[Mostrobelle]

1994 Monster M900 with about 40,200 miles on it.

I'd noticed that my clutch had begun to slip a little leaving stoplights about a month ago. I was also having increasingly worsening issues with getting into neutral. There appeared to be a trace of some sort of black, slick residue that was being flung off of the clutch. (It's a dry clutch, so I leave it completely open) I thought it might just be road grime, but I hadn't remembered having the specks on my boot and the junk on my bike before. (Hard to tell...I've been riding in the rain some.) I checked my oil level--looked OK. Bled the clutch--fluid level was fine. The grime looked like carbon and brake fluid mixed together. I have no idea what it is/was.

I pulled the clutch apart to see what was going on. A couple of the plates were pretty worn, but the others appeared decent. There didn't appear to be any of the residue on them that I had expected to find. The push rod was beginning to have the look of being worn I was told. The seals all looked good as far as I could tell. I had just changed out the clutch pack maybe 9 months ago, but I seem to burn through clutches pretty quickly--like in less than 10K miles. I swapped the order of the two worn plates to buy myself a little time while the new pack was on order. It seemed to help a lot with the neutral issue and might have helped with the slipping for a bit.

Since I was ordering a new clutch pack I got a new push rod, seals and needle bearings...the only thing I didn't get was the big seal thingie that goes between the clutch and the motor(?) It was expensive, and since the gooey stuff didn't look like oil, and the shop dude said that that part didn't fail very often, I didn't get it.

So this thing gets all put back together and it rides wonderfully for about 50-60 miles. I take it out for an afternoon jaunt and notice that it slips once or twice. During the course of my 50 mile cruise (some goat-trail stuff) it begins to slip badly on some of the really tight turns where I found myself using the clutch. I find none of the black goop being slung off the clutch, but now there's a visible drip coming out of the bottom of the face of the clutch. I ride it to work over the course of the next week...and it's slipping more and more. The leak appears to be gone, but the slipping is as bad as ever. I called my shop and they said that I should have sealed the bolts holding the basket on--I didn't do that, but I don't remember doing that last time I changed the basket and it didn't leak before (I don't think.)

The clutch comes apart tonight and there's what appears to be clutch fluid (not oil) all over the push rod and inside the housing that it sits in. The plates *look* clean, but every single one of them has been slipping BADLY. I've got no idea where this fluid is from. Slave cylinder? It's an Evo that I had put on a couple of years ago. I had a seal go bad in it once after I did something stupid, but that was probably 18K miles ago and it's been fine. I'm at a loss...where the heck is this leak coming from? Is that the obvious answer to my slipping or is it something unrelated? Stiffer springs are needed maybe? Stack height?

t.i.a.

 

[WhereTheSunDontShine]

Did you use a lotta lube on the clutch rod seals and in the needle rollers ??
Or not enough ??

I'd try washing the friction plates thoroughly in degreaser then detergent, and scratching up the other plain plates with 3 M Scotchbrite pads.

Then " shuffle the deck ", make sure the springs are all OK, see if the pressure plate lifts off the deck evenly, and have a ride.

"(It's a dry clutch, so I leave it completely open) " And how dusty are the roads in your territory ??

WTSDS

 

[Mac900]

One thing for sure is that it's not clutch fluid that is leaking into the clutch pack. If the slave cylinder leaks the fluid will drip out of the left side by the slave & countershaft sprocket. It will not travel down the pushrod, in through the transmission and past the two seals on the pushrod. Any "oil" that might be getting on the plates can only be engine oil and that can only basically come from a bad seal on the back side of the clutch basket or possibly from bad seals on the pushrod itself. It would be a stretch to have oil leaking past the bolts that fasten the clutch basket.

 

[greenmonster]

It`s a longshot but when I changed crank vent oil seeped out via the rod.
Switched back and changed the 2 Orings & the small seal on the rod, problem solved.
So engine oil could get to clutch via rod. I don`t believe in coming through basket screws.

 

[Mostrobelle]

Thanks for all the feedback so far.

