Don Terrill’s Speed-Talk

Had to pull the k-frame on my E-body Mopar for frame rail repairs, so there's no better time if I want to upgrade the front suspension. I'm looking at aftermarket upper control arms that have different features and bushing types, depending upon the manufacturer.

If I rule out using Heim joints due to this being a street/strip car, the options come down to polyurethane or Delrin bushings. I've read that the poly-types create additional resistance to movement ("stiction") vs Delrin. Delrin, being a harder material, is less forgiving of control arm mounts having any geometry issues, which can result in binding during motion.

I don't know if the type of grease used with polyurethane affects this or not. Some of the arms that come with polyurethane bushings have grease fittings, but not all. Only the high-end multi-adjustable UCAs with Delrin have grease fittings, but my interest is in the fixed-geometry design.

Any feedback from your experiences or knowledge of pros and cons for bushing materials is appreciated. It's also an option to keep the OEM UCAs with the current rubber bushings, if this upgrade isn't going to make a noticeable improvement in how easily the front suspension rises off the line. Thanks - Brad

Brad , I had fancy chrome moly tubular control arms w/ heim joints on the front of my strip only car . After less than 100 runs the lower arms showed a noticeable kink in it . Off they came and replaced with stock arms but what I did was . Looked over the bushings very closely and found the rubber stuck out past the inner steel bolt sleeve . I took a razor knife and trimmed the rubber back enough to allow the sleeve to stick out . Then took a file and removed the serrated teeth off the end of the sleeve so the were smooth . 're assembled with new gr.8 bolts and all metal lock nuts . Tightened the bolts till the just touched the framed and didn't cause any bind to the control arm and the arm would fall free from it own weight . Far from the need to use a bar to get leverage on it to move as they were stock . Hope this helps you Dan
Sorry just saw you were talking upper arms . Site won't let my delete post

I'll have to look at the OEM-style UCA bushings and see if that same approach to lower their resistance to movement can be applied. Thx

Not exactly relevant but I gotta say, man do I love Delrin. I've used it for feedscrew nuts and handwheel bushings in machinery rebuilds/upgrades. It can be set up with negative clearance on moving/rotating parts and still runs smooth as butter and lasts nearly forever.