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Discussion Starter #21
Is the front also dragging? The rear and the front, don't remember left or right, are linked together. If both are dragging the problem would be the master cylinder, if only the rear it may be the rubber hose.

Thanks Dave,
Already replaced the rubber hose and rebuilt the caliper with new seals and pistons. The pedal returns all the way. Yes, the front brake drags as well. Although I took the master cylinder apart and ran a thin wire through the relief hole, it still drags. I'm pretty sure it is the master cylinder that is the issue. Didn't want to rebuild it to put it back on only to find the problem is still there. I'm tired of F*%#*ing with it! Was trying to buy a new one after market, but I guess no one sells them? May have to resort to buying a used one off from Ebay and hope for the best?
Thanks,
Gary
 

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Discussion Starter #22
To add to what Dave said also possible pedal linkage problem if it does not return all the way. Anything is possible on a 33 year old machine. Especially if it sat for some time.
Thanks Redwing,
See my reply to Dave below...
 

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Gary,
If both the front and rear act up it almost must be a master issue. That is assuming nothing really odd like both pistons are sticking etc. Not likely with all your work. What puzzles me is that if the hydraulic lines are not obstructed (and I doubt both are) once the fluid is returning to the master there are really only 2 possible issues. The fluid must return to the resevoir via the small hole and you say you have cleaned that hole. That is the hole in the cast iron part of the inlet of the master. You got that right? If the hole id open nad there are no kinks or obstructions between the master and reservoir the only other possibility I can think of is that the piston seal is not returning back far enough to let the fluid get back to the hole. If you are sure the pedal goes all the way up to the stop, I would ask if you adjusted the pushrod where it is too long? I know you ordered another and somehow I bet it fixes your issue but the original cause is vexing. Let us know if you find the root cause. Bore/piston corroded and dragging? Piston worn bad enough it cocks and hangs in the bore? Inquiring minds want to know....for the next Guy. :)
 

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Although I took the master cylinder apart and ran a thin wire through the relief hole, it still drags.
Are you sure you got the relief hole? There are 2 holes, the tiny ( I have to use magnification to see it) hole down in a larger hole is the relief.
 

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Discussion Starter #25
Are you sure you got the relief hole? There are 2 holes, the tiny ( I have to use magnification to see it) hole down in a larger hole is the relief.

Yes Dave, it was a very tiny hole that I could only fit a single strand of very fine wire into...
Nothing in the pedal or linkage has changed. The brake started dragging after sitting for an extended period. I removed the rear caliper and rebuilt it with new seals and pistons. Also cleaned and lubed the guide bolt and sleeve. That didn't fix it. I then replaced the rubber brake hose with a new one. That didn't fix it! Then removed the master cylinder and cleaned and poked wire into the relief hole. Installed new fluid and bled. That didn't fix it! I never touched the adjustment of the pedal. It has always been the same and it used to work properly. At this point I am looking to replace the master cylinder. It is the only thing I can think of...
 

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Discussion Starter #26
Gary,
If both the front and rear act up it almost must be a master issue. That is assuming nothing really odd like both pistons are sticking etc. Not likely with all your work. What puzzles me is that if the hydraulic lines are not obstructed (and I doubt both are) once the fluid is returning to the master there are really only 2 possible issues. The fluid must return to the resevoir via the small hole and you say you have cleaned that hole. That is the hole in the cast iron part of the inlet of the master. You got that right? If the hole id open nad there are no kinks or obstructions between the master and reservoir the only other possibility I can think of is that the piston seal is not returning back far enough to let the fluid get back to the hole. If you are sure the pedal goes all the way up to the stop, I would ask if you adjusted the pushrod where it is too long? I know you ordered another and somehow I bet it fixes your issue but the original cause is vexing. Let us know if you find the root cause. Bore/piston corroded and dragging? Piston worn bad enough it cocks and hangs in the bore? Inquiring minds want to know....for the next Guy. :)

Hi Redwing,
See my reply to Dave...
Thanks
 

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Discussion Starter #27
Had a 750 supersport that had all calipers rebuilt.when they reinstalled calipers on rear they left the shim washers off one caliper bolt it caused caliper to drag took weeks to figure out .

Thanks for your input 81MarineE5
 

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Hi Ken,
Not sure how you get to that conclusion? When bleeding the brakes, you are pumping fluid down the main tube and releasing it out the caliper. The return hole is not in use when sending fluid "To" the caliper or pressing Down on the pedal. as I understand it, it is only in use when the pedal is released? If in fact it is clear, then I am really stuck on why my brakes are dragging? I have done everything I can think of!...
Well I guess we beat this one to death, huh? The only thing that maes sense to me given all your efforts is that for some reason the piston is not returning far enough to get behind the little holes and let the fluid return as it should. One more question. How bad does it drag? Get the brakes smoking hot? A slight drag is normal of course, but you know that. :) Keep us informed on this puzzler. :)
 

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I had my driver front brakes stuck/dragging on my Dodge Dually, and rebuilt all the calipers while I had it down, and flushed the fluid. I "honed" out the cylinders on the stuck one (it had a bad/broken seal is why it went bad).

