IC Improvement Options

[83Stage1]

A few years back it seemed the hot ticket for improving your instant center was lowering the bottom mount on the axle. I can't remember the last time I've seen an ad for that style kit anymore, but there's a number of kits offered for raising the upper mounts.

Has changing the uppers proven to be better? Easier?

What are your experiences & opinions on which is better?


My Regal is set up with a Ford 9". I'm assuming that precludes me from using any of the common bolt-on upper kits, especially with the upper mounts being home-made.

I'm thinking about cutting off the uppers and recreating them taller. I should still get all the advantages of the better IC the kits create, plus its cheap, simple, and should allow me to keep my existing upper & lower control arms (already have them boxed out with new bushings).

What angle do the upper-mount kits change your control arms to in comparison to the lowers or to the frame? I think comparing angles is going to be my best bet for determining where to place the new mounts.


Just out of curiousity - on the lower-mount kits, do they use longer control arms, or just move the bolt hole forward? If its just moved forward, wouldn't that tend to increase the axle's tendency to "wrap up" like you think of with leafs?

[Jeff Kitchen]

The lower control arms you are referring to were made by Southside Machine. I don't know if they are in business anymore or not. You're right, I haven't seen them around much lately. I never used their set-up, but I know some folks had good luck, some bad.

From a design standpoint, when you lower the rear of the lower arm, you not only move the IC back, but you raise it higher above the ground. A higher IC tends to be more violent than a lower IC. When you raise the rear of the upper arm you keep the IC lower.

Most kits raise the rear of the upper arm about 3". This shouldn't be too hard to accomplish with a Ford 9". While you're at it, put another hole just below that one. The lower hole will work better for consistency, but it will slow your 60' times a little.

Have fun.

[otter]

I just got my new Jegs catalog in the mail a couple days ago and they had the Jegs style SSM rear lower bars for the Skylarks for $149.99 And they had the kit for raising the uppers for $124.99. From a strictly cost standpoint I will probably go with the later choice but then I got to thinking, in a street vehicle, do I want my lower control arms even closer to the ground? There's alot of stuff on the streets and if I ran over something or got a flat, would I mangle my rear arms? This makes my decision to get the kit to change the upper mount even more convincing.
I am sure both products are great just my opinion.