1963 Olds Cruise Control Head Restoration

Buick, Olds and Cadillac all used a version of this control head from about 1957 to 1963. It sat on the left hand wing of the wrap around dash. You would dial in the speed you want to go and push the button at the bottom to lock it in, all mechanical set-up. The dial rotates a small pinion gear that causes a rack gear to pull a cable (similar to a lawn mower throttle cable) clamped to the extension on the right side of this picture. The cable went through the firewall to a control box in the engine bay that did the work with vacuum power.

From the three units I have restored, these heads fail in one or all of three ways: 1. The rack gear (long white part) breaks off where the cable engages, 2. The pinion gear splits through the center hole across a smaller hole used to align the gear, or, 3. The extension housing breaks off at the transition between the rack portion and the extension. The metal spindle shown passes through the housing and engages the pinion gear while the larger flange mounts the control dial.

Here is the broken rack gear and the new one I machined from aluminum. You can see the tail on the right is missing from the original piece. There is a groove and a through hole into which the control cable is captured. The original appears to be nylon which, while self lubricating, ages and becomes brittle in about 10 years. For those who want to know, the teeth are 20 degree pressure angle at 0.949" pitch ( a very odd size indeed!)

After milling the rack gear blank from 1/4" X 1/4" 6061-T6 aluminum bar stock to 0.204" X 0.156", I made up this simple holding fixture from MDF. The rack blank is trapped in a groove between two halves of the fixture. This is the set-up in my Sherline mill. The cutter was turned from O-1 oil hardening steel and hardened by heating to red-orange hot and quenching in oil. Then the cutting edge was honed to razor sharp. Once I touched off on the part for location, the teeth were cut in 5 steps for depth of 0.077", then progressed downwards for the pitch spacing of 0.096". Fourteen teeth were cut. Total time for making one rack was about 2 hours.

The final operation in this restoration was to add a reinforcement to the cable extension where it breaks off from the main housing. This was milled from a 6061-T6 aluminum angle 1/2" X 0.060". Cyanoacrylate glue attaches the "splint" permanently. Luckily this one did not need the pinion gear replaced.

Once completely assembled, the restored components are hidden behind the dashboard and so are not visable to an inspection. This restores the function without taking away points from judging in case the car is to be shown competitively.

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