Radial play in splines between clutch hub and mainshaft

I've just stripped down the clutch in order to investigate continual loss of clutch pushrod adjustment, start out with normal amount of play at the lever and after a few miles it would have too much and drag. Figured it would either be at the clutch actuation end (as I've had the slotted ring come loose last summer) or possibly a loose mainshaft clutch nut, or possibly a soft pushrod?

Sure enough, the clutch actuation was all in order (I invested in the proper tool to tighten this) and the clutch centre was loose on the mainshaft, no apparent harm done.

My concern is there is approx 1mm radial play at the edge of the hub, between the splines on the hub and mainshaft, is this normal and/or acceptable? A search has revealed very little, threads tend to refer to play (wobble) in the hub bearing , which seems fine in mine.

I am (overly?) sensitive to this as I've just completed a clutch rebuild on my BSA Rocket Three, and detected similar levels of play between the clutch and shock absorber in that. This is pretty common on BSA/Triumph triples, but is considered less than desirable as it can cause shock absorber nuts to come loose (effectively the same issue as in my commando) ! I am trying Loctite 660 Quick Metal as some people have had success with it.

However, there was no lock-washer on the clutch nut in the commando, so that didn't help. My question is, how much, if any, play is acceptable. The hub itself is relatively unworn otherwise and everything else is in good order, the previous owner did a very extensive, high quality rebuild. I have now way of knowing, but I doubt the loose nut would have caused the spline wear that quickly, have only done a few short journies with this issue apparent?

I'll be doing a more extensive primary rebuild this winter when I fit a belt drive, but would rather just ride whilst the weather is good.
P.s. I'm well aware of the issues around the locating circlip behind the hub and the need to reduce the torque values on the nut and augment with blue loctite.

Thanks for any advice on this.

I noticed this with a clutch centre I purchased from Andover. When I called to tell them I wasn't happy, they asked me to send it back. They checked it along with others from their stock, but they all seemed to be the same. As I needed the part to get my bike back on the road that year I fitted it, & have had no problems over several thousand miles. Just torque to 40 ft/lb & all will be well. If I was in the market for a new centre, I would try one of the CNW ones which look to be very well made.

Martyn.

Its a parallel spline,. If it was tight you probably would not get it apart. All Parallel splines have clearance [ eg drive shaft splines to g/box tail-shaft ]. Now you know why the mainshaft nut always comes loose. You are relying on end to end compression to keep things tight, but that cant work for long. That's why they put a lock-tab under the nut. Also best to use a decent hardened or high tensile thick washer against the splines to help stop wearing. Also, lock tab goes between nut and the washer, not as some suggest, putting the lock tab against the clutch hub.

Thanks guys, I'll button her up tomorrow as for some reason (possibly as I was going to fit the belt drive THIS winter) I have the correct lockwasher on the shelf! I'm going to check the degree scale on the timing window first with a degree disc and positive piston stop for tdc.

wavey_davey said:

I have the correct lockwasher on the shelf!

Click to expand...

Lock washer (early)...
Item 58:

...or tab washer?
As the tab washer, 60 should only be used with the hardened steel washer 58.

Some prefer not to use the tab washer at all.

kerinorton said:

Its a parallel spline,. If it was tight you probably would not get it apart. All Parallel splines have clearance [ eg drive shaft splines to g/box tail-shaft ]. Now you know why the mainshaft nut always comes loose. You are relying on end to end compression to keep things tight, but that cant work for long. That's why they put a lock-tab under the nut. Also best to use a decent hardened or high tensile thick washer against the splines to help stop wearing. Also, lock tab goes between nut and the washer, not as some suggest, putting the lock tab against the clutch hub.

Click to expand...

In the MK3 parts book I have It shows the lock tab, then the washer and then the nut. I have always done it that way. And I use a little blue lock tite.

The washer placement helps the nut to tighten down on a smooth surface, the way I see it.

I never had trouble with one loosening. I used to put quite a bit of torque on them when I was younger.. Now I use a little less torque. In the old days , OEM clutch centers were a good fit on the main shaft splines and never got real sloppy and always fit quite nicely even after a lot of use. I guess times have changed.

Thanks everyone. I had the right (cruciform) tab washer rather than the earlier split washer. I went with washer against the hub, then tabwasher then nut with blue loctite and 45ft/lbs.

In Norman White's book, he says the washer is often forgotten, but advises tabwasher against the hub (I can't see it making any difference tbh?) and he goes with factory torque setting.

wavey_davey said:

Thanks everyone. I had the right (cruciform) tab washer rather than the earlier split washer. I went with washer against the hub, then tabwasher then nut with blue loctite and 45ft/lbs.

In Norman White's book, he says the washer is often forgotten, but advises tabwasher against the hub (I can't see it making any difference tbh?) and he goes with factory torque setting.

Click to expand...

Putting the soft metal bend-over tab washer behind the nut itself results in damage to it , (as the nut turns to tighten up ) it mangles it up behind and against the nut. The nut chews at this safety lock item . It's too soft to handle this abuse well. So things get loose a bit resulting in sloppy clutch pull / releases. I don't use the tab washer anymore. Just hardened washer or washers and blue locktite in the clean threads and a clutch seal as a final on the mainshaft. Works for me. Never backs off creating slop.