Rear Brake Drum Replacement
Mid America Motorworks 1971-1979 Bus Rear Brake Drum 5 x 112
Article used with Permission: www.vw-resource.com
(Does not apply to disc brakes.)
1. Block the front wheels to prevent movement.
2. Fully release the parking brake.
3. Back off the brake adjusters slightly.
4. WITH THE REAR WHEELS STILL ON THE GROUND, remove the cotter pin from the castle nut on the rear wheel shaft. Mark both the nut and the end of the axle where the cotter pin went thru so you can torque the nut to the same place when replacing it. Break the rear axle nut loose with a 36mm (1-7/16" socket) on a 3/4-inch drive breaker bar and "cheater" -- a length of pipe about four feet long to slip over the braker bar to give more torque. Remove the castle nut, then raise the car.
WARNING -- Loosen the two castle nuts (one on each side) while the car is on the ground. The castle nut should have at least 217 ft-lbs of torque on it -- the leverage needed to remove it is enough to topple a car off the jack stands.
Note: If you car is equipped with spinners, the castle nuts will not be accessible with the wheels on the car. After removing the rear wheels, we had success with lowering the brake drums down onto large blocks of wood and firmly applying the parking brake. This plus the weight of the car on the wooden block held the brake drums in place while we removed and later replaced the castle nuts.
5. Loosen the wheel lug bolts/nuts and raise the rear of the car and place it securely on jack stands.
6. Remove the wheel lug bolts/nuts and remove the rear wheels.
7. Back off the brake adjusting stars, then remove the brake drum from the splines in the rear wheel shaft.
Note: If the adjusting stars are "frozen" in place, it is often possible to loosen them with a good penetrating oil (we prefer Kroil). Even with the adjusting stars turned all the way in, it still may be difficult to remove the drum, and the wheel may be "stuck." This is usually caused by the drum rusting to the brake shoes after sitting too long. Someone has suggested disassembling the rear brakes by first removing 36 mm axle nut, then drilling out the pins which hold the shoes in place (from behind) and removing the wheel cylinder bolt from behind the shoe plate. Then you should be able to use a puller carefully to remove the entire assembly.
Before attempting to disassemble the brakes as suggested above, remove the tire/wheel and tap the drum on the side with a hammer, all the way around. You can place a piece of wood between drum and hammer to soften the blow. Often, this method will break the rust loose and allow you to remove the brake drum.
8. Inspect the braking surface. If it is excessively scored, that's why we're here.
9. If you're going to be working on the brakes (i.e., shoes, cylinders, etc.) do that now in accordance with the Brake Shoe Replacement Procedure.
10. Since there is no bearing in the rear brake drums, installation is straightforward. Simply slip the new drum onto the splines in the rear wheel shaft.
Note: The only problem you may encounter is getting the new drum over the new shoes. Back off the brake adjusting stars completely to provide clearance.
11. Lower the car to the ground and firmly apply the parking brake.
12. Torque the axle nut to 217 ft-lb.
Note: Hopefully you marked the axle nut and the end of the axle so you can return the nut to the same place (i.e., achieve the same torque). If not, and if you don't have a torque wrench that reads up to 217 ft-lb, measure the length of your "cheater" bar and estimate the amount of weight you will have to apply to it to attain 217 ft-lb. For instance, if the total length of your "cheater" is four feet, you will have to apply 54 lb to the end of it to get 217 ft-lb on the axle nut. It's okay if it is a little over, but it must not be under 217 ft-lb.
13. Adjust the brakes according to the Brake Adjustment Procedure.