I’m pretty much a self taught mechanic. I’ve done brakes for everything from a 1950 GMC pickup to a 1992 Civic but I’ve never worked on anything with antilock brakes. Are they something your average shade tree mechanic can do with a decent selection of hand tools? The vehicle in question is a 1996 Jeep Grand Cherokee, rear wheel drive, 4 wheel discs, and four wheel antilock. Both pads and rotors need to be replaced.
Thanks in advance - DESK
Normal brake service is generally the same with or without ABS. However, there are some precautions well worth heeding:
When pressing a caliper piston back into its caliper, have the caliper bleed screw open. You do not want the fluid, which contains tiny particles of brake hose material (that’s why it’s darker than fresh fluid) to back up through the system. A little speck of something blocking a tiny orifice in the accumulator can be a huge, expensive headache. Run a hose from the bleed screw to a container to avoid a big mess. And of course, throw away the used fluid and add fresh fluid to the master cylinder reservoir.
Be very certain not to let air into the system at the master cylinder – watch its level carefully when depressing the brake pedal to move the caliper pistons back into contact with the new pads. Getting air in there may necessitate using a special bleeding procedure, sometimes requiring a scan tool and various pain-in-the-butt steps.
This applies to any brake system – when pressing the pedal to move the pistons back out, don’t go all the way to the floor. Press it about 1/4-1/3 of full stroke. Pressing full stroke moves the internal master cylinder seals to positions they normally don’t reach, and sometimes there’s some crud in there that will damage the seals, requiring a master cylinder replacement to fix. This is not an issue with a new (or rebuilt) master cylinder, which will be quite clean inside.
Replacing a caliper (or wheel cylinder) can usually be done without special bleeding procedures. Gravity bleeding will safely do the job, and if necessary using a few pedal strokes (still not full strokes, see above) is OK. Again, make sure you don’t allow air into the upper part of the system.
If you have access to the wheel speed sensor tips and the tone rings that rotate next to them, clean off any accumulated metal particles (like iron filings sticking to the magnets). This will help minimize the chance of the speed sensors acting goofy. Compressed air does this efficiently, but a small brush (e.g. toothbrush) can work also. With the rotors off, you should be able to see these.
Keep the ignition off while doing the work.
Gary T, I just wanted to thank you for the advice. I did my brakes yesterday with no problem. I printed out your post and put it in my toolbox with my manuals. (I tried to e-mail this to save the hamsters but the e-mail in your profile is disabled)
Thanks again - DESK