Cleaning Brake Caliper Seal Grooves

[twr1776]

I am rebuilding the rear calipers on an 850 and the grooves that the piston seal rides in have some gunk in the bottom that does not want to come out only using brake fluid to clean with as the service manual recommends. What have you used to get the grooves clean? I think the calipers are made of aluminum so I do not want to use anything that is too abrasive and take a chance on ruining them. Thanks for any help.

 

[longgreensilverado]

I've rebuilt many brake calipers. i know exactly what you mean by "gunk". I use steel wool and dental tools to lightly scrape away the hard spots. i also use a lot of scotch brite. take your time and be paitent

 

[SPARKSS]

I am rebuilding the rear calipers on an 850 and the grooves that the piston seal rides in have some gunk in the bottom that does not want to come out only using brake fluid to clean with as the service manual recommends. What have you used to get the grooves clean? I think the calipers are made of aluminum so I do not want to use anything that is too abrasive and take a chance on ruining them. Thanks for any help.

Unless you get that "gunk" out of the grooves, you have junk (as the seal may not work correctly or worse....binding the piston perhaps). You can clean or at least break this stuff up with a hand-held hacksaw blade only......just lightly work the teeth through the stuff breaking it up, then reclean with brake fluid. This is NOT a vice and 2 handed-hacksaw operation......just light cleaning.

Have fun

 

[twr1776]

Thanks for the response, I did use the scotch brite pads and still have some leftover gunk. Do you use the 0000 wool? I was also wondering if PB blaster would also help to break up the junk as well without hurting the base material.

 

[Nessism]

I recently cleaned out a brake caliper and mechanically picked the chunks out with a scraper tool. Followed up with fine grit scotchbrite. To clean out all the debris I used liberal doses of brake cleaner spray. Brake cleaner does not leave behind a residue so it's okay to use as long as you wait for it to dry throughly before putting the caliper back together again.

 

[matt_gs450]

Also rebuilding a caliper

Also rebuilding a caliper

I'm rebuilding the front brake caliper for my 81 gs450 T. This is what the gunk looks like for me. So far I've soaked it and went after it with a wire brush. There is still a lot of junk and I was a little worried about too much of the wire brush. After soaking it overnight, I'll start in with 0000 steel wool. Where do you get the fine scotch brite pads?

-Matt

Filthy caliper (picture taken before soaking and wire brushing):

 

[Nessism]

I'm rebuilding the front brake caliper for my 81 gs450 T. This is what the gunk looks like for me. So far I've soaked it and went after it with a wire brush. There is still a lot of junk and I was a little worried about too much of the wire brush. After soaking it overnight, I'll start in with 0000 steel wool. Where do you get the fine scotch brite pads?

-Matt

What are you soaking the caliper in and is that photo pre or post soak?

Scotchbrite pads are available at Lowe's and Home Depot's. You are going to want to scrape that crud out with a hard implement first though. Just becareful not to scrape the metal in and around the groove and you will be okay.

 

[first timer]

just got done rebuilding some with gunk too, what works well and is safe is, gentally use a pick and remove the seal inside the caliper, gentally remove all the oht rubber things too, then get a small bucket of kerosene and dip the caliper in there, pull it out use some good picks (sear craftsmen, they are priceless for old bike) and start gentally scraping away all the gunk, get a tooth brush and srcub around in there too, rinse in the kerosene and see whats left a pick some more, just keep doing that until all the grooves are clean, then just spray every thing down with some carb or brake cleaner to get rid of the kerosene residue. you can also use some #800 sand paper to smooth out the insides or the pistons if they are in pretty good shape.

i have found that Kerosene works pretty well on cleaning most bike things and is pretty gental and won't trash things.

 

[txironhead]

I use carb cleaner a lot (Tech 2000 Wal-Mart brand, I buy the stuff by the case) to clean bike parts, works great and doesn't leave a residue. Fantastic for degreasing parts prior to painting, too. However, prolonged exposure on painted parts will take the paint off, so unless you're planning on repainting the calipers I'd stick with kerosene or brake parts cleaner, although BPC will take paint off, too, if you use it enough.

If you're really, really careful, you can use a Dremel and a brass bristle wheel on LOW speed. I've resurrected "unsalvageable" calipers this way.

I would not recommend using steel wool on aluminum, as bits of the wool break off and imbed themselves in the aluminum and cause rust. Synthetic steel wool (Scotchbrite, basically) is great. I've used the generic, store brand Scotchbrite pads with great success. The generic ones tend to be a bit gentler than the actual 3M brand.

 

[49er]

When I did the rear caliper on my 850 recently, I used kerosene to soak it in and then shaped a piece of steel TIG welding wire with a right angle bend in it.
I carefully used it as a scraper in the groove until all the gunk was dislodged. Then I sprayed the caliper internals with brake cleaner and finished with compressed air, before re-assembling it with new seals.

 

[matt_gs450]

Right now I'm soaking it in brake fluid. I do have several of the other solvents mentioned by other posters but I'm not going to use them unless I have to. The picture was taken pre-soak and brush.

 

[first timer]

break fluid isn't going to cut it, all it's going to do is remove the paint from the calipers if you let it soak to long, that gunk is break fluid, you aren't going remove break fluid with break fluid. From your pictures it looks like you removed all the rubber already, kerosene and carb/break cleaner isn't going to hurt the aluminum or anything in the caliper. Another thing, that gunk isn't going to go away by soaking, you WILL have to get in there and clean things out with some sort of tool, most of the gunk is hardened brake fluid or oxidized aluminum. It's a simple break so don't be to scared or delicate with it, just be nice to the rubber seals.

 

[matt_gs450]

Point taken. I'm going to take it out of the brake fluid and drop it in the carb cleaner. I really don't care if the paint gets damaged. I assume I can repaint it later if I want. Also, I have an extra parts bike that I think I'll just steal the caliper from in the meantime.

 

[rustybronco]

Bent cotter pin and emery cloth.

 

[first timer]

i would be real carefull using that berryman style bucket of carb cleaner on those calipers for to long that is pretty strong stuff, i would use that as a last resort. i just used the spray stuff on that kind of work, use kerosene (bought at home depot) or some lacuer thinner first, and elboe grease.

 

[matt_gs450]

I've cleaned my caliper and the brake has been re-installed on the bike. The trick to removing the junk in the earlier picture was to soak the caliper in brake fluid all week. The soak turned the hard deposits spongy and I was able to pick and scrape them off with a dental tool. I also wadded up some steel wool and ran that through the seal grooves, and did the same with a bit of paper towel.

I followed all that up with a final soak in clean brake fluid and re-assembled. From the picture below, you can see that there is significant pitting in the o-ring groove. I assume it is either a result of corrosion or maybe some over-zealous cleaning by a previous mechanic. Hopefully it's not so bad as to render the caliper useless. So far the brake is working well but I'll keep an eye on it for any leaking brake fluid or other problems.

Oh, and the caliper did not turn green. That's the result of an amateur photographer.