Need Brake Help Desperately

[kycaveman]

Ok, this is where I am. I have rebuilt all 3 brake calipers and the rear master cylinder. After plenty of bleeding, both the bike and me, I finally got the blasted thing to hold pressure. Went for a quick test run and everything was going fine and then the darn brakes locked and would not let go. I pulled out the ol` wrench and bleed of the rear and wamo`, I was off again. Did a few laps around the pond and then they where dragging again. This time I bleed of the left front, and then I was off again. OK, I check the rear master cylinder, made sure the little hole was clear, and tried it again. After several goes, sure enough they started dragging again….. So what do I do now? You guys have been a wealth of info and anymore would be great!!!!! Oh Yea, if it helps I have a 1985 VR. and the right brake (front) is working just fine.

[mm482]

The rear brake pedal return spring may not be returning the pedal or you may not have enough free travel in the rear brake linkage.

Earl

86 VR

00 RSV

[hipshot]

man! that is a weird one.

have you dismantled and cleaned the "proportioning valve"?

that would be my next move.

it would appear, that you are not getting the fluid release that is required.

i.e. pressure is being held in the lines somewhere.

just a thought.

just jt

[Marcarl]

That's where I would look, in the pedal travel, may be hanging up on something. or need some lubrication.

[kycaveman]

Thanks all,

I just checked the travel and it was really tight, so I am HOPING that was it, just not enough release and holding pressure. I did completely clean all pieces including the P-valve and flushed new fluid through everything. What should the free play/travel be on the pedal? I did comment to my friend I thought it was really tight and high up when I first tested the bike.. and of course I am the one who moved the adjustment forward for my long legs, and did not even think about the linkage. I have to work in the morning, but will take it for a run after lunch. Now on to other issues, the bike had been sitting for 2 years and at first would not run, but now it is idling and not missing to bad on acceleration. I have flushed the gas, changed the fuel filter, air filter, plugs, oil, and seafoamed the tank. I am hoping to run it for a while and wash out the effects of sitting. I will update as the project goes on, and of course on how my test run goes tomorrw.

[pegscraper]

Did you put new pads in while you were at it? If so, did it take much force to get the pistons farther in to make room for the new fatter pads? It sounds to me like the pistons are stuck and are not releasing for some reason.

[Venturous Randy]

I think you have over filled the rear reservoir and when it gets warm it is causing the brakes to engage.

RandyA

[Guest KitCarson]

This is a dangerous subject as none of us are there to put our finger on what it is.....and you did not say which bike....will assume it is one of those that parts fall off all the time?? A first Gen!!:stirthepot: From what you have described the first thing I would check is the proportioning valve. If it gets blocked it will not allow the fluid to return and will lock the brakes onto the rotor. If that is not it, could be if you fully rebuilt the calipers, someway the calipers have been assembled to where they do not pull up even....check that, make sure they work even.......and yes if you had the pedal adjustment run so tight it was holding the calipers shut that would do it to. As you have said you had trouble with both front and back......I would first suspect the proportioning valve if it is a first gen. Kit

[BOO]

Dirt, that's my opinion. Dirt or something in the system.

I would flush it out completely and refill it with clean fluid. It don't take much to plug in one of those little holes in the syslem.

Randya's idea is worth checking also, does happen and don't ask me how I know.

Jerry

[Yammer Dan]

Randy wins this one. I'd almost bet on that one. Just bleed the rear out til it drops the level a little and go RIDE!!

[muffinman]

Lee something else that has not been mentioned is the position of the rear brake pedal If it is adjusted too high it will keep pressure on the brakes.Adjust it down for more free play and try that before you start tearing things apart.I would be willing to bet that with moving the pedal forward the freeplay was removed that is whats causing the problem .Dont ask me how I know that this could be the problem.

