Wednesday, August 5, 2009

On Removing Brake Drums

Our first car, a 1969 Plymouth Satellite, had drum brakes all around. I got to be an expert at working on drum brakes.

Our second car, a 1974 Chevy Impala station wagon, had drum brakes on the back, and I think it had disk brakes on the front. I don't remember. But because of my experience with the Satellite, the Chevy's brakes were no big deal.

A succession of minivans and small commuter cars followed, most of them with disks in front and drums in back. (Disk brakes, by the way, are a cinch.)

Today, in an effort to save money, I decided to do all four brakes on our 1990 Geo Prizm myself. Disks up front, both finished in about an hour. Drums in back, a different story. I pried one drum off with two large screwdrivers and some lucky hits from a rubber mallet. The other drum refused to give itself up. It was frozen to the axle, and it wasn't about to move.

I thought I was an expert. Phooey on my expertise.

Herewith, some advice gleaned from personal experience and from the Internet.

1. If it doesn't simply slide off, then try the following steps in the order given.

2. If it's a rear brake, then block the front tires and release the parking brake. (Duh.)

3. Check the lugs for retaining clips. Many new cars and some VWs have retaining clips on two of the lugs, used to hold the drum on during assembly. Remove the clips. Don't worry if you break them; you won't need them again. (Not on my Geo.)

4. Check the face of the drum for small bolts or a Philips head screw. Some cars use these to hold the drum on during assembly and maintenance -- sounds like a good idea. If you remove them, the drum should magically fall off. (Not on my Geo.)

5. Check the face of the drum for two threaded bolt holes. If you find them, you're in luck. Screw in a couple of bolts of the correct length, and as soon as they contact the backing plate, they will gently but firmly push the drum off the axle/hub. This is an elegant solution, as the drum becomes its own extraction tool. (Not on my Geo.)

6. If it's still not coming off, then you really do need to remove the rubber plug from the slot on the backing plate, reach in with two screwdrivers, hold the ratchet up and spin the star wheel all the way closed. (Read the manual; you'll understand.) If the drums are very old and have never been turned, then the shoes may have worn down the drum, leaving a lip on the edge, and the only way to get that lip past the shoes is to back the shoes off, all the way. You want the wheel/drum to spin freely, with absolutely no rubbing. (This applies mostly to old cars, but pretend it applies to your car, too.)

7. Still not coming off? Okay, the next step lets you take out your frustrations on the wheel. WARNING! WEAR GOGGLES OR SAFETY GLASSES WHEN YOU DO THIS! Long sleeves, long pants, closed toe shoes and work gloves might be a good idea, too. But at the very least, PROTECT YOUR EYES.

Apply PB Blaster, WD-40, or some other penetrating oil to the seam between the drum and the axle/hub, and to the lug nuts where they pass through the drum. Do this several times. Wait an hour or more -- be patient. Then, take a regular old metal hammer and give the drum an enthusiastic whack, right on the shoulder -- where the face curves around and becomes the side of the drum.

Hit it straight on, perpendicular to the face, not at an angle. The harder you hit it, the better. The drum is built to withstand stronger impacts than a human-powered hammer.

One whack should be enough to break the drum loose. If not, rotate the drum a half turn and hit it again. Do this repeatedly on different areas around the shoulder of the drum. Eventually, you will see the drum pop loose. Then you can wiggle it off. (Works every time. Almost.)

8. If that didn't work, then you can use a spreader bar, a gear puller, or some other tension tool to yank off the drum. Work slowly and carefully if you want to save the drum and reuse it. Working too fast, or using an impact tool to tighten the puller, may ruin the drum. If you don't see any action, leave the drum under tension overnight. That clanging sound you hear at 3:30 a.m. will be the drum finally giving up.

(Thanks to Nathan McCullough and Expert Village ( for the hammer tip. That did the trick for me.)

(The discussion at also suggests heating the drum with a torch to break it loose from the hub. Apparently it works very well, but it's not something I'd be willing to try in an enclosed space.)


Lori-Mom said...

Bob says, if it doesn't work the first time get a bigger hammer.

Kellie said...

I like the picture my mind conjures of you working on the car...giggle, giggle!