Polyurethane bushings: An ideal cure for clunking?

After running a couple of track days and classic car tours with our 1967 Shelby GT350, we detected some clunking and decided that we’d better get the car up on a lift. Surprise, after just a few thousand miles, the original-style, rubber anti-roll bar and strut rod bushings had ripped and deteriorated.

We were loathe to face the same clunk in short order, so we sought something better than rubber. In the past we have had good luck with Energy Suspension’s polyurethane bushings, so we checked their catalog. Thankfully they offer a variety of parts for these early Mustangs, including our needed bushings. We had a choice of color, too: stealthy black or can’t-miss red. Parts houses like Summit Racing offer these bushings, and everything we used cost less than $50. Call it an easy, inexpensive handling upgrade.

These firmer urethane bushings don’t deflect nearly as much as soft rubber pieces. As the strut rod bushings face constant abuse, a stiffer-than-stock option should withstand more pounding and aid in handling, especially on bumpy roads.

The polyurethane anti-roll bar bushings also improve handling by removing the dead spot sometimes encountered with rubber pieces. Theoretically these stiffer bushings compromise ride quality, but we have found Energy’s Hyper-Flex material to still be very comfortable for street use despite the increase in performance.

Installation simply required freeing the old bushings and then popping on the new ones. To avoid a trip back to the alignment shop, we marked the location of the strut rod bushings. Total time for this entire job is less than an hour–even less if you have a lift.

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Comments

wspohn Dork
10/8/18 3:42 p.m.

A good thing about rubber bushes - they are a press fit into the A arm socket and once in there the motion of the A arm as the suspension goes up and down is absorbed by the flex in the rubber bush (best bushes are often metelatsic with rubber bonded to a metal inner).

A bad thing about the various plastic bushes you can use is that they all turn inside the A arm big end that encompasses them as well as on the pivot that holds the A arm in the car. Inevitable result is wear and plastic bush ovality.

So yes, plastic will make the car feel like new - but only for awhile, because they actually wear faster than a captive rubber or metelastic composite bush.

Tim Suddard Publisher
10/8/18 9:44 p.m.

wspohn

I have been using Polyurethane bushings on project cars for over 30 years and have not had wear and harshness issues. The key is to choose a name brand and not some inferior off brand products. I just took this Shelby on our 800 mile Orange Blossom Tour and it drove great.

andrewhorning New Reader
10/8/18 10:47 p.m.

I had an Alfa Milano 3.0 that ran poly bushings for over 30K of its 170K miles. The car rusted danged-near in half, while the only rotten bushings were the rubber engine and transmission mounts.
But...
The roll bar and upper control arm bushings did squeak pretty badly with their rotation. I was bad about greasing (OK, and other maintenance too, apparently), but still...they do tend to squeak.

Jerry From LA SuperDork
10/12/18 7:40 p.m.

Tim:

Hopefully you chose the stealthy black ones.

rustriddenB
12/28/20 10:24 a.m.

Got a question re; the poly bushings. We have a 2003 Mustang, V6. When purchased about 4 years ago in Arizona, It ran well but handled like a drift car! Not a secure feeling. I took it to a local Ford dealer who said that among other things (of course) it need rear control arm busings. They suggetsed poly after markets which when done, helped immensly. After returing to NJ with the car (flat towed behind our motor home) I had the front struts done. BTW, the rear shocks were also done in AZ.

I find that even adjusting my tire pressures at the settings reccommended by my SCCA racing but to 32 rear and 28 front it did handle better, but not great. Loose in turns and squirelly.

The question...should the front sway bar bushes be replaced with poly as well as the struts busings?

And would adding a rear GT sway bar help?