The seals on the pushrod are new. I replaced them with the pushrod. The slave looks clean. I'm not losing much fluid or oil from this apparent leak. My oil level is unchanged as far as I can tell. The fluid level on the clutch is fine. It would make sense that it's an oil leak and not a clutch fluid leak. There's a much larger volume of oil--I wouldn't notice a drop in level until I'd lost quite a bit of oil. The clutch fluid should have dropped significantly after having that big a leak.

So it doesn't sound like it's a slave leak or the screws holding on the basket. Interesting. I can't think of too many other places from where the leak could be originating. So that's the good news. However, is this what's causing the slipping? Seems reasonable to think so, no?

 

[Mac900]

Well, I don't know anything for sure. It does sound a bit off that you go through a clutch pack in 10,000 miles. But, hey! All of our collective mileages vary for sure. Maybe it's in the make up of your last clutch pack, as in there is something different in the last packs composition and maybe it's a parts problem???

 

[Mostrobelle]

You're not the first person to say that about me going through clutches so fast. I'm not alone in that, however. I spend a lot of time between cars, so that might have something to do with it. I've changed my riding style and still--the clutches wear out abnormally fast. This is my third clutch in three years on this bike. First one was all stock. Second was alum. basket with steel inserts and alum. plates. I've kept the alum. basket and am now running stock plates. It doesn't seem to make a difference. <shrug>

I have also complained about having trouble with getting the bike into gear at speed. Doesn't seem to always stay in gear once I put it there. I figured it was a rider issue though. I also have been hearing a loud "clunking" noise when I shift between 2 and 3 and 3 and 4. Happens in higher gears too and occasionally in lower. Seems to be more common when shifting down than up. I blip it when shifting down and that seems to help it a little. I dunno...I've always had clutch issues on this bike.

 

[Mostrobelle]

Just to answer a few questions and ask a few more:

It's not dusty where I'm at--I live in Oakland, just outside of San Francisco. No dust.

What are the tolerances on springs? Is there an acceptable measurement range for them? Mine are stock but are relatively new.

Does anyone know what the stack height on a '94 clutch should be. I know my clutch is a little different than other model years. Not having luck finding what it's supposed to be. I'll keep searching, but I'd like to know if I can keep using this clutch pack or if it's been worn beyond its useful life.

Thanks.

 

[greenmonster]

Is there an acceptable measurement range for them?
Does anyone know what the stack height on a '94 clutch should be.

There is but I don`t remember.
38,5mm clutch pack height IIRC.

 

[test-reg]

You're not the first person to say that about me going through clutches so fast. I'm not alone in that, however.

You're right in that it may just be riding style, but if you've got through more than one clutch pack in less than 10k miles each, I'd be having a careful look at the bearings and runout - there's two sets of bearings (the hub/input shaft bearings, and the basket bearings) that might be allowing extra movement, and I'd also check that the hub and basket are both centered and circular - if one (or both) were not quite aligned properly when they were manufactured they might be sliding the plates across each other slightly causing premature wear.

Having said that, like you point out, 10k miles is early, but it seems to be "at the early end of normal wear" rather than "seriously, unexpectedly, somethings definitely not right early"...

big

 

[Mostrobelle]

Here's a little update: I talked a couple of the boys into looking at this last night in exchange for a steak dinner. They tried a number of things--pushrod from another Monster, adjusting the needle bearing in (it was a bit far out, possibly allowing leaking,) playing with different plates and stack heights, and changing to stiffer springs. The plates, btw, appeared clean however they had a strange wear pattern on them.

Nothing made a big difference EXCEPT the new springs. I now have to really rev the engine up and feather the clutch to get it to "groan" (I'm going to say "groan" instead of "slip" from now on--one of the guys said that calling what I had "slipping" was misleading--the bike has never/rarely "slipped" while the clutch was fully released at speed.) I can get it to groan if I throttle hard and don't release the clutch immediately or if I start from 2nd. The problem appears to be pretty much fixed, but I need to keep an eye on it for further leaking.

