Serious Problem With Rear Hub

[Bilko]

My rear hub nut keeps coming lose, to the point where the hub will loosen .

I AM using a locking plate. In fact I've gone through 3 hub nut and locking plate combo's now. I use a torque wrench to tighten the hub nut. What the f@@k's going on? Why is my hub nut coming loose all the time?

The layshaft is not loose & the bearings are good.

Here's what happens to the plate each time.

[dapper]

Have you checked that the split in the cone is sitting over one of the raised turrets on the spline? Have you got the correct shim under the cone? Have you got the correct washer under the nut? Is it the correct taper on the cone to fit the taper in the hub? If all these are correct, than I'm fecked if I know Haven't you got that LC finished yet

[J1MS]

If it's come loose more than once, chances are the cone and hub taper are now damaged whatever the original cause was. Check both using engineers blue to see where the cone and hub are making contact.

Also check the stub axle where the cone sits as they can become damaged when run with a loose fitting cone and hub, leaving a wear ridge at the point the cone sits, rubbing you thumb nail down the axle (but first remove the cone) as if checking for a wear ridge on the top edge of a barrel, this will Normally show you if its worn/ damaged.

[Knowledge]

All the above is good advice.

There is nothing to stop you fitting two locking plates around the main nut. Whether this will help or not.....?

[100mphlambrettaclub]

No need to check it the whole lot will be knackered hub,cone and more than likley it will have stepped the layshaf splines. Change the lot or it will keep coming off what ever you do.

[Bilko]

Thanks for the advice everyone.

Think it's time to put the original engine back in and strip the 225 engine. It's not been touched for years.

Dapper: Struggling on with the LC. Running way behind with it too.

[corrado]

Post some pics of the splines on the layshaft and the hub.

Check that the outer nut isn't bottoming out on the layshaft, it's not easy to be certain with the current style of domed nut.

[davidblythe]

there is a similiar issue with DRZ400's with the front sprocket always coming loose, very similiar setup to a Lammy with splined layshaft and sprocket, it uses a locking plate to retain the nut once tightened

problem is caused by slight wear on the interface between the splines of the sprocket and layshaft (quality of machining on aftermarket sprockets is not what it should be, no point using OEM as no one uses standard gearing on the dirt), when they come off, the cases can get scrapped

the solution has been to use a semi permanent loctite between the splines when putting sprockets onto the layshaft for the first time,

they come off easily enough with a bit of heat and a 3 legged puller

[Bilko]

Took the engine out and noticed these heat marks on the bearings and layshaft, but the bearings are sound.

Measured the layshaft to see if someone could do a comparison to the one in the pic