Endless clutch woes

[jimmyenglish]

Hi everyone. Last spring I rebuilt the clutch master cylinder, slave cylinder and bought all the clutch lever wear parts. It continues to go flat. However, when the bike warms up it would pump more and almost feel normal. It actually went completely flat 2500 miles from home and Sturgis BMW/Yamaha disassembled, cleaned and bled the crap out of it. It was good for the next 5000 or so. Now it's almost totally flat again. it's not leaking anywhere.

 

I'm going to replace everything. New master,slave, lines etc. I know the slaves are cheap but is there an inexpensive alternate master? I don't care what kind of bike it's off of or if the lever matches. I just want this dam thing to work. I'd hook up a cable if I could. What are my options? Thanks in advance. Great forum!

[MasterGuns]

What do you mean by "flat"? And is shifting affected? If so, how?

[Rocket]

What do you mean by "flat"? And is shifting affected? If so, how?

 

By the sounds of it, there is still air in the clutch master / line. It can be a real PITA to remove, even with using a mityvac hooked up to the bleed screw. Yooper & I had lots of fun with his, in Ontario last year, after rebuilding the master.

 

[CrazyHorse]

Yes it sounds like air still in it when it heats up it works better. When I replaced my clutch line and slave I had to feed fluid down the line to fill it completely up. Filled the resovoir pumped and pumped filled the resovoir pumped and pumped until nothing but fluid came out the other end of the line. Took the nipple off the slave and filled fluid into the best I could and then connected the line and continued the pumping.

[painterman67]

what about the return hole in the bottom af the master. Between dirty fluid and that little hole being clogged mine would do the same thing.

 

 

Hoope this helps.

 

Davdi

[Grisolm1]

Try an old harley trick. Bleed as well as you can, top up the master then tape lever to grip (i.e. full on), loosen cap and let sit overnight. Bubbles can then make their way up the system and escape through the open port in the resevoir made by the pulled in lever. Not sure it will fix problem but worth a try i nothing else works

[Venturous Randy]

Try an old harley trick. Bleed as well as you can, top up the master then tape lever to grip (i.e. full on), loosen cap and let sit overnight. Bubbles can then make their way up the system and escape through the open port in the resevoir made by the pulled in lever. Not sure it will fix problem but worth a try i nothing else works

 

I have seen this comment several times, but do not understand how it could work. If the piston is pushed in, it would block any flow back into the reservior from the line. Because if there was flow back from the line, there would be no pressure.

Since I don't have speed bleeders, I just open the valve some and put my finger over it and pump the master. My finger works as a check valve. By doing this quickly, it pushes any air in the line into the slave and bleeds off. Once I don't feel bubbles, I will bleed by pumping up and cracking the bleed valve some, then retighten it.

The down side on this is it can be a little messy, so I put a rag around my hand and you can quickly empty the reservior, so make sure you don't let it run dry. I have been using this system for many years and it has always worked for me.

RandyA

Edited November 4, 2009 by Venturous Randy

[Condor]

IMHO.... Reverse bleed the system.....

[6pak]

with the '89, I had to go two steps further. First, I took the line off at the slave, and held fingers over both sides of line. pumped handle til it made a mess. put line on slave then removed bleed screw. Held finger on hole and pumped til it made a mess. Put screw back in, connect autocraft brake bleeder kit from advance auto parts, about $8.

Part No. AC818/W80617

Once I had the line connected to the kit, I pumped fluid until I had no more bubbles and then continued pumping handle until I filled the little resivoir on the kit 2 times. This is the 2nd '89 that I've had, and have done the same thing with both. Takes about 1/2 to an hour (depending on thirst and beer supply). If all else fails, this will work.

[camos]

I have seen this comment several times, but do not understand how it could work. If the piston is pushed in, it would block any flow back into the reservior from the line. Because if there was flow back from the line, there would be no pressure.

I changed the brake pads on my Virago during a break at work. Unfortunately I was not prepared for issues when retracting the pistons and ended up cracking the bleeder to get them in. So with no brake fluid and no brakes the best I could do was get it to three pumps before it would harden up enough to get brakes. Time had run out at that point so I pumped up then bungeed the lever closed, loosened the reservoir cap, turned the handlebars so the reservoir was up. Checked it on the next break and could see bubbles in the sight glass. Pumped it a bunch of times then left it to sit again. After work the brakes had improved to one pump which was better than expected and good enough to get me home.

