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Rear Brake Replacement Notes

April 21, 2002

This page is not going to be a "follow along as I rebuild my rear brakes" page. Instead, what I'm going to do is provide some helpful hints that will save you a headache if you decide to tackle this project yourself.

Before I go any further, let me mention that if you've never serviced drum brakes before, you should get someone who has to help you out. It is very easy to misassemble a drum brake in a way that is not obvious to a beginner that will cause major problems once you take the car on the road. If you can't find someone to help you and you don't have a factory service manual, clean the brake assembly and take a few pictures (use an instant or digital camera or even a video camera) so you can correctly reassemble the springs and levers. Also, you'll want to invest in a few specialty tools that will make life easier. You'll need a drum brake return spring tool, a hold down spring tool, and if you'll be replacing wheel cylinders, you'll need a special bleeder screw wrench (K-D 2811 or GM J-28434), a 3/8th flare nut wrench (do not use a box wrench -- you'll destroy the fittings), and a pair of awls.

The brakes on 1978 (and possibly other years as well) "A" body cars have several important differences from the typical GM drum brake. These are the differences:

  • You'll need a special tool to bleed the brakes if you use stock type bleeder screws since they are recessed into the wheel cylinders. The tool is K-D 2811 or GM J-28434. If you don't want to buy this tool (or if you can't find it), you can use Russell Speed Bleeders (I purchased mine from Summit Racing - http://www.summitracing.com - they were $10 plus shipping) and an 8mm deep socket.
  • The wheel cylinder is attached to the backing plate with a metal clip instead of a pair of hex head screws. You'll need a pair of awls to bend the clip away from the wheel cylinder (you have to bend both sides away at the same time) to get it out.If you're going to reinstall your existing wheel cylinder, you'll need to replace the clips. To reinstall it, put a block of wood (I had a scrap of 1" x 4" that worked perfectly) between it and the axle flange and then drive the clip on with a 1-1/8th inch socket on the end of a 10 inch extension. Also, make sure there are no young children around when you do this if you have a tendency to cuss.
  • The self-adjuster lever has an override spring on it that is a huge pain to install (see previous note about cussing). If you have a bench vice, it will make the job a little easier since you'll be able to clamp it to something solid. You'll probably want to use a pair of locking pliers (such as Vise-Grips™ -- and I highly recommend the Vice-Grip™ brand) to hold the pivot to the lever while you stretch the spring.
  • When installing the self-adjuster lever to the brake shoe, make sure that the spring seat for the hold down spring is properly seated or you will not be able to install the hold down spring. I had to drive mine in with hammer and a brass punch (you could also use a wooden dowel or a socket and extension to do this) to get everything to fit. If you have to drive it in, make sure the lever still moves freely or the self-adjusting mechanism will not work.