Rebuilt front caliper leaking!!


Information and questions on GL1100 Goldwings (1980-1983)
Post Reply
User avatar
Doolin05
Posts: 28
Joined: Sun Jun 18, 2017 9:24 am
Location: Lake City MN
Motorcycle: 1980 GL1100

Rebuilt front caliper leaking!!

Post by Doolin05 »



Hi, I just finished rebuilding the front brakes on my 1980 gl1100 for the first time. I redid the master cylinder, new lines, and both calipers. Yesterday I put in new fluid and used a Mity vac to bleed them. Everything went fairly smooth, but this morning much to my dismay there was a big puddle of brake fluid under the bike. I have it up on a lift.I traced the leak to the left piston..I carefully removed the caliper and examined the pads, which seem to be dry, after removing those I removed the caliper, and popped the piston out....I have no clue as to what went wrong.
I got the rebuild kit from PartsnMore....anybody have this happen? The cylinder wall doesn't have any gouges I can see...does it make a difference which way the rubber gasket goes in the caliper? I put in dot 4 fluffy d instead of dot 3, would that matter?

Thanks


FM-USA
Posts: 2944
Joined: Wed May 18, 2011 8:40 am
Location: here, there, WHY?
Motorcycle: mc's

Re: Rebuilt front caliper leaking!!

Post by FM-USA »

My 1500 is a non directional square seal.
Yours might have partly rolled when pushing in the piston.
Check for crud in the caliper seals recess. A sharpened bent nail works getting into the corners.

Brake fluid lube the piston and seal then gently push the piston in while turning it in one direction.
IF it rolls again, push the piston in with a circular wobble motion. In essence you're walking the piston in.

BEST OF LUCK! ;)
User avatar
Doolin05
Posts: 28
Joined: Sun Jun 18, 2017 9:24 am
Location: Lake City MN
Motorcycle: 1980 GL1100

Re: Rebuilt front caliper leaking!!

Post by Doolin05 »

Thanks for the reply! Yes I pulled everything apart and then put the old rubber seal back in that caliper thinking maybe I'd gotten a fault new one. After rebleeding the brakes it seemed all was well. The next morning no puddle under wheel, but when I ran my finger under the calipers on BOTH sides it came away away wet with fluid...imagine my joy :(
So I'm looking at pulling everything apart, and starting over...I did order a new piston, and a caliper off of eBay as well. One thought that occurred to me was that maybe these seals just weren't designed to handle the increase in pressure that may result from the new stainless lines from Galfer i
put on the bike?

Best regards and thanks!
User avatar
Doolin05
Posts: 28
Joined: Sun Jun 18, 2017 9:24 am
Location: Lake City MN
Motorcycle: 1980 GL1100

Re: Rebuilt front caliper leaking!!

Post by Doolin05 »

BTW It is my thinking that these brakes should not leak ANY fluid if everything is togeather right...is that not so?

Thanks!
FM-USA
Posts: 2944
Joined: Wed May 18, 2011 8:40 am
Location: here, there, WHY?
Motorcycle: mc's

Re: Rebuilt front caliper leaking!!

Post by FM-USA »

Doolin5, My personal history on brake seals.

My front caliper seals lasted 200,000 miles. In that time I've pulled inspected and cleaned the seals and found them still usable. Around 140,000 miles I've reversed the fluid and dust seals with satisfactory results. At 200K mile mark the seals were becoming stiff and that was the reason for installing new ones, otherwise they were still working fine.

The pistons have become pitted and with steps of sandpaper 320/400/600 I've been able to refurbish said pistons and they have not leaked even though the pits were not completely removed. Said seals were doing a FINE job. The amount of material removed from the pistons was about 0.004 inch. The seals are still snug enough to hold panic stop pressures with the slightly smaller pistons.

Higher pressures due to S.S. lines? Not likely, you have a different issue. Molded rubber seals can have splits. Take them and twist, fold back, etc. to see if there is any.
ALSO, pistons can develop pinholes unseen during new inspections. Maybe a hairline crack?

BY ANY CHANCE did you put the dust seal as the brake seal? It's very easily done since they look identical.

.
User avatar
WingAdmin
Site Admin
Posts: 21989
Joined: Fri Oct 03, 2008 4:16 pm
Location: Strongsville, OH
Motorcycle: 2000 GL1500 SE
1982 GL1100A Aspencade (sold)
1989 PC800 (sold)
1998 XV250 Virago (sold)
2012 Suzuki Burgman 400 (wife's!)
2007 Aspen Sentry Trailer

Re: Rebuilt front caliper leaking!!

Post by WingAdmin »

My experience is the same - my pistons were pitted, but with successively finer sandpaper, ending up with 1500 grit, I polished them smooth, even though some of the pits still remained. There are now aftermarket stainless steel pistons available: Wingovations stainless steel pistons and if they had been available at the time, I would have replaced mine.

There could be several causes for leakage:

- mixing up brake seal and dust seal
- Not completely removing dried crud from seal grooves when cleaning the caliper
- rolling a seal during piston installation
- banjo bolt washer leak

Stainless brake lines will not increase the pressure - they just stop some of the pressure being used to expand the brake lines, making the brakes less spongy.
User avatar
Doolin05
Posts: 28
Joined: Sun Jun 18, 2017 9:24 am
Location: Lake City MN
Motorcycle: 1980 GL1100

Re: Rebuilt front caliper leaking!!

Post by Doolin05 »

Third time is the trick I quess...I took everything apart and really paid attention to cleaning out the grooves for the seals. I took a small screw driver and ground it a little smaller than the grooves and bent it 90 degrees, and was more generous with brake fluid to slick things up when I put in the Pistons. It's been 3 days and no leaks so I think I'm good to go...BUT, now I am getting fluid leaking ever so slightly from around the new reservoir I put on it from PartsnMore....I'm just gonna live with this and hopefully it will just go away eventually.
Thanks for the replies everyone!!

Now on to fixing the cracks in the windjammer...
FM-USA
Posts: 2944
Joined: Wed May 18, 2011 8:40 am
Location: here, there, WHY?
Motorcycle: mc's

Re: Rebuilt front caliper leaking!!

Post by FM-USA »

Doolin05 wrote: Sat Jul 22, 2017 10:05 pm Third time is the trick I quess...I took everything apart and really paid attention to cleaning out the grooves for the seals. I took a small screw driver and ground it a little smaller than the grooves and bent it 90 degrees, and was more generous with brake fluid to slick things up when I put in the Pistons. It's been 3 days and no leaks so I think I'm good to go...BUT, now I am getting fluid leaking ever so slightly from around the new reservoir I put on it from PartsnMore....I'm just gonna live with this and hopefully it will just go away eventually.
Thanks for the replies everyone!!

Now on to fixing the cracks in the windjammer...
Reservoir leaks is almost always the accordion seal, it's usually expanded a little and one or both of the two long sides don't lay flat for a good seal. I searched a cure for that expansion, many said to boil that rubber so it shrinks. It don't, buy it new and use DOT 4 fluid.
User avatar
Hoosier Jack
Posts: 419
Joined: Thu Oct 02, 2014 4:21 am
Location: Terre Haute, IN
Motorcycle: 1982 GL1100 Interstate

Re: Rebuilt front caliper leaking!!

Post by Hoosier Jack »

Agreed. Leaks invite air. Needs to be fixed.


Post Reply