Rear brake caliper

[edtheguy]

While removing rear wheel for tire change, removed rear caliper and noticed it has 4 pistons. 2 aren't moving causing pads to wear very unevenly. Thick on end where no motion and thin on end still working.

Can I rebuild the caliper? How difficult is it? Who has parts? Would I be better off getting another caliper if possible?

[luvmy40]

The calipers are easily rebuilt. The OE parts are available from Yamaha, Partzilla, Revzilla, etc. There are also many aftermarket parts available on amazon or ebay. I'd recommend staying away from Chinese manufactured seals and gaskets.

 

There are a plethora of videos on youtube showing how to rebuild brake calipers.

 

 

Getting the pistons out can sometimes be a challenge but I have yet to have one stump me. Compressed air(be very careful when the come out, they come out fast and hard!) or a grease gun will almost always work.

 

Clean is the rule. I use scotchbright pads and brass wire Dremel wheels to clean the bore and seal seats. Rotate with the circumference, don't wipe in and out when cleaning with even the mildly abrasive pads. Pre lube with brake fluid when installing the seals and pistons.

[cowpuc]

Might try pulling the pads, clamping the pads that will move and pressing on the pedal real hard to see if you can force the stuck pistons out some. Watch em closely as you press down on the pedal, if one moves, allow it to move out about a pads width and clamp it and continue pressing to unstick the last one. Once ya get em all out a little more than the full width of a new pad, clean em up real well with brass brush or a brillo pad, smear a little brake fluid on em and push em back in again. Repeat a few times looking for scrub marks on the pads each time when ya move em out.. Sometimes you can free em up and not have to rebuild,, not always but it might be worth a try..

[edtheguy]

Great advice fellas. Thanks a bunch

. St.

[djh3]

2nd Gens always seem to have uneven rear pad wear. Most of us every other oil change just flip pads from inside to outside.

[cowpuc]

2nd Gens always seem to have uneven rear pad wear. Most of us every other oil change just flip pads from inside to outside.

 

Wonder if misalignment at the Pumpkin to swingarm connection could cause this.. If I had one that was doing that and knew the pistons were not sticky in the calipers, I would check the axle alignment while coming into the right side of the swingarm just for kicks...

[Marcarl]

Might try pulling the pads, clamping the pads that will move and pressing on the pedal real hard to see if you can force the stuck pistons out some. Watch em closely as you press down on the pedal, if one moves, allow it to move out about a pads width and clamp it and continue pressing to unstick the last one. Once ya get em all out a little more than the full width of a new pad, clean em up real well with brass brush or a brillo pad, smear a little brake fluid on em and push em back in again. Repeat a few times looking for scrub marks on the pads each time when ya move em out.. Sometimes you can free em up and not have to rebuild,, not always but it might be worth a try..

 

I don't often jump in to disagree with anyone, but in this case I just might be accused of that. Cleaning pistons without taking them apart is asking for trouble down the road. There is a reason they got stuck and dirt is usually the culprit. If you would get them 'working' are you then sure the problem is solved? or just delayed a while. And if they do start 'working' did you get all the dirt out or is there some left that will cause complete failure next time. We're talking brakes here, not signal lights or radio. Brakes need to work in their best capacity at all times. My opinion: take them apart and don't scrimp on the repairs, if you don't you may not be around to tell us about the results.

[djh3]

After disassembling, cleaning etc they still wore more on piston side. In my line of work we teach these new auto techs thats because the pins get stuck. It was not that big of deal to swap pads side to side. Not really any slide pins on the rear caliper if I remember rite.