Drum Brakes

The Ocala Jeep Club of Florida

Servicing Rear Drum Brakes by Ron Tyrie II

In continuation of my neglected components series, this month we will delve into the most important thing on your jeep, the braking system. A great mechanic once said to me, “Son; tires are paramount, but your brakes are tantamount.” Yes, it was my dad that told me that when I was in high school, but it is as true now as it was then. Sure, it’s nice to have a smooth running engine and all the latest in suspension hardware, but if your vehicle cannot stop reliably, then what is the point?

Disc brakes are great, we find them on the front of every vehicle nowadays, and there is a reason for that. Disc brakes self clean, self adjust, and nine times out of ten, you can examine their wear without removing your fancy aftermarket wheel. However, there is a dinosaur lurking in the rear with the age-old drum brakes.

The main drawback of the drum brake is its enclosed design. While it is completely shielded from large chunks of debris, the rear brakes have a bad habit of trapping water, silt, mud, and axle grease. While modern drum brakes are designed to self adjust, they do not self-clean. Therefore in an off-road application it becomes necessary take off your rear wheels and drums and manually clean and adjust the brakes.

There are many methods one can use to clean rear brakes. But due to the possibility that there may be dangerous elements involved (i.e. asbestos), the two that I recommend are brake cleaner or water. Thoroughly clean the brake shoes using a parts brush to get some of the ground in mud and brake shoe material from around the wheel cylinder (the hydraulic component that pushes the shoes outward during braking). Now that we can clearly see all of the components, examine the hardware. Replace any springs that appear to be rusty or broken (tell the auto parts store that you need a hardware kit, they’ll know what you are talking about), and look for evidence of any leakage from the wheel cylinder or the axle seal. The best way to check the wheel cylinder for leakage is to pull back the dust cover that wraps around the cylinder’s housing. If any fluid drains out, or if there is any sign of dampness, replace the wheel cylinder and bleed the brakes according to manufacturers recommendation. Make sure to also check the wear on your rear shoes, if they are riveted, there should be more than 1/16^th inch of material above the exposed rivet at the thinnest part of the shoe. If your brake shoes are bonded (glued), replace the shoe if the thinnest part of the material is the same thickness of the steel below it. Now, all that’s left is freeing up the adjuster (located at the bottom between the brake shoes), and adjusting brake shoe tension until you can hear the brake drum dragging lightly while rotating it.

As always, if you do not feel comfortable doing these repairs on your own, at least you now have an idea if the guy working on your Jeep is servicing it correctly. Your brake system is the key to safe and happy Jeeping.