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Brake Caliper.....Urrrr!

  • Thread starter Thread starter mavpsa
  • Start date Start date
M

mavpsa

Guest
Greetings,

So i decided to clean out the caliper and change out the piston seal, boot and axle holder boot. To get the piston out, i took the caliper to a mechanic down the street to blow air into the bleeder valve and remove the piston for me. He takes the caliper and puts the hose to the bleeder valver and before i can say anything, he removes the piston. Well, the force of the piston shooting out nicked the top metal lip where the piston boot fits ](*,). The piston itself is fine, it doesn't have any nicks or anything like that.

So, the question of the day is....am I screwed now? Will i have to get a whole new caliper???[-o<

Any help will be much appreciated. thanks in advance.
 
If it's just the lip that's nicked and not the part of the piston that slides into the bore you'll be fine - might need a tickle up with a fine file if there's a sharp edge that could cut the boot. Seen loads of really nasty looking lips where POs have tried pulling the pistons out with grips etc and they've been fine.
 
Maybe I'm not bright enough to know the correct way to free up a stuck caliper piston, but here's what I did with it:

Removed the caliper from the motorcycle, took the pads off and gently squeezed the brake lever 'till the piston popped out. Seemed less damaging than using a vise-grip to pull on it.
 
your supposta stick a small block of wood there to stop the piston from hitting the caliper and you can also shove some rage in between there to to soften the impact, watch out for your fingers that smarts.......
 
LarryA_Texas said:
Maybe I'm not bright enough to know the correct way to free up a stuck caliper piston, but here's what I did with it:

Removed the caliper from the motorcycle, took the pads off and gently squeezed the brake lever 'till the piston popped out. Seemed less damaging than using a vise-grip to pull on it.
Click to expand...

I used to use the compressed air method to pop the pistons out. But this required taking the caliper off, going to the gas station to use their hose. Yes, you can use the wooden block but using a thick rag absorbs the residual brake fluid from spattering everywhere when they pop out and keeps your fingers clear of holding a wooden block in place.
Now, I just unmount the caliper and using a wire hang it carefully with the hydraulic line attached, remove the pads, stuff a rag and start carefully squeezing the brake lever or pressing the brake pedal until they start moving out.
Before you pop them out completely, what I do is put a thick enough block of wood so there is some travel but not enough to pop the piston beyond the o-ring. Then I carefully position a c-clamp to squeeze the piston back in. If you do this you may find that a few times in and out is enough to free and lubricate a stuck piston. Otherwise it's time to take it all apart. Using the hydraulics you can control the rate of the proceess whereas the compressed they just come flying out!

NOTE: most calipers have 2 pistons, one on each side and whether you use the air or hydraulic method, one may pop first leaving you with no pressure to pop the other. The c clamp comes in handy again to keep one side from going to far and the pressure is now forced to the other piston.
NEVER use pliers or channel locks to try and yank out a piston as it's probably going to bugger it up. Maybe not enough to make it unusable, but.....
 
Last edited:
hampshirehog said:
If it's just the lip that's nicked and not the part of the piston that slides into the bore you'll be fine - might need a tickle up with a fine file if there's a sharp edge that could cut the boot.
Click to expand...
Ditto. Small file and some emery cloth. Just make sure you don't get the filings in the bore.


first timer said:
your supposta stick a small block of wood there to stop the piston from hitting the caliper and you can also shove some rage in between there to to soften the impact, watch out for your fingers that smarts.......
Click to expand...
A small piece of thin plywood or some thick cardboard will do it. A mechanic should have known better.
 
You know how it goes, a guy that knows how to run a spyware program suddenly feels that he is a computer tech and a guy who picks up a buffalo wrench feels that he is a mechanic.

There are parts changers an there are diagnosticians; ask to see their master tech certification card in their wallet. I carry mine along with the advanced level cert and EPA stuff as well. You don't leave home without it if you're any sort of professional.
 
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