Rear Brake Issues.

[Phil_Norwich]

Hi,

I've been away for the last 6months and had my bike laid up. One of my friends took it out when I was away and told me the rear brake didn't work very well. I can stand on it and when I let the clutch out the bike moves forward. It was never great anyway. Slightly better when I put a braided line on the back though.

I've bled the brake today and that hasn't made a change. The disc and pads look alright. Is it a case of a brake overhaul?

Any ideas of what else to try. It needs an MOT and it won't pass like it is.

Thanks, Phil.

[Neosophist]

Its a slider type.

Take of it off and make sure the slider pins are clean and greased with the proper grease (do not use copper grease.

Remove the pads and pop the pistons out a little by pumping the lever.

Check there is no crap on the pistons.

You can remove the pistons and clean them up and check the seals are not swollen..

not expensive to fix new seals too.

[iDemonix]

I thought the rear brake on a VFR was purely cosmetic?

[bikemonkey]

I thought the rear brake on a VFR was purely cosmetic?

[nc30chris]

I thought the rear brake on a VFR was purely cosmetic?

[Phil_Norwich]

New pads on order and the caliper cleaned. Fingers crossed it'll work!

[speedy231278]

I've got similar issues, except mine actually does do some braking, it just doesn't immediately let go. MOT on Sat, but I don't have the ability to get the pistons out because they're incredibly sticky. I'm going to advise the tester beforehand, and ask if he doesn't mind ripping them out and putting the new pistons and seals in which I have ordered, if there's enough drag to fail. if it's just advisory, I'll find a way to do it myself.

You might find that the pistons are stuck so badly that all the effort on the pedal is used up trying to move them, or as stated above, the slide pins might be corroded to death. In my case, the exposed pin that goes through the pads is a little tarnished, however it was replaced four years ago (as were the seals) and the old one was badly scored. I had to use a lot of effort to get the pistons to come out, and I also needed a g-clamp to press them back in!

Last year the rear brake seemed to be very weak, and I took new pads to the MOT expecting a fail. In actual fact, it had almost as high an efficiency as the front brakes, which actually managed to lift the bike out of the rollers on the test kit....

[Neosophist]

I've got similar issues, except mine actually does do some braking, it just doesn't immediately let go. MOT on Sat, but I don't have the ability to get the pistons out because they're incredibly sticky. I'm going to advise the tester beforehand, and ask if he doesn't mind ripping them out and putting the new pistons and seals in which I have ordered, if there's enough drag to fail. if it's just advisory, I'll find a way to do it myself.

You might find that the pistons are stuck so badly that all the effort on the pedal is used up trying to move them, or as stated above, the slide pins might be corroded to death. In my case, the exposed pin that goes through the pads is a little tarnished, however it was replaced four years ago (as were the seals) and the old one was badly scored. I had to use a lot of effort to get the pistons to come out, and I also needed a g-clamp to press them back in!

Last year the rear brake seemed to be very weak, and I took new pads to the MOT expecting a fail. In actual fact, it had almost as high an efficiency as the front brakes, which actually managed to lift the bike out of the rollers on the test kit....

I wouldnt ride any bike that I know fully has sticking pistons.

What if you use it and it gets stuck on?

If you needed to use a g-clamp to press them back in then something was wrong, and braking isnt going to be wonderful if you needed super force to get them in...

After doing an overhaul on the rear brake, the trick to keeping it working is to clean and maintain it. Not every week but every month or so give it a check over, clean brake dust off the pistons before it mixes with crap and hardens.

Make sure the rubber boots on the sliders are in good condition else they wont seal and it will sieze up properly.

Use proper grease and the right seals it should last a long time.

I did mine 2 years ago when I bought the bike and it still works fine now. Slows the bike down well enough for corners and slow speeds.

[speedy231278]

The slider is fine. The slide pins are nicely greased and it moves very well. The pad pin is a tiny bit corroded, but nowhere near enough to cause any issues, and it doesn't have any scoring like the old one. The boots are all in very good condition. The pistons may or may not clean up, however I ordered new ones as I'd rather have them and not need them than not have them and end up damaging the new seals if they are marginal. Pistons new are aftermarket, but the seals are genuine. It didn't take a significant amount of effort with the g-clamp, however it was more than I could do to push them in with my fingers. That said, I needed a small bar to do the fronts when I put the new discs on the front, and they don't grab in the slightest, and braking is very, very good with the (now relatively) new discs and pads. The rear isn't sticking on in the sense that you apply the brake and it keeps slowing the bike after you take your foot off the pedal, it just has a very slight drag on it which makes the bike a little more effort to push on the drive if you were to press the pedal and let go again. After a few seconds everything seems fine. It doesn't seem to affect the bike when riding. Of course, I may find that after rebuilding it, I feel like I've gained 10bhp...

Either way, your concern is duly noted, and you are of course right that it isn't right. And I hate things that aren't right, hence ordering the bits. To tell the truth, I've never been happy with the thing in the 10 years I've had the bike. The first time I had it serviced the place that did it told me it was crap! It's had a replacement master cylinder which made no difference, several new sets of pads, new seals a few years ago, and it always feels like it's doing very little, yet always passes brake efficiency tests for the MOT by a country mile. I know the rear doesn't need to be as good as the front, but it's not a huge gulf between the requirements, yet the feel on the bike certainly is!

If get brave on Friday, I may have a go at it, but I'm worried about screwing something up and not being able to sort it by the morning. If the MOT were in a few weeks, I'd already have stripped it and cleaned it so I could fit the new bits.

[speedy231278]

I now have a very robust feeling pair of Sealey brake piston removal pliers in my grubby little mitts. Nice and substantial feeling, and I am now feeling confident about getting those pistons out tomorrow evening and getting the new ones in (plus new seals, of course). :-)