Rear Drum Brakes

Rear Drum Brakes: Why you should adjust and clean them


You may think that rear drum brakes are self-cleaning. This is a true statement for disc brakes. And for all intents and purposes, brakes do clean themselves. The article below may prove to be a very divisive topic. What we will attempt to do is provide you with the reasons for needing your rear drum brakes both cleaned and adjusted.

Why should you clean your rear drum brakes?

Drum brakes a closed system. The drum brakes are made up of the drum, the shoe, and the cylinder. One of the main advantages of rear drum brakes is that they are cheaper to manufacture. They also weigh less than disc brakes. The housing on the brakes is typically designed to last upwards of 150k miles under normal conditions. Excessive and prolonged use causes the inside diameter to increase enough to affect the contact with the brake shoe. Over time the friction will allow dust to build up in the housing. This dust build-up will cause squeaking. eventually, with heat, it can cause glazing on the disc. This can affect your vehicle’s stopping distance since now only the front part of your vehicle is being stopped.

How can you tell if your rear drum brakes are bad?

The first symptom of a bad or failing drum brake is found in the brake pedal. When the brakes are worn excessively it can cause vibrations. You could notice this more if you’re attempting to slow the vehicle down while riding on a downgrade or hill. Worn drums can also cause a pulsating that will be noticed as you step on the pedal.

Do I have to adjust the rear drum brakes?

Drum Brakes may need to be adjusted if you find that you are having to press down harder on the pedal before the brakes engage. Adjustments should only be done on brakes by a professional. Keep in mind that not all rear drum brakes are able to be adjusted. And, the brakes should only be done when the brakes are in good shape. Attempting to adjust the brakes when the component is bad or failing can only make the problem worse and the situation more hazardous.


What do the Pros have to say about cleaning and adjusting?


As we have stated before this can be a very divisive topic. So many people have so much advice when it comes to brakes. What we have done below is taken some threads from REDDIT regarding brake discussion. Enjoy!!!

Question: Mechanic wants to clean rear brakes. Rip off or not?


From: Wobbley-Sausage

“Cleaning and adjusting drum brakes is a necessary service. I’d recommend it on a yearly basis pending mileage. Disc brakes clean themselves hence the dusty wheels. Drums are a closed system with no way to release the brake dust. Also as shoes wear down the air gap between shoe and drum grows larger which is where the adjustment comes into play. Either the dealer did not do the job or the second shop is fishing for a sale.”

From: GimmeGreyFries

“It seems like a scam. Your car has self-adjusting brakes and all they do when they “clean” your brakes is spray them down with brake cleaner and let it dry. I don’t see any point in them cleaning the brakes or “adjusting” them for you.”


“I clean and adjust drum brake systems on a regular basis. Due to drums being an enclosed system (as in the shoes are always in the drum) brake dust accumulates and can cause brake noise. I usually take the air blower and blow off the shoes and hardware. As far as ‘automatic’ adjustment of brakes, I have yet to see a car that truthfully has ‘automatic’ adjustment. Most of the time the drum systems adjust when you brake hard while going in reverse. How many people brake hard while in reverse?

Of all the brake jobs that I have done (thousands) I’ve had a handful (maybe 10 at the most) that haven’t had to have a brake adjustment in the back. If drum brakes are not adjusted on a regular basis, you will notice that your front pads will not last as long as if you had your brakes adjusted. Essentially since the shoes are further away from the drum, it takes depressing the brake pedal further down, meaning that the front pads are engaging the rotors and receiving more friction and load than if your brakes were adjusted. Properly adjusted shoes will actually make a small amount of contact with the drum, meaning that the shoes and pads will engage at the same time, thus causing a little less wear on the pads and more efficient braking.

Not all mechanics are out there to scam you, there are a lot though I know. But please know what you are talking about before you say that ‘they are just doing this’ and I think I have made a valid point in the support of cleaning and adjusting drum brake systems.”


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