Rear hub nut tightening

[Bob Culver]

I am not totally opposed to lapping, but to indiscriminate lapping as the inexperienced are likely to indulge in based on most of the readily available info. If the axle and/or hub are significantly distorted as is often the case launching straight into vigorous lapping just ruins both.

(Some fits may be superior to a uniform lap ie interference at the large end of taper. On very many other makes and on the later Seven flywheels  tapers are deliberately relieved in the middle. Failure of tapers in general is reckoned to commence from the large end.)

[Charles P]

For the joint to work properly, the drive has to be through the taper, not the key. So, the hub and shaft need to fit together properly. If you push the hub onto the shaft, you should need a puller to get it off again. If not, you need to lap the parts together until they do fit. I know this will get howls of protest from BC, but trust me, I’m right. Then you need to make sure the hub isn’t riding up on the woodruff key. Fit the parts together with no key and count how many flats the nut turns to be finger tight. Take it apart and when you assemble with the key in position you should get the same number of flats. At the same time check that the nut is bedding on the hub and not the shoulder below the thread in the half shaft. The gear fouling inside the casing has already been mentioned.  If you do all of this , 120ftlbs is perfectly ok on the spanner and you won’t be wrecking halfshafts.

Perfect advice Alan. 

C

[Stuart Giles]

For the joint to work properly, the drive has to be through the taper, not the key. So, the hub and shaft need to fit together properly. If you push the hub onto the shaft, you should need a puller to get it off again. If not, you need to lap the parts together until they do fit. I know this will get howls of protest from BC, but trust me, I’m right. Then you need to make sure the hub isn’t riding up on the woodruff key. Fit the parts together with no key and count how many flats the nut turns to be finger tight. Take it apart and when you assemble with the key in position you should get the same number of flats. At the same time check that the nut is bedding on the hub and not the shoulder below the thread in the half shaft. The gear fouling inside the casing has already been mentioned. If you do all of this , 120ftlbs is perfectly ok on the spanner and you won’t be wrecking halfshafts.

One thing it might be worth adding to Alan's sound advice above, is that after lapping, a small step may well be formed at the small end of the taper in the hub. It's important to remove this with a file so that the hub call pull up the halfshaft taper and not pull up against the step in the hub when the nut is fully tightened.