Rear brake problem

[14-O]

In 10,000 miles I haven't really had any problems with my '05 FXD until now. Over a period of about a week, my rear brake lever started traveling further and further when I used it. Finally, there was no brake at all until I pumped it a half dozen times or so. But then it worked fine with no spongy feeling or anything. Leave it alone for a minute or two and I'd have to pump it another half dozen times to get it to work again. I added a little fluid (even though it really wasn't too low) and now I only have to pump it 2 or 3 times to get good rear brakes, but it still bleeds down after it sits for a minute. Sounds like there's a check valve or something that's bleeding the caliper/line fluid back to the reservoir as it sits unused. Anybody ever have this happen before?

[DEW2112]

Bleed the brake and see if the problem goes away. If not, air is getting into the system. Just a guess.

[mtnlvr]

Yeah...sounds like a leak in the system.

Check the lines from the rear master cylinder to the caliper for wetness to indicate a leak.

If nothing found, the linkage could be out of adjustment where the master cylinder's piston is not returning back far enough to clear the second little inlet between its resevoir and its bore. Have you adjusted anything in the rear brake's linkage?

If that doesn't work, try bleeding the brake.

If all else fails, then look into rebuilding either the master cylinder or the caliper or both. I wouldn't think that would be necessary with 10K miles though.

[14-O]

Checked and re-checked for leaks: none. Bled it: same thing (didn't get any bubbles at all, and it's stiff once pumped up). Master cylinder is coming off.

[14-O]

On a hunch, I jacked up the back end and spun the rear wheel. The rear disc is seriously bent. When it rolls, it pushes the brake pads apart. I have no idea how it got bent, and the funny thing is, it doesn't even wag its tail when the rear brake is pumped up and working. Go figure.

[tireater]

They are not that hard to straighten...Spin the tire and mark disc with a felt pen...
Hit the high spot with a rubber mallet. if it is low, bend it up with a large adjustable wrench...
It is very easy...or they are cheap on e bay..

[mtnlvr]

Originally Posted by 14-O

...The rear disc is seriously bent...

That'll do it. I'd fix that before going through the hassle of rebuilding the caliper or master cylinder. Good eye!

[14-O]

That's what I did. Found an adjustable spanner (Crescent) that's as long as a nine dollar clothes line and tweaked the disc until it was straight again. Works great.

[mtnlvr]

Great! Now the big question...why did it bend? Or did it warp?

Keep an eye on it, you may find that the caliper is not retracting very well causing excess heat to build and warp the disc.

[tireater]

Gotta love a 3ft Crescent..good job...It may be advisable to clean the caliper with carb cleaner while working the pistons in and out...
I'm not sure why they get bent...But I had to straighten a couple of them...

[14-O]

Heading to Cheboygan this weekend. I'll keep and eye on it. No marks on it or heat discoloration, so it's still a mystery. Both brake pads seem to be retracting fine.