B12 Clutch Won't Disengage

[rider384]

Got my built 1216 twin turbo back together, running well, and ready to go with the exception of the clutch. It won't disengage. Clutch lever feels completely normal and it does move the pressure plate. When the clutch is fully disengaged, I can wiggle the frictions around a bit. Not a lot, maybe 1-1.5mm, but the whole pack is loose enough that they can be moved by hand without much force. 

However, in practice, the clutch will not disengage. It's got enough clamping force that it will actually stall out the starter motor when trying to start in first gear with the clutch lever fully in. Stock clutch, no lockup, both factory diaphragm springs replaced with HD units. I have been through the clutch no less than 6 times at this point, each time paying VERY careful attention to the manual on the placement of all the different frictions and steels. The thicker steels are exactly where they're supposed to be, as are the different frictions. Frictions have been re-soaked in oil every time they've come out. I believe the clutch basket is fully seated. The input shaft/diaphragm spring nut is torqued to 110ft/lbs. 

A couple of factors that might be contributing: 

• The alternator/oil pump drive gear was replaced with one from an '86(ish) 750, which, by part numbers, is supposed to be the exact same part. 
• The diaphragm springs are completely flat with the nut torqued down. Not sure if this is right, it seems a little off to me based on the diagrams in the manual.
• The threaded part of the input shaft barely has any threads visible before the nut goes on. I can maybe get 1/2-1 turn out of it by hand before the assembly starts to clamp down on the diaphragm springs. Again, this doesn't seem right to me. 

Sorry for the essay, I'm just really lost on what it could be given that when fully disengaged I can wiggle the frictions around, but the engine is still solidly locked to the rear wheel. Any and all advice is appreciated. 

[TonyGee]

sounds like the clutch basket is not fully seated, are the alternator and crank gears fully engaged?  undo the alternator and see if it goes back all the way. if it does the alternator gear is wrong or not engaging.   

[rider384]

5 hours ago, TonyGee said:

sounds like the clutch basket is not fully seated, are the alternator and crank gears fully engaged?  undo the alternator and see if it goes back all the way. if it does the alternator gear is wrong or not engaging.   

As far as I'm aware, the clutch basket is fully seated. At least the drive gears on the alternator and oil pump are fully seated, confirmed via pulling the alternator out and peering in the hole. The one caveat to that is that I replaced the alternator/oil pump drive gear, and I'm now wondering if I didn't press it all the way down. The part is hard to find and fairly expensive, so I'm worried about putting any more pressure on it. 

As a slight update on the whole situation, I got the clutch to "work" by assembling it incorrectly. I moved the washer in the picture from the front of the spring retainer basket to the rear, effectively lowering the spring pressure when the clutch is pulled. The clutch now "works", in that the engine can idle in gear clutch pulled without moving, but it is dragging pretty bad, to the point where if I don't give it a bit of throttle when at a standstill it stalls out. Also, the dragging seems to get worse when the engine is hot, but I could have been imagining that. 

Not sure what this means in terms of what's wrong with my clutch, I'm hoping someone smarter than me can point me in the right direction of what to look for with what I've learned. And as a side note, all the washers listed/displayed in the service manual are in place in the correct place, with the exception of the one that I moved for diagnostic purposes. 

[rider384]

Pulled the clutch basket out again to check on the alternator/oil pump drive gear. Is it supposed to sit flush? I had to replace it during reassembly because I broke the original due to not fully seating the clutch basket the first time I installed it and didn't take note of how it sat. I beat it on with a piece of wood and a rubber mallet until it stopped going on further, but I'm wondering if it's supposed to sit flush. If so, it would explain both the issues I'm having with the clutch not disengaging AND why moving the spring retainer basket further away made the clutch start to work a bit. 

[Devilman]

Took this pic off Eblag for reference...

It definitely appears you do not have the gear on far enough, on the following pic you can see the only place the splines from the gear are visible is in the lower "lands" on opposite sides of the shaft.

[rider384]

Update:

Pulled clutch basket again in an attempt to further seat the drive gear. No luck, it was hard stuck at that point. Luckily I had a spare clutch basket lying around so I swapped the drive gear onto that one and it went on all the way. Must be a lip or something on my original clutch basket that was preventing it from seating all the way. 
 

The clutch now seems to be functioning fine. Still seems to drag a bit, but I haven't warmed it up or ridden it around yet. Fingers crossed. 

[rider384]

Ok, so fired it up and took it for a spin earlier. The clutch is definitely still dragging, and it's dragging to the point where the engine will actually stall out when put into gear when warm. I can't hold it back from moving with just my feet, have to use the brakes. I replaced the 2x 2mm steels with 2x 1.6mm steels in an effort to give the clutch a bit more room to disengage, but it made no difference. 

