Brake caliper rebuild - Suzuki GSX-R Motorcycle Forums Gixxer.com
 
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post #1 of 12 (permalink) Old 04-04-2010, 02:11 PM Thread Starter
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Brake caliper rebuild

Hi, so the season has started here in Denmark, so I have been working on the bike to get it ready, but I'm having some trouble with my front brakes.
The pin that holds the brake pads was seized in one of the calipers, and of course I broke it, so I had the Suzuki dealer drill it out, and in the process he poped the pistons out, and they had a fair amount of rust on the top, so I replaced all the pistons.

So I have put new seals and pistons in the calipers, and it all looks good, but I can't get all the air out of the braking system, I have tried 3 times now, but it's still not right, so could there be a leak by one of the pistons that allow air to enter but still keep the fluid inside ?

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post #2 of 12 (permalink) Old 04-04-2010, 02:29 PM
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Re: Brake caliper rebuild

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Originally Posted by mortenmorfar View Post
Hi, so the season has started here in Denmark, so I have been working on the bike to get it ready, but I'm having some trouble with my front brakes.
The pin that holds the brake pads was seized in one of the calipers, and of course I broke it, so I had the Suzuki dealer drill it out, and in the process he poped the pistons out, and they had a fair amount of rust on the top, so I replaced all the pistons.

So I have put new seals and pistons in the calipers, and it all looks good, but I can't get all the air out of the braking system, I have tried 3 times now, but it's still not right, so could there be a leak by one of the pistons that allow air to enter but still keep the fluid inside ?
Are you still getting air at the caliper bleeders?
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post #3 of 12 (permalink) Old 04-04-2010, 02:33 PM Thread Starter
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Re: Brake caliper rebuild

nope they are clean, but maybe there is an air pocket that doesn't want to move, I have tried zip tying the brake lever down over night, a little bit of air came out, but it's still not braking like it should.
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post #4 of 12 (permalink) Old 04-04-2010, 02:45 PM
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Re: Brake caliper rebuild

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Originally Posted by mortenmorfar View Post
nope they are clean, but maybe there is an air pocket that doesn't want to move, I have tried zip tying the brake lever down over night, a little bit of air came out, but it's still not braking like it should.
I had the same problem after my rebuild. The MC was my culprit. Yours may have an air bubble in it and need bleeding. The way I did mine was to cover up everything wanted paint to remain on and then loosen the master cylinder banjo bolt. Then I squeezed the lever, looking for bubbles in the fluid (of which there were plenty). Then while holding the lever, I tightened the banjo bolt, and then released the lever. I gave the master cylinder a few taps and then repeated the process until I had no bubbles. After that, I rebled at the calipers just to be sure, and I've had no problems since.

I heard that the vacuum bleeder was the best method, but that one worked pretty well for me.
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post #5 of 12 (permalink) Old 04-04-2010, 02:52 PM Thread Starter
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Re: Brake caliper rebuild

Okay I will give that a try tomorrow
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post #6 of 12 (permalink) Old 04-05-2010, 01:11 AM
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Re: Brake caliper rebuild

good advice: yeah, try to bleed it from the top banjo bolt. make sure to use plenty of towels/rags to absorb brake fluid. this method works for me.
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post #7 of 12 (permalink) Old 04-05-2010, 04:46 AM Thread Starter
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Re: Brake caliper rebuild

Stupid air :/, I think one of the bleeder screws are bad, but it could just be some leftover fluid that's coming out.
I will try and replace them both when the shops open tomorrow
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post #8 of 12 (permalink) Old 04-06-2010, 01:12 PM Thread Starter
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Re: Brake caliper rebuild

I think there are some air bubbles in the hose going to the left caliper, I tried to connect only one caliper at a time, and it was fine.. so I will wait for my mityvac and see if it can fix it
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post #9 of 12 (permalink) Old 04-06-2010, 03:06 PM
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Re: Brake caliper rebuild

hi my dad showed me a trick he's been a mechanic all his life he's now 60. start with the caliper furthest away from the master cylinder loosen the bleed nipple press the brake lever then when you go to let the brake lever out put your thumb over the nipple to create a seal this acts as a vacume drawing the fluid and air out of the system repeat this a few times filling the resevoir as you go and bingo some nice firm brakes dads you gotta love um
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post #10 of 12 (permalink) Old 04-14-2010, 05:46 AM Thread Starter
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Re: Brake caliper rebuild

Mityvac sucks big time :/
I think I have a problem with my master cylinder, I have used over 1L of brake fluid, and it's still not firm like it used to be.
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post #11 of 12 (permalink) Old 04-14-2010, 06:46 AM
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Re: Brake caliper rebuild

Clicky

Sometimes when you start fixing stuff, wear items will go ahead and give up the ghost. A cylinder rebuild is a good way to eliminate worn/worn out seals as the culprit, and it's cheap and relatively easy. If you rebuild, make sure you clean your cylinder bore thoroughly. Something I noticed when I took my brakes apart was that there was what looked like crystallized brake fluid gumming up the works. Also wet your seals with fresh brake fluid before you reassemble the master cylinder, and try to get as much air as possible out of the MC before you start bleeding at the calipers. Then bleed at the calipers, and come back to the MC to get those last little bubbles. A trick that may also help is gently tapping the MC with a screwdriver while you're bleeding it to dislodge any stubborn bubbles.
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post #12 of 12 (permalink) Old 06-08-2010, 11:24 AM Thread Starter
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Re: Brake caliper rebuild

Okay so I gave the bike to a dealer so he could look at it, turns out my spongy brakes was because my forks are bent, so the calipers doesn't seat right on the discs.
So I hope the forks I got from ebay are straight, otherwise it's going to get expensive :/
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