For What Its Worth

Drum brake R&R

Prices from 2009

I redid my rear drum brakes.  They would grab at times.  Previous owner had them checked and they didn't find the problem.   It looks like drum brake knowledge has deteriorated.  I found many problems. Some info on redoing drum brakes from my ancient experiences.

Watch out for the brake dust.  It can be nasty stuff.  I would wear a paper mask at least.  If you vacuum the stuff up, be careful, since the filters are not usually fine enough to catch the dust.  I recommend sweeping it up slowly. There is always some dust on the drum and backing plate.

Flexible Brake lines

On rear brakes there is a single flexible line for the brakes to the rear end.  If it looks cracked or is 30 or more years old, replace it.  They can still look good on the outside, but rotted or cracked inside and can cause problems. Front wheels have a line for each side.  Same recommendation for them. 

Backing plate

Make sure it is not bent.  There should be three pads on the front and rear where the brake shoes ride.  They may have little dimples in them.  These should be clean and a VERY LIGHT coat of white grease (Rated for brakes) should be used on them.   You may have to wire brush or lightly file them to get rust off.   Same thing for the area between the stud and brake cylinders on top where the ends of the shoes ride. (See yellow box below)  If you clean and paint the backing plate, be careful with the pads.  They are sliding surfaces.


Brake cylinder pins

Make sure the pins coming out of the brake cylinders fit into the brake shoes well, but not tight.  Make sure they are clean and smooth in the slots and ends.  Red box in Picture above.

Brake Material no overlap

Make sure the brake material on the brake shoes DOES NOT overlap the brake shoes on the side.  If it does, replace or return the shoes.  The metal edge is supposed to slide on the 3 pads not brake material.

Brake Cylinders

Don't take chances with old cylinders.  Rebuild or replace them.  As my GM authorized mechanic teacher taught me, don't try to re-use the brake cylinders as is, at least 1 out of 3 will leak after you mess with the brakes.   Make sure the new cylinders are the correct ID size.  Be sure Left and right sides match in inside diameter size!  If they don't match one side will brake harder than the other.  Front and rear may look the same on the outside, but are usually different diameters. 

One other Brake cylinder warning.  On some of these older cars the parts have been on the shelf for a while.  Even a new brake cylinder for a 60s car should be checked for what I would term as shelf rot.  Rust or rubber component rot. 


Brake shoe quality

DO NOT use cheap brake shoes. Use good name brand shoes. The difference between the cheap brand and good Wagner shoes was $8 for 2 axles on my purchase this week.   


Drum brakes have adjusters at the bottom between the shoes.  As the adjuster spreads, the shoes widen.   An automatic adjuster is shown in this picture.  Auto adjusters when working continually adjuster the brakes when stopping in reverse.   Make sure the adjusters turn freely.  If not take them apart, clean the threads and a light coat of brake/lithium grease.  If that doesn't fix it, buy new ones. The Auto-adjuster arm should not have a groove or be rounded off where it meet the adjusting notches on the Auto Adjuster. 

On older, manually adjusted brakes, the adjuster tabs are just a little taller than the spring, that is what holds the adjuster from moving.  Manual adjustments needed to be done every 1500-2000 miles.  It was a pain.

When putting on new shoes, make sure the adjuster is all the way in to begin with. Test fit the drums and adjust out as needed.  Adjusters are directional, they are designed for left and right sides.  L/R threaded.  When the adjuster arm pushes down on the star wheel it should be opening the distance between shoes.  Reverse them and you have anti-adjusters.  I have seen this done in shops before and it is dangerous if not caught in time. 

Bigger shoe goes to the rear!

One shoe will have more brake material than the other.  The one with more goes to the REAR.  It is the one that stops against the stud when going forward and takes most of the wear. 


If the springs or adjusters are rusty, replace them.  It may take 2 kits.  A brake spring kit, usually covers 2 axles, but you need to know front or back since the keeper pins are usually different lengths front/back. Front brakes are usually wider.  About $10 for a kit.   Also Automatic Adjuster kit, one for each side.  $8-10 each.  A little white lube on the pivot of the adjuster.  ONLY A LITTLE BIT. 

Take care of the spring on the bar that fits between the shoes.  This is for the emergency brake and this spring is not usually in the kits.  The short one in this picture.

If you can't replace the springs, adjusters etc. from memory, only do 1 wheel at a time.  Use the other for reference.  Front to rear is similar.

Drum maintenance and shoe fitting

Turn the drums.  ($6 each) If you have a good brake shop, they should be able to "arc grind" the shoes to match the drums after they are turned.  This eliminates the wear in period over the first few hundred miles.  Warning, "arc grinding" of the shoes may be a dead art.

Final adjustments and Bleeding

By turning the adjuster, adjust the shoes to fit the drum to specs.  NOT TOO TIGHT.  The drum should go on and turn, but not have a lot of slop between the brakes shoes and the drum. 

Make sure the drum does not drag on the backing plate.

What keeps the brake assembly centered?   The Drum.  If you push the pedal without the drum on, double check every thing is where it should be before putting the drum back on.  Especially the top pins in the cylinder and the brake cylinder itself.

Once the drums are on and initial adjustment is finished, time to bleed the brake lines to get the air out.  See Vacuum bleeding notes. 

Final adjustment with Automatic Adjusters.  When the wheels are on, go backwards and use the brakes. Forward then back and brake etc.  A few times.  If you backup slowly or use the brakes lightly or not at all while backing up, you may not be keeping your drum brakes adjusted as they wear.


What was the difference in my rear brakes?  It went from using 3/4 of the distance on the emergency brake to 3 clicks. The car stops well and smooth.

This was on my 66.  The springs, adjusters, shoes and cylinders were listed for a 72, the oldest the local parts houses books went.  Same thing in this case.  The front and rear brake flex lines were NOT the same as a 72, be careful.

When disc brakes first came out in the late 60's,  shops charged MORE to service them.   They even charged extra for alignment if you had disc brakes.  It only lasted a few years until mechanics figured out how much easier disc brakes were to work with.

Happy Motoring, VHubbard.  May 2009 Last Update Aug 8, 2020

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