So, a brief summary of what I know:

• The alternator/oil pump drive gear is FULLY seated on the clutch basket
• The steels/frictions are stacked in the correct order, verified several times
• The spring washer/retainer are installed in the correct orientation at the base of the clutch pack
• The washer between the input shaft seal and the clutch basket is installed
• The washer between the clutch basket and the clutch sleeve hub is installed
• The system has been bled many, many times

Anyone have any ideas? At this point I'm thinking master/slave/wrong washer somewhere, but the clutch feels completely normal, same engagement point as before I disassembled the bike, doesn't bleed pressure when the clutch is engaged, pumping makes no difference, basically just feels completely normal and functional. 

Edit: Also, is there something that's supposed to go in between the slave cylinder push rod and the main push rod? I didn't see anything in the manual but I'm kind of surprised they're just supposed to butt up against each other with no buffer.

Edited October 30, 2022 by rider384

[Devilman]

3 hours ago, rider384 said:

Ok, so fired it up and took it for a spin earlier. The clutch is definitely still dragging, and it's dragging to the point where the engine will actually stall out when put into gear when warm. I can't hold it back from moving with just my feet, have to use the brakes. I replaced the 2x 2mm steels with 2x 1.6mm steels in an effort to give the clutch a bit more room to disengage, but it made no difference. 

So, a brief summary of what I know:

• The alternator/oil pump drive gear is FULLY seated on the clutch basket
• The steels/frictions are stacked in the correct order, verified several times
• The spring washer/retainer are installed in the correct orientation at the base of the clutch pack
• The washer between the input shaft seal and the clutch basket is installed
• The washer between the clutch basket and the clutch sleeve hub is installed
• The system has been bled many, many times

Anyone have any ideas? At this point I'm thinking master/slave/wrong washer somewhere, but the clutch feels completely normal, same engagement point as before I disassembled the bike, doesn't bleed pressure when the clutch is engaged, pumping makes no difference, basically just feels completely normal and functional. 

Edit: Also, is there something that's supposed to go in between the slave cylinder push rod and the main push rod? I didn't see anything in the manual but I'm kind of surprised they're just supposed to butt up against each other with no buffer.

Do you have any visible signs of wear on either the inner or outer basket? 

Sometimes even a little bit of a "lip" at the edge of each plate can make them hang up and drag.

[rider384]

5 hours ago, Devilman said:

Do you have any visible signs of wear on either the inner or outer basket? 

Sometimes even a little bit of a "lip" at the edge of each plate can make them hang up and drag.

Are you talking where the frictions/steels slot into the assembly? If so, I have checked for visible wear and didn't see anything, everything slides extremely smoothly, no hangups or anything like that. Maybe I'll give them a quick bit of metal file just to be sure.

Also, does anyone know if the diaphragm springs are supposed to be flat when the hub nut is fully torqued? It makes sense why they are, but it just seems off to me, and I don't have a working clutch to verify with. 

_______________________________________________________________________________________________________________________________________________________

Summary of everything done/checked so far:

• Verified that alternator/oil pump drive gear is fully seated on clutch basket
• Verified that clutch basket ring gear and crank gear are perfectly flush, which AFAIK means the clutch basket itself is fully and properly seated
• Verified stacking order of plates and frictions. Thicker steels are where they need to be, larger diameter friction is where it needs to be.
• Verified thickness of clutch plates and frictions - plates are all 1.59mm-1.61mm or 1.99mm-2.00mm, frictions are all 2.96mm-3.02mm
• Verified that washer between input shaft and clutch basket is installed, and that washer between the clutch basket and clutch hub is installed
• Verified that spring washer and spring washer seat are installed in the correct place and correct orientation (concave side facing out)
• Verified that all parts are correct OE via part number
• Verified that the frictions are able to be wiggled around when the clutch is fully disengaged. They have 1.5-2mm of total movement back and forth
• Verified that system is fully bled

Diagnostic steps taken:

• Removed diaphragm springs, put bike in gear, and rolled it back and forth to make sure clutch pack itself wasn't stuck/binding up
• Put a couple washers between clutch push rod and "clutch push piece", effectively extending the length of the push rod. No change in performance.
• Moved washer from inside diaphragm spring holder to rear of diaphragm spring holder. Made no difference once alternator drive gear was seated correctly
• Loosened clutch sleeve hub nut and took the bike for a very short ride. Clutch performed as expected and did not drag, but clutch needed to be pumped to work properly and felt like garbage. Obviously not a permanent/sustainable solution by any means. 
• Replaced the 2x 2.00mm steels with 1.6mm steels in an effort to "shorten" the clutch stack. No change in performance

Potential causes for concern:

• Diaphragm springs are completely flat with the hub nut fully torqued. Not sure if this is normal, I can't remember what it looked like originally
• Clutch basket and input shaft roller bearing are not flush when installed. According to the manual this is normal, but it seems off to me. 
• Screws that hold the diaphragm spring basket and clutch sleeve hub together are not installed, but they weren't when I pulled it apart and it worked fine. 

