How to Change Rear Rotors
No brake repair is complete without replacing or machining the rotors. Over time as the pads are pressed against the brake rotors they wear them down little by little. If you've put off the repair until the pads are nearly gone chances are the damage to the rotors is greater. The rivets holding the pads to the backing plates have likely been rubbing against the rotors for quite some time by that point.
When working on your brakes it is recommended that you do all four wheels at the same time. At the very least you should examine all wheels and do all repairs necessary on either the front or the rear brakes at the same time. Brakes must be reasonably matched from side to side so never work on the brakes on only one wheel.
Since location of some parts will vary slightly from manufacturer to manufacturer and model to model it is a good idea to have arepair manualfor your vehicle when doing this work. While many of the steps are the same some of the specifics might vary.
With the vehicle properly lifted off the ground and supported on jack stands, by the time you have come to the rotors you will have removed the brake calipers and supported them properly to prevent damage to the brake lines.
On some vehicles, including nearly all front wheel drive vehicles, the rotor will likely just come right off of the hub. If it is not integrated with the hub and held on with a nut this is likely the case. If such an assembly fails to come apart easily a few taps with a hammer will likely do the trick.
Other vehicles, primarily rear wheel drive cars and trucks, will have the hub integrated with the rotor and this part is held on with a bolt. You will see a dust cap that keeps dust out of the bearing grease. That can be pried off with a bar or a large, flat-blade screwdriver. With the dust cap removed you'll see a cotter pin holding the nut in place. With a pair of pliers straighten the cotter pin and pull it out. Then you can remove the nut, washer and outer bearing and, finally the rotor.
With the rotor removed you will need to determine if it can be machined or it needs to be replaced. Your local machine shop can measure the remaining thickness of the rotor and determine if it is adequate to be machined. Sometimes, however, rotors are cheap enough that you can buy new ones for not significantly more than the cost of machining.
When you have your new or newly machined rotors in hand reinstalling them is fairly straightforward. If the rotor just slid off the hub assemby just slide the new on onto the hub. If you had to unbolt the old rotors, however, there is a bit more.
When replacing a rotor/hub assembly you will want to take the time to repack the wheel bearings. Anytime you have this disassembled you should do so. With the inside bearing repacked and slid onto the wheel spindle, slide the hub onto the spindle followed by the newly repacked outer bearing. Slide the washer on over that bearing and put the nut back on.
In most cases that nut will only be finger tight but this is where a repair manual becomes important. You may need to torque that nut to a specific amount or follow some other procedure to ensure it is reassembled to manufacturer's specifications. Once the nut is properly installed you will use a new cotter pin to finish that assembly. Put the dust cap back in place, tapping lightly with a hammer or rubber mallet if necessary and the rotor is back in place.
With the rotors replaced you can continue with your brake repairs. The next steps will involve reinstalling the calipers with new pads andbleeding the brakes. After that, put on your wheels and tires, take your vehicle off of the jack stands and you're ready to test drive your repair.
