Stelvio Clutch not disengaging

[Kuni0]

Thought I'd pose this question to the group here and get some opinions and feedback.

Hoped on the Stelvio to head into work today, and not half a mile down the road I realize pulling in the clutch isn't fully disengaging, and the bike is still creeping forward with it fully pulled in. It's at this time I notice that shifting suddenly became a lot more difficult as well. I was able to creep it back without issue and hop on another bike. 

I've experienced this exact issue once, on my V11 when the clutch plates were done.

I opened the clutch master cylinder to inspect the fluid and saw that it was all black and started attempting to bleed it before realizing I should just get a brake bleeding kit to make it easier. I've had the issue in the past, but it hasn't prevented me from disengaging the clutch. I'll attempt to properly bleed the system, but I'm not that hopeful. 

Is there anything I should look into and troubleshoot before assuming the worst? Or should I add clutch plates my checkout and start dismantling the Stelvio? 

[footgoose]

Black? gosh, purge the system, maybe twice, then consider the next thing. fwiw, I've never used a bleeding kit or pump to do this job on any system. Just pump it out and replace it as you do, just don't let the rez go down to let air in. Do the prep, a nice clean, clear hose to watch what comes out. Your body goes through some weird contortions but it can be done. don't be afraid to waste a can of fluid.

[pete roper]

I can give you advice and what will probably be a cheap fix for this, if you're lucky. If you're not so lucky I can give you a 'Cheaper than clutch replacement' fix. Gimme a few hours though because I'm on holidays at the beach and I need to go to bed and sleep first.

pete

 

PS. What year model Stelvio?

[Kuni0]

2013 Stelvio NTX with about 48k miles. Picked it up from the original owner with less than 7k. No clutch work other than bleeding the master cylinder, which obviously needs a rebuild kit given the state of the fluid.

And thanks Pete! No rush and enjoy your vacation

[pete roper]

There was a bad batch of clutch plates in 2012 and I've heard of a 2013 bike having the problem too so let's not rule out the clutch entirely. I'll come back to that though.

Firstly, all the CARC bikes and to a lesser extent the V11's are murder on their clutch fluid. It's for this reason that we change it at every 10,000km service or yearly, whichever comes first.  If your fluid hasn't been changed regularly it may just be that the bore and seals of your master cylinder are rooted. If it's just the seals it can be rebuilt but if the bore is damaged it will need sleeving and finding somewhere to do that nowadays is getting hard, at least it is here. If that isn't a possibility new M/C's are still available but they're spendy! An alternative, more expensive but with the benefit of a lighter pull, is to go to a 16mm radial master. You'll probably need to change the hose to the slave though.

Another, much cheaper, possibility is that the actuating plunger on the clutch lever has come loose and backed off. How much travel is there in the lever before you feel the piston in the master cylinder start to move? If you look at the lever you will see there is a barrel with a plunger coming out of it that actually goes into the back of the master cylinder to press on and operate the piston. That plunger is threaded and screwed into the little barrel in the lever and is usually loctited in place but it's real locating mechanism is a tiny 1.5mm hex grub screw threaded into the underside of the barrel that locks it in place.

Now it's not uncommon for the grub screw to loosen or fail to properly locate the plunger so, if the Loctite fails, the plunger can move in the threads in the barrel and usually it winds out, away from the piston. When this happens more and more of the travel of the lever is used taking up the *Space* between the plunger and the piston before the piston itself starts moving, pressurising the line and lifting the clutch. When it winds out far enough there is no longer sufficient lift for the clutch to engage so the bike will 'Creep' in gear when halted and gear changing becomes difficult.

If that is the problem the cure is simple. Remove the lever, loosen the grub screw in the barrel, (Use a VERY good Allen key or you'll round out the hex in the screw.) then wind the plunger out of the barrel a bit. The aim is to have only the tiniest bit of clearance 0.25-0.75mm or 10 to 25 thou between the end of the plunger and the piston of the master cylinder while the lever is at rest but the piston has to be able to fully return to the end of its travel to open the priming port to the reservoir. If it can't then the system becomes 'Closed' and as the fluid expands as it heats up it has no way to return to the reservoir so it starts lifting the clutch leading to slippage under load. It takes a bit of faffing about and trial and error but once you've got the length right the clutch should both work without dragging and not slip under load when hot. Once it's working OK nip up the grub screw to prevent the plunger from moving again. Although the plunger does have a slot for a flat bladed screwdriver in the back to allow adjustment it is usually full of Loctite so what I tend to do is simply hold the plunger in soft jaws in a vice and turn it by using the clutch lever as a lever to turn the barrel on it. If it's very tight? Heat the barrel to soften the Loctite with a propane torch, (Carefully obviously!).

