M900 clutch issues

[Yakoo752]

So I stored the bike for the winter. Took it out of storage last weekend and took her for a spin. Bike fired up well and ran strong, no visible issues. Put the bike away and fired it up the next day to go to work. Made it a block and the clutch started slipping. Made it another block and the clutch was done.

I ordered a clutch from Barnett and it arrived the other day. I opened the side case and pulled off the pressure plate. Pulled out the old plates and put in the new, both mirroring what I removed and what the instructions said to do.

I put it all back together, matching the machine marks on the pressure plates with the mark on the stud.

I pull the clutch, pressure plate extends. I release the clutch, pressure plate doesn't not retract. The clutch lever gets harder to pull with every squeeze.

I removed the slave and the oring was blown, new one ordered. There was a bunch of grease everywhere. It's a yoyodyne so not much serviceability. I plan on pulling it and cleaning everything out. I can't find any tech materials on it so any info here would be appreciated.

The push rod was difficult to remove. I pulled it out from the clutch side and it is missing all of it's orings, they too are on order. My thoughts are the push rod is binding somewhere. I've already checked it is not bent.

What am I missing here? I know I need to bleed and I'm hoping that may help but I can't see where I introduced air and wouldn't the opposite be occurring, not able to generate enough pressure?

I plan on opening up the clutch side and inspecting. If I am in there I may just replace the sprag and the fly wheel. Starting this thing can be rough in colder temps, that should help.

Should I open up the other side? Or am I opening a can of worms? I've never been in the transmission of a moto so I am hesitant.

Thoughts? Direction? Anything?

Old clutch plates - the first pressure plate on the engine side had zero material remaining. The thin friction plates with the damper spring was cracked in half. Clutch done.

 

[bobl]

It may be a bad master cylinder not releasing from a blocked compensation port. When the clutch won't engage after pulling the handle, open the bleeder. If pressure releases and the clutch engages, the master cylinder isn't letting fluid back into the resiviour.

 

[Rob]

I think bobl is on the right track...

I'm going with a clogged line (somehow) and each time you pull the lever you clog it a bit more. I'm wondering if you'll even be able to bleed it.

I'd pull the whole line apart and give it a good cleaning... as that would seem to be the easier problem to fix. If it's not the culprit you have the comfort of clean hydraulic lines to keep you warm at night.

 

[Yakoo752]

ruled that out today

I'm not sure whats going on but the slave and master function as they should

with the clutch pack assembled, pressure plate and springs installed. I can slide the whole pack in and out., maybe 1/4 of an inch. The springs should be preventing this movement from my understanding. I first thought I misaligned the pressure plate but the machine marks align so that can't be it.

I'm just going to pull everything apart, pull the basket off and see what's going on behind it.

I think the burnt clutch was a symptom and not a problem :|

 

[Demoni]

with the clutch pack assembled, pressure plate and springs installed. I can slide the whole pack in and out., maybe 1/4 of an inch.

What is your total clutch pack stack height ? It sounds like your stack of plates is too thin preventing the springs from properly compressing everything.

There is nothing under the stack that would affect the push rod operation. So long as the push rod moves smoothly in and out.

If it's not your stack being too thin I would look at the hydraulic system, when you pull the lever the slave cylinder piston should extend. With the lever at rest you should be able to push that piston back in with little resistance. If it's hard to push back in that resistance is keeping your clutch partially disengaged.

 

[Yakoo752]

What is your total clutch pack stack height ? It sounds like your stack of plates is too thin preventing the springs from properly compressing everything.

There is nothing under the stack that would affect the push rod operation. So long as the push rod moves smoothly in and out.

If it's not your stack being too thin I would look at the hydraulic system, when you pull the lever the slave cylinder piston should extend. With the lever at rest you should be able to push that piston back in with little resistance. If it's hard to push back in that resistance is keeping your clutch partially disengaged.

That's what I thought.