Well, a week later it stuck again. So I ordered a new caliper, and put that on (like most people do instead of trying to fix a stuck caliper). It's Ben two months and all is well. Those pistons fit so tight in the cylinders that any old grime can make them stick.

I'd try a new caliper.
 

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Discussion Starter #30
Well I guess we beat this one to death, huh? The only thing that maes sense to me given all your efforts is that for some reason the piston is not returning far enough to get behind the little holes and let the fluid return as it should. One more question. How bad does it drag? Get the brakes smoking hot? A slight drag is normal of course, but you know that. :) Keep us informed on this puzzler. :)

Hi Redwing,
Once the pedal is pushed, the brakes drag so heavily that I can barely roll the bike while in neutral! I have to crack the line to release the pressure. I'm going to try and get a used master cylinder and see what happens... Will let you know. Thanks
 

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You can get a rebuild kit for that master cylinder. If you are going to replace it, meaning you will have to remove it, might as well rebuild. There is no new replacement for that. Good luck on the removal it's a b---h. You didn't replace the rotors by any chance did you? Standards and Interstates use a 5MM width and the others have 10 MM rotors. I am currently rebuilding a 84 Standard myself, my second one.
 

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Interesting forum, but I was the only one visiting there today.

Thought I would check in while I was there, activity seems to be a bit low.


Welcome, AZgl1500 Last visit: 08-09-2016, 08:42 AM
Since then, there have been:
» 0 new announcements
» 74 new threads
» 357 new posts


This is the kind of thing that I have noted with forums that get Model Specific, they turn into Dinosaurs.

and that is exactly the reason we refuse to create sub-forums for specific Model types here.
 

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From that link, very good to know. Thanks AZ

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Be sure that the push rod is adjusted so that the rear brake master cyl. is released entirely when the pedal is released. The first thing that happens in there is that the return port is covered in the first small amount of piston movement. If it remains covered because of misadjustment it will have the same effect as a plugged return port. Both problems will cause the rear and one of the front calipers to remain applied
 

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Discussion Starter #35
From that link, very good to know. Thanks AZ

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Be sure that the push rod is adjusted so that the rear brake master cyl. is released entirely when the pedal is released. The first thing that happens in there is that the return port is covered in the first small amount of piston movement. If it remains covered because of misadjustment it will have the same effect as a plugged return port. Both problems will cause the rear and one of the front calipers to remain applied

Thanks Jimh352 :)
 

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Discussion Starter #36
You can get a rebuild kit for that master cylinder. If you are going to replace it, meaning you will have to remove it, might as well rebuild. There is no new replacement for that. Good luck on the removal it's a b---h. You didn't replace the rotors by any chance did you? Standards and Interstates use a 5MM width and the others have 10 MM rotors. I am currently rebuilding a 84 Standard myself, my second one.
Hi Dodge,
I have had the master cylinder off a few times now. I have not rebuilt it, just ran a wire through the relief hole and put it back on. Was not that difficult. I have not changed the rotors. I have never touched the pushrod adjustment and the brake used to work fine? Was hoping to find a new master cylinder after market but I guess there is no such thing. I guess I will try a rebuild kit and will re-check the pushrod adjustment first. Thanks
 

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And the saga continues.:surprise:

As I said earlier if you can bleed the brakes the return hole isn't blocked.

The problem is downstream.
 

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There is a pressure reducing valve that is not serviceable in the rear master cylinder. I think it's purpose is to reduce rear pressure so the rear wheel does not slide. I am not familiar with the master as I did have an 85 but never a rear brake issue. Are you sure both right front and rear brake is dragging? When it locks do you crack the front? Did you try the rear? Did you try turning the front tire when it was stuck.
I am just beginning to think you might have an issue with the pressure reducing valve but I am not familiar with how it works. The service manual says it is not serviceable but sometimes you can find a way around that.
I would be very interested to know if both wheels lock and if both release by opening the front or rear bleeder.
Might tear into it if you are persuaded that is the issue. Either way you will have to buy another master and it would be very interesting to see what is in there. Beware! it is possible there is a heavy spring. Might be why they say non serviceable. Don't want you to get hurt. :)
 

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Glad it's easy for you ! Usually the threads on the master are messed up and are hard to start. That internal pressure thingy isn't reachable. If you haven't rebuilt the master it would be a good place to start. Be sure to get you boot cover in right and your split ring in correctly. If you don't the entire internals will move and not function correctly. Just a thought.
 

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Discussion Starter #40
There is a pressure reducing valve that is not serviceable in the rear master cylinder. I think it's purpose is to reduce rear pressure so the rear wheel does not slide. I am not familiar with the master as I did have an 85 but never a rear brake issue. Are you sure both right front and rear brake is dragging? When it locks do you crack the front? Did you try the rear? Did you try turning the front tire when it was stuck.
I am just beginning to think you might have an issue with the pressure reducing valve but I am not familiar with how it works. The service manual says it is not serviceable but sometimes you can find a way around that.
I would be very interested to know if both wheels lock and if both release by opening the front or rear bleeder.
Might tear into it if you are persuaded that is the issue. Either way you will have to buy another master and it would be very interesting to see what is in there. Beware! it is possible there is a heavy spring. Might be why they say non serviceable. Don't want you to get hurt. :)
Thanks Redwing!
 
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