How do I remove the bolts that keep the caliper together?

[Noreg]

I finally managed to get the rear caliper off (the trick is to first remove the cotter pin thing in back and then remove the brake holding bolt). I managed to do so without spilling brake fluid on my tyre too, so good thing I did it by intuition rather than by following youtube.

I got the caliper clear, and I got the breather bolts off. But these ones will not move:


I am pretty sure I will break my yuge ikea wrench before they come off (I would not mind, it was cheap). I tried penetrating oil, it doesn't do anything.

Should I use my hot air thing? How hot air does it need? I have a torch too.

Any other tricks?

[Rijko]

i usually put it back on the bike so it sits solid.
Then you will get them loosened most of the time.
Looks like yours have been painted so paint may help the bolts refusing to turn.
Sometimes a few taps with a hammer on the tool will help persuade.
A bit of heat may help soften the paint up.

And if nothing works, get a bigger hammer

[Noreg]

i usually put it back on the bike so it sits solid.
Then you will get them loosened most of the time.
Looks like yours have been painted so paint may help the bolts refusing to turn.
Sometimes a few taps with a hammer on the tool will help persuade.
A bit of heat may help soften the paint up.

And if nothing works, get a bigger hammer

You attach it the wrong way? the bolts are towards the wheel attached normally.

I tried some more penetrating oil, will let it sit for a bit.

[Rijko]

You attach it the wrong way?

yes, any way i can, just check nothing gets pinched or crushed.
I prefer this to a vice, since it's simple and holds the caliper well in place while i put force on the bolts.

[Noreg]

yes, any way i can, just check nothing gets pinched or crushed.
I prefer this to a vice, since it's simple and holds the caliper well in place while i put force on the bolts.

I tried it, attaching them the wrong way doesn't work (there is no threads in the metal thing they are attached to. I stuck some extensions through the hole, but then I just moved the entire attachment thing. The other way my tool won't fit (only the long end, so no leverage).

Tried sticking it in the vice, I am fairly sure the vice would give before the bolt table is sort of flimsy), I am worried about breaking my tools and splinters going everywhere. I think I need a better tool.

I wonder if acetone will strip the paint of it...

Edit: I think Ill have to go tomorrow and get a longer tool, and 1/2" hex bits

[Grimly]

Heat it locally, where the bolt threads are in the other half of the caliper.
Use a small butane torch.
Hell, use a big butane torch if you're replacing the seals anyway.

[hillsy]

An air impact / rattle gun should make short work of them. You can even hold the caliper in your hand (wrap it in a shop rag).

[chuck hahn]

wrap it in a rag and lock it in a vice.

[Noreg]

I went to wurth and got hex half inch bits, the finest penetrating oil they had to offer and a 600mm torque arm. Attached the caliper to the bike and used the extension from the ratchet set. It freed them right up. Impresdively easy with longer arm ( pretty sure I can break the half inch attachment thing with that length).

There seems to be rust inside my calipers. The o ring between them is a non round kind.

Now I wonder how to get the pistons out. They appear to be stuck.

[Rijko]

You learn as you go , could have done that before you got the caliper off ...
but that's a lesson learned for the front brakes, right ?

several ways to do this :

- There are special tools that clamp inside the pistons to get them out.
- you can blow air from a compressor in them (watch your fingers they come flying out sometimes)
- or connect the brake hose back on and use your brake to pump them out.

[Noreg]

You learn as you go , could have done that before you got the caliper off ...
but that's a lesson learned for the front brakes, right ?

several ways to do this :

- There are special tools that clamp inside the pistons to get them out.
- you can blow air from a compressor in them (watch your fingers they come flying out sometimes)
- or connect the brake hose back on and use your brake to pump them out.

In retrospect that makes a lot of sense. I am at work now so Ill try the brake hose reconnect method when I get home. Will it work without brake fluid in the system?

I was thinking of just clamping the piston in the vice and pulling it off. Im assuming they are not something I should restore.

I dont have a compressor, but I do have co2 cannisters, but I dont see how to attach the nossle to the caliper. I have the thing to inflate my bicycle.

Edit: is dot4 dot4 always or os there differences between brands?

[mehall2]

Noreg - like you I’m a cyclist and a GS rider. I’ve had some luck with prying pistons out by using 2 bike tire levers at the same time on opposite ends of the piston lip. It takes some fiddling but I found my blue park tool levers worked best. Plus they’re plastic and will not scar the lip of the piston. If the corrosion has them locked in well, you may need some other methods. Good luck.

[Noreg]

Noreg - like you I’m a cyclist and a GS rider. I’ve had some luck with prying pistons out by using 2 bike tire levers at the same time on opposite ends of the piston lip. It takes some fiddling but I found my blue park tool levers worked best. Plus they’re plastic and will not scar the lip of the piston. If the corrosion has them locked in well, you may need some other methods. Good luck.

I tried this first, as I had tire levers lying around and it seemed to be easiest. It worked a charm. First I pried it up, then I flipped the caliper pieces upside down and pushed with the tyre levers, and they popped right out.

Now I just need to clean this rusty mess. Acetone?

[Rijko]

In retrospect that makes a lot of sense. I am at work now so Ill try the brake hose reconnect method when I get home. Will it work without brake fluid in the system?

NO, you need fluid in there.

I was thinking of just clamping the piston in the vice and pulling it off. Im assuming they are not something I should restore.

Did you order new pistons ? The usual repair kits have just the rubber parts.
Clamping the piston in a vice will damage it if you are not very, very careful.

I dont have a compressor, but I do have co2 cannisters, but I dont see how to attach the nossle to the caliper. I have the thing to inflate my bicycle.

If you can think of a way to connect the pump to the caliper that should work.
Some use a grease gun to pump out the pistons.

Edit: is dot4 dot4 always or os there differences between brands?

DOT4 is a specification. Any DOT4 brake fluid will do.

[Noreg]

I put them in a bucket with acetone, seems to be getting most of. Any special chemicals I should invest in? Would love something that also takes the paint off.