Brake Light Issue/Front Master Rebuild?

[TDMX595]

So I've lurked on here for a while, but am just now joining the board because I could use some advice from more experienced people. I've searched the forum but I haven't seen *this* particular issue on here.

My rear brake light is currently always on. I know exactly why it's always on. It's because the front master cylinder is not pushing the brake handle out far enough to turn the switch off. Pictures can be supplied if needed. I'm not sure how long it's been doing this, but I just noticed it. I'm thinking that maybe I need to rebuild the front master cylinder? Should I just buy a used one off of ebay? My other thought was just machining a little brass shim to fix the problem.

Any comments, ideas, thoughts?

[TDMX595]

This is the problem:


How it should be:


Where the brake handle sits on the plunger:


Where the brake handle should sit:

[PHMCS]

It may be an issue with the brake switch. Normally when you press lightly on the brake lever you can hear the spring move and the switch activate. If you aren't hearing that, you might want to check there first. also if there is any crash damage (bends and whatnot) in the lever or the perch, there may be a lack of clearance that isn't allowing the lever to move its full stroke.

In regards to the master cylinder, are you having issues with fluid leaks, or spongy braking/poor performance?

[TDMX595]

Thank you for replying! It was lonely in here.

Originally Posted by PHMCS

It may be an issue with the brake switch. Normally when you press lightly on the brake lever you can hear the spring move and the switch activate. If you aren't hearing that, you might want to check there first.

The brake switch is working wonderfully. When the switch is depressed, the brake light goes off. My problem is that the switch is always activated.

Originally Posted by PHMCS

also if there is any crash damage (bends and whatnot) in the lever or the perch, there may be a lack of clearance that isn't allowing the lever to move its full stroke.

There was crash damage on that side, but I've replaced the bar and the lever and you'd never know there was. I recall it working correctly when I replaced everything. I'm not sure when this started. There's plenty of clearance, I can move the lever back and forth no problem.

Originally Posted by PHMCS

In regards to the master cylinder, are you having issues with fluid leaks, or spongy braking/poor performance?

I have no fluid leaks, spongy braking, or poor performance. The brakes work great! The reason I think I need the cylinder rebuild is that the cylindrical piston that the brake lever compresses when pulled is not returning to the correct position when I let go of the brake lever. This results in the brake lever sitting so that it doesn't compress the switch and thus my brake light doesn't go off. I can push the brake lever out with my hand and it turns the switch off, but that doesn't pull the cylinder out of master. Unfortunately when uncompressed the master cylinder doesn't naturally sit in the correct position anymore. This is why I think I need a new one or a rebuild.

My current plan is to buy a rebuild kit and rebuild the front master cylinder to see if that fixes the problem. While I'm at it I'm going to install stainless steel brake lines and new pads. (Since I'll be bleeding the system anyway.) Thus I'm waiting till I get paid again.

I'll post up the results of my efforts when I'm done in case anyone else ever has this problem.

[FvnnyL3tt3r1ng]

Standard case of blinker fluid leak.

[Desmoluci]

Have you tried spraying a little WD-40 on it?