LF200gy-5 back brake calliper seizing

[layneroxxx]

It was just a matter of opening the leak valve all the way.

It's working fine now with no seizing yet.

[red2003]

Did you adjust the master cylinder bolt as suggested early on? IF not, you WILL have seizure problems again. It's just a matter of time....

[elroyjetsn]

+1

The link bolt needs to be adjusted so the reservoir hole is open when the brake is released. If not, it'll bind the brakes as the caliper heats up. :?

On my Viva, the foot brake pivot was binding slightly causing it to not fully return to the rest. The brakes still worked fine, but the brake light would stick on. Had to loosen up the pivot with grease.

If your pedal doesn't return to it's stop properly, the master cylinder may not reach the vent hole opening to equalize pressures during therma expansion of the fluid.

[layneroxxx]

Originally Posted by elroyjetsn

+1

The link bolt needs to be adjusted so the reservoir hole is open when the brake is released. If not, it'll bind the brakes as the caliper heats up. :?

On my Viva, the foot brake pivot was binding slightly causing it to not fully return to the rest. The brakes still worked fine, but the brake light would stick on. Had to loosen up the pivot with grease.

If your pedal doesn't return to it's stop properly, the master cylinder may not reach the vent hole opening to equalize pressures during therma expansion of the fluid.

I'm not sure how to adjust so the reservoir hole is open when the brake is released.

Do you hold the pedal down and then put the master cylinder in? How about bleeding afterward?

I'm not sure why this happened in the first place, but yes, it did freeze up once again.

[elroyjetsn]

Originally Posted by layneroxxx

I'm not sure how to adjust so the reservoir hole is open when the brake is released.

Do you hold the pedal down and then put the master cylinder in? How about bleeding afterward?

I'm not sure why this happened in the first place, but yes, it did freeze up once again.

You may need to set the "stop" for the brake pedal. Loosen the stop bolt and adjust so the pedal rises a little. Or, you can also adjust the linkage bolt that connects the pedal to the master cylinder piston.

Basically, you need to let the master cylinder piston move out a little more so the piston slides past the reservoir hole in the cylinder. (when the brake pedal is released)

If you look into the reservoir(with safety goggles on) while you release the brake, there should be some movement in the fluid when the piston clears the tiny reservoir hole. If there is some air in the system, it may spit air when the hole opens.

[elroyjetsn]

Another way you can tell is if fluid drains continuously from the bleed valve when you open it and the brake pedal is not depressed. (That's why you must close the bleeder valve before you release the brakes while bleeding air from the system.)

Fluid should drain out of the reservoir when the bleed valve is open and the brake is at rest.

[layneroxxx]

Well I tried to adjust it.

Before I tested it out I went over to my friends and I thought as I got closer to my house I'd try to test the back brake out. But it locked up before I even tried it. I was just riding and my bike started to slow down.

How is this possible? Is my back rotor probably messed up? I've had 2 of my friends check wheel alignment and they said it was ok.

This is getting old as I've been messing with this for weeks. I've never seen a brake caliper this touchy.

[katoranger]

My master cylinder finally just quit all together. I replaced it with a Honda CBR rear master and have not had a problem since.

Requires some slight modification to the master and mounting points.

Bought the master off ebay for about $25.

Allen

[layneroxxx]

Originally Posted by katoranger

My master cylinder finally just quit all together. I replaced it with a Honda CBR rear master and have not had a problem since.

Requires some slight modification to the master and mounting points.

Bought the master off ebay for about $25.

Allen

would this work?

[elroyjetsn]

Originally Posted by layneroxxx

would this work?

I'd take the master cylinder apart, first and see what's what with the inlet, "reservoir hole".

The piston should move in against a spring and out on it's own. If it doesn't, the spring may be broken or missing. When the piston is all the way out against the stop (c-clip maybe) you should be able to see the tiny hole open up.

If not, they may have misdrilled the hole at the factory. In that case, the unit is useless.

If the piston doesn't return to that "stop" when the brake is reseased, the brakes will never work correctly. IOW, there cannot be any pressure applied to the piston when the foot is off the brake pedal.

If the linkage is correctly adjusted, you should need to move the brake pedal a little before the piston even starts to move. This is to make sure that the brake hydraulic pressure always gets released when the brake pedal is at rest.

[red2003]

Listen to Wayne (elroyjetson). He is giving you the correct procedure. At least 20 guys here (me included) have had to adjust the brake linkage, as he has told you, to keep the rear brake from seizing. If you do this simple adjustment, you will be all set. Don't try ANYTHING else until you have followed his simple directions.

[katoranger]

My master actually failed. It blew the seal out.

What Red and Elroy said is right. I was able to get mine working for the first 4000 miles or so until the master finally just blew.

Shortening the plunger bolt helped alot.

If you need help finding a replacement I will see if I can find a similar honda part to mine.


Allen

[layneroxxx]

Sorry about my poor knowledge here. As I learn I see how I haven't made sense in the prior comments. I'm understanding the terminology and function of the system better now thanks.
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Ok. I took the master cylinder off and the spring does work.

I drained the fluid out of it and pushed the piston all the way up (against the spring pressure). The piston moves back into place on it's own.

I see no hole as you describe. I imagine the hole is supposed to be visible when the piston is completely pushed back by the spring, and it is probably supposed to be located in line with the descending incoming fluid line? There is no visible hole there, but how else would fluid be getting in there?

How big is the hole? I can't see one at all and I got a pretty good look at it. The master cylinder is completely removed from the pedal, so I'm sure it is all the way open.

I'm sure that the piston was adjusted so it was all the way open last time I rode. I wonder if air in the line could have caused the caliper to seize? Or do you think that the fact that I can't see a hole in the reservoir is the culprit?

[layneroxxx]

so should I get another master cylinder?

[elroyjetsn]

Originally Posted by layneroxxx

so should I get another master cylinder?

Yeah, the hole should be about 1 or 2mm diameter i suppose. It should only be open when the piston is at released. It could be blocked by debris, or the piston may not be able to return all the way due to a foriegn object behind it? If you have a high pressure air nozzle you may be able to clean it out.

Might just be defective and you'll need to replace it. Maybe a motorcycle shop can match one up for you.