replaced the upped arms. It allowed me to get 6.5* positive caster and they came with offset shafts to assist with camber.
JIM
Safety Car
Joined: Mar 2009
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From: Corpus Christi, TX
I have offset arms on my car for camber, but just to add caster, you may want to slot the holes on the shafts if it's more than a degree or two. Using a slot filler is a really good idea, if for no other reason than the caster won't change if the nuts loosen a bit. Trying to add in 4 or 5 degrees of caster with offset arms isn't a good idea. If the shaft is offset to increase caster, then the axis of the shaft will get rotated from close to parallel with the frame. Too much rotation and the front end will do weird things over bumps and road camber changes, namely that the caster will change a lot when the upper control arm moves. Will give you squirrely steering.
Melting Slicks
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From: merritt island fl
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If you increase the negative camber a bit, say to -1/2 degrees, you can get more caster with your stock set-up. I got 3-3/4 degrees caster that way. Car handles and rides fine.
Melting Slicks
Joined: Jul 2011
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From: Bornem
I am at 5.5° caster with the offset upper A arm shafts. Compromise is minus 1° Camber and the A arm rotated backwards, that does not look too healthy (see previous post #5). I will slot the shaft this winter for even more camber and less rotation of the A-arm. 
Melting Slicks
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From: Bornem
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My frame is not bent or collapsed inward, and I have a good stack of shims between the frame and the upper a-arm shaft to achieve this alignment. The rear shim stack is thick enough that I replaced the rear bolts with longer grade-8 bolts so I could maintain full thread engagement with the long factory nuts. Replacing the rear bolts took some trial and error, and can be accomplished with minimal disassembly. The forward bolt can remain loosened, on the car, while the rear bolt is replaced (fished under the upper a-arm and through the frame hole). My factory bolts did not have any knurled section, and I used sockets on both bolt and nut to torque the new bolts. The bolt head friction holds it in place.