Rear brakes lock up

Noise after replacing rear brake shoes and drums...help! - Toyota ...

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With the older drum brake system going in reverse will often tighten the adjuster on the brake mechanism. The adjuster has a thumb wheel to adjust the shoes in and out. BUT there should be a little plate that locks the thumb wheel once you are where you want it to be. I would guess that either you don't have that little plate or it is not keeping that thumb wheel from turning on the right side.

REMOVAL & INSTALLATION
It is a good idea to only disassemble and assemble one side at a time, leaving the other side intact as a reference.

1. Raise and support the vehicle safely.
2. Remove the brake drum.
3. Disconnect the parking brake rear cable and conduit.
4. Remove the brake shoe hold-down springs and brake shoe hold-down pins.
5. Remove the brake shoe adjusting screw spring.
6. Remove the brake shoe adjusting lever and adjuster screw.
7. Remove the brake shoe retracting spring.
8. Remove the brake shoes from the backing plate.
9. Remove and discard the parking brake lever clip. Remove the washer.
10. Remove the parking brake lever from the rear brake shoe.

To install:

1. Thoroughly clean the backing plate with brake cleaning solvent and dry completely.
2. Use silicone grease to lubricate the brake backing plate-to-brake shoe contact areas.
3. Apply a light coating of premium grease to the threaded areas of the adjuster. Turn the adjuster in and out to spread the lubricant. Turn the adjuster all the way down on the screw and loosen one-half turn.
4. Install the parking brake lever to the rear (secondary) brake shoe with a new clip.
5. Position the brake shoes on the backing plate and install the brake shoe hold-down springs.
6. Attach the parking brake rear cable and conduit to the parking brake lever.
7. Attach the brake shoe retracting spring.

The socket end of the brake adjuster screw is stamped with "R" or "L" to indicate that it is to be installed either on the right (passenger's side) or left (driver's side) of the vehicle. The adjuster nuts can be distinguished by the number of grooves machined around the body of the nut. Two grooves indicate a right-hand adjuster nut and one groove indicates a left-hand adjuster nut. Another way to identify brake adjuster assemblies is to check thread pitch. The right side adjuster assembly has right-hand threads and the left side has left-hand threads. If installed correctly, the brake adjuster assembly will increase in length when the brake shoe adjusting lever is operated.

1. Install brake adjuster screw in the slots on the brake shoes. The wider slot on the socket end must fit in the slot on the front (primary) brake shoe.
2. Install the brake shoe adjusting lever on the lever pin.
3. Install the brake adjusting screw in the slot on the secondary brake shoe and in the slot on the brake shoe lever. The brake shoe adjusting lever should contact the brake adjuster screw.
4. Adjust the brake shoes.
5. Install the drums.

ADJUSTMENTS

The drum brakes are self-adjusting and require a manual adjustment only after the brake shoes have been replaced, or when the length of the adjusting screw has been changed while performing some other service operation.
Drum Installed

1. Raise and support the vehicle safely.
2. Remove the rubber plug from the adjusting slot on the backing plate.
3. Insert a Brake Adjustment Tool (D81L-1103-C) or equivalent into the slot and engage the lowest possible tooth on the starwheel. Move the end of the brake spoon downward to move the starwheel upward and expand the adjusting screw. Repeat this operation until the brakes lock the wheels.
4. Insert a small screwdriver or piece of firm wire (coat hanger wire) into the adjusting slot and push the automatic adjusting lever out and free of the starwheel on the adjusting screw and hold it there.
5. Engage the topmost tooth possible on the starwheel with the brake adjusting spoon. Move the end of the adjusting spoon upward to move the adjusting screw starwheel downward and contract the adjusting screw. Back off the adjusting screw starwheel until the wheel spins freely with a minimum of drag. Keep track of the number of turns that the starwheel is backed off, or the number of strokes taken with the brake adjusting spoon.
6. Repeat this operation for the other side. When backing off the brakes on the other side, the starwheel adjuster must be backed off the same number of turns to prevent side-to-side brake pull.
7. When the brakes are adjusted, make several stops while backing the vehicle to equalize the brakes on both of the wheels.
8. Lower the vehicle.

