XBR woes

[guest7]

My XBR front brake has been a bit crap lately, requiring two quick squeezes to build up decent pressure. In emergency braking you can stop without pumping the lever, but it comes back a fair way before biting.

I assumed that the fluid was low although it didn't take much to top it up, but it doesn't seem to have cured the problem. If it had been leaking then surely I could have expected the fluid to have been much lower than it actually was?

turning to the back brake, when I fitted new shoes some months ago, they didn't want to go into the drum until I had eased off a lip with some emery paper. However, once in place they worked fine. Recently the brake arm hasn't been returning properly so I thought I'd better strip it apart to see if the springs were knackered and/or the pivot bolt was dry. After a 15 minute tussle I gave up on trying to get the brakeplate out of the drum. I'm not sure on the next course of action, but I suspect it will involve sorting out a spare wheel and brakeplate.

Most pressing of all my woes is the snapped frame tube on the bike. Once again a sidecar mounting clamp has exerted too much stress on a frame tube and it has sheared. Not being able to do without the sidecar, I added a strengthening strut and did some other bodges that I'm not inclined to share with you and the thing should hold together until I can see my welder 

GC

[guest18]

Sounds like the fluid in your front brake has gone off (tech term  ) I'd bleed through with fresh fluid until you reckon you've replaced it all. If that doesn't work then I'd suspect something in the master cyl but my bet is bad fluid (or it's overheated old fluid which has cause a bubble or two somewhere in the system, cure is the same either way.)

Not sure about your back brake, can you rattle it back and forward to force the brake shoes back and give you enough play to remove it? I think you might be right about the risk of knackering it removing it 

Frame tube...  can you get your welder to put an internal sleeve in? Obviously an external one would give you problems with the mounts but maybe you could strengthen it that way? Or maybe take 50 or 60lbs of gear out of the chair to reduce the loading? 

[guest7]

...Or maybe take 50 or 60lbs of gear out of the chair to reduce the loading? 

I suspect the saddle loading is partly to blame 

I'm happy that I know how to fix the problem, it has happened before and that repair lasted nearly 6 years. Once it's done then I will be using it with less weight in it. This outfit is going back to child-carrying duty and I have a new(ish) 500 twin to pull a new works chair.

GC

[guest27]

Front brake

Have you checked...

Piston/s binding, pivot binding - if one piston is not moving you have to twist the disk to get brakes - this forces the piston back as soon a it is off.

Rubber lines had it?

Binding piston in the master cylinder.

Oil return in the MC blocked?  (If it has one)

Old fluid

Back brake - I have had shoes bind on the little lip that is left by wear.  Have ended up getting brutal and eventually the shoes flipped off the pivots and the thing came apart. - As I remember I took all the gubbins off the cam pin on the outside and tapped this back into the brake taking the shoes with it.

R

[Andy M]

Sounds like the fluid in your front brake has gone off (tech term  )

Sounds Hydroscopically degraded to me 

My first thought would also be the fluid. When it's old it absorbs water. The heat at the pads gets at it and some of it turns to steam and it gets past fluid seals, hence the level drops slowly. The steam bubbles in the fluid though act like air, compressing and letting the lever come back.

GC of course won't have this as he'll have been changing all the fluid for nice clear, new stuff every two years or so 

The drum sounds like it's got the lip back. The main lining is clear of the rubbing surface, but the sides are against the ridge. The friction can't be overcome by the return spring. Only idea short of serious violence is to get the cam to the brake off position by feel, then pull while turning. The idea is to get the shoes to ride over the ridge. Once it's part out you can get violent with the screw driver hopefully getting the brake plate out in one piece even if the shoes stay put.

Andy

Andy

[guest18]

Sounds like the fluid in your front brake has gone off (tech term  )

Sounds Hydroscopically degraded to me 

Andy

That's what I said  but I thought if I use the word hydroscopic people will think I'm showing off...
so...

"OOOOOOH Hydroscopically degraded!"   

[themoudie]

OOOOOOOOO, Scrabble for two, ducky!

[guest7]

Thanks for the brake tips. I will be playing with the bike again this weekend, now where's my FBH? 

GC