Help with an AMC Gremlin

August 1, 2009 | By Richard Prince


I’m building a 1972 AMC Gremlin “X” with an AMC 401 cid engine and a T10 4-speed transmission and I have two questions regarding the project.

First, I would like to put a serpentine belt on this engine. It has power steering and air conditioning using the factory 304 cid engine mount. I cannot find any aftermarket serpentine set-up for this. I have tried searching both AMC and Jeep motors with no luck. Do you know of anything that would fit this application?

The second question is on the brakes. The car came with manual drum brakes on all four wheels and I replaced these with a set of front discs from a 1982 AMC Concord, and I have a 9” Ford rear end from a 1978 Lincoln Versailles that came from the factory with rear disc brakes. Would the original master cylinder and booster work for this? And, what should I use for a proportioning valve?


Bulltear Industries ( now offers a complete kit to convert 1967-91 AMC V-8 engines to a serpentine belt system. The kit does not accommodate your air conditioning but the company is planning to offer an expanded kit that includes air conditioning in the near future.

You cannot use a drum brake master cylinder with a disc brake system. Compared with drum brakes, disc brakes normally require higher fluid pressure as well as a greater volume of fluid. Also, your drum brake master contains a residual valve, which would cause the disk brakes to constantly drag. Your original booster should function fine with a disc brake master cylinder.

It is possible that you may not need a proportioning valve at all as these are normally used in front disc, rear drum systems to modulate the pressure to the rear brakes to prevent lockup.

In an OEM 4-wheel disc brake system the components are sized to properly balance front and rear braking action but since you have a front setup and a rear setup that were not designed to work together, with both on a car that neither was designed for, you may well need a proportioning valve.

I’d suggest an adjustable proportioning valve because it will give you greater flexibility in balancing front and rear brake function.