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Author Topic: Binding Disc Brake?  (Read 2387 times)

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Offline Leanier

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Binding Disc Brake?
« on: January 08, 2012, 07:58:33 PM »
Ok, so haven't had time to go through this alot, but figured I'd see if anyone has any tips.  So, if I turn the bars all the way left, and then try to back up the bike the disc binds, and I can't even push it.  However, it can still push forward with little resistance.  and turning to the right has no effect forward or back.  Any ideas why it would bind?

Thanks!
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Offline Spanner 1

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Re: Binding Disc Brake?
« Reply #1 on: January 08, 2012, 08:30:16 PM »
Wow !... of all the posts I've seen over the last 2-3 years .. this one is a complete 'brain teaser '  :o.... usually a bound-up front brake is not affected by the bars turned left or right, would be still bound-up... what-the -heck. Wheel bearings ? Nah!... How about speedo drive ???
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Offline the technological J

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Re: Binding Disc Brake?
« Reply #2 on: January 08, 2012, 08:40:32 PM »
im gonna assume that you have turned the bike to the left and checked that nothing was pinched or would cause extra pressure.... how is the  brake line routed?
 do you have a center stand? can you put the bike on it and see how the wheel turns while off the ground?
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Offline Leanier

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Re: Binding Disc Brake?
« Reply #3 on: January 08, 2012, 08:54:57 PM »
Nothing was pinching or rubbing that I could see, seemed like it had to be in the brake, felt like it.  Line is routed the stock way, haven't touched it ever.  I will check it on the center stand tomorrow, didn't think of that.
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Offline Danno

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Re: Binding Disc Brake?
« Reply #4 on: January 08, 2012, 09:35:14 PM »
had this problem myself once the weep back hole in the master cylinder was plugged use a guitar string the right size for the hole to clean it out it can also indicate that your old rubber lines are going to pieces inside so clean them out and have a look you may need to replace them

on mine I was able to clean the lines out using brake clean and drying them well don't forget the valve at the fork brace too
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Offline Don R

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Re: Binding Disc Brake?
« Reply #5 on: January 08, 2012, 11:05:18 PM »
I've seen this too, there is one in the shop right now that didn't want to go back in after I rolled it out saturday. it has extended forks and was down at some point because that's why he sold it. Looks great except the forks. i was assuming he has something tweaked on the front end. We haven't taken it apart yet. There's a nice 75F front end here I imagine it will go on.
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Offline Don R

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Re: Binding Disc Brake?
« Reply #6 on: January 08, 2012, 11:07:16 PM »
Oh yeah, try loosening the fork bolts at the triple trees apply the brake then re-tighten, Can't hurt to try.
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Offline Leanier

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Re: Binding Disc Brake?
« Reply #7 on: January 09, 2012, 06:12:22 AM »
Thanks for all the ideas, hopefully I'll get some time to try out all of your suggestions today!  Its odd because it never used to do it, then I let it sit for about 4 months while I was doing a full rebuild on the engine.  I have had suspicions of a slightly bent fork on one of mine before, but it was never bad enough to bother actually looking into since it didn't affect anything at the time.

Thanks again!
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Offline MCRider

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Re: Binding Disc Brake?
« Reply #8 on: January 09, 2012, 06:28:19 AM »
The plugged return hole in the master cylinder is the most common cause of a brake locking up and not releasing. Doesn't explain the turn to the left lock up, then the release. If it were that hole it wouldn't release for anything.

Bent fork could be.

Along Spanner's line: Really bad wheel bearing could be. Turn to the left, wheel tilts a little, rotor engages the B pad. Turn back straight, wheel untilts. Long shot.
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Offline Kong

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Re: Binding Disc Brake?
« Reply #9 on: January 09, 2012, 08:18:46 AM »
The first two things I'd check would be the tightness of the axle holding blocks and if that wasn't the problem I'd look at the front wheel bearings.  I think one of the best comments given so far was your own when you said you'd put it on the stand and check it again with the wheel off the ground.  Also, though it may be far-fetched, check the rear brake and make sure there isn't something odd going on with the chain/sprocket system while you're at it. 

It will be interesting to hear what you come up with.  Oh, this just sort of popped into my head too.  If you take the front wheel off go ahead and pull your brake pads out and measure their thickness - on one side and then the other.  See if there might be uneven wear such that the pad (puck) has become sort of wedge-shapped with the thin end facing the rear.
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Offline Leanier

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Re: Binding Disc Brake?
« Reply #10 on: January 09, 2012, 04:41:52 PM »
Well haven't had much time, or tools.  But i threw it up on the center stand and the wheel spins freely even when turned all the way left.  So seems to have something to do with the weight of the bike pressing on it.  the holding bolts are tight for the axle.  Adjusted the rear chain and made sure that is all fine back there.  Need to find a little more time in order to get the wheel off and do a good inspection.  The wheel does spin very well, so its not like the wheel bearing is causing any friction when the wheel is in the air. 
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Offline Danno

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Re: Binding Disc Brake?
« Reply #11 on: January 09, 2012, 10:51:04 PM »
that spells bad bearing bud
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Offline MCRider

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Re: Binding Disc Brake?
« Reply #12 on: January 10, 2012, 05:36:54 AM »
Quote from: Danno on January 09, 2012, 10:51:04 PM
that spells bad bearing bud
Yeah. I think a wheel bearing won't disclose its weakness with no load on it. Tough to diagnose.

Maybe not.   :-\
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1988 NT650 HawkGT;  1978 CB400 Hawk;  1975 CB750F -Free Bird; 1968 CB77 Super Hawk -Ticker;  Phaedrus 1972 CB750K2- Build Thread
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Offline Leanier

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Re: Binding Disc Brake?
« Reply #13 on: January 10, 2012, 05:59:42 AM »
It's probably about time to do all my bearings and probably swing arm bushings any I suppose.  Thanks for all the help guys, It would have taken me awhile to think of bearings.
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My motorcycle collection thus far:
'74 CB360
'73 CB750
'72 CB125s
'68 CA160
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