When it comes to upgrading the suspension of your classic Chevelle—or any muscle car for that matter—the number of options is pretty much unlimited. It can range from bolting on a set of aftermarket control arms, spindles and lowering springs to a performance coilover conversion kit, larger sway bars, or even going all-in with a complete aftermarket chassis.
But if you aren’t quite ready to jump into any of those suspension upgrades, you can still get better handling performance by merely replacing the original rubber body mount bushings with a fresh set of urethane bushings. In fact, if you do plan on making suspension upgrades, it makes even more sense to go the urethane route.
Brian Cox, a member of our team here at Chevy High Performance owns a ’67 Chevelle that has a stockish suspension, sporting aftermarket springs, shocks, and sway bars. Brian’s Chevelle was still outfitted with the original 50-year-old rubber body mount bushings, which on their best day offered sloppy handling, undesirable vibrations during highway driving, and strange noises and squeaks when Brian pulled the car in or out of his driveway—all common symptoms associated with cracked and worn rubber body mount bushings. It was definitely time to upgrade.
We went to Prothane Motion Control in Placentia, California, for their 1965-’67 Chevelle, El Camino, Monte Carlo Urethane Body Mount Kit. Launched in 1991 with fewer than 100 products, Prothane now makes more than 5,000 kits and parts ranging from engine mounts, transmission mounts, leaf spring pads, control arm bushings, strut arms, shocks, and more for domestic and import vehicles—all proudly made in the USA.
While rubber components offer a soft ride for a limited amount of time, they tend to deteriorate rather rapidly from the extended exposure to the elements, which contributes to premature failure, resulting in a “spongy” ride and a reduction of ride quality and performance handling. Prothane’s urethane bushings are impervious to gas and oil, are stronger than rubber, and will offer a better overall performance driving experience, especially in a vintage 1960’s muscle car.
All these benefits are just what we were looking for, and the longevity is very appealing, as we don’t plan on doing this exercise again anytime soon. As Prothane puts it, “Rubber will rot, urethane will not.”
So let’s dig into this ride and get rid of those vintage rubber bushings. CHP
1. Chevy High Performance account manager Brian Cox’s ’67 Chevelle was rocking the same body bushings it came with from the factory so the car’s less-than-stellar ride was starting to wear on him. We brought the car into the Chevy High Performance tech center where installation technician Chris Arriero handled the wrenching.
2. Prothane Motion Control’s 1965-’67 Chevelle body mount kit (PN 7-121) comes with all the new urethane body bushings, sleeves, and washers and are a direct replacement for the original, cracked, 50-year-old rubber bushings. They come in red or black; there is no difference in quality between the two colors—red just photographs better.
3. Arriero got started by hitting all the body mounts with good dose of spray lubricant to help loosen the stubborn nuts and bolts. Every bit helps when you are dealing with nuts that haven’t turned in over 50 years. Once done with the spray process, all of the body mount bolts were slightly loosened before starting the replacement process.
4. Arriero got started at the core support by removing mount #1 (Prothane numbers all the mount locations in the instructions to ensure the correct bushings are used) with a 5/8-inch socket. Note, this is the only mount with the slim bottom bushing. We removed and replaced one mount at a time (one on each side) to keep the body square to the subframe.
5. The stock bolts were a little too short for the new body mounts so we called an audible and went with Grade 8 bolts that were 1/4-inch longer to help make installation easier.
6. We applied a little antiseize to each bolt for good measure.
7. At this point, with all the body mount bushings loose, Arriero used a pole jack and a length of 2x4 to carefully raise the body on one side. You’ll have to further loosen the body mount bolts on the side you are working on in order to raise the body enough to remove the old bushings and slide the new ones into place. For safety purposes, be sure the chassis remains fully supported, in our case with the lift.
8. Due to the stock #2 body mount having the top washer and a portion of the sleeve integrated as one piece, we had to raise the body a little higher in order to get it out over the top of the subframe. This photo illustrates how long the original body mount sleeve is compared to the new Prothane bushing that will replace it. Again, it’s important you slowly lift the body to make sure the door gaps don’t tweak too much and that the frame is still fully supported.
9. As you can see here, the stock #2 bushing’s washer and rubber are integrated together (black arrow), making it more difficult to remove. We yanked on it for a while before realizing it wasn’t coming out without a fight and the help of a cutting disc.
10. The new Prothane bushing slides in between the body and subframe. It went in a whole lot easier than getting the stock piece out.
11. As you go through replacing all the bushings, just hand-tighten each one until all are in place.
12. Moving on to body mount #3. Keep in mind this body mount bushing is the one with the larger bore. It’s important to use the correct mounts in the designated positions per the supplied instructions. Bushings #2, #3, and #4 can all go in at the same time at this point. Again, be sure to hand-tighten for now. We’ll torque them all down at the same time as to not upset the door and fender gaps.
13. Raising the body at the rear of the car enabled us to get bushings #5, #6, and #7 installed.
14. Just when we thought it was smooth sailing, the body mount bushing (#5) near the rear upper shock mount also has an integrated washer and inner sleeve like #2.
15. It was not possible to raise the body high enough to remove the body bushing so Arriero did some cutting on the bottom part of the sleeve. That worked.
16. And here it is after. This shows how much was cut off in order to get that nasty thing out.
17. It was a little tight, but we were able to get in the new Prothane body mount bushing and hand-tighten it for now.
18. Compared to the #2 and #5 bushings, replacing the rest were drama free.
19. With all the new bushings installed, Arriero carefully lowered the body back in place and torqued each bushing bolt to 40 ft-lb or when the bushing just begins to bulge, per the Prothane instructions. It’s a good idea to start from the middle of the car and work your way to the front and rear bushings. Prothane also suggests re-torquing the bolts once you hit the 1,000-mile mark.
Before: Brian tells us the car had annoying squeaks and rattles, and every bump in the road upset the car, making it feel loose and unpredictable, which wasn’t very safe. Taking freeway onramps at any sort of speed was dicey due to the sloppy handling characteristics. Basically, the thrill was gone.
After: Brian informed us that when he drove the car off the lift he noticed an immediate improvement in stability, and when he pulled out of the driveway the car felt way more solid. Gone were the annoying squeaks and unexplainable noises and the car was more in tune with the road, offering instant driver feedback. The unpredictable nature of the car at highway speed was also absent and he was much more confident stepping on the gas pedal and taking corners more aggressively. Quicker steering response was also noticed, and as Brian put it, “This car is just way more fun to drive now.”