Adjustable A-Arm Fabrication

Do you know where that A arm came from, I do not recognize it as an OEM Pantera part. You might want to check the Pantera master parts book. The front pivot point on the arm connects to the front tube at a pretty extreme angle so I expect that you will not be able to connect the Johnny joint directly to the tube. Why is stock A arm not working for you?

Mike

Mike, you are correct - it's an image of an extended A-arm that I used for convenience. I understand what you are saying about the angle on the front tube. That could be difficult work. My mocked up plan conveniently minimizes the angled tube. My car has too much camber from being lowered and thus I need either extended A-arms or adjustable A-arms.

Hi Steve,
Do you still have youe engine test stand for sale?
I would like to buy it.
Let me know,
Jerry in Lake Forest
jerrypantera4003@earthlink.net
cell 949 584-1492

Jerry, sorry, the engine test stand already has a new owner. On the up side, it is not very difficult to duplicate. Please let me know if you want some details.

Steve,

I looked into fabricating extended/adjustable a-arms and would have done it exactly the way you propose, although I was looking at using heims for even more flexibility, as they can be spaced fore or aft and/or the two sides can be unequal length setting to alter caster.

The heims provide a bit more freedom on the angle issue too.

The downside to either is that they are not truly adjustable as you have to dismantle the suspension to turn the Johny joint in or out, but once you have it where you want your aren't likely to need to adjust it again anyway.

I say go for it....

Julian

Because the two pivoting ends in the illustrated a-arm seem to be running at quite different angles, you will need a heim-joint in at least one of the pivots. Johnny-joints are simply encapsulated urethane (or other material) bushings with very limited capability for misalignment. At those points, a pair of adjusters' only advantage might be for setting toe- which on the Pantera suspension is done with very similar parts and shims already on the lower a-arms. And since a bent tube (between the pivots) has little stiffness, I would triangulate the 'brace' up to the ball-joint end with a pair of gussets.
As for fabricating adjustable upper a-arms from scratch, if I was to do such a thing, I would use stock-type chassis pivot ends (with urethane bushings) and make the connection to the upright the multi-angle/pivoting/adjustable part. Advantages are, you have one part to adjust, and if a heim joint to added there in the fashion McLaren did on their racers, camber adjustment can be done without disassembling anything at all; lock-nuts hold the adjustment.
By using a cheap & readily available tapered stud in the stock upright to adapt a heim, no changes there are needed either, and the same suppliers have heim-joint seals reasonably priced. Varying the height of the heim to the upright on a stud with shims can allow changes to the instant-center in the rear, which will yield changes in handling- maybe good, maybe not. Each car is a little different.

Agreed if starting from scratch it's easier to have the heim replace the balljoint, that is the system I have on both cars. In modyfing stock, IMO the inboasrd is easier.

BTW, not sure if you were implying so, but it is not possible to alter toe with upper a-arm, no matter how much adjustment you have.

Julian

My idea is that the two pivoting ends are in parallel. It is poorly depicted that way in the mock up. In any case, it looks like I'm in over my head. It is probably more practical to simply get extended A-arms from a vendor or private party. It is now clear to me that shims can be used to get the proper camber with the longer arms while retaining my existing toe setting.

quote:

Originally posted by SteveBuchanan:
Jerry, sorry, the engine test stand already has a new owner. On the up side, it is not very difficult to duplicate. Please let me know if you want some details.

Thank You Steve,
All the construction details would be awesome. I have my pantera radiator to use
and the rest hopefully will come together with your design.
Thanks Again,
Jerry

Jerry, I sent you a PM. Thanks, Steve