Hi gents,

I am attempting to remove the clutch from my M20 and wanted to make sure I was doing it correctly before moving forward.

I removed the sleeve nut and when I tried unscrewing the clutch nut, it wasn't going very easily. To clarify, I'm turning the nut counter-clockwise? When I did that, it seemed like the clutch plates were moving along with the nut, rather than the nut, itself. I have the chain sprocket braced with some clamps, so those are not moving.

I'm a bit terrified of the nut and spring flying off — how do I keep the damage to a minimum?

Here's a pic to show you what I'm working with. http://farm4.staticflickr.com/3789/9676636630_6762a8fb6b_z.jpg

email (option): berryman.brian@gmail.com

Sounds like the transmission main shaft is turning along with the clutch center nut which means the nut is not unscrewing from the clutch center. When the transmission in gear and the drive sprocket is secured from rotating, you will be able to turn the clutch nut counter-clockwise and it will begin to unscrew from the clutch center.

Removing the clutch center and chain wheel will require a puller to break the clutch assembly free of the transmission shaft. (Clutch pullers are available) You will be able to inspect/replace the steel and fiber clutch plates by removing the clutch nut.

Remove the clutch pushrod and reinstall the mainshaft clutch securing nut . A suitable 5/16 bolt long enough to engage the threads in the clutch assembly securing nut along with a large washer big enough to span the clutch nut will prevent the clutch nut from flying off and help limit damage to the threads on the clutch nut and clutch center as it fully unscrews.

Using this procedure, as you unscrew the clutch nut, it will come up against the large washer, so the bolt/washer needs to be backed out along the clutch nut a few threads at a time. The reverse procedure can be used to reinstall the clutch nut, as holding tension against the spring while trying to reinstall the nut squarely on the clutch center can be a chore without some sort of mechanical help. (Reassembly of the clutch unit can be done off the bike as well)

I believe that the M20 maintainence manual available in the WDBSA tech section describes the procedure much better than I!

(Page 21, figure 32

http://www.wdbsa.nl/technical_information.htm

Hope this helps.

email (option): teladelujo@ msn.com

Robb Nortier of British Tool in Michigan, USA makes a compressor for the spring, there's also details on the forum here how to make your own if you have access to lathe and machining facilities.
See my post here , last pic shows the compressor tool.
http://pub37.bravenet.com/forum/static/show.php?usernum=3155626639&frmid=16&msgid=1280203&cmd=show

You can also remove the clutch complete using the screw-in puller only, and disassemble the clutch on the bench using a press to compress the spring- see the tech section on the site.

If you are in UK, Ron Pier has a supply of the tools I make. Please contact him through the forum.

Thanks for the plug Vince!!

email (option): britool51@hotmail.com

So I tried using the screw-in puller, and after giving it a fair bit of torque, it wasn't budging. If I'm understanding it right, the clutch assembly should just slide outward as you tighten the screw-in puller?

Thanks for your help on this. It's the last damn thing I need to get disassembled before being able to free up the frame so I can get it over to the powdercoater!

email (option): berryman.brian@gmail.com

It's always been suggested to screw it up tight, then give it a whack with a BFH and it will pop off, but as somebody said last week, overzealous pounding with a big hammer can cause damage at the other end of the mainshaft- possibly breaking the case. An impact gun was said to offer lower risk to the cases. Just screwing the puller in tight rarely works. FWIW.
Be forewarned, once it breaks free it will come off quite easily and could drop off if not prepared.

It's always been suggested to screw it up tight, then give it a whack with a BFH and it will pop off, but as somebody said last week, overzealous pounding with a big hammer can cause damage at the other end of the mainshaft- possibly breaking the case. An impact gun was said to offer lower risk to the cases. Just screwing the puller in tight rarely works. FWIW.
Be forewarned, once it breaks free it will come off quite easily and could drop off if not prepared.[/quote]


You are attempting to break the clutch center loose from its taper fit on the transmission shaft. In my opinion, taking your time and a judicious use of force will suffice without resorting to an air impact wrench.

You are breaking loose a taper by using the mass inertia of the stationary clutch assembly. Your puller's threaded shaft end should be made (or a suitable spacer used) to fit squarely against the end of the transmission shaft so as to minimize any potential for damage.

With the puller body well-threaded into the clutch center, and the puller well-tightened up again the transmission shaft, apply a sharp "rap" with a brass mallet laid square against the hex-end of the puller. This will normally break the taper fit. If it does not, re-apply the tension of the puller and rap it again. If it still does not break loose, leave the puller in place under tension, and go do something else. Try again in several hours, or the next day, resetting the tension of the puller after each mallet rap. Eventually the taper fit will break loose as the transmission shaft shifts its position in the clutch assembly.

email (option): teladelujo@ msn.com

I agree entirely with the above advice...This is the 'tried and tested' method for the job...The key point is to apply a sharp blow of moderate weight after the tension is applied...
Obviously if you just beat the whole thing with a large hammer it is possible to do some damage but why would anyone do that?...Ian

email (option): ian@wright52.plus.com