Monday, March 23, 2009

New Front Brakes!! Finally!!!

  • Changed front brake pads and rotors
  • Minor improvements in braking (much better results when I replaced the wheel cylinders)
  • Brake pads worn, reveal uneven calipers.


Several months ago my grandfather gave me the gift of safety in the form of reliable braking. Knowing quite well what happens if you don't hit the brakes on time (and a building is inconveniently in the way ;-) ), he advised me early on in this project that I wear my seatbelt and obey speed limits. When he heard about the B's poor braking he jumped on the occasion and bought me a set of new rotors and pads.

This was before I left on my trip, and after I got back the weather rather dismal for many weeks. Last weekend, about three months later, we finally had two days in a row of pleasant warm weather. Perfect weather for fitting new rotors and brake pads.

The following is a step by step guide on replacing both the rotors and the brake pads. The first time I did this took me about five hours to complete, the second time about an hour and a half. Be ready for some really dirty, greasy work, as well as many frustrations with pins. Also I would recommend keeping a pan under the caliper while working on it (to catch dripping brake fluid), and have a box nearby to rest the caliper on while working (so you don't stretch the brake line). I must also stress people use a floor jack and jack stands while working on any of this (I used to use the jack the car came with ... very very stupid).

1. Loosen the wheel lug nuts, raise the car, remove the wheel entirely.
2. Remove the two pins and two panels on the caliper holding back the pads. You'll have to play around a bit with the end of the pin: straighten it out to pull the pin out (see image on right).
3. Unscrew the bolts holding the outer caliper part, and set it aside. You'll probably lose some brake fluid doing this. Take out the brake pad attached to this part (see image on right).
4. Unscrew the bolts holding the inner caliper part, take it out and rest it on a box or something so the brake line isn't under pressure. Take out the brake pad.
5. Remove the grease cap off the wheel hub (yes, you need to remove the wheel hub to change the rotors). Use a screwdriver to pry it open.
6. Straighten the wheel hub pin and pull it out. This was by far the hardest part of the entire operation.
7. Remove the nut holding back the wheel hub. It's very loose, and you should be able to mostly use your fingers for this.
8. By gently pulling the rotor forward, take out the various components of the wheel hub and place them somewhere, keeping in mind in which order they came out (pin-bolt-washer-bearings). I strongly recommend you not let anything touch dirt, and that you not drop the bearings.
9. You can now (easily) pull off the rotor.
10. Place the rotor in a table clamp, and remove the four bolts and nuts (with washers) holding together the hub and the rotor.
11. Now take off the old rotor, attach the new one, and reassemble everything in reverse order.
UPDATE: Read this on the wheel bearings and how far to tighten the end nut. This is a safety issue! (Skip to the end to read the instructions if you don't feel like reading the story behind this discovery.)
12. When refitting the calipers, make sure the cylinders that press together to apply the brakes have been pushed back into the housing. An easy way to do this is to place your old brake pad on top of the cylinder and squeeze it together with a c-clamp. You'll see brake liquid oozing out. Be sure to install the new pads!
13. Make sure you bleed the brake system before using the brakes or reattaching the wheels! This is to remove all air from the brake lines. With the bleed valve closed, press down the brake pedal four times, holding it down the last time. Open the bleed valve, and close again. If brake fluid did not spout out in a decent stream you still have air in the lines, so repeat till this happens. Make sure you have enough brake fluid to start with or you'll just pump more air into the system.
14. Friction after putting in the new pads is normal. As long as you can still turn the rotor with your hands you're fine. By pressing the brakes you shouldn't be able to turn them anymore.
15. Now do the other side, and you're done!

The old pads were extremely worn, though they still had some life. This is probably why I had to push down so hard on the brakes; now I don't have to push down as hard on them to brake. However, braking is still not as good as it should be. I'm guessing the rear brakes have locked up (which is probably also why my parking brake doesn't work anymore), so I'll be looking into this soon. I'll probably be replacing the cylinders on the drum brakes (locking up is common).

The pads on the driver side were worn down at an angle, suggesting that an uneven amount of pressure was being applied. I'll have to look into this in future, and perhaps recalibrate or even replace the caliper. But that's for another time.

Many thanks to my grandfather for the parts, my friend Gautam for some much needed brute force help, and my girlfriend Luz for taking detailed pictures and assisting throughout the procedure (she's changed brakes many times before, and unlike me actually knew what to do).

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