Mk III Clutch Drag

cash · Mar 16, 2007

LAB,
As my home made mainshaft / clutch pushrod seal is 5mm thick the clutch centre adjuster had to be screwed out to clear it. I then found I was running out of stroke as the actuator had to be adjusted to make up the 5mm. To compensate for that I added 5mm on to the pushrod which put the actuator lever back where it came from.
I think I did the mod 7 years ago and the clutch has never given me a problem since.
I've never seen Dyno Dave's seal, perhaps it's slimmer and might not cause the same problem. However, If you do want to try a longer pushrod send me the length and I'll make one up for you.

79x100 · Mar 16, 2007

jumpjg,
I don't think that you have to worry about the standard bronze clutch slipping unless it has suffered quite a lot of oil contamination and even then, it is not terminal.

I have never used anything other than bronze plates and have subjected mine to phenomenal abuse two-up with camping gear and have never had problems.

If the time has come to clean the plates then it will start to show this by slipping at maximum torque, around 4750 / 5000 rpm. However, it cannot burn out and is not like a single plate car clutch where you have to almost stop before the clutch finds grip again. The weird thing about a slipping bronze clutch is that it grips again on the way down. Back off the throttle a bit and as the revs drop below 4500, it will start to grip again and you can happily carry on like that.

To be honest, unless you're related to Ernest Thrasher :evil: ,you'll probably never notice it.

L.A.B. · Mar 16, 2007

cash said:
LAB,
As my home made mainshaft / clutch pushrod seal is 5mm thick the clutch centre adjuster had to be screwed out to clear it. I then found I was running out of stroke as the actuator had to be adjusted to make up the 5mm. To compensate for that I added 5mm on to the pushrod which put the actuator lever back where it came from.
I think I did the mod 7 years ago and the clutch has never given me a problem since.
I've never seen Dyno Dave's seal, perhaps it's slimmer and might not cause the same problem. However, If you do want to try a longer pushrod send me the length and I'll make one up for you.

Thanks, but I don't really seem to have a clutch lift problem (although Reggie did enquire why the need to fit a longer pushrod) the Norvil pushrod seal is no more than a captive O-ring contained in a housing that screws to the end of the mainshaft on top of the clutch centre nut: http://www.norvilmotorcycle.co.uk/068833.htm

Reggie · Mar 16, 2007

Cash wrote;

As my home made mainshaft / clutch pushrod seal is 5mm thick the clutch centre adjuster had to be screwed out to clear it. I then found I was running out of stroke as the actuator had to be adjusted to make up the 5mm.

It all makes sense now. I thought that you were using a DynoDave oil seal. Sorry for the misunderstanding.

cash · Mar 17, 2007

I used a lip seal mainly coz I thought 'O' rings though cost only pennies don't like sliding and I found it was easier to make with the limited tooling I had back then.
I'm sure there will be a nice slim lip seal on the market somewhere, but heck this one works.

The next time I pull the gearbox apart I'm going to fit a sealed mainshaft bearing with inner shield removed. I reckon this will stop the gear oil getting into the main shaft in the first place.
Got to be a better engineered solution, it'll put all the mechanism back to normal.

jumpjg · Mar 19, 2007

79x100 said:
jumpjg,
I don't think that you have to worry about the standard bronze clutch slipping unless it has suffered quite a lot of oil contamination and even then, it is not terminal.

Thanks for the reply. This weekend I finished buttoning it up, but was only able to get in a short ride in between the snow flakes. The Bronze plates seem to hook up just fine. They have a buttery engagement and I experienced absolutely no problem selecting neutral while stopped. Even the shift from neutral into first was without any "clunk", just like doing it with the engine not running.

Thanks for the help, guys!

Joe in St Louis

Mk III Clutch Drag

cash

79x100

L.A.B.

Moderator

Reggie

cash

jumpjg

Similar threads