Rear brake pads stickin'

[bicyclegraduate]

think i can get away with just replacing the pad spring or will i need 2 drop more $$ on my $300 police auction bike? (give me a break i'm a college student and just had a spam sandwich for lunch)!

[Nessism]

Could be the caliper piston is sticking which keeps it from retracting smoothly. This is a very common issue with 25 year old motorcycles and signals the need to remove the piston and clean the gunk out.

Remove the piston with compressed air injected into the fluid inlet port. Clean the piston/caliper and inspect. If the piston is pitted, it will need to be replaced. Some people reuse the rubber seals as long as they are not damaged but I recommend replacing them. Clean everything using brake fluid and reassemble.

Good luck.

[Redman]

Low budget thing to try first is to push back the pads/piston (watch to see if going to overflow master cyclinder), then pump back.. do this a few times. And also bleed out old fluid from caliper and replace with new fluid. Can be doing both of these things at about same time.

This may or may not help, but is low budget thing to try first. Has worked for me on bike I got that had been sitting.

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[tkent02]

Could also be the brake line is collapsed internally, the old rubber inside the line goes bad and swells up or somehow blocks the passage. Brake fluid can be pushed into the caliper under pressure but doesn't freely leave the caliper afterwards, there is nothing to force the fluid to move. So the brakes come on but don't release. Just something to check, easier than pulling the caliper apart.

[bicyclegraduate]

yeah, i already flushed all the old brake fluid & pushed the pads apart numerous times. i'll check the piston hopefully it just needs a good scrub down. thanks for the replies!

[Mark whiz]

One other cheap thing you can do is check those 2 slider pins that the pads suspend from. Over time they pit where the pad contacts them and it cuts a groove into the pins, keeping the pads from retracting from the rotor. On my 700ES I've found that the pins need to be cleaned and the pits/grooves sanded out every few thousand miles.

[smagnusen]

Does the rear master have the little return hole like the front? If so, clean that sucker. My front stuck and all I had to do was clean out that little guy.

[jetta90]

I have the identical issue with my 1984 GS 750E.
don't think I've found the problem yet.
I have taken the master cylinder and the caliper apart.
Even though I had previously flushed the system several times with fresh brake fluid, once i had it apart I still found some crud in the master cylinder and caliper. Cleaned everything out and put everything back together.
My pins that suspend the brake pads also had wear grooves in them at the point where the pads sit. I sanded the areas down to make these grooves go away................couldn't get the grooves totally out but the pins are much better than they were.
All this to say that I may need to revisit some (all?) of the above.

One thing I just noticed that could be the problem. I compared the rear wheel parts (axle, shims, spacers etc) on my bike with one of the diagrams on the web (i think it was Bike Bandit site) and noticed that I may have a washer missing. The washer acts as a spacer on the rear axle.
Anyway, this might amount to nothing but i bought my bike used and it appears that someone at some point reassembled the rear wheel and neglected to included this washer.
Might be the issue with my rear brake system. If nothing else, with the washer inlcuded the rear wheel, chain and sprockets should line up a little better.
Check to make sure all your rear axle parts are where they should be.

[tfb]

A common cause of pads not retracting properly are the caliper seals getting old and stiff. Changing to new seals is the way to go. But by all means try the other 'budget' fixes first... I know what it's like to be a college student on a shoestring! Except my culinary low-point would have made a spam sandwich look quite good. :shock:

[gremlin]

check your chain, if its not adjusted right it will couse the pads to bind and heat up the brake fluid.

next, clean every thing. take the calper off the bike and clean the bolts that hold it to the bike. also pull the piston out and make shure there is no varnish or gunk in the cup area. do the same for the front calaper. if your having problems with one the other one will be in the same mess. next remove your brake arm, clean and grease it. some times sand, and rust will couse it not to return to the full up position.

[Steve]

Does the rear master have the little return hole like the front? If so, clean that sucker. My front stuck and all I had to do was clean out that little guy.

Yes, it does. Take the master cylinder apart, you will see a small hole in the main bore, very close to where the piston "lives" in its normal position. Use a paper clip or strand of copper wire to poke the gunk out of it, then spray with carb cleaner and compressed air to make sure it's clean.

Also would not hurt to replace the seals in the caliper. Even though you are on a tight budget, the cost is minimal. Bike Bandit shows the seal and dust boot for under $4, and it takes two of each, so for about $20, including shipping, you will have basically new rear brakes. If you are feeling extravagant, you can get a new piston and seal kit for the master cylinder. $24 + shipping on that one.

While you have the rear caliper apart, remove the pistons, carefully clean them with a worn ScotchBrite pad to polish all the crud off of it. You can carefully pry the seals out of the caliper bores to inspect them, then use the ScotchBrite pad to clean the caliper bore, too. Make sure all the crud is out of the grooves for the seals, otherwise they will cause extra drag on the piston.

The equalization hole is probably the cause of your problem. New seals in the caliper will help retract the pads away from the disk.


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