front brake is weak.


Information and questions on GL1200 Goldwings (1984-1987)
  • Sponsored Links
User avatar
lovemyzx9r
Posts: 34
Joined: Thu Jun 28, 2012 9:09 pm
Location: Cincinnati, Ohio
Motorcycle: 1984 gl1200 interstate
1984 700 magna
2000 kawi zx9r

front brake is weak.

Postby lovemyzx9r » Thu Jun 28, 2012 9:31 pm



hi, this is my first post here. i have found this site extremely helpful. thanks for all the info! I am working on my dads 84 gl1200i 50k mi. he has taken it to two mechanics to fix the brakes and they have not made it better. I have rebuilt the front master cylinder, taken the caliper pistons out and cleaned them, replaced the pads and bled the whole system. The front brake still doesnt have any feel until half way into lever pull, vast improvement but still not to my standards. My bikes have much better pull and feel (84 magna, 00 zx9r). I noticed the dust seal and piston seal on the caliper are extremely hard and the pistons don't move as freely as my other bikes. Would the seals being hard cause the brake to feel weak? or is there still just an air bubble since the pull is slightly inconsitent? thanks ahead of time for any help! i have to get this sorted by next friday as he is leaving on a week long trip through the ozarks and i want him to have excellent brakes being in the mountains. before front brake wouldn't stop bike, barely slowed it, lever pulled all the way to grip. Now the brake stops the bike from 60 in about a quarter mile and the lever pulls until its about 1/8 in. from grip. thanks again!



User avatar
WingAdmin
Site Admin
Posts: 17050
Joined: Fri Oct 03, 2008 4:16 pm
Location: Strongsville, OH
Motorcycle: 2000 GL1500 SE
1982 GL1100A Aspencade (sold)
1989 PC800 (wife's!)
1998 XV250 Virago (sold)
2007 Aspen Sentry Trailer

Re: front brake is weak.

Postby WingAdmin » Fri Jun 29, 2012 9:25 am

Absolutely the caliper piston seals can cause this sort of problem. The pistons should slide very easily in and out of the caliper. I would replace the caliper piston seals, make sure the pistons AND caliper cylinder walls are spotless, lube everything up with brake fluid, and slide the pistons in - they should slide in very easily. If not, you may have to clean some more. Make sure also that you clean the channels that the seals live in very thoroughly - crud will build up in there, and will cause the seals to push out on the pistons too far.

Once you have it back together and bled, pump the brake lever a few times, then pull the brake lever in to the handlebar and tie it there. Leave it for a few hours.

That should all strengthen up your brakes. You can make them even better, but that requires replacing the old, swelling rubber brake lines with new braided stainless brake lines. Look at this link from HEL for a good option on doing this.

Honestly, putting stainless brake lines on my 1100 made it a whole new bike - the brakes became strong and powerful instead of weak and mushy.

User avatar
lovemyzx9r
Posts: 34
Joined: Thu Jun 28, 2012 9:09 pm
Location: Cincinnati, Ohio
Motorcycle: 1984 gl1200 interstate
1984 700 magna
2000 kawi zx9r

Re: front brake is weak.

Postby lovemyzx9r » Fri Jun 29, 2012 10:29 pm

thanks alot... i have ordered new seals and will look into brake lines. can't wait to get it fixed and take it the mechanics and show them how incompetent they are!!!!!! you rock man!!!!!!! ill have her stopping like a ninja in no time. and i was about to make a bracket and put 6 piston calipers on it... lol

User avatar
patbrandon1
Posts: 442
Joined: Mon Mar 26, 2012 1:39 am
Location: Bay City, Michigan
Motorcycle: 1982 GL1100 I
1981 Honda CM400C

Re: front brake is weak.

Postby patbrandon1 » Tue Jul 03, 2012 4:46 pm

lovemyzx9r wrote:thanks alot... i have ordered new seals and will look into brake lines. can't wait to get it fixed and take it the mechanics and show them how incompetent they are!!!!!! you rock man!!!!!!! ill have her stopping like a ninja in no time. and i was about to make a bracket and put 6 piston calipers on it... lol


To me, the most critical part of the rebuild of the caliper was cleaning the channels for the seals. Yes it is important to have the pistons and such very cleaned and polished. If these channels aren't cleaned out totally, the seal will hold the pistons. I have had to take one apart and re-clean it on my very first rebuild attempt. In the pic that I have included from one of Wingadmin's how to's, you will notice a tool he is using to clean it. I used a steel nail file that I bent the tip of to a 90 degree angle to get into it well. Just make sure, whatever you use, that the channels are completely clean. His polishing technique are also very helpful, and must be done well for them to slide as needed.
Attachments

User avatar
WingAdmin
Site Admin
Posts: 17050
Joined: Fri Oct 03, 2008 4:16 pm
Location: Strongsville, OH
Motorcycle: 2000 GL1500 SE
1982 GL1100A Aspencade (sold)
1989 PC800 (wife's!)
1998 XV250 Virago (sold)
2007 Aspen Sentry Trailer

Re: front brake is weak.

Postby WingAdmin » Thu Jul 05, 2012 3:05 pm

patbrandon1 wrote:To me, the most critical part of the rebuild of the caliper was cleaning the channels for the seals. Yes it is important to have the pistons and such very cleaned and polished. If these channels aren't cleaned out totally, the seal will hold the pistons. I have had to take one apart and re-clean it on my very first rebuild attempt. In the pic that I have included from one of Wingadmin's how to's, you will notice a tool he is using to clean it. I used a steel nail file that I bent the tip of to a 90 degree angle to get into it well. Just make sure, whatever you use, that the channels are completely clean. His polishing technique are also very helpful, and must be done well for them to slide as needed.


This is 100% correct. Any debris left in those channels will push the seals out into the pistons. There are VERY tight tolerances there, and if a seal is pushed out, it will bind the piston.

I'm using a dull-tipped tool there to clean them out, to avoid scoring the channels (they're relatively soft aluminum). A plastic (or even wood) tool that is incapable of scoring aluminum would be even better.

User avatar
lovemyzx9r
Posts: 34
Joined: Thu Jun 28, 2012 9:09 pm
Location: Cincinnati, Ohio
Motorcycle: 1984 gl1200 interstate
1984 700 magna
2000 kawi zx9r

Re: front brake is weak.

Postby lovemyzx9r » Fri Jul 06, 2012 1:37 am

i got it working... i started another thread because i had another problem. about the caliper moving. thanks guys. saved vacation!




Return to “GL1200 Information & Questions”




Who is online

Users browsing this forum: No registered users and 1 guest