Rear Brake Cylinder Replacement

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Rear Drum Brakes and Replacing Them

Spraying solvent on a brake drum to clean it.

genekrebs/Getty Images

Brakes are the most important system on your car. It doesn't matter how well your car starts or moves if you can't stop it. That's why it's super important to regularly inspect your brakes and replace any parts that you think might be suspect. There's never a good time to skimp on brake repairs. If you suspect that your brakes are acting up, check out our brakes troubleshooting guide to get to the bottom of the issue.

If you know you need to replace one of your drum brake cylinders, we hope you're considering doing it yourself. Don't be intimidated by the job. Sure, brakes are super important, but it's also easy to know whether you've done the job right. Proper and thorough testing after a brake repair is essential to your safety. But once you've tested the system, chances are you did the repair correctly and your vehicle is safe. Besides, brake work isn't that hard to do!

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Remove the Brake Drum to Access the Wheel Cylinder

Dust cap removed, brake drum is next
The brake drum mut be removed to access the wheel cylinder.

Photo: Matt Wright

Before you can even see the brake cylinder, you'll need to remove the brake drum. It comes off fairly easily with one bolt in the center holding it on. Be sure your emergency brake is NOT pulled up for this job (but use some wheel chocks to keep your car from shifting while you have it on the jack stands safely). 

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Accessing the Brake Cylinder

Brake shoes and wheel cylinder
Brake drum removed, you can see the brake shoes assembly with lots of springs, and the wheel cylinder at the top.

photo: Matt Wright

With the brake drum off, you will be able to see the brake shoes and the wheel cylinder that requires replacement. Unfortunately the brake cylinder (also called the wheel cylinder) is guarded closely by two brake shoes and a cluster of springs. This mass can be very intimidating. The good news is on most cars this cluster of shoes and springs can be removed as a single unit without taking it completely apart. There are two pins that hold the brake shoes onto the backing plate. These are spring loaded from the front, so the best way to remove them is to push them in from the front, and then reach around to the back and give them a twist. Twist each pin a quarter turn and that cluster of brake shoes and springs is almost out. The brake cylinder at the top is the last thing attaching the shoes assembly to the backing plate. Using a large spreader, or two screwdrivers, pry the top of the shoes assembly apart enough to clear the wheel cylinder ends, and you'll be able to see the wheel cylinder clearly. If you were lucky enough to keep the brake shoes assembly in one piece, set it aside for reinstallation later.

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Disconnect the Brake Line

brake line removal
Remove the brake line before you unbolt the wheel cylinder.

Photo: Matt Wright

Before you start to remove the bolts on the back of the wheel cylinder, you've got to disconnect the brake line. The brake line is threaded into the back of the wheel cylinder through the large backing plate. To remove it, find the correctly sized line wrench to loosen then unscrew it. We strongly recommend using a line wrench to avoid stripping the hex on the brake line. Once this is ruined the whole line must be replaced. A regular open end wrench doesn't have enough surface area on the hex head to remove a stubborn brake line.

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Removing the Old Wheel Cylinder

Wheel cylinder coming off
Removing the old wheel cylinder.

Photo: Matt Wright

With the brake line removed you're finally read to remove the wheel cylinder. It will be held in place by one or two bolts through the back of the brake backing plate. Many original steel or iron wheel cylinders are held in place by two bolts, but the replacement part may be held in by a single bolt. This is normal, and if your new wheel cylinder has only one bolt, there should be a note in the box telling you it's normal.

Remove the bolts on the back of the wheel cylinder, then pull the old one off. You might hae to give it some light taps with a hammer because that thing's probably been there a long time.

As they say in car repair, installation is the reverse of removal, so get to it. And don't forget to bleed the brakes when you're done!