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Discussion Starter #1
I have a 1987 GL1200 Standard. My rear brake has been dragging. I have taken the master cylinder apart and checked the small port and put a small piece of wire through it. It is clear. I have cleaned the pistons in the caliper and replaced the rear brake line rubber hose with new, flushed with new brake fluid, cleaned the slider bolt in the caliper which is free, and the brake is still dragging! Ughh! Any suggestions? Maybe time for new master cylinder or new caliper?
Thanks,
Gary
 

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When you have the caliper in your hand but still connected to the hydraulik system on the bike you should see the piston move out when you apply pressure to the brake , AND THE MOST IMPORTANT , - when you release pressure the piston should restract a little ( around 0,1 mm.) If the piston dosnt retract there is something wrong , most common is dirty caliper or piston .
 

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You have to do much more than clean the pistons ( 600 and 1200 grit sandpaper ? )
And if pistons do not shine up completely ? Check them over the fence ...

See here, for instance for other steps :
http://goldwingdocs.com/forum/viewtopic.php?t=44

As it was explained to me, the retraction ( by .1mm ) is caused by a square cross section O ring in the pistons ... when the piston comes out a bit, the square ring is distorted just a bit, and as it straightens back, it pulls the pistons back a bit . ( That and probably back pressure in the lines ).
so ...
you have to gently gently ( plastic tool ) pry the rings out of the groves ( step #20 ) and gently clean out the channel... carefully with a dental pick , perhaps ( step #22)... its fiddly and time consuming .

if the seals look at all crappy, new seals and new dust seals are essential ... Thick seal in lower grove, upper seal with thin ridges inward ..

Pivot bolt also need to be completely shined up with fine sandpaper , and well greased with high temp grease as well ... You already did that part .

If its all properly done, spinning the wheel, applying brakes , and then re-spin . If it grabs still after release , you are not finished cleaning up every moving part ...
But all this fiddly work is still cheaper than a new caliber unit $200 for complete piston and seal kit for all three, #300 for a pair of "new" calibers .

AGH

SilverDave
 

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According to this very useful article :
http://www.dansmc.com/hydraulics3.htm

There are 3 possible reasons for brakes to drag , depending on whether its a double sided or single sided caliber :

1) The very important square section o-ring is worn , or old and no longer causes " spring back" of the piston
( It could also be sitting in a very dirty groove )

2) The slider pin is corroded , dirty , or bent , and the entire caliber unit cannot slide in and out the 0.1 mm needed to get the pads off the disk.
Shine it up with fine sandpaper, and check the slider tube as well. It should go in and out with just a finger push .

3) Finally ( Rare ) the disk is slightly bent. Check for run out of the wheel and disk in the shop, not on the bike .

To which I would add a forth : The Motorcycle gods don't like you . Get one of those little highway bells ,
or regain Karma by stopping roadside to help a stranded Harley ....

http://www.ebay.ca/itm/Highway-to-Hell-Guardian-Bell-Motorcycle-Harley-Luck-Gremlin-Ride-/381844787874?hash=item58e7b912a2:g:ZlAAAOSw44BYJJqR&vxp=mtr


LOL

SilverDave
 

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When the brake is dragging can you rotate the wheel with bike on centerstand with your hand? If you can't rotate the wheel try cracking the line loose to see if that helps you rotate the wheel? You could do the same with the bleeder screw but beware. The bleeder screw can rot shut and confuse you. If you use the bleeder maybe remove it completely and then try rotating the wheel.
 

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Discussion Starter #11
Thank you Silver Dave, Dennis, Redwing, and Ken. Gonna try a new seal kit. Dennis, I have cleaned and greased the sleeve. It moves freely. Ken, A Goldwing 1200 standard is not the Interstate or Aspencade. It is a base version bike without the full fairing. Just has a windshield...
 

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Thank you Silver Dave, Dennis, Redwing, and Ken. Gonna try a new seal kit. Dennis, I have cleaned and greased the sleeve. It moves freely. Ken, A Goldwing 1200 standard is not the Interstate or Aspencade. It is a base version bike without the full fairing. Just has a windshield...

What Ken is referring to is the year. The standard model was only made in '84.
 

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Discussion Starter #14
Update :
Pulled caliper again. Rebuilt with new pistons and seals. All working fine now....
Thanks for your advise...
Gary
 

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Discussion Starter #16
Hi Tom,
The pistons had some signs of pitting in them. I didn't like them so just decided to change everything! Pads too...
 
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