front brake stuck on?

Hi, first post here... I'm looking for some help with my viffer. The other day, when I went to ride the bike, it wouldn't move at all, because the front brake was engaged. The lever for the brake wasn't pulled in at all, and it is now incredibly difficult to squeeze it in. So, the brake won't disengage, and I can't operate the lever for it.

My bike's been down on both sides before, but not recently (3 months or so ago, last time). It was also left out in the rain for a couple days prior to these symptoms -- perhaps the rain is related?

Any way, thanks for reading, and I'd really, really appreciate some advice to diagnose/fix this problem. I'll check back on the thread a little later to answer any questions or what have you.

1st.. remove the brake lever..
did it free up the brakes?
if so.. you have to file down the contact'bump'that slides against the plunger..
if it did not free the brakes..

remove the top of the master cylinder .. remove the fluid. (i know people will flame me :rolleys: ).. with a wadded paper towel or old sock will absorb 99% of it as you most likely dont have a syringe or other suction device.
look in the bottom of the MC you will see 2 small holes.. take a fine peice of stiff wire and clear out the holes the best thing for that is a welding tip cleaner....
if the holes are clear.. your pistons are stuck..
remove the calipers is it dirt build up stopping the pistons from sliding back? or RUST??? spray with brake cleaner and scrub with a toothbrush if its rusty .. rebuild the brake .

oh.. if the fluid is dark.. or brown. or black.. you need to change the fluid. sure the search button.. everything is here..at your finger tips :fing02: .

To get the bike rolling, you can pull the calipers off. Then it will at least roll.

My '86 was frozen front and rear when I got it last month. The master cylinders were fine, but the calipers were all stuck. You may only need to clean the pistons....then again at the age of the bike, you may need to rebuild the calipers, which is NOT hard or expensive. That's what I did. Everything's either in the manual or on the forum...but if you can't find it, ask away!

+1 on coffeebrake's comment.

My 87 did the same thing. My best bet is that the calipers are the issue (pistons stuck). You can remove calipers, pump out pistons, clean pistons and put them back in. The little seals for the pistons are cheap to replace but I got away with reusing them once it was all cleaned out.

Good luck! :cheerleader:

My bike will occasionally do this... they aren't fully locked on but dragging hard. Squeezing the lever hard for a few seconds and then releasing and rocking the bike (rinse and repeat a few times) will pop them loose. I think the calipers need a rebuild. I picked them up used on ebay to fit the F3 front end swap I did. Get whatcha pay for :-)

And yes Mr gll429, I did flush the hell out of the whole system when I put the front end on this summer. ;-D

[image: View Post]Blakeo, on 17 December 2010 - 07:26 PM, said:

My bike will occasionally do this... they aren't fully locked on but dragging hard. Squeezing the lever hard for a few seconds and then releasing and rocking the bike (rinse and repeat a few times) will pop them loose. I think the calipers need a rebuild. I picked them up used on ebay to fit the F3 front end swap I did. Get whatcha pay for :-)

And yes Mr gll429, I did flush the hell out of the whole system when I put the front end on this summer. ;-D


remove the brake lever from the mount.. rub black marker on the area that contacts the 'plunger rod' install lever.. there SHOULD be a little play.. but lots DONT have the play..so. the brake NEVER FULLY RELEASES ..
squeeze the lever.. the contact area will rub off the black marker.. remove the lever. and file down the rubbing area.. repeat until a little play has been achieved. :fing02:

Hi guys. Sorry for the super-long wait on a reply -- I had to go put my bike on the back burner for awhile, but I've got time for it now. Yesterday I took apart the master cylinder, cleaned it out, and measured the bore and piston with a micrometer... it seemed fine. So today I began work on the calipers. I took the front-right caliper off first, and I'm trying to take it apart, but I can't get the pistons out. Clymer manual suggested blowing it out with an air compressor, but that didn't work at 120 PSI with the compressor right inside the brake fluid inlet. So, I guess I've finally found my problem (frozen pistons), now I just gotta unfreeze them somehow. Any advice on how to get the suckers out?

You can generate more force with hydraulics than air pressure, so hook things up and force pistons out with pressure from mc.


Don't neglect to clean and re-lube the slider pins.

i had this problem with my cafe racer, its probably the pistons seized in the brake caliper.

might need new seals, i had mine stuck because a peice of seal had poped out and jammed between teh pot and the outside. jammed it good.

basially to check, take ya caliper off, and see if any are sticking out, if they are, push em back in, pump brakes to push em out, then push em back in again. u can free them up just doing that, if its just gunk making it stick..

when i found the piston that was stuck, i used a clamp to clamp the working one in, so when i pushed, all the force went to the sticking one, just wiggle a little bit, took me a week to get it out, bugger of a thing..