True Connections

This month we are going under the car to talk about rear ends and mounting hardware. The only rear end available for the 1964 Chevelle and El Camino was the 10 bolt, the bolts being counted are the bolts holding the rear cover on. The 10 bolt was the standard rear end from 1964 to 1972. If a beefier rear end was needed, the 12 bolt was used as an option from 1965 to 1972. All 10 bolts used an 8.2” ring gear diameter where the 12 bolts used an 8.875” ring gear. From 1964 to 1966 all Chevelle and El Camino rear ends used a flat coil mount pad and an oval bracket that bolts to the pad, holding the coil in place. From 1967 to 1972 GM changed the coil mount to a pilot or cone type, where the coil rides on a small cone without any type of attaching hardware. Also the 1968 to 1972 rear ends were 1” wider from drum to drum. From 1965 to 1972, all trailing arm and rear end mount bushings were the same, however, 1964 used a small bushing on the top ears of the rear end. In 1965, GM used extra strengthening ribs on the center section of the housing. These ribs were on the top of where the axle tube slides in, and go up towards the top of the housing as in the picture. This would also be the same as a 1965 Z-16 12 bolt.

Recently, 12 bolt rear ends were becoming difficult to find. Fortunately a company has emerged that can repair an existing housing or even build a new one. From the factory, the axle tubes were pressed into the center and were tack welded in place. It is always a good idea to have the housings checked for straightness in a jig and have the tubes fully welded. Along with that option we also can have these rear ends built with any combination of ring and pinion, new Eaton posi units, and forged axles. These completely new assemblies sure beat fighting the old, seized up junkyard rear ends that have seen 30+ years of hard service. We can also have these rear ends narrowed for added clearance on your street cruiser or for the 22 inch slicks under your pro street car.

Removing or installing the rear end in your car is fairly straight forward. The safe way to do it is with two people, one person on the floor jack, the other steadying the rear end. The vehicle should be supported by a pair of jack stands on the frame and the rear end supported by the floor jack. Start by unbolting the shocks from the rear end using an 11/16” wrench. Next remove the brake flex hose near the center of the frame. It is usually easiest to disconnect the hose from the front to rear hard line and leave the hose and axle lines with the rear end. Next you can lower the rear end a couple of inches so you can reach the four mounting bolts that attach the rear end to the trailing arms. A 3/4” box end wrench and a ratchet with a 3/4” socket usually work the best to remove the nuts and bolts. If you are working on a 64-66, now would also be a good time to remove the coil mount bracket mentioned above. To slide the bolts out of the trailing arms, raise or lower the floor jack in order to get the rear end at the height were tension on the bolt is minimal, or tap them out with a hammer and a punch. Once the bolts are out the rear end is free, so be careful lowering it to the ground. The installation is the reverse of this procedure. In the next issue, we will continue under the car and discuss the trailing arms and rear disc brake kits.