Week 7 of the Basic Auto Mechanics class at East Brunswick Vo Tech was another class all about brakes. We did a quick refresher on floating calipers, since we skipped the previous week due to the school being closed, and after we moved on to other brake setups.
For the quick refresher on the floating caliper, he had us take apart the disc brake assembly and remove the O rings that are in the caliper guides. He then had us put the caliper back on the assembly without the brake pads. This gave a very good view of how the caliper moves along the guides. Without the O rings in place, the caliper easily slid back and forth along the caliper guides without a lot of force, we were able to easily slide it back and forth with our hands. When the demonstration was complete, I had to put the O rings back and reassemble the entire unit.
The next setup was a typical front wheel drive disc brake setup. This consists of a knock off rotor as well as the wheel bearing and hub assembly. We took the brake caliper off, just like with the other setup, and were told to stop at the rotor. The teacher then explained to us that in order to get the rotor off the hub assembly you need to use a ball peen hammer and hit the rotor in the area where the lugs are. He told us that the round part of the hammer actually puts a dimple in the rotor and pushes it away from the hub assembly. That is why it is necessary to use a ball peen hammer.
We then covered how to remove the wheel bearing cartridge on the front drive vehicle. When doing the wheel bearings the Envoy that I have been working on I used a slide hammer. He showed us how to use the brake rotor as a slide hammer to pull the bearing out. You just put the rotor on backwards and put the lugs on so that they don’t come off. You can then use the brake rotor as a slide hammer to pull the assembly out of the bore. To put the new one in, you just use the bolts to pull it into the bore, doing a little bit on each one so that you pull it in evenly.
We were warned about the axles on the front drive vehicles and not to hit the axel bolt with a hammer to get the axle out of the wheel bearing. Hitting it with a hammer can cause damage to the CV joint and possibly the transmission. Don’t use a puller or hammer to remove the axle! This part should just slide out with a little help once the bolt is out.
Drum brakes were next. I’ve never worked on drum brakes before and I was paying pretty close attention to the material being presented. We learned that the small pad is the primary and that longer one is the secondary pad. On a normal setup, the primary will be the pad in the rear. We learned about all the springs and devices that make up the system. There are two retaining springs that hold the pads in place, two return springs that pull the pads back after the brakes have been applied, and a self adjusting mechanism that is pretty ingenious. The way the self adjusting mechanism works is when the pad moves too much away from the brake cylinder, a cable get pulled which in turn lifts a lever that turns the adjustment screw. The screw is meant to only go in one way and the two sides cannot be interchanged.
We were then tasked with disassembling the entire drum brake assembly all the way down to the backing plate. When that was complete, we needed to put it back together. It was a little difficult since I have never done it but I was able to accomplish the task. Remembering how all the springs and levers go was the biggest challenge. Once I figured that out, I was able to call it done.
This class was quite good and I probably learned the most in this one. This was most likely due to the fact that I never worked on a drum brake before and all of that material was new to me. They don’t seem that difficult as long as you take your time and pay attention. The front drive assembly was very familiar to me and I was able to do the work with ease.