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My Front Brake Lever is Sticking Slightly Keeping Brake Light On - Why?

captainmako21

New member
Brakes have been bled a few months ago and new fluid added on my '86 R80. Reservoir in good shape. Fluid
honey-colored. The front brake lever was staying ever so slightly engaged before the bleed and
cleared-up afterwards. Now, some several months later, the front brake lever is again staying
just slightly engaged so the brake light is staying lit. I can ride along and keep pressure on the
brake lever forcing it fully "out" if you will, but I know that's not a proper fix. Any ideas why I'm having
this problem. Master cylinder needs rebuilding?
 
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Go with the low hanging fruit first -- is the pivot pin and perch greased? After that, it's got to be something in the hydraulic system, MC or caliper or (unlikely) some blockage in the line. I'd pull the caliper and see if the pads push in easily.
 
If cleaning & lubing the lever doesn't get you anywhere, you're going to end up cleaning out the master cylinder. I rarely bother these days; in my experience they never feel the same after the surface finish has been compromised. $200 usually gets you a brand new one.
 
Thanks for the help everyone. I just took it out for a couple hour ride and it
still experiencing the problem. Will probably bit the bullet like you suggest Anton
and get a replacement. Thanks again.
 
Hey, when I yank on my front brake lever a cable actuates the shoes down below, and the front brake light switch is actuated directly by the lever.

Is the R80 switch hydraulically actuated? From the microfiche it looks like a discrete, replaceable, mechanical switch [#24] If that is the case, maybe you could back the switch out a quarter turn, or so, to pull the plunger away from the lever? A drop of blue loctite would keep it from rotating.

B0003751.png


61311459569_1_B.jpg
 
Front Brake light staying on.

Thanks for the help everyone. I just took it out for a couple hour ride and it
still experiencing the problem. Will probably bit the bullet like you suggest Anton
and get a replacement. Thanks again.
That happened to me. I simply removed the Master Cylender Piston, cleaned the cylinder and piston reinstalled and now it works like new
 
Hey, when I yank on my front brake lever a cable actuates the shoes down below, and the front brake light switch is actuated directly by the lever.

Is the R80 switch hydraulically actuated? From the microfiche it looks like a discrete, replaceable, mechanical switch [#24] If that is the case, maybe you could back the switch out a quarter turn, or so, to pull the plunger away from the lever? A drop of blue loctite would keep it from rotating.

B0003751.png


61311459569_1_B.jpg

I will research the switch Imo1131. Sure would be a lot less $$$ if it were only the switch....... Thanks and cheers.
 
I had the same problem on same type of switch. Removed the switch, sprayed it generously with WD40, then blew it out as best I could with compressed air and re-installed it. No problems since and that was a couple of years ago. I think dust and grunge can build up in there and cause it to stick.
 
I think dust and grunge can build up in there and cause it to stick.

:thumb

I didn't even think of the "stiction" element. You're right (I'll bet). From the clearance around the plunger (pictured above) it sure looks like it could get packed with crud; 28 years should have been about long enough.

Here's the P/N for the switch assembly pictured > 61 31 1 459 569

There's also a service bulletin that addresses over-tightening. > http://www.maxbmwmotorcycles.com/fiche/NotesParts/61311459569_1.pdf
 
If the Break lever returns as far as it can and brake light does not go out it would be the switch. But if you can push the lever as far as it will return it is crude around the piston.( That is to say if the break light go's out it is crud around the piston at the rear seal. Be sure the return hole in the reservoir is not blocked.
 
I had the same issue on my 86 and it was just the pivot pin needing cleaning and lubrication.
 
Update

OK - unscrewed the brake switch and it tests fine. Very clean for an '86 bike. Cleaned and lubed and
cleaned and lubed the internals of the lever case, if you will. Cleaned lever. Cleaned the screw and wavy washer
and even the nut. Put it all back together and while the lever is not as "wiggly" it still does not seat fully to the forward
position and hence, the brake light kicks on again.

Question: Could a new brake lever remedy the problem possible? The fitment section of the lever is worn, but have
no way to determine how much metal has been degraded from use.

Or: You folks think it's time to get into the piston and m/c?

Lever is about $50 from Max BMW, btw.
 
Anton........THANKS for what you do for us..................For me, I would follow the excellent advice that many have given. One can clean out the MC and put in a kit after a bit of sanding/polishing the bore........One can send of the MC to several very competent folks to rebuild.........or buy a new MC.

It really does seem a waste to have to maintain these master cylinders like we have to; but yours, and on my 83 RT are prime examples of what happens if it isn't done often enough. The annual bleeding and flushing out the old fluid with new.....NEW, not left over from last year, really does keep this from happening.........Bite the bullet Bud and do it right...........God bless.........Dennis
 
Hi DennisDarrow - my attempt at a funny was only made tonque-in-check.
I realize Anton is a premier Airhead expert and in fact, I plan on sending my tranny to him
for a rebuild sometime in the not-to-distant future.

Thanks all for the good advice. :bliss
 
If you've got the money for a new MC, Anton's advice is the way to go - you should get many trouble-free years of service out of a new MC.

If you don't have the cash, it is pretty easy to polish the bore. I put a MC rebuild kit (3rd one) into my 85's MC and it hung up so that it did not return the brake lever to its normal resting position. With a really bright flashlight, I could see lots of really tiny white spots all over the inside of the bore. With a new, un-worn piston, it was hard for the return spring to push the piston all the way back out with those little rough spots of corrosion in there.

I happened to have a small-bore shotgun cleaning kit and the rod that would hold a bit of wadding would also hold a rectangle of scotch-brite. I used the least agressive scotch-brite that is supposed to be like 0000 steel wool. I sized the rectangle of scotch-brite so that it folded around the end of the cleaning rod like an "S". I chucked the cleaning rod into a drill and spun it up and down the bore. I stopped and blew out the bore, lubed it with brake fluid and checked the action of the piston until it stroked smoothly through its travel in the bore.

That was many thousands of stick and leak-free miles ago. One of these times I'll just replace the MC. Somebody even cheaper than me pointed out that a small wooden dowell with a split or a thin saw-cut in the end could be used to hold the rectangle of scotch-brite.
 
Somebody even cheaper than me pointed out that a small wooden dowell with a split or a thin saw-cut in the end could be used to hold the rectangle of scotch-brite.

Or even use some super fine "Wet and Dry" to hone with.......GO EASY though. Just enough to get rid of the corrosion.....God bless.....Dennis
 
Actually I misspoke. A new MC does NOT come with a new lever. I know that; I order them all the time. You can buy a whole new control perch (MC, lever, res, housing, everything but the throttle tube and cam) for not all THAT much more. A new MC comes with a new reservoir.

You need to fix this. When it gets bad enough, pushing the lever won't be enough, and the brake system will retain pressure in it. That'll wear your rotor and pads, eat fuel, and ultimately make you crash when the brake system becomes unable to vent enough pressure.
 
keep pressure on the brake lever forcing it fully "out"

Means the lever is not freely moving? If so I would look at the parts 3, 4 and 5 in the diagram.

I just replaced all 3 parts on the clutch lever and the inner bore of the plastic bushing was too small and the lever never moved all the way back to its idle position.

Just my 2 cents...

/Guenther
 
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