It's been a month since I was attacked by a car resulting in a torn rotator cuff. Although I'm unable to ride, I've been firing up the bike once a week and doing one arm cleaning and waxing.

Last week I noticed that the front brake lever was stiff. I gave it some thought, knowing that this was not a good sign but covered the bike back up for the time being. Today I gave it a closer look and noticed the caliper is frozen shut with the brake pads squeezing the rotor. Did a bit of research and it sounds like the piston is stuck in place. Could be from the bike sitting in the cold rain for the past week, or just because it's a 22 year old bike. The brake line parts are pretty rusted also.

I'm guessing that I'm not going to get out of this without removing the caliper and trying to get the piston free so I can clean it out. Not an easy task, especially with one arm. I was going to replace the pads before my surgery next week, but it seems like I'm in for a total tear down of the front brake system, including a bleed.

I'm also thinking that it may be easier to just replace the caliper with a newer used one, and clean out the old one when I'm a bit more healthier. I'm fairly certain the one on there is the original.

I'll be totally out of commission for 1-2 months after surgery and won't be able to perform this type of work.

Any tips on getting this done the simplest way possible would be appreciated.

Thanks in advance for any suggestions.

Could be froozen. Try the hair drier on it.

Dj12midnit wrote on 10/19/09 at 17:25:28:


Joe,
 He must know the weather here on the east coast.....  

The Salt air of living a few blocks away from the Atlantic ocean and the wonderful weather we have had lately probably caused some corrosion build-up.

So, as a Photo wizard (award winning I must add to those that don't know) do you have alcohol laying around?  (90% or better).  You'll need it to clean up after I tell you what you need to do.  

This advice is coming from a "Fixer".  

- Get a old plastic 35mm flim holder (thingy, can, container ... pick a name).

- Spray wd-40 into it to get a nice puddle in there.  

- Take the straw that came with the WD-40, or use one from a used Aero-Duster.  Put one end in the WD-40 and hold your finger over the other end.  

- While still holding the end with your finger, go to the piston of the brake caliper and put a drop of WD-40 there, making sure not to get any on the pads.   Repeat several times making sure you do not get any on the brake pads and get WD-40 all around the piston.

- Take an old tooth brush and clean the damp crud off the piston.

- Repeat the drops again and let sit over night.

- Next day, take a rubber mallet, or wood block & hammer and slightly tap the brake caliper to gently push it in a tiny tiny bit.

- Try to move bike.

-If it moves next step is to take the caliper off, pads off and then clean, clean, clean.   The Alcohol will get rid of the WD-40 nicely.  Brake-Cleaner would work too but knowing your profession, I think you can get alcohol easier (cheaper).

Use the some scotch-brite to clean the rust off the brake rotor.

Obviously the easiest way is if the penetrating oil just works and unsticks the caliper for you.  

But failing that, the caliper will have to come off and take a nice long bath in used motor oil.  Verrry carefully heat it in the oil, on the stove if your wife will let you.  That will loosen the piston & seal possibly to the point you can work it out by hand.  If not, a little compressed air in the brakeline hole will shoot it out of there in no time (seriously, use a soft piece of wood to stop it).
EDIT - this can be dangerous.. use only a little squirt of air, then another method if the piston is still stuck.

This assumes the problem is the caliper.. crack open the air bleed and make sure it's not the master cylinder as jabman suggests..

If the piston is sticking in the caliper, & assuming you already have it off the disc, remove the pads, wrap caliper in old  towel & apply pressure to master cyl. lever slowly. The piston will pop out & the towel will catch the mess. You may have to pump the lever a couple of times to push the piston out. This has always worked for me.

I have never tried it, but I have read that you can use a grease gun to remove a stuck piston from a caliper. I presume one would remove the brake line, install a Zerk, and pump away. The grease gun will generate a lot more pressure than the usual air compressor. Of course, you will then have a caliper full of grease which will have to be carefully cleaned out.

I have to agree with that.. using a liquid or grease to push the piston out is a much safer way to do it, just because liquids don't compress.  If the piston is really stuck tight and you jack up the air pressure to 120psi, then it does let go..  you've set off a large caliber airgun there.  Sorry for the dangerous suggestion.

I took my caliper down to the gas station air compressor and no luck getting that piston out, thanks for all the good ideas though, I'll try hooking it back up and filling it back up with brake oil and pushing it out with the brake, I know it's going to be a mess though!