 

At home, bungeed it again and the next morning a half a pump got to hard. Ended up doing that for four days before it I had time to bleed them. By that time they were still a little spongy but that method works surprisingly well. I figure pumping it up to hard before bungying with the lever pulled to the grip the relief hole must have opened as the pressure fell off, enough to allow the air out.

[Condor]

I figure pumping it up to hard before bungying with the lever pulled to the grip the relief hole must have opened as the pressure fell off, enough to allow the air out.

 

When the lever is pulled up to the grip the expansion hole in the reserve is on the backside of the compression cup. There is no way air can get to it to pass into the reserve. The air bubbles probably would have excaped out of the lines over a 4 day period even if you hadn't bungied the lever. Over night the bubbles rose to the top of the line and were trapped there by the cup until the next day when you started riding the bike. Each day you removed a little more air. If you had turned the bars so the reserve at the highest point the air would have excaped out the hole a little bit at a time without the bungy. It just takes a long time to bleed the clutch. Reverse bleed them and go riding within a half hour with 100% clutch.

[jimmyenglish]

Thanks for all the responses. I've tried the take the cap off, strap the lever for a week trick and it didn't work. The guys in sturgis tried to bleed it and they said it wouldn't bleed. They disassembled the whole master and flushed new fluid through. It was pretty good for awhile. I'm really feeling like there's something else wrong. I guess I'll try the reverse bleeding trick. Thanks.

[jburrell]

I replaced my slave and within 2 weeks my fluid level was low again. Two weeks later completely lost clutch again. Seatler had to rebuild the master cylinder before I stopped having leaks (I never saw any leakage but sight level would go down). Once the master cylinder was rebuilt I have been fine for 9 months and counting. IT appars it wasnt a slave cylinder issue after all. Consider having the master cylinder rebuilt with the kits that are offered.

[jimmyenglish]

I should add that the other weird thing is as it's going flat, it's not that it's pushing the piston and nothing is happening, the piston is not returning all the way. ie, I have to pull the lever 1.5 inches or so until it even hits the piston. Maybe I bought a bad rebuild kit last spring?

[camos]

@ Condor:

That was the only time I ever tried the bungied lever trick and perhaps you are right that the air would have bled itself out over time.

 

Later when I bled the brakes properly it took about 20 minutes to completely flush and replace the fluid with new doing it without special bleeders or pumps. The Virago front brake is a fairly straight run but perhaps I was lucky or perhaps I used proper procedure by accident.

 

I could be wrong but it appears to me the trick is the drain hose off the caliper bleeder must go up before it goes down into the waste container. If it doesn't there is no air lock and the air in the hose will continue to infect the bake line. I've done it that way the few times I have had to bleed brakes and never experienced a problem. I have not yet had the privilege of bleeding my Venture which appears to be a more complex system so only time will tell.

[Squeeze]

... the piston is not returning all the way. ie, I have to pull the lever 1.5 inches or so until it even hits the piston. Maybe I bought a bad rebuild kit last spring?

 

This is the Cause of your Problem. When the Piston doesn't return on it's own, Either the Spring inside is broken or gone, the Piston sticks in the Boring for whatever Reason.

[Condor]

This is the Cause of your Problem. When the Piston doesn't return on it's own, Either the Spring inside is broken or gone, the Piston sticks in the Boring for whatever Reason.

 

I had that happen when I first rebuilt the master, and the problem was that I'd used silicon assembly lube instead of DOT 3. It softened the rubber compression cup to the point it stuck to the wall of the cylinder and wouldn't move. Tighter than a frog's a$$. Had to rebuild it again. Experience is expensive....

[Squeeze]

I had that happen when I first rebuilt the master, and the problem was that I'd used silicon assembly lube instead of DOT 3. It softened the rubber compression cup to the point it stuck to the wall of the cylinder and wouldn't move. Tighter than a frog's a$$. Had to rebuild it again. Experience is expensive....

 

A Buddy of mine sent me his recently bought and expensive ISR Brake Master Cylinder. Piston was stuck in there to the Point where i had to use 6 bar/87 psi of compressed Air to blow it out of the Boring.

 

The O-Ring which is the first rubber Part seen from outside was swollen up to twice the normal Size. Just a little Spray of Ballistol (Gun Cleaning Spray/Multi Purpose, similar to WD40) .....