RATS! Frozen rear caliper

[FLAVALK]

Replacing pads on the rear tonight and was only able to retract the pistons just enough get the old pads out. I preyed, pushed and cussed but the pistons would not retract. Time for a rebuild? I have always replaced the brakes on this bike and never had a problem until now. The bike has been ridden in the rain VERY little, but I guess rust might still be suspect....'98 tourer with 54k miles. Suggestions?

TIA

[csj]

I had my rear caliper sieze up on my 98 tourer last year,
tried every tool I could find to pry those calipers apart,
nuthin, wouldn't get open. A piston was frozen/rusted in.
Because the caliper wouldn't pry open, I couldn't get 
the caliper outta there.

I didn't have the tools or space to take the wheel off,
that was the solution, and that's what the stealer did
to fix it. If you can drop the wheel yourself, the whole thing
will become accessible. Try not to take it to the stealer,
if you do, your wallet will end up much lighter.

[RP#62]

Did you take the rear brake reservoir cover off?
-RP

[hubcapsc]

If you don't have a studly air compressor, borrow the use of one... take the caliper off and
blow the pistons out by putting air in the where the banjo bolt goes. Put a one-by or something
in where the rotor goes so that the pistons won't come flying out and maybe hurt something.
Clean the pistons up all shiny and if you can wait on it it is probably time to order and replace
the seals. If you're unlucky, like I was when my rear caliper actually froze up when I
was riding to work one day, there will be icky fused-in contamination on the inside of the
caliper... good calipers that you can rebuild can usually be had from Pinwall on eBay
for around $25. Black calipers are for Interstates, not-black ones are for Tourer/Std.

In my picture I've got two one-bys (two pieces of 3/4 inch thick floorboard) jambed in where the
caliper goes, I blew the pistons out that much, then removed one of the one bys, blew the pistons
out some more, and by the time they were out that far I was the boss of them 



-Mike

[bigdog99]

i have never really pryed the calipers, i always use a C clamp to press them back out and seems to push them back straight. i just changed the rears for the first time with 78,000 miles and no issue. you may want to C clamp them
it worked for me.

[FLAVALK]

Did you take the rear brake reservoir cover off?
-RP

Yes, always do. Thanks

[FLAVALK]

I considered spraying the pistons with PB Blaster (my favorite penetrating oil), letting it work and trying again. Then clean the entire area with brake cleaner to remove all the lube. Anyone try something like this?

[Tropic traveler]

Had a similar problem on Kim's LF caliper. Seems it was very reluctant to retract which is the same problem you have. What I found was there was a lot of crud built up on the pistons and outer part of the caliper bores. After removing the caliper I tried to use air pressure to get the pistons out..... No dice, you could get one out but then how do you blow the 2nd piston {the worst stuck one} out?
Solution, put the piston back in & use the brake systems own hydraulic pressure to push them out. Used a C-clamp to equalize the pistons, switching back & forth until both pistons could be pulled out by hand. Both pistons were cruddy with black sticky stuff as well as the outer part of the caliper bores. Some 400 grit sandpaper took care of cleaning/polishing the pistons & a careful scraping with a pick cleaned the caliper bore areas being very carefull to not damage the seals which stayed in the bores. Reassembled the calipers and rebled the system and all was good! Brakes worked smooth & the pistons retracted properly.    

I would advise against using PB or any other penetrant on the brakes. Also don't get brake cleaner on the rubber seals if you intend to reuse them. Lube & clean with brake fluid and clean rags.

[FLAVALK]

Had a similar problem on Kim's LF caliper. Seems it was very reluctant to retract which is the same problem you have. What I found was there was a lot of crud built up on the pistons and outer part of the caliper bores. After removing the caliper I tried to use air pressure to get the pistons out..... No dice, you could get one out but then how do you blow the 2nd piston {the worst stuck one} out?
Solution, put the piston back in & use the brake systems own hydraulic pressure to push them out. Used a C-clamp to equalize the pistons, switching back & forth until both pistons could be pulled out by hand. Both pistons were cruddy with black sticky stuff as well as the outer part of the caliper bores. Some 400 grit sandpaper took care of cleaning/polishing the pistons & a careful scraping with a pick cleaned the caliper bore areas being very carefull to not damage the seals which stayed in the bores. Reassembled the calipers and rebled the system and all was good! Brakes worked smooth & the pistons retracted properly.    

I would advise against using PB or any other penetrant on the brakes. Also don't get brake cleaner on the rubber seals if you intend to reuse them. Lube & clean with brake fluid and clean rags.

I will give your solution a try this weekend. I decided a long time ago that nothing is easy anymore.....at least not for me.  

[hubcapsc]

Had a similar problem on Kim's LF caliper. Seems it was very reluctant to retract which is the same problem you have. What I found was there was a lot of crud built up on the pistons and outer part of the caliper bores. After removing the caliper I tried to use air pressure to get the pistons out..... No dice, you could get one out but then how do you blow the 2nd piston {the worst stuck one} out?

The block-of-wood handles that too... the "unstuck" one only comes out so far, air is still pushing on the stuck one... after both come out
some, remove one of the blocks of wood and repeat...

-Mike

[cutter]

Did this job this past weekend. I pull the caliper off of the bracket with out removing the banjo screw. No need to remove the tire. I use brake cleaner to clean the pistons before compressing them back in. I remove the reservior cover and use the old pads and clamp to compress the pistons in. Put the caliper back on then the pads. Couple pumps on the lever, check level and cover it back up.

[hubcapsc]

Did this job this past weekend. I pull the caliper off of the bracket with out removing the banjo screw. No need to remove the tire. I use brake cleaner to clean the pistons before compressing them back in. I remove the reservior cover and use the old pads and clamp to compress the pistons in. Put the caliper back on then the pads. Couple pumps on the lever, check level and cover it back up.

I haven't tried taking the caliper off the bracket yet... it would be nice to skip the tire removal.

Check out this picture (same one as above)... I cleaned the snot out of everything, and then used compressed air to
pop the pistons out some... I believe you're mashing contamination back into your caliper...



-Mike

[FLAVALK]

Did this job this past weekend. I pull the caliper off of the bracket with out removing the banjo screw. No need to remove the tire. I use brake cleaner to clean the pistons before compressing them back in. I remove the reservior cover and use the old pads and clamp to compress the pistons in. Put the caliper back on then the pads. Couple pumps on the lever, check level and cover it back up.

I haven't tried taking the caliper off the bracket yet... it would be nice to skip the tire removal.

Check out this picture (same one as above)... I cleaned the snot out of everything, and then used compressed air to
pop the pistons out some... I believe you're mashing contamination back into your caliper...



-Mike

Mike, how did you attach the air line to the banjo fitting? Also, did you replace the seals?

[hubcapsc]

Mike, how did you attach the air line to the banjo fitting? Also, did you replace the seals?

Once the caliper was off the bike, and the hydraulic line no longer attached, I just
held one of these where the banjo bolt goes and let 'er rip...



Those pistons will (hopefully) come flying out of there like bullets, so something to do the job
of the pieces of wood is important. And compressed air and a caliper with residual fluid makes
for a good time to have safety glasses on...

Different nozzles have different shaped tips, the tapered tip on the nozzle I have was a really
good fit, I could hold it on there tight and not buggar up the banjo bolt threads...

I've removed pistons from calipers numerous times this way. My father's bladder-type painting
compressor almost never works. Neighbor Dan's 10ish-gallon direct-drive compressor sometimes
works, and the big bad compressor down at the NAPA store's machine shop always worked <g>.

-Mike