rear caliper rebuild fail


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quasi2008
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Joined: Fri Oct 05, 2018 12:18 pm
Location: morgantown wv
Motorcycle: 1982 GL1100I INTERSTATE

rear caliper rebuild fail

Post by quasi2008 » Tue Nov 20, 2018 6:28 pm



took bike out for the first test ride the other day, rear brake felt a little soft. had rebuilt all calipers, installed all new stainless lines. rebuilt the master cylinders, new pads. did it up right. at least I thought I did. turns out when I installed the new pistons in the rear caliper the outer O rings got damaged. how I don't know, but I did something wrong. I used the red grease that was with the kit. maybe I should've just used brake fluid? any advice on preventing tearing up the next set of O rings? tks.


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WingAdmin
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Motorcycle: 2000 GL1500 SE
1982 GL1100A Aspencade (sold)
1989 PC800 (wife's!)
1998 XV250 Virago (sold)
2007 Aspen Sentry Trailer

Re: rear caliper rebuild fail

Post by WingAdmin » Tue Nov 20, 2018 10:05 pm

quasi2008 wrote:
Tue Nov 20, 2018 6:28 pm
took bike out for the first test ride the other day, rear brake felt a little soft. had rebuilt all calipers, installed all new stainless lines. rebuilt the master cylinders, new pads. did it up right. at least I thought I did. turns out when I installed the new pistons in the rear caliper the outer O rings got damaged. how I don't know, but I did something wrong. I used the red grease that was with the kit. maybe I should've just used brake fluid? any advice on preventing tearing up the next set of O rings? tks.
I always just use brake fluid. Make sure that the channels in the caliper are COMPLETELY clean of any dried brake fluid gunge, so that the seal is fully seated in the channel. I then lube up the seals with brake fluid, and coat the piston liberally in brake fluid. If everything is correct, you should be able to push the piston into the caliper easily with just your thumb.

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quasi2008
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Re: rear caliper rebuild fail

Post by quasi2008 » Tue Nov 20, 2018 10:31 pm

Thanks for the info. I actually had a little trouble getting the pistons in. used a dull 90 degree pick to clean the grooves. also scrubbed them with a toothbrush. the pistons still went in with some difficulty. took more than just thumb pressure to. the front calipers went together with ease. but I used the old pistons, just cleaned them up. got a nice bike that is purring like a kitten, but the brakes have been my biggest headache on this thing. tks,
man can't live on air alone!

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WingAdmin
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Posts: 19691
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Motorcycle: 2000 GL1500 SE
1982 GL1100A Aspencade (sold)
1989 PC800 (wife's!)
1998 XV250 Virago (sold)
2007 Aspen Sentry Trailer

Re: rear caliper rebuild fail

Post by WingAdmin » Wed Nov 21, 2018 8:54 am

quasi2008 wrote:
Tue Nov 20, 2018 10:31 pm
Thanks for the info. I actually had a little trouble getting the pistons in. used a dull 90 degree pick to clean the grooves. also scrubbed them with a toothbrush. the pistons still went in with some difficulty. took more than just thumb pressure to. the front calipers went together with ease. but I used the old pistons, just cleaned them up. got a nice bike that is purring like a kitten, but the brakes have been my biggest headache on this thing. tks,
I had the same problem with the rear brakes on my 1100 the first time I rebuilt the calipers. There was a TON of crud in those channels, and I hadn't completely removed all of it. Even the smallest amount makes a a difference. I also had quite a bit of pitting and corrosion on my pistons. I sanded them by hand, first with 250 grit paper, and working my way up to 1500 grit, so that they were as smooth as I could get them.

Today, I would probably just replace them with a set of stainless pistons from Wingovations but they weren't available back then.

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quasi2008
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Location: morgantown wv
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Re: rear caliper rebuild fail

Post by quasi2008 » Wed Nov 21, 2018 9:12 am

WingAdmin wrote:
Wed Nov 21, 2018 8:54 am
quasi2008 wrote:
Tue Nov 20, 2018 10:31 pm
Thanks for the info. I actually had a little trouble getting the pistons in. used a dull 90 degree pick to clean the grooves. also scrubbed them with a toothbrush. the pistons still went in with some difficulty. took more than just thumb pressure to. the front calipers went together with ease. but I used the old pistons, just cleaned them up. got a nice bike that is purring like a kitten, but the brakes have been my biggest headache on this thing. tks,
I had the same problem with the rear brakes on my 1100 the first time I rebuilt the calipers. There was a TON of crud in those channels, and I hadn't completely removed all of it. Even the smallest amount makes a a difference. I also had quite a bit of pitting and corrosion on my pistons. I sanded them by hand, first with 250 grit paper, and working my way up to 1500 grit, so that they were as smooth as I could get them.

Today, I would probably just replace them with a set of stainless pistons from Wingovations but they weren't available back then.
i used the kit with pistons from Brake Crafters. i think it is a good kit, but i messed up. think i will boil it in some vinegar solution. tks,
man can't live on air alone!

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quasi2008
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Re: rear caliper rebuild fail

Post by quasi2008 » Thu Nov 22, 2018 9:39 am

when I bought the bike I ended up driving back over into Maryland to get the rear caliper. the caliper had already been stripped. well, whoever stripped it evidently hammered on edges of the piston holes. both of the outer O ring grooves have been messed up, as in to narrow. didn't notice it when I was "attempting" the rebuild. so now I got to source a replacement rear caliper. that should be fun. these things appear to be as rare as a chicken with a full set of teeth. Happy Thanksgiving everyone!
man can't live on air alone!

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quasi2008
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Re: rear caliper rebuild fail

Post by quasi2008 » Fri Nov 23, 2018 7:35 pm

well, not to be outdone by a ruined caliper because some idiot doesn't know proper procedures, I looked around at what tools I have left after over 30 years in the collision industry and I spotted my little Dremel again! a couple of the little sanding discs and about 5 minutes and the top edge of both outer grooves dressed up rather nicely. caliper is installed with all new O rings again, bled and appears to be no leaks around the pistons. pedal is firm.


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