Took the NC30's rear wheel off for powder-coating. The LHD rear wheel nut was just hand-tight. Since this had happened before, I had drilled and put a split-pin through the hub thread. Without the pin, the nut would have come off.

Given that I had tightened the nut to 140Nm according to the workshop manual, is this a common problem? Should I be lubricated something (like the RHD side of the hub, which was very difficult to remove) to stop torque from the rear wheel passing to the LHD nut?

If you're referring to the nut on the opposite end of the axle to the wheel, it doesn't need drilling and pinning. It is a stake nut. According to the manual, the torque is 165Nm. However, once it is torqued, you need to rotate the wheel until you can see the flat on the axle where you punch the edge of the axle nut down to prevent it from turning.

Take a look at page 13-4 of the following doc:

http://400greybike.com/files/NC30%20Ser ... Manual.pdf

Thanks, Speedy. My mistake, the torque is 165Nm.

My question is, if the nut wheel nut is tightened to such a degree, surely it should stay tightened? I am nervous that the nut wants to undo.

If it is only the staking or, in my case, the split-pin, which stops the nut from coming off the axle thread completely, is it really normal that the nut becomes so loose?

I want to re-use the wheel nut hence the decision to use a split-pin rather than staking the edge of the nut. This is the same principle as Kayla s Titanium nut, so I thought it would work (http://www.projection-components.co.uk/ ... -127-p.asp) Does anyone else have this problem on the NC30?

The issue is that the nut undoes in the same direction that the torque is applied to the rear hub. So, when you are on the power on the bike, the engine is trying to undo the nut, and with the best will in the world, there's no guarantee that it might not shift even when torqued up to spec. The torque specified could be because at a higher level that would completely resist the undoing effort from the engine, it might damage the bearings, or cause the axle to become excessively stiff (I'm hypothesising here). Either way, a secondary method of fixing is required because it's only a single nut, and if it comes loose, you're in serious trouble, unlike a car where you'll get some sort of warning and the other nuts will hold it on. If you used 140Nm last time rather than 165, maybe that was enough difference that it could come loose quite easily. Of course, there's no reason you can't use a drilled nut and axle. It sounds like in this case it has saved the day. I would check the bits very carefully, torque it back up to 165 if there's no sign of any obvious damage, fix the nut in place using your preferred method, and keep a very close eye on it to see what happens.

Had this problem myself before but that was my stupidity forgetting to put the bearing spacer in after changing the bearing hub. Had me perplexed as to why it kept needing retorqued then I noticed alloy filings where the sprocket carrier and bolts wearing away hence the nut becoming slack .
Bit embarrassing to admit my mistake but probably not the first to it.

Take the sprocket carrier off and check spacer is there and carrier not grinding away against bearing holder hub if so you'll need a new sprocket carrier and a thorough clean and regrease of the wheel bearings.

Thanks for the suggestion, Dave. I will check the spacer, and the order of all the components on the axle. There must be some mechanical reason the nut is undoing. It's a good excuse to fit an alloy rear sprocket, too. :-)

Update; this might be useful for someone. There are two washers on the NC30 LHD axle. A c.3mm thick washer (part no 90653-MR7-000), and a thin conical spring washer (Honda 90501-MR7-003, superceded by 90501-KV3-951; also used on VFR750R and RC30). On my bike, instead of the spring washer I found a thin flat washer. I suspect this is the cause of the wheel nut unscrewing in use. The correct part is now on order from David Silvers. If it does not cure the problem, I will report here...