Join Date: Dec 2001
Location: Belleville, Illinois
Thanked 22 Times in 17 Posts
Re: CJ-5 Rear Brake Don\'t work well
If your brakes are otherwise working properly, you might be up against the laws of physics.
In normal braking while moving forward the front brakes do most of the work - 70% to 80% usually. That's because weight shifts to the front axel under braking, and the front is heavier than the back to begin with.
When you're going downhill backwards there is considerably more weight on the back axel, but the front brakes are still trying to do twice as much. That will cause them to lock long before the backs get with the program. I don't know of any practical cure; it's something that you have to learn to work with as a driver.
Another thing to keep in mind; drum brakes are self-boosting. The drag on the forward shoe pushes the aft shoe harder into the drum, increasing the braking effect. The same thing happens when braking backwards, but to a significantly lesser extent because shoe sizes, geometry and friction materials are picked to optomize the effect while going forward.