Resurrecting an old, existing thread on this topic ...

Anyone have experience with the offset upper control arm shafts for their A-Body? (See for example, Moog # K5250.) They are offered as a solution to providing 1.5 degrees more camber / caster than stock shafts. Here's a short video on the topic >


'70 Cutlass conv't. hasn't had an alignment in decades. The driver's side does have several shims front and back. I rebuilt the intermediate steering shaft, installed new 12.7 quick ratio steering gear and rag joint, pitman arm, center link, inner & outer tie rods, idler arm, upper and lower ball joints and shocks. The front springs are 30+ years old (could easily replace those as well). While the steering is quite good, I was trying to avoid going for an alignment only to find that they can't get enough caster / camber for a good performance alignment.

Thanks in advance.

 

The offset arms allow more CAMBER adjustment. They do nothing for CASTER adjustment. You change caster with differential shim thickness under the front and rear bolts that hold the shaft to the frame. The offset doesn't change the amount of differential adjustment available. Vendors who claim otherwise are lying or uninformed. And frankly, I've never had an issue with achieving the required camber adjustment, so I've never understood the need for these.

 

I moved this to its own thread instead of resurrecting an old one. The real question is what settings are you looking for in a performance alignment?

 

Thanks, as always, for your reply Joe.

I understand. In a situation where one needs more shims to add more + camber (due to sag or whatever), it's my understanding that one would have to add more shims to both front and rear bolts to increase + camber. Then, if you also want more + caster, even more shims are needed in the rear shaft bolt. You could need a whole lot of shims on that back bolt.

I currently have four shims (about 1/2" - 9/16" total thickness) on the driver's side shaft, both front and rear bolts. I want to achieve more + caster as I understand it will help steering feel and return-to-center on turns.

 

Thanks Eric. Looking to add + caster. I have some specs in my file, I'd have to retrieve to get them.

 

The easiest way (though not the cheapest) is to install a pair of aftermarket upper control arms with more caster built into them. The only problem with these is they won’t look stock.

 

Yes, thanks, I’m aware of after-market appearance and tubular control arms. I really want to keep it all stock (even though the upper arm is covered). If I was going that way, I’d install a rack & pinion too.

 

Since Eric moved the thread to its own, this more recent prior relevant thread popped up > https://classicoldsmobile.com/forums...-shaft-141266/

 

Yes, that is correct. Dial in as much caster as you can. Unfortunately the basic design of the A-body front suspension limits this. It is possible to modify the upper control arms to move the upper ball joint rearward. The other problem is the undesirable camber change with suspension travel. Tall ball joints or tall spindles helps with this, but then you may need shorter upper control arms to properly set the alignment.

 

Thank you Joe.

I understand your point. The offset shaft would appear to only provide + camber (unless it’s installed opposite/flipped for - camber). It would then only reduce the amount of shims needed to create + camber.

With all of the steering & suspension changes as well as the passage of time, it’s probably best that I leave it alone for now and get an alignment check first. (Adding 15” wheels as well.) See where the alignment numbers are, how much + camber is needed (if any), and then how much + caster can be added.