Drum Removed
See Figure 2

Fig. Fig. 2: When using a brake adjustment gauge, first measure the inside diameter of the drum (top) and then adjust the brakes shoes to the proper outside diameter (bottom)

1. Remove the brake drum.
2. Make sure that the shoe-to-contact pad areas are clean and properly lubricated.
3. Using a Brake Adjustment Gauge (D81L-1103-A) or equivalent, check the inside diameter of the drum.
4. Measure across the diameter of the assembled brake shoes, at their widest point.
5. Turn the adjusting screw so that the diameter of the shoes is 0.030 in. (0.76mm) less than the brake drum inner diameter.
6. Install the drum.

INSPECTION

See Figure 3

Fig. Fig. 3: Measure brake shoe thickness in several places around the shoe
Inspect the brake shoes for wear using a ruler or Vernier caliper. Compare measurements to the brake specifications chart. If the lining is thinner than specification or there is evidence of the lining being contaminated by brake fluid or oil, replace all brake pad assemblies (a complete axle set).

You will need to have the parking brake adjusted to the minimum clearance possible and double check the shoes & drum while off.

It sounds as though the shoes are loose, they move forward, grab & unil you center the brakes by applying them and then they release until put into a bind again.

These usually don't get adjusted or even looked at since they are hidden inside the brake rotor hub on the rear wheels.

good luck.

I had noticed that the rear brakes would lock up whenever the were cold and had even the smallest amount of moisture on them. I didn't really think any thing about it because it was not that big of an inconvenience. Until last January. I was coming to an intersection and I needed to turn. I started turning and the brakes locked up, and right into the stop sign I went. So I decided that before this winter gets here I should get it checked out. So I took it to a brake shop and they told me it was a common problem with that type of GM car. The drums that they put on apparently had a stupid designer because people were complaining of the same thing about 2 years after. The problem is that there is a pin in there that keeps the shoes from working right. When it gets the smallest amount of rust and moisture mixed it just locks up. Oh yeah, they also quoted me a price of $707.62 to repair all of the problems that I have with the brakes.

I suspect that you have front disc and rear drum brakes.You did not say which of your brakes are locking up. I suggest that if your front brakes are locking {skid} that means your rear brakes are not engaging. If your rear brakes are locking {skid} then I suggest you have problems with park brake or brake fluid leaking onto the rear shoes.
More info would help me help you. I will check back soon.

The rear wheel bearing is cause of failure .
I would have the rear hub and bearing assemlby replaced.

Drum, Rear Brake System Standard Rear Brake

Item Part Number Description 1 2069 Brake Shoe Hold-Down Spring Pin 2 — Rear Wheel Cylinder Retaining Bolt (2 Req'd) 3 — Washer (2 Req'd) 4 — Anchor Pin (Part of 2211) 5 — Wheel Cylinder 6 2028 Brake Shoe Anchor Pin Guide Plate 7 2A637 Parking Brake Lever 8 2296 Brake Shoe Retracting Spring (Short) 9 2296 Brake Shoe Retracting Spring (Long) 10 2200 Rear Brake Shoe and Lining (Secondary) 11 — Washer 12 2106 Parking Brake Lever Pin Retainer 13 — Brake Shoe Adjusting Lever Cable Guide 14 2A642 Primary Brake Shoe Parking Brake Lever Link 15 2A601 Parking Brake Link Spring 16 2068 Brake Shoe Hold-Down Spring 17 2A176 Brake Shoe Adjusting Lever 18 2048 Brake Shoe Adjusting Screw Socket 19 2047 Brake Shoe Adjusting Screw Nut 20 2041 Brake Adjusting Screw 21 2049 Brake Shoe Adjusting Screw Spring 22 2200 Rear Brake Shoe and Lining (Primary) 23 2A178 Brake Shoe Adjusting Lever Cable 24 2211 Brake Backing Plate
Heavy Duty Rear Brake