 

 

 

 

 

Jeff

[Condor]

Ok, this is where I am. I have rebuilt all 3 brake calipers and the rear master cylinder. After plenty of bleeding, both the bike and me, I finally got the blasted thing to hold pressure. Went for a quick test run and everything was going fine and then the darn brakes locked and would not let go. I pulled out the ol` wrench and bleed of the rear and wamo`, I was off again. Did a few laps around the pond and then they where dragging again. This time I bleed of the left front, and then I was off again. OK, I check the rear master cylinder, made sure the little hole was clear, and tried it again. After several goes, sure enough they started dragging again….. So what do I do now? You guys have been a wealth of info and anymore would be great!!!!! Oh Yea, if it helps I have a 1985 VR. and the right brake (front) is working just fine.

 

You're gonna get a lot of responses and suggestions to your problem, but.... I've been there and done that. So believe me when I tell you......Your expansion relief orifice is plugged.

 

When the fluid heats up and expands from normal braking it has to go somewhere, or it applies more pressure to the brake pads, which causes the brakes to heat even more, which eventually ends up locking up the brakes tighter than a frogs a$$.

 

This can happen on every master cylinder on the bike, but it's most common in the rear brake master. If you remove the plastic reserve hose fitting, held on buy 2 screws, from the side of the rear master (there's an 'O' ring seal), and look down inside you'll see two holes. One goes all the way thru to the cylinder, and the other looks like someone tried to drill and then stopped. Believe me, there's a tiny hole at the bottom. This hole is plugged and causing all your problems. Crud settles down from the reserve and clogs the hole. That's why it's so important to bleed the master cylinders on a regular basis. I finally took the master back apart and blew it out. The best way to tell if it's open is shine a small flashlight into the cylinder and look for a speck of light coming out the side. I tried very small needles to clean it, but even they were too big. I've used the wire from a grocery store wire tie on the clutch, but I think that may even be too big for the rear.

Hopes this helps.

[kycaveman]

Thanks agian,

 

I knew I would get a bunch of good information from you guys. After looking it over, I think it was a combo of overfilling the rear

reservoir and having the pedal adjustment too high/tight.

 

As far as flushing the system, new pads, free moving calibers, ect. I completely rebuilts all systems and everything was moving freely and clean. That is why I was having such a hard time figuring out the cause. But thanks to your great info and suggestions, I believe it is now good to go..... . As soon as I get off work, I will take it around the pond a few times and see how it works out.

[skooter]

I had the brakes 'come on' by themselves my '84 VR soon after I purchased it in '04. The culprit turned out to be the washer for the brake pedal. It was the wrong diameter, and when the bolt for the pedal was tightened, it would interfere with the free movement of the pedal. A little dirt or corrosion thrown into the mix, and eventually the pedal did not fully release. The brakes started dragging, which heated the brake fluid and caused it to expand, etc. A larger diameter washer, and everything was OK.

[Thom]

Jeff is rite , when got my 1st gen , i had the same problem , it drove the stealers nuts , that is the reason i joined this site , i rebuilt the whole brake system , but as soon as i used the brakes they would lock up , but after i rebuilt the rear master cylinder for the 4th time , i left too much slack in the linkage and the brakes worked great ,

yep , i hate to say it but as usual jeff is rite :rotfl:

 

 

 

Lee something else that has not been mentioned is the position of the rear brake pedal If it is adjusted too high it will keep pressure on the brakes.Adjust it down for more free play and try that before you start tearing things apart.I would be willing to bet that with moving the pedal forward the freeplay was removed that is whats causing the problem .Dont ask me how I know that this could be the problem.

 

 

 

 

 

Jeff

[Yammer Dan]

Might want to check with Freebird about that riding around the Pond!!!

[a1bummer]

I've seen similar problems like that in cars. That was after ya step on the brakes though. The flexible brake hoses would get old and deteriorate on the insides. They would ack like check valves and only let fluid move in only one direction. I wouldn't think this is your problem though. i would agree with the brake pedal adjustment idea. Now that I think about it more a bad brake hose would either cause one wheel to lock up and not release and the other work fine, or one brake not work at all and the other caliper would get all the fluid and cause it to lock up quickly but still release when you let up the lever. That's haw it works on a car anyway.

[mark reed]

In rare cases the pins that hold the pads in place can get grooves worn in them where the pads hang on them.On road racing bikes the pins are replaced every time the shoes are.Just my 2 cents worth.The other guys have given some very good advice also.