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Rear Caliper and MC problems...

  • Thread starter Thread starter TheCafeKid
  • Start date Start date
T

TheCafeKid

Guest
Ok im starting to get really really irritated with this brake assembly. I've rebuilt the master, taken the caliper apart and rebuilt it twice and even REPLACED the whole damn thing...yet still my rear wheel sticks. I cant figure it out and its starting to really pi$$ me off...anyone have any ideas??
 
TheCafeKid said:
Ok im starting to get really really irritated with this brake assembly. I've rebuilt the master, taken the caliper apart and rebuilt it twice and even REPLACED the whole damn thing...yet still my rear wheel sticks. I cant figure it out and its starting to really pi$$ me off...anyone have any ideas??
Click to expand...

Did you clear out the relief port in the master cylinder? If thats not cleared out, then the fluid has nowhere to go when you release the brake. Also, is it an old rubber brake line? Those can swell internally and hold brake pressure when you let off of the brake.
Also, did you liberally grease the pins that the pad slides on? Was all the gunk cleaned out from behind the seals?
 
Hey Tobiism..nice to see you made the jump over from the DTT forum (TonUpSoldier) No i didnt grease the pins...i was told they didnt need it, i will try that but i dont think that is in fact the problem. I guess i may have to replace this hose and see what happens. Im half tempted to pull everything apart and start over...I feel that i cleaned that MC really well and paid special attention to that relief port, but it could be gunked up again. Son of a Beesting. *SIGH* LOL I guess i;ll prolly wait till my knew pads show up anyways.
 
Clogged line or swollen. Inside of it might be breaking down too & then blocking the caliper.

Replace the line, check the rotor is true & put some silicon high temp grease on the caliper slider pins etc.

Dan :)
 
Definately will be replacing the lines this week. But it was still sticking without the hoses even hooked up. I am starting to wonder if the caliper bracket is bent or twisted somehow. I suppose the rotor could be warped but it sure doesnt look like it. And if it was it would seem to me that i would have felt pulsing in the pedal when i had been using it.
 
Just a thought, but if you don't assemble the rear brake in the right order with all the spacers onto the rear tire, it can be pushed far enough sideways to make the brake stick. of course, this would stick all the time, not only after you hit the brakes for the first time.

been there.
 
I was just lookin at that actually man! lol...i was staring at the fiche on bike bandit and the one in the manual and thinking to myself i dont remember seeing all those spacers on that wheel. I didnt put it together nor have i taken it apart since ive owned it, but it looks as if one of the spacers may in fact be missing...dunno for sure..
 
I found when I was rebuilding a brake that the tiniest piece of crud behind the seal lets fluid in there which forces the seal against the piston and jams it. I cleaned it until I thought it was spotless then cleaned it some more and all was well. :)
 
I would at first check your disc to see if its bent or out of true first. Then check the spacers. There should only be two, one each side out side the wheel.

After that it can only be the caliper itself.

Suzuki mad.
 
Hmmm, a friend described an issue with brake fluid crystalizing in a hydraulic clutch. That could prevent flow, or greatly impair flow. Line replacement sounds like a good idea. Ahh, who needs a rear brake ;)
 
Have you checked piston movement with the pads out? You can easily restore the pistons with a C-clamp and padding. It might be interesting to see if both pistons are moving at the same rate. Also, look on the sides of the extended piston for rust or anything else that might be impairing movement.
 
Yeah i pulled the pistons apart...and neither looked bad. One has some TINY pitting in a couple of spots, but nothing that would seem to make it hang up. I cleaned out the piston cups, the seal channel and all the ports really well just a bit ago, and slapped it back on the bike and connected everything this morning, and its leaking around the bridge seal from the outside caliper to the back. So that further inforces my thinking that the seals themselves are no good. Probably swollen just enough to cause the piston to hang. I'll order those seals, and see what happens when they get here. I should probably just go ahead and order some new pistons too while im at it, they arent that expensive.
 
This may sound stupid but check the brake lever itself. on my 78 my brakes started to lock on me and i thought that a line collapsed or the piston was siezed. it turned out that there was a build up of rust on the pivot shaft on the rear brake pedal. i sanded off the rust and anit seized it and it works great ever since.
 
Thanks for the input! Actually when i rebuilt the MC i wirebrushed all the rust off, and yeah the linkage was purty rusty. But shes clean now, actually i think that maybe PART of the problem might lay in the linkage though. I dont think i had the stop set short enough to let the MC piston to clear the return port. Today i adjusted it, and it seemed a bit better, but unfortunately now my bridge seal in the caliper is leaking, so its time to order new seals too...lol
 
I replace the lines with stainless anyway and have found that to be a good move, especially on old bikes.
 
#1 cause of your problem (as you describe it) is old piston seals not allowing the piston(s) to back off enough or at all.
And just in case you may be thinking about it, never use anything aggressive to clean up the piston bore. There's typically only a .001" service wear limit on the bore. Some finger polishing with Blue Magic/Semi-Chrome or similar polishing compound will usually shine up things well but I've never gotten any more aggressive than that. Same treatment for the piston.
When you re-fill, I suggest the newer "5.1" brake fluid. Glycol based but a much higher boiling point than Dot 3 or 4.
 
KEITH KRAUSE said:
#1 cause of your problem (as you describe it) is old piston seals not allowing the piston(s) to back off enough or at all.
And just in case you may be thinking about it, never use anything aggressive to clean up the piston bore. There's typically only a .001" service wear limit on the bore. Some finger polishing with Blue Magic/Semi-Chrome or similar polishing compound will usually shine up things well but I've never gotten any more aggressive than that. Same treatment for the piston.
When you re-fill, I suggest the newer "5.1" brake fluid. Glycol based but a much higher boiling point than Dot 3 or 4.
Click to expand...
Thanks Keith i think that may indeed be part of it, and i have new seals and pistons on their way. I shall update!!
 
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