Motor mounts are not trick or sexy speed parts and we generally don’t give much thought to them, but if we did, we’d realize they’re pretty much the only things holding the engine and trans in the car. Usually we get stock replacements at the local parts store (often made in Korea or India and looking like they were hand-carved out of a chunk of rubber). Heck, we’ve even been known to “recycle” motor mounts every now and then, which is dirtball but we get away with it most of the time (except for the time we broke all three mounts in a Duster at the dragstrip and nearly dropped the engine out from under the car).
Get 470 lb-ft of torque twisting through a drivetrain, however, and you’ve got the makings of another exciting story like the Duster. We learned this again after recently swapping a brutal 383 small-block with a four-speed into a ’65 Biscayne. The first time we dumped the clutch, the air cleaner practically lifted the hood off the car, which was probably the only thing that kept the mount from breaking in half. Even part-throttle acceleration stretched the mount enough that the block came back down onto the crossmember in mid-shift with a disconcertingly loud thud—not a confidence builder when you’re trying to sort out a new engine combo.
The design of the early-style GM mount used from 1964-1972 (which has no backup interlock mechanism like the ’73-and-later clam-shell design) is very weak. It was so bad that even two-barrel 283/Powerglide cars regularly broke mounts, and GM designed a retrofit torque-strap arrangement to service all the warranty claims back when these cars were new. The torque strap itself is a pretty neat piece, consisting of a braided steel cable that wraps around the upper control arm and attaches to the manifold or alternator bracket. More about that later.
Performance Suspension Components stocks ultra-strong Energy Suspension polyurethane motor mounts for most popular GM applications, as well as Fox-body Mustangs and Chrysler transmission mounts. Polyurethane offers a good compromise between strength and comfort, which we can’t say about solid mounts. We got a set, dropped them in the car, and solved the problem.