 

Edited October 31, 2022 by rider384
Clarification

[clivegto]

Is there any sticky gunk on the back of the sprocket cove stopping the pushrod moving properly in and out of the slave cylinder. Is the slave cylinder moving freely. 

[rider384]

11 hours ago, clivegto said:

Is there any sticky gunk on the back of the sprocket cove stopping the pushrod moving properly in and out of the slave cylinder. Is the slave cylinder moving freely. 

Just whipped it off and cleaned it up, it wasn't actually that bad but there was definitely some gunk. 

When I was in there, I noticed that the slave cylinder piston retainer was actually bent out fairly severely. I tried to flatten it and it made no difference, but I think that points to potential issues with the slave cylinder. I'm going to order up a rebuild kit and new retainer and see what happens.

[clivegto]

Yes, I would strip the slave cylinder clean it replace the seal. Even if it's not that it'll give peace of mind that is not the problem. 

[rider384]

Updates:

• Local dealership had a slave kit in stock so I rebuilt the slave cylinder
• Tried another set of steels that I had lying around
• Hit the edges of the clutch basket where the frictions slide in with a metal file and made sure they were perfectly smooth
• Built a longer push rod for the clutch at the clutch lever itself to take up some of the "dead zone" when initially actuating the clutch. It's ~1-1.5mm longer than the stock push rod

No change in performance from any of these. 

So that brings it to either the master cylinder or something in the clutch itself. I'm definitely leaning more towards it being something in the clutch itself as again, the clutch feels completely fine and the hydraulics hold pressure, even over extended periods of time. I'm going to pick up a master cylinder rebuild kit anyways, but if that doesn't fix it, I will have literally replaced EVERY single component of the system.

No idea where to go from here, any and all advice is appreciated. 

[Captain Chaos]

can you not borrow/buy/steal/find a sprocket cover and clutch cable + lever from a Teapot or B6? That would definitely eleminate any issues with the hydraulic bit.

[Dezza]

Is the pushrod of the correct length? It's easy to accidentally install the wrong one if you have several from different bikes lying about.

[rider384]

14 hours ago, Captain Chaos said:

can you not borrow/buy/steal/find a sprocket cover and clutch cable + lever from a Teapot or B6? That would definitely eleminate any issues with the hydraulic bit.

I kind of like that idea, I'll see if I can find something on Eblag. I don't think the 600s are as common over here in America as they are in other parts of the world, but I'll see if I can get my hands on one. 

13 hours ago, Dezza said:

Is the pushrod of the correct length? It's easy to accidentally install the wrong one if you have several from different bikes lying about.

Interesting thought. I don't think I have any other pushrods lying a round as this is the first major motorcycle project I've ever done, but I'll see if I can't track down the specs on the stock pushrod and measure them up against mine. 

And on to some other updates:

I rebuilt the master cylinder and replaced the frictions today, so at this point, literally every single component of the clutch system has been replaced/thoroughly inspected. The clutch pack itself has about 2mm of wiggle/movement when the clutch is fully disengaged, which should be more than enough that it doesn't drag, but here we are. I think I'll try doing another oil change just in case the oil I used was mislabeled or something, and after that just start riding it around as I'm not sure there's anything else to do at this point. Hopefully it either frees up or breaks to the point where the problem becomes obviously identifiable. Not sure there's much else I can do at this point. 

Edited November 1, 2022 by rider384

[clivegto]

Do a burn out, doughnut  that'll free it of a bit . Then fit new genuine Suzuki steels and fibers  

[FJD]

When shifting up and down is it disengaging properly or not ?

Usually downshifting is more critical.

I have a YZF 1000 with a problematic clutch as well, this is a really annoying problem.

[rider384]

I finally have a good update to share! 

As stated before, I decided that there was nothing to do but ride it and hope that it frees up, so I clamped the clutch lever down with a worm gear clamp and started gently riding it around. Slowly, it started getting looser and looser to the point where I could actually stop it in gear with the clutch disengaged and it wouldn't stall. Still drags a bit, but a tiny bit of throttle and it'll stay running. I actually had to stop and remove the worm gear clamp as I could no longer sustain speed with the clutch lever pulled in. Hopefully as I ride it more and more it starts to get looser and looser to the point where it's actually functional as a clutch. But for now, I'm just happy I can ride the bike with a marginal degree of safety.