There is one thing discovered that was a bit troubling. The basket has some play in it. That is, it can move in and out perpendicular from the engine just a little under 2 mm. We checked on at least one other Monster--same year--and it does not have this movement. Any thoughts?

Hey, Big (how are ya? ) and how do I check that hub and basket are circular? I don't think we've checked any bearings other than the needles. How do I go about doing that and what am I looking for?

 

[Speeddog]

------snip-----------------
There is one thing discovered that was a bit troubling. The basket has some play in it. That is, it can move in and out perpendicular from the engine just a little under 2 mm. We checked on at least one other Monster--same year--and it does not have this movement. Any thoughts?
------snip-----------------

That's due to wear on the inner hub, under the big, thin washer that goes underneath the nut.
The hub has rubber damper wedges in it, yours may be worn out, allowing a lot of rotational muvement, and thus the wear.

Someone posted up on this issue recently, but I don't remember who.

I think they shimmed the inner hub, but I don't remember much more.

 

[ducpainter]

I modified my clutch pack by adding an extra beveled steel plate facing in the opposite direction from the stock one. I also cleaned up the steel plates with a scotchbrite disc on a grinder.

The groaning stopped. YMMV.

 

[Mostrobelle]

Yeah, we tried adding in another plate. It didn't help. My stack height is within acceptable tolerances. The clutch pack is new/stock, and all the plates appeared clean. I can rough 'em up a little if that might help.

Speeddog--what affect could a worn inner hub have on the clutch's ability to engage? Is there a hub I can buy or do I need to have one made?

 

[test-reg]

Hey, Big (how are ya? )

I'm doing well and you?

and how do I check that hub and basket are circular? I don't think we've checked any bearings other than the needles. How do I go about doing that and what am I looking for?

Have a look at the pdf parts diagram available here on the ducati.com site.

Page 26 shows the engine case with the input shaft bearings as part #s 9 and 12. They're the bearings that support the clutch hub center. (I think these are the least likely to be your problem, which is good because they're pretty much impossible to get a good feel for damage less than catastrophic failure without splitting the cases.)

Page 14 shows the clutch, and parts 18 and 20 are the bearings that support the basket.

To check both the bearings and the circularity of the basket and hub you'll need a dial gauge (which looks a bit like part # 23 on page 4 of that pdf).

If there's a problem with the shaft bearings, you'll be able to detect the whole clutch assembly moving up and down and/or forwards and backwards. If there's a problem with the basket bearings you be able to detect movement between the end of the input shaft where the hub nut goes and the basket (you'll need to pull the pressure plate and the clutch pack to test this). Use the dial gauge and check for both forward/backward and up/down movement. Shove the clutch around pretty hard, you won't break anything by hand - if you see more than a thou or so of movement, get someone who has a good feel and a lot of experience to confirm your findings (or just replace the bearings...)

To check circularlty, use the dial gauge again, and check to see if the flat nose bit on the left end of part 7 (on page 14) moves forwards/backwards or up/down when you rotate the shaft, and do the same for the outside of part 13, somewhere down near the bottom of the fingers. That rubber damped hub the dry clutch motors have is new to me (on my bike the hub is splined to the input shaft and doesn't have the part 10,6, and 7 assembly), so I can't quite picture how you'd measure that up directly.

I'm not sure how much movement there's supposed to be between parts 7 and 10, but the rubber blocks (part 6) are clearly intended to at least allow some rotation, I don't _think_ there should be any endplay there though. I think the problem Speeddog is talking about is part 9 wearing itself into part 10 (on page 14) and allowing those two parts to move unintentionally. You'll need someone with more dry clutch experience to help you our there though...

cheers,

big

 

[Mostrobelle]

Thanks guys--got my homework cut out for me. I'll get back to you on this and let you know how it's going. [thumbsup]

 

[Mark1305]

That's due to wear on the inner hub, under the big, thin washer that goes underneath the nut.
The hub has rubber damper wedges in it, yours may be worn out, allowing a lot of rotational muvement, and thus the wear.

Someone posted up on this issue recently, but I don't remember who.

I think they shimmed the inner hub, but I don't remember much more.

