Can't get clutch to pump up like it should. What to do?

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mvvette97

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For the last 5 years my clutch lever has had a problem. It gets soft feeling and doesn't want to pump up. I rebuilt the master cylinder a couple times but the last time it didn't help. figured the master was just worn out so bought a new master cylinder. Installed it and it's the same way. I have pumped over a quart of fluid through this thing and no matter what it just won't pump up the way it should. There are times it will feel normal but most of the time it is messed up. Only thing I haven't changed is the slave down on the engine where the bleeder is. Could that possibly be bad? Are they hard to change?
 
I don't see any leaks at all. the only way I can get the clutch to work somewhat normal is that I added a tiny shim between the clutch lever and that rod that pushes in the master cylinder. It has been doing this for a while but just been getting worse over time. Like I said years ago when it did this I put a rebuild kit in the master and it was good for a couple years. Then started feeling soft and not wanting to disengage very well. Rebuilt the master again last year but it didn't change it. so bought a new master and still the same. As for the mechanical part of the clutch I think everything is fine. Does not slip or anything like that. Have something going on with the hydraulic part.
 
Try bleed again.... You could have some trap and the slave valve or banjo bolt.

Or a bad slave valve/cylinder...
 
Next time it gets soft, carefully cover everything near, and under the handlebar master. Pop loose the banjo bolt there where the line attaches to the handlebar master and burp the bubble out there first, before any addt'l bleeding down to the nipple on the left hand side of the motor.

When you fill up your handlebar reservoir, BE CERTAIN you are putting in enough brake fluid so as to NOT be allowing any stirring, or mixing of air bubbles when leaning into corners, or simply slamming the bars all the way to one side while parking/storing the bike. I had a recurring problem like this on both my 85 Vmax, and my 86 Venture Royale. Come to find out, I was being way too conservative when topping off the reservoir in an attempt to ensure I didn't have any slopping out later through the tiny breather hole. I was causing my own grief, and didn't know it for a couple years. Topped them both properly, and my problems never returned.
 
When Ive bled the clutch....and the brakes, I do it the old fashioned way. I pump it up probably 50 times....and then crack open the bleeder valve....and I do that a couple of times. The I tie a rag around the lever and the grip and leave it for the night. That way any air in the system will snake back up into the master cylinder.

That technique has never failed me.
 
When Ive bled the clutch....and the brakes, I do it the old fashioned way. I pump it up probably 50 times....and then crack open the bleeder valve....and I do that a couple of times. The I tie a rag around the lever and the grip and leave it for the night. That way any air in the system will snake back up into the master cylinder.

That technique has never failed me.
Never thought of that. I will have to give it a try. I did go back out and try to bleed it again but it's no better. Since I have a new master cylinder i just went ahead and ordered a new slave so I can rule out defective parts. My bike is an 89 so that slave has to be worn some I would think. I'm guessing to change the slave all I have to do is pull that round cover to get access to the two bolts on the slave?
 
You can get kits to refit both the M/C and S/C - it's worth doing on an '89.

Also in my experience, normal bleeding (as in brakes) has never worked for me on a vmax, I found I needed to reverse-bleed (push fluid through the cracked open nipple on the S/C using a syringe) to get all the air out. Do make sure to protect everything from fluid splashes around the M/C though!
 
You can get kits to refit both the M/C and S/C - it's worth doing on an '89.

Also in my experience, normal bleeding (as in brakes) has never worked for me on a vmax, I found I needed to reverse-bleed (push fluid through the cracked open nipple on the S/C using a syringe) to get all the air out. Do make sure to protect everything from fluid splashes around the M/C though!

I've struggled to bleed both systems every time with these bikes too. I reverse bled the clutch last time and it worked right away. But I haven't had a need to try again yet to see if it was a flook or repeatable. Reverse bleeding did work great for me though......once..........
 
Yes, the syringe/reverse bleed is what to do before you change the slave cyl. Do a search to locate the ways others have done it. A start: http://www.vmaxforum.net/showthread.php?t=28499&highlight=syringe+bleed
My # 14, 25, 28, 31. And, all the others , too.

Be careful removing the screws that hold the slave in-place. I suggest you use a hand impact tool and a brand-new #2 Phillips tip to loosen the screws. If you bugger the heads, you will have a very hard time to get the screws out. You may need to use an extension between the hand impact tool and the tip holder to get into the recessed screws. Be sure you are holding the hand impact driver perpendicular to the screw, and I prefer a baby sledge hammer to hit the impact driver, or at least a 20 oz. hammer, or a larger ball-pein hammer.

