Dragging Clutch

[AFPU]

Hi
I am hoping for some advice as I am just getting towards the end of recommissioning and tidying up my 2 previous owner unrestored 1961 Matchless G12 CSR and have the engine starting and running fine but cannot get the clutch not to drag.

G12-6_01.jpg

As part of the work done to date I diassembled the clutch and fitted new shock absorber rubbers and fitted a new thrust rod. However, no matter how much I try by varying clutch spring tension and adjusting the cable etc I cannot get the clutch not too drag.

So am I missing something?

[AFPU]

I have this morning released the clutch cable in readiness for potentially removing the out gearbox cover and noticed that the clutch operating lever is wobbly and on occasions clicks, so could this be a contributory factor?

[Andy G]

Just to confirm, by "drags" are you saying that the clutch is not fully disengaging with lever pulled in? Or clutch slips with lever out?
If drags, you do have correct levers with cable to pivot distance of 7/8?
And have followed the adjustment sequence per manual?

[AFPU]

Yes Andy G, I have new Replica Doherty 407P brake levers 7/8" fitting. (7/8" pivot centres) bought from AMOC Spares and have followed the adjustment sequence. When I pull the clutch lever in and engage 1st gear the back wheel spins up quite a lot and cannot be easily stopped by putting my foot against it and spins up again quickly if I take my foot off.

[AFPU]

Whilst we are talking clutch should the spring cups be a tight or loose fit in the pressure plate?

Also what is the significance of the small ridge on the outside of the spring cup just below the top lip?

[Andy G]

Hmm, can't recall correct plates count (someone will) but let's assume they are all there, flat, and not all glued together as it's a recent rebuild.
There could be wear in the operating arm, but assuming again that it worked before, and your new rod is at least as long as the old one, then I'd take a hard look at the cable. Is it possible it's flexing rather than pulling? I've a similar bike, and I'll try to measure an operating distance at the business end if that helps?
Failing that it's surely just foibles of setting up.
I believe cups should be free floating, the ridge is to prevent spring rotation causing the nuts to unwind?

[AFPU]

Many thanks Andy G.

And to confirm I just checked the plates very carefully, as I have to admit I had omitted to do so on the basis that it was all working OK before recommissioning but had got all stuck together after standing for 18 months; and some of the friction plates are slightly warped so I have today ordered some new ones. As for plate count I have 3 x double sided friction plates, 4 plain (dimpled) plates and 1 x single sided friction plate.

As for the rod it was new and slightly longer than the old one, which is why I replaced it.

The ridge on the cups makes sense.

[MalcW]

Yes Andy G, I have new Replica Doherty 407P brake levers 7/8" fitting. (7/8" pivot centres) bought from AMOC Spares and have followed the adjustment sequence. When I pull the clutch lever in and engage 1st gear the back wheel spins up quite a lot and cannot be easily stopped by putting my foot against it and spins up again quickly if I take my foot off.

Really, really silly question, but before starting the engine are you pulling the clutch lever in and operating the kickstart until it doesn't turn the engine over? Once you've done that, does the kickstart move freely against its return spring, or does it still feel stiff. When you pull the clutch lever in, does the pressure plate move out evenly, or move more on one side?

Malc

[Andy G]

Is it just me or does that plate count sound a bit short?
For general unscientific interest I measure 11mm travel at the operating lever without any drag.

[1608]

reasons for clutch drag-
warped plates due to slipping and over heating
incorrectly adjusted
notches formed on the basket and or clutch centre
poorly routed or fraying cable
common problem with the centre nut coming loose and subsequently being over tightened over time can cause the clutch centre to impinge on the out put shaft and sleeve bush. This will be evident by witness marks on the back of the centre. Renewal is expensive but an easy fix is to take a few thou off the back of the centre on the lathe. If the centre is a bit wobbly on the in-put shaft see 'wobbly clutch' under the Tech Tips section.