It's a full plate higher then the previous stack. (I'm on the road today so i don't know measurements)

 

[ScottRNelson]

Check that the throwout bearing is good. It's on the clutch side and what that rod pushes against when the slave cylinder pushes on it from the other side. Even if it's not bad, replace it anyway because it's cheap.

A seized throwout bearing destroyed the slave cylinder on the ST2 that I used to ride. I ended up needing three trips to the dealer for parts before I finally got that all straightened out. :mad

 

[JimE]

Check that the throwout bearing is good. It's on the clutch side and what that rod pushes against when the slave cylinder pushes on it from the other side. Even if it's not bad, replace it anyway because it's cheap.

A seized throwout bearing destroyed the slave cylinder on the ST2 that I used to ride. I ended up needing three trips to the dealer for parts before I finally got that all straightened out. :mad

Yeah do this. Better yet buy a STM bearing replacement. Never ever had a problem with mine after I replaced the old open assembly with a sealed STM one.

I also remember going through this on my M900 and at the end of the day the Barnett just wanted me to bleed the damn thing. Again. I had just done a bleed after I got the bike, put the Barnett in.... and it dragged. Did another mondo bleed with it in place and problem went away never to return. Weird.

 

[Yakoo752]

Will do

Any other "consumable" that is wise to replace while I am in there?

I didn't have a chance to work on it this weekend. I am waiting on some parts to come in before moving forward

 

[Yakoo752]

So this is what I am dealing with. The slave is disconnected. I shouldn't have this much slop, right? With springs installed, I shouldn't be able to do this by hand. The machined notches are properly aligned

 

[ontherearwheel]

The clutch nut is backing off letting the hub move in and out.

Btw the hub is a two piece design.....there are rubber dampers in there.

 

[Yakoo752]

My thoughts as well

regarding the nut backing off and not the vintage black porn

if it floats your boat...

 

[two wheel tramp]

:nchantr

I know we're all adults but sorry about that spam.

Yakoo thanks for reporting that jerk.

 

[Demoni]

So this is what I am dealing with.I shouldn't have this much slop, right?

Yea that really does look like the clutch hub nut is loose, you should be able to view it just by removing the pressure plate. That amount of movement might allow the plates to twist in a way that could cause the binding you are experiencing.

 

[Maddevill]

It's been awhile since I've worked on ducks so I could be way off but...some bikes use a 2 piece push rod with a small ball between them. Or a ball at one end of the push rod. That thing can fall out pretty easily. Maybe look at a parts diagram and see if yours has one.

 

[Yakoo752]

It's been awhile since I've worked on ducks so I could be way off but...some bikes use a 2 piece push rod with a small ball between them. Or a ball at one end of the push rod. That thing can fall out pretty easily. Maybe look at a parts diagram and see if yours has one.

This is a thought as well but I didn't notice anything when I removed. It appears that the pushrod is a 1 piece design in mine.

I have searched the garage floor repeatedly to see if I dropped parts accidentally, to no avail.

 

[Yakoo752]

Yea that really does look like the clutch hub nut is loose, you should be able to view it just by removing the pressure plate. That amount of movement might allow the plates to twist in a way that could cause the binding you are experiencing.

I think this is it the more I think about it...

could a stuck plate cause enough friction to back the hub nut out?

Would make sense as the bike just came out of storage, was ridden for a very short distance, ran fine, and then the next morning problems started...

hmmm

 

[Demoni]

Could a stuck plate cause enough friction to back the hub nut out?

No it should not, that nut has a torque spec of 100 ft/lbs and should not back off (not sure exactly, I can check the manual but it's high).

I would remove the 6 bolts that hold the springs onto your pressure plate and remove that. Should be pretty clear if that nut is loose, will be unthreaded from the shaft the same amount that clutch hub is moving in and out.

Report back !

 

[Yakoo752]

I don't think that is the problem.

Pulled it all and nut seems awfully tight. I have a socket on order so I can pull it apart

It's almost as if I am missing a plate but the old set and new set count out identical.

 

[Yakoo752]

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