Of course if none of these things help then yes, you will have to go in and investigate the clutch. The *Usual* failure on the bad batch of plates is that the cush/anti rattle springs in the centre of the plate destroy their seats in the hub and eventually make a break for freedom. When this happens though the result is usually catastrophic and very, very noisy! What happens and what you have to do about it was well documented on Wildguzzi a few years ago in a thread titled 'Horrors in my bellhousing' by a bloke called Sean in British Columbia. Lots of pics to help too.

[Kuni0]

So this is what the clutch fluid looked like at the start. Went through and bled the entire system until it was finally clear, but still didn't help the clutch disengage

[Kuni0]

Taking Pete's advice, I checked the play in the lever, and seeing that it was ~1.5cm of freeplay until the clutch started to engage, I decided to adjust the plunger hoping that would fix my issue

 

[Kuni0]

Was able to get out the grub nut without issue, and I adjusted the plunger as far out as it would go. On a side not, it seems the issue of the master cylinder not being properly sealed is coming from where the plunder engages, since when I took it out for adjustment, it seems to have been covered in brake fluid

[Kuni0]

Doing so greatly improved the tightness of the lever, decreasing it to ~0.5cm of freeplay. However, it unfortunately wasn't able to get the clutch disengaged in any gear (though it did make it much easier to rotate the rear wheel). In rotating the wheel with the clutch engaged, there was a very obvious scrapping sound and dragging feeling when moving the wheel. I took of the starter motor fearing the worst, but it doesn't seem there is a catastrophic failure inside the bellhousing at the moment. Though I havent had a new seal kit/ master cylinder, I think this might be pointing down to the failed clutch path at the moment...

[pete roper]

With the engine off have a bit of a fish about through the slot at the bottom of the bell housing with a magnet on a stick. You could have a poke about through the starter portal too. If the anti rattle springs jump ship they soon get smashed up and you usually get bits of them in the bottom of the bell housing. There also tends to be 'Pock marking' of the alloy on both the back of the crankcase and front of the gearbox caused by the bits of frag being flung around vigorously by the spinning flywheel.

Victor Mattei from VA somewhere is doing a clutch and engine swap on his Stelvio right now and documenting it on ADV. lots of pics of the engine coming out and the damage in his clutch. Starts about here.....

https://www.advrider.com/f/threads/moto-guzzi-stelvio-merged-threadfest.113158/page-3283

I've had a fair bit of input encouraging him and supplied the clutch so I have a dog in this particular fight! 
 

Oh, and blowing up that picture of the starter motor mounting hole as far as I can does seem to show some minor 'Pock marking' in the alloy of the case so it may well be that you've had a clutch explody failure.

[Kuni0]

Started digging around the bellhousing a bit, rotating it as I moved along, and lo and behold, what do I manage to fish out!!!

I suppose this now answers why the clutch wasn't disengaging 

[pete roper]

Yup, that's a bit of the anti-rattle/cush spring. With a bit of luck you got it before it can do much damage and you'll get away with just a plate.

[pete roper]

here's a pic of what my plate was doing when I swapped gearboxes on my Griso. It was a 2012 motive unit. It was getting ready for the spring to jump ship.
 

http://<a href="https://flic.kr/p/2mi3Frv" title=" by -convertpervert-"><img src="https://live.staticflickr.com/65535/51388731235_cbc137c80b.jpg" width="375" height="500" alt=""></a>
 

Sorry, still can't work out how to post up pics on this site from my iPad.

[KINDOY2]

18 minutes ago, pete roper said:

here's a pic of what my plate was doing when I swapped gearboxes on my Griso. It was a 2012 motive unit. It was getting ready for the spring to jump ship.
 

http://<a href="https://flic.kr/p/2mi3Frv" title=" by -convertpervert-"><img src="https://live.staticflickr.com/65535/51388731235_cbc137c80b.jpg" width="375" height="500" alt=""></a>
 

Sorry, still can't work out how to post up pics on this site from my iPad.

Petes spring...

[Kuni0]

After accomplishing about 3 solid days of work over the course of a month, I was finally able to get the motor and transmission free. It wasn't easy, but surprisingly not super difficult either all things considered. I swear checking the valves on my 98 VFR800 or doing any work on my Futura was more difficult