Item Part Number Description 1 — Rear Wheel Cylinder Retaining Bolt 2 00538 Lock Nut 3 2212 Rear Brake Backing Plate 4 2262 Rear Wheel Cylinder 5 2A642 Primary Brake Shoe Parking Brake Lever Link 6 2A601 Parking Brake Link Spring 7 2A637 Parking Brake Lever 8 2106 Parking Brake Lever Pin Retainer 9 — Parking Brake Lever Bolt 10 — Secondary Shoe Assembly 11 2A179 Brake Shoe Adjusting Lever Cable Guide 12 2068 Brake Shoe Hold-Down Spring 13 — Adjusting Lever Pin 14 — Adjusting Lever Return Spring 15 2A176 Brake Shoe Adjusting Lever 16 2047 Brake Shoe Adjusting Screw Nut 17 2049 Brake Shoe Adjusting Screw Spring 18 2041 Brake Adjuster Screw 19 — Primary Shoe Assembly 20 2068 Brake Shoe Hold-Down Spring 21 2200 Rear Brake Shoe and Lining 22 2035 Brake Shoe Retracting Spring 23 2A178 Brake Shoe Adjusting Lever Cable 24 2092 Brake Adjusting Hole Cover 25 2069 Brake Shoe Hold-Down Spring Pin
The rear drum brakes:

• Have internal shoes that expand against the brake drum (1126).
• Are a single-anchor type.
• Are actuated by one rear wheel cylinder (2262).
• Have two pistons in the rear wheel cylinder (2261). One exerts force against the upper end of the primary shoe; the other exerts force against the upper end of the secondary shoe.
• Adjust rear brake shoes and linings (2200) automatically.
• Need manual brake adjustment if the adjusters are not operating properly or after the rear brake shoes and linings have been replaced.

When the brake pedal is applied, hydraulic fluid pressure forces the pistons in the rear wheel cylinder outward, moving the rear brake shoes and linings against the brake drum.
The rear drum brake system includes the parking brake mechanism. Refer to Section 206-05 .

When the ABS light comes on that means that the sytem has a problem and whenever light is on the system is in-operable. Most of the time there is a problem with one of the wheel speed sensor. On this particular vehicle there are(4) abs/speed sensors (one in each wheel)basically the all tell the computer what speed that particular wheel is going, at anytime. This sensor is mounted on/in the wheel hub and gets its signal from a gear mounted in the hub or and axle in the hub with a gear on it. When the sensor sends a signal to the computer that the wheel is about to skid/lock-up it pumps the brakes 15 times per second to prevent it from locking up. I believe that the sensor on the right rear wheel is not working and therfore it locks up. Good Luck and contact me if you need more help. Please leave me a fixya if I fixed ya.

Not wanting to be too general but at least trying to help I would suggest looking under the back end, and specifically at the rear backing plates and to the insides of the rear wheels, to see if you notice any fluids dripping. If these are drum brakes, then you could very well have either a wheel cylinder leaking brake fluid, causing the brake shoe linings to swell up, or it could be a leaking axle seal, allowing differential gear lube out, which will also cause the linings to swell, and minor braking will cause that particular side to lock up.
If this vehicle has rear disk brakes, or was just recently changed from rear drum brakes to rear disk brakes, it is possible that the proportioning valve in the brake line was not changed to match with the disk setup.
Drum brakes operate at approximately ten pounds per square inch pressure (10 PSI) whereas disk units operate at a lower pressure of about 2 PSI.
Just some things to look at. Some brake fluids have no smell, others are very distinctive in odor, and differential gear lube has a very distinct odor...not hard to miss once you've smelled it.