Hi everyone,

I have a problem with a binding rear brake on a XB9R.

I changed the pads at the weekend - everything came apart and went together just fine. The wheel spins freely when up on the paddock stand and no sound of anything rubbing.

Unfortunately the brake is binding slightly when riding (caplier gets warmer than it should and I'm cooking the disc). I know binding brakes are usually due to a sticky piston or seal, but the piston side pad is just fine - its the "fixed" pad that appears to be rubbing on the disc.

Before I take a file and remove 0.5mm from the "fixed" pad, does anyone have any suggestions as to what the problem is?

Cheers,

Dave

Front slider pin is seized.

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Mithered ta death.
92 MB
96 S2T
98 S1W
00 M2
01 X1
03 P3
10 CR

Thanks Maz,

Forgive me for being thick - are you saying that the pad is getting stuck on the pad hanger pin?

I thought I'd cleaned all the crud off the pin - the pad slid up and down it easily enough. Is it just a case of cleaning the pin again or something else? (Like I said, I'm being particularly thick tonight.)

Thanks,

Dave

Dave ,the caliper itself should slide on its pins .......that way as the piston forces one pad towards the disc it also pulls the caliper across on its pins to apply the other pad..if the pins are seized the caliper wont slide back when the brakes released.

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2001 X1 2009 1125CR 2006 Uly X3 2010 Uly a fully Maz'd S1 and a 1991 RS1200 Westwind.

Correct...the rear pin has a proper steel bush but the front pin goes directly into the ali carrier.

_________________
Mithered ta death.
92 MB
96 S2T
98 S1W
00 M2
01 X1
03 P3
10 CR

Common fault for bikes ridden in salt treated roads and or jet washed.
With no pads in the caliper you should be able to slide the caliper from one side the disc to the other very easy.

Easy job

Nate.

Nate / Kevmean / Maz,

Thanks for your very helpful input.

We had a "divided by a common language" problem (what you call "pins" I have always called "sliders" - to me, "pins" are what the pads hang from and sliders are what the caliper moves on).

A quick update: the pins /sliders are baby-bum smooth (plastic "wire wool" and brake cleaner for an hour or so to remove any sign of crud). The "tube" that the front slider moves through is also really clean.

With everything torqued up just so, I can wobble the caliper back and forth, clearly moving the "fixed" pad onto and off the disc. (Just like it should.)

I go out for a three mile "round the block" shake-down run. When I get back home, I can still wobble the caliper just as before, but the caliper itself is hot to the touch and I could fry an egg on the disc.

So, something is rubbing on the disc and I think it has to be the fixed pad (the piston, and so the pushed pad, moves really smoothly). But, even when its hot, the whole caplier still wobbles easily by hand.

I've tried measuring the run-out on the disc and its less than 0.1 mm half way across the disc (ie at the mid-point of the disc braking surface), so it doesn't seem to be a warped disc.

I spoke to Maz today and I think that the easiest solution is to simply replace the whole caliper / carrier assembly (surprisingly cheap option!) - if that doesn't solve it, I'll just put the original rear disc back on too (just to eliminate that possibility) and beyond that, I'll be out of ideas.

Dave

hi DFS might be worth checking , the brake pedal is not tight on the pivot,the brake master cylinder is not overfilled ,........whichway?

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........have you tried turning me off & then turning me on again ?

Avery good point. I had a sticky lever on my 1125 and it trashed a set of pads. Get the pivot lubed

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If your dreams don't scare you, they are not big enough.

Thanks Whichway!

I checked the pedel pivot before the latest shakedown run - moving just fine, no sign of binding or not moving back as it should.

Was careful to ride with my foot set back on the peg so that I wasn't "covering" the leaver, just to make sure that I wasn't dragging the brake either,

Fluid level is just bouncing off the Max mark, as is should be for new pads.

(I've run a bunch of 20+ year old GPZs, all with single pistion capliers front and rear and have come across all sorts of binding / seizing etc probs in the past, but this one is defeating me!)

Dave

Adam,

I've bounced up and down on the lever with the bike on a paddock stand, trying to hear any change in the sound of the disc running through the pads before and after - no change.

I've watched the lever move as I press on it and move back afterwards - all looks 100% OK to me.

I think its time to reinstate the occasional "Dave's bottle of whisky" competition. I'll replace the whole assembly and post the old one to anyone who wants it. If you can work out what the problem is, the bottle is your's. (If you can't, you repay the postage.)

I end up with a working spare caliper assembly for the price of a bottle of whisky - works out good for me!

Dave

What about just getting new seals for the pistons if you feel the need to change the whole caliper?

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Should Have Stuck To making Tubers

Tis posible to be the seals or rather salt has furred up the ally in the seal groove causing it (the seal) to bind on the piston!

Also have you adjusted the pedal at all? I do to get it how I like but it is possible to not allow the master piston return just enough etc.

HTH.

Nate.

Hi Nate,

I used to run a 20 year old Kwak all through Scottish winters (you wouldn't believe how much salt they chuck on the roads up there) and am used to having to clean out the crud and corrosion from the seal groove / running a rats-tail file up the slider holes / de-crudding the sliders and the piston.

The problem is that the piston is moving really sweetly - its not binding on the seal at all (if it was, the caplier wouldn't wobble easily immediately after a ride).

I've even taken the bike out for a 3 mile run and not used the rear brake at all. The caplier wobbled freely at the start and at the end, but still the calpier is hot to the touch at the end. I've tried this again with the pedel really "backed-off" and same result!

I don't want to get into a "Is it the sliders? - I'll try replacng them. Is it the seal? - I'll try replacing it. Is the disc warped? - I'll try changing it" situation. You can guarantee that every part I want to replace won't be in stock, so it'll be a week's wait for each one. (My loal dealer did NOT have in stock any banjo bolts, any bleed nipples, any seals, any anti-chatter springs, any pad pins etc etc!!) To be fair, they do have pads and DOT 4 on the shelf.

Entire caliper / hanger plate assembly is about £120 all in and its worth that to me to pretty much guarantee a solution (plus the cost of a set of disc bolts to put the original disc back on), rather than spending most of this summer off the road trying to find a solution. More than anything else, I don't want to miss East Kirkby!

Dave

Dave, is the brake binding or not ?.......from everything you've said, apart from stuff getting hot, it is not ?

With the bike on a paddock stand, does the rear wheel turn after applying the brake ?.....or having used the brake is the wheel binding ?

I reckon you're chasing a fault that aint there

_________________
Mithered ta death.
92 MB
96 S2T
98 S1W
00 M2
01 X1
03 P3
10 CR