If you have an air-tight system (except for the master cyl cap vent) and you do the reverse-bleed correctly, you should have absolutely no need to tie-down the clutch lever overnight, it should work as it should once you are done. As the air bleeds to the master cyl, the lever should go from a clutch lever pressure point next to the bar, or no resistance, to an increasingly-further from the bar pressure point for the clutch lever. You should end-up w/a firm feel at about 2/3 of the way from the bar, w/the resistance being the same as you squeeze the lever to the bar. You can just picture in your mind's eye the diaphragm clutch spring compressing and the outer pressure plate moving away from the clutch friction disc pack.
 
I've always had issues with bleeding clutch systems. The trick that I figured out (at least it works for me) is to remove the slave cylinder from the engine and clamp the piston with a C-clamp as if you were trying to push it back in like a brake piston. Then hand bleed like normal. The clamp helps build the pressure in the line quicker since you have something solid like the clamp to push rather than the clutch spring that compresses a little.

Just my $0.02.

Later, Doug
 
Well I went back out and messed with it some more. It seems there is air in the system still. I keep getting tiny spits of air like every 4th time I crack the bleeder after pumping the master. out of fluid so will have to get some more tomorrow. Now just thinking about something here. I am trying to bleed it on the side stand so the bike is leaning to one side. Could this make it harder to get trapped air out from the slave cylinder? Thinking maybe I should get the bike level or maybe even lean the bike to the right a bit so the bleeder will be upward at the highest point. Maybe this won't make any difference but just thinking how air will try to settle at the highest point I didn't know since the bike is leaning to the left that if there may be a place in the slave that air could get trapped. Oh I don't have a center stand so that's why I was trying to bleed it leaning. Ya think that could be a possible problem or am I just thinking way too much?:confused2:
 
I've always bled mine with it on the side stand. The master cylinders....are still the highest point in the system.
 
Do you have a mightyvac? To get all the air out of mine I had to hook the vac up to the slave cylinder, build up 25psi of vacuum, and crack the bleeder for half a second and then build up pressure again (basically be constantly pumping) and keep doing this while refilling the reservoir periodically. It took about 3 full reservoirs of fluid to get all the air out, but next year when I bleed the system again I'm going to buy another bottle of fluid so I'm not worried about being conservative with the $6 bottle. Then just to make sure all the air was out, I zip tied the lever down for 48 hours and I'm confident there's no air in the system at all. I did all this with it on the sidestand
 
I would think bleeding the slave on the sidestand wold be more difficult. Wouldn't that put the "high end" of the slave cyl opposite of the bleeder?
 
You can also try food extractor, A oil can the has a trigger pump to it, to push the fluid up to the master cylinder. These are things that work to for bleeding the systems out.

I bought a few years ago, 3 vacuum pump witch I use for AC work. I started using 1 for bleeding the brakes or cars, then trade it on my motorcycles and it work like a champ. 1.5 mins on the vmax clutch.... Very fast to used.

I no this is little extreme but it works and on cars it pulls the dirt out of the lines to.


https://www.youtube.com/watch?v=ZViG9FMXhzw
 
Yes, the syringe/reverse bleed is what to do before you change the slave cyl. Do a search to locate the ways others have done it. A start: http://www.vmaxforum.net/showthread.php?t=28499&highlight=syringe+bleed
My # 14, 25, 28, 31. And, all the others , too.

Be careful removing the screws that hold the slave in-place. I suggest you use a hand impact tool and a brand-new #2 Phillips tip to loosen the screws. If you bugger the heads, you will have a very hard time to get the screws out. You may need to use an extension between the hand impact tool and the tip holder to get into the recessed screws. Be sure you are holding the hand impact driver perpendicular to the screw, and I prefer a baby sledge hammer to hit the impact driver, or at least a 20 oz. hammer, or a larger ball-pein hammer.

If you have an air-tight system (except for the master cyl cap vent) and you do the reverse-bleed correctly, you should have absolutely no need to tie-down the clutch lever overnight, it should work as it should once you are done. As the air bleeds to the master cyl, the lever should go from a clutch lever pressure point next to the bar, or no resistance, to an increasingly-further from the bar pressure point for the clutch lever. You should end-up w/a firm feel at about 2/3 of the way from the bar, w/the resistance being the same as you squeeze the lever to the bar. You can just picture in your mind's eye the diaphragm clutch spring compressing and the outer pressure plate moving away from the clutch friction disc pack.

Thanks for this post. I have been looking for more details on the "reverse bleed" This forum has SO MUCH information!
 
Here's another possible cause for sponginess in your lever. You might check your lever CLOSELY to see if you have a similar issue with yours.

Spongy front Brakes.jpg

:biglaugh:
 
I would think bleeding the slave on the sidestand wold be more difficult. Wouldn't that put the "high end" of the slave cyl opposite of the bleeder?
That was my thinking but don't know for sure. I will get the bike level and try it again. If not I will try to reverse bleed it
 

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