That would be me The basket shouldn't move in and out. Take your pressure plate off and look at the edges of the rather large thrust washer on the face of the hub under the big nut. The washer should be on top of the Cagiva elephant and year/date markings cast on the hub face. If its sunk down into those raised markings any at all, the hub is ready for the trash bin. I found a machine bushing to take up the 2mm of wear I found in the track bike clutch hub, but ended up using a fresh looking hub instead. I noticed LT Snyder ( www.desmotimes.com ) had three good used hubs in his clearance stuff last week. Again, I have to give credit to Chris Kelly for steering me to find this problem on my bike.

I cured the in and out play in my clutch, but still have a small but detectable bit of radial play at the basket. I had none on the bare input shaft, so I believe the bearings inside the driven primary gear may be worn. It can wait until the next teardown.

As mentioned above, you can rule out brake fluid from the slave getting over to the clutch pack because if any did get past the two o-rings on the left end of the rod it would arrive at an open space about 10mm further on and drip into the crankcase. When you say the pushrod seals were replaced are you including the tiny seal just inside the end of the transmission input shaft? That would be the culprit if the oil is coming from the pushrod bore. And what you are finding is oil, it just doesn't look or smell like the rest of the oil for some reason, DAMHIK. Anyway, that seal is a standard industry item. Ask your favorite bearing supply house for a seal; 8-12-3 (size in mm); The Chicago Rawhide (SKF seals) part number is 3030. The old seal will pull out pretty easily with just a small hooked tool or stiff wire.

The big expensive seal where the primary driven gear flange that the basket bolts to where it sticks through the housing is also a standard item, size 75-95-12 double lip or auxilary lip style (depending on how precise the counter guy is with terminology). That seal will let oil leak at the back of the basket behind the clutch pack. If its clean and dry back there, rule it out.

Back at the front of the stack, you also have an o-ring in a groove inside the big collar/spacer that fits on the input shaft between the hub and primary gear and another o-ring and another that fits just inside the splines at the top/face of the hub. Either of those can let oil travel up to the front area of the clutch pack. I haven't measured them for sizes yet.

Hopefully some of this info will help you zero in on the problem.

Edit: I forgot one other seal, the one on the driven primary gear bore that the large collar sticks into before seating on the bearings inside the gear. It's a 35-47-7 or CR # 13945. It, or either of the two nearby o-rings I described above would most likely leak into the inside of the basket somewhere. The largest seal around the primary gear would more likely leak into the housing and onto the backside/ouside of the basket.

 

[greenmonster]

That seal will let oil leak at the back of the basket behind the clutch pack.

Sounds very likely like the cause to my leak when crank vent wasn`t fully OK.

 

[Tigre]

Hmm... I've got to digest some of those posts, but here is how I would describe the "play" so that we're all on the same page:

Remove the plates, take out the clutch nut, remove the hub, undo the 8 bolts with the hex heads and detach the basket. On the face that's remaining, you'll see the 8 holes those bolts used to screw into. Thread one bolt into those holes, and you can push/pull with 1.8mm of "play".

Belle -- get Enzo to post the photos we took of this in action. It might help to clarify.

 

[Tigre]

Ahh... using that diagram:
When we remove 13 and outward, we experience the phenomenon of the "in/out" movement.

You can put bolt #11 into 17, and pull 17 outwards by 1.8mm. We first witnessed this phenomenon when we were pounding the needle bearing back into place -- we could observe the basket moving in/out due to the impact on the primary shaft from the rubber mallet.

I assume that the clutch drum nut will hold all this stuff together and not cause any problems, but I'm still a bit mystified.

I didn't eyeball the other 94 monster 900 that was sitting next to this one closely enough. I assume that when we "pull" the part out, that is the "unnatural state". Is it possible that something is missing? I don't think it's part 16, but is there something like a part 16 on the back-side of the clutch-side engine cover that keeps pressure and doesn't allow you to pull the gear forward?

We haven't taken the side cover off, but I'm not afraid of that operation. I've done it before. Just not sure what to be looking for just yet.

Thoughts?