Few things go more unnoticed than body mounts on body-on-frame Chevy classics like Chevelles, Impalas, Bel Airs, and Biscaynes. For one thing, it is not always known how to replace them or how often they should be replaced. Most of us don't even notice they are missing until we're nosing around underneath.
Body mounts are rubber donuts located between the body and frame to isolate road boom and engine/powertrain harmonics. They aren't necessarily an item that wears out, but instead a component that deteriorates with time and quietly vanishes without notice.
We were out at Joel Rode's Hot Rod Specialties shop in Upland, California, when we noticed his 1967 Chevelle up in the air with a body on frame void of the rubber body mounts. We looked to Energy Suspension for replacement polyurethane body mounts.
Body mounts live or die depending upon the environment in which they live. In Los Angeles, we enjoy rust-free automobiles unless, of course, you live near the ocean. The salty air by the sea takes a toll on steel quickly. For the rest of us who live inland in the desert, soft parts such as plastic and rubber deteriorate from ozone, dryness, and excessive heat. Weatherstripping and rubber mounts wither away to nothingness.
The toughest part about changing body mounts is getting the body elevated off the chassis enough to install new mounts. Another potential pitfall is damaged or stripped-out body mount bolt holes, which will have to be fixed if you want the body to remain attached to the frame.
Joel has the good fortune of a lift on which to replace body mounts. For the rest of you with garages, concrete floors, and jack stands; body mounts can still be replaced given good 2-ton jack stands at all four corners. There are 12 body mounts on the 1966-'67 Chevelle, which is pretty much the rule across all Chevrolet body-on-frame vehicles. All are simple to get to except those behind the front wheelwells. Also tricky to get to are the rear wheelwell mounts located above the rear axle. CHP
The body should be lifted at boxed frame locations and not at flat stamped sheetmetal surfaces, which can buckle under the load. The aft body should be lifted here where the body employs a boxed frame at the fuel tank. We've placed a 2x4 between the screw jack and the body, lifting carefully just enough to create a 1-inch gap between the body and frame. This should give us enough room to install the bushings.
For the perimeter body mounts, you can lift the body at the rocker panels, which are very strong and can handle the load.
Our Chevelle's rubber mounts are completely gone. They broke down and deteriorated over time in the desert harshness.
Here's the body mount location over the rear axle at the shock mounts. These mounts didn't survive either. Installing the new Energy Suspension urethane mounts will be easy given raising the body approximately 1-inch to get the mounts in.
Each Energy Suspension body mount kit comes with everything you will need to replace all 12 body mounts. Although we're doing a Chevelle, body mount replacement is universal. It is performed the same way on all Chevrolet body-on-frame models.
Each mount looks like this, with two mounts, two flat washers, a sleeve, and attachment hardware. These mounts are also available in red.
With the body elevated off the frame, you have room for mount installation. Use a common screwdriver to center the mount.
With the body mount properly located, you're ready for the frame mount. Make sure this guy is perfectly centered. The frame mount sports a raised "male" surface, which fits into the framerail. This, coupled with the sleeve, keeps the mount from moving around.
The bolt, flat washer, and frame mount are properly centered and good to go. Use chassis lube on the bolt threads, which will prevent corrosion. Torque the bolt until the outside diameter is flush with the washer and sporting a slight bulge.
The body mounts beneath the trunk area are next. Follow the same procedure here. You may locate the body mount halves any way you like, either with the male half (with the raised surface) on top or on the bottom.
The male half is installed on the bottom here at the frame. Lube the bolt threads and torque until a bulge is noted in the outer wall.
As with the rest, torque the body mount bolt using lubricant on the bolt threads. Tighten until the outer walls begin to bulge.
The aft body mounts located behind the fuel tank can be tricky to get to because it is tight back there. You're going to need at least an inch between the body and frame in order to slip this mount in place.
The male half is installed next along with corresponding hardware. Although the task of body mount replacement seems overwhelming, it can be accomplished over a single day.