Twin clutch Question..?

[Ducdude]

Greetings all,
The C20 clutch retaining nut has developed a nasty habit of repeatedly coming loose while riding.
I fitted new main clutch shoes yesterday as well as generally cleaning up behind the clutch drum and all around from an oil leak...
The repair was straight forward .
The nut was applied and torqued with blue Loctite on it with an air wrench and it came up snug very snug.
Only 50 miles later it is loose again.
Are there any tricks to keeping this nut in place?
I do not want to use stronger Loctite as I know I will have to be in there again one day and do not want to have an issue..
I have considered the following :
Using red Loctite or bearing lock (Loctite) real strong stuff
Getting a new C20 or C20/1 nut (what is the difference?)
Getting new C19 thrust washer
Safety wiring the thing some how..
Any ideas out there ?
What is causing this nut to loosen is not clear to me as it all goes together well.
Thanks for your assistance as always.
Eric

 

[bmetcalf]

Are you using the C45 spring?

 

[timetraveller]

If you re not familiar with the C45 spring then one end of it is bent inwards at 90 degrees (a tang) and should go into one of the slots in the nut and the slot in the end of the main shaft. Sometimes the tang breaks off, either wholly or partially, hence no locking. It is easy to bend a new tang if it has broken off. If properly fitted then there is no need for Loctite or any other form of control. It just cannot come undone. I have seen a case where there was a mismatch of main shaft to nut type and the nut would not screw in far enough to allow the slots to line up so that the tang could do its job. Ensure that you do not have a mix of 'C' and 'D' parts. Cheers.

 

[greg brillus]

Perhaps one issue is that the Air wrench you talk of is not tightening the nut as much as you think. Put the gearbox in top gear, place a piece of broomstick through the rear spokes and swingarm, and tighten with a torque wrench to 65 Ft lbs. If the spring that Bruce and Norman talk of is missing this will not help, even so the nut should not come undone that easily. Almost as if something else is not right.....When the nut is tight, how much can you move the C 13 carrier in and out....? this with the C 19 thrust washer in place. If no clearance exists this could undo the C 20 nut. Need about 0.010 to be ideal. The inner face of the nut actually tightens on the outer splined face of the C 3 shoe carrier, and some have a bonded sealing washer in this recess.....if this is missing, the nut could be tightening up on the mainshaft only and not the C 3 face. So you need to check a few more items to see what is causing the issue...........Greg.

 

[Ducdude]

Are you using the C45 spring?

Yup C 45 is there but the tang does not go past the C20 gap into the shaft so it is not locking anything...I will get a new one though this is a recent part. The nut is just coming loose as that is what is found once disassembled. Free play increases at the lever as the entire clutch is pushed out. Until this goes to far the bike still shifts well and the clutch does not drag. Clutch carrier C3 pulls out easy as can be, so I may have escaped expanding damage to C3 from to much torque as if it was expanded and grabbing PD22 and PD24 I would think C3 would be hard to pull out....
What causes the nut to undo is not obvious to me..

Much Thanks
Eric

 

[bmetcalf]

As noted above, you can bend in a longer tang with needlenose pliers, ride now, and put a new one in next time you are into the clutch.

 

[Ducdude]

If you re not familiar with the C45 spring then one end of it is bent inwards at 90 degrees (a tang) and should go into one of the slots in the nut and the slot in the end of the main shaft. Sometimes the tang breaks off, either wholly or partially, hence no locking. It is easy to bend a new tang if it has broken off. If properly fitted then there is no need for Loctite or any other form of control. It just cannot come undone. I have seen a case where there was a mismatch of main shaft to nut type and the nut would not screw in far enough to allow the slots to line up so that the tang could do its job. Ensure that you do not have a mix of 'C' and 'D' parts. Cheers.

Thanks Time,
I am familiar with the C45 spring and the springs tang does not go past the C20'thickness into the slot in the shaft. It is not locking any thing. I can line the slots up but the tang can not lock. I will replace this it and look into confirming I have the proper nut on there. Does any one know the difference between the C20 and the later C20/1 nut ? Is the C20/1 thicker at the head?

Much Thanks,

Eric

 

[timetraveller]

Just a tip. When you bend in a new tang make sure that there is a reasonable curve at the bend. Many of the original ones had a very sharp right angle there and that is where they break. It really does only take a minute to do. There is much more work getting at it and putting it all back together afterwards.

 

[Ducdude]

Perhaps one issue is that the Air wrench you talk of is not tightening the nut as much as you think. Put the gearbox in top gear, place a piece of broomstick through the rear spokes and swingarm, and tighten with a torque wrench to 65 Ft lbs. If the spring that Bruce and Norman talk of is missing this will not help, even so the nut should not come undone that easily.

Almost as if something else is not right.....When the nut is tight, how much can you move the C 13 carrier in and out....? this with the C 19 thrust washer in place. If no clearance exists this could undo the C 20 nut. Need about 0.010 to be ideal. The inner face of the nut actually tightens on the outer splined face of the C 3 shoe carrier, and some have a bonded sealing washer in this recess.....if this is missing, the nut could be tightening up on the mainshaft only and not the C 3 face. So you need to check a few more items to see what is causing the issue...........Greg.

Ahhh Now I see .....I did have the bike in top gear with the rear brake on in the hopes that I would get the nut tight. Problem one is the C45 tang does not lock, as the tang is to short. I will tend to this....I will also look into where the C20 nut actually tightens. I have not yet checked the play in C13 but once I am into that bit I will make sure it is as you have stated..

Will report what is found in a week or so when I get back into it..and some new parts arrive

Much thanks,

Eric

 

[Ducdude]

As noted above, you can bend in a longer tang with needlenose pliers, ride now, and put a new one in next time you are into the clutch.

Thanks I have to check a bunch of stuff in t here any way may as well just get a new one with the rest of the bits...:-(