brake squeal /5
I started getting an embarassingly loud rear brake squeal when it was raining. Now it does it when it is dry and sounds awful. I can't find anything on the forum b/c once you put in the word 'brakes' you get too many hits.
There is about 3 mm of brake pad left and the Clymer's says you should have only 1.5 mm before replacing the pads. If the pads are shot anyway, how would you remove the brake spring to replace the pads?
thanks for helping....
For searching, try this...go to google and type in this "site:bmwmoa.org brake squeal" without the quotes. You get quite a few hits that way...you'll need to look around a bit.
Is the squeal there all the time or only with the first application? How is the brake rod set up? It should be set so that as you spin rear wheel, turning the wing nut CW reaches a point where the shoe just begins to touch the drum, then back off CCW maybe 1 or 1.5 turns. That will put the shoe in a good position to get most of the shoe hitting the drum. It could be that you're out of adjustment and only a small part of one edge of the shoe is touching.
[QUOTE] If the pads are shot anyway, how would you remove the brake spring to replace the pads?[/QUOTE]
Most folks try to "unhook" the springs. It's a nightmare; I guarantee you will invent swear words.
The easiest method I've found is to "unfold" the brake shoes from the drum. I think it was [url=http://www.bmwscotter.org/brake-test/]Mark Valenti[/url] that turned me on this this trick.
To reinstall - reverse the process. It's takes a little more effort to do the reinstall, but nothing, [I]even close[/I], to trying to stretch those springs onto their shoes when the shoes are already installed.
I can't believe I found this image ... much easier than trying to write about it.
Rear brake image; c. Brook Reams -> [url]http://www.flickr.com/photos/brook-reams/8618592968/[/url]
I have a 85 R80RT and I have the same problem after a rain or setting for a few damp nights without being ridden. I use the rear brake HARD a few times (not lock up hard, just more aggressive) and it clears up. Worth a shot as it doesn't cost money or labor to try it. Good luck frank
Into the brakes
It was starting to take longer to get rid of the squeal and the brake was fading faster. I went into the rear drum and took some fine emery cloth to the glazing on the shoe and drum. On the drum I was careful to leave a witness mark all the way around. On the shoe It just took a quick rub. When I reassembled the wheel to the final drive, I gave it a quick spin and could feel it drag a bit. I took it apart a couple of times to find the problem. The upper shoe was tilted outward and rubbing the aluminum of the wheel along side of the drum. With the springs off I held each shoe in place one at a time. The lower shoe did not rock, but the upper shoe did. So as I looked at it and watched it, I could see that it would sit on the pivot pin properly, but it would tip out at the cam. I filed the brake shoe, going front to rear with a mill file, so as not to round it where it sits on the cam. The cam left a witness mark in the shoe so I could tell where and how much material I was talking off. About a third of the mark was left when I got it to quit rocking. I used the draw file method to get the end of the shoe flat, again front to rear not sideways. No more squeal and the brakes are better. No money, just time. It might worth taking a look. Good luck Frank
franko, you're a man after my own heart; a guy who knows how to use a file. Not to mention knows how to diagnose a problem.
[B]How to know when you've re-installed your old brake shoes in the wrong position[/B]... .. .. I had a bout with a leaking final drive seal and had to remove and clean the shoes a couple of times. Since the drum doesn't wear with perfectly cylindrical sides (in other words, a frustum, or taper) inverting the shoe positions (which wore-in to match the surface of the drum) causes higher pressure on one side of the shoe than the other (witness the highly polished surface on the drum and the corresponding wear on the shoe).
This was the front brake. With smaller contact surface on the drum, surface pressure was almost doubled; braking was very aggressive and brake lining wear was excessive.
What this has to do with your thread.. .. . :dunno just thought I'd throw it out.
Imo1131: Your photos explain the wear/witness mark from the tilted shoe I had around the drum as I broke the glaze. Thanks, pictures make things clearer. Frank