lapping hubs

[steve davidson]

Hi Steve,
 try to settle for not removing ALL the pits and score marks, as removal of too much metal will draw the axle too far into the taper. Two things result, the taper can protrude beyond the hub causing the axle nut to bottom against the axle and more importantly the inner spur gear on the axle will bind against the diff carrier.  Difficult to then correct you would have to buy a new hub.   regards  Russell

Thanks mate, these ones were so old that there is a very real risk of the risks noted above eventuating.  Our mate Trev has found me a few others that look in better shape so I'll be checking them out this week.

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As said, you just need to lap until you get a good contact area, it's not usually practical to remove every pit from the hub. One thing to watch for is that a step often forms in the small end of the hub taper after lapping. If this is left in place it will  stop the hub pulling up onto the halfshaft taper when the nut is tightened. I file the step off leaving a very short parallel section at the outer end of the hub.

You can usually get an idea of whether the sunwheel gear at the end of the halfshaft is going to bind on the inside of the diff if you do a loose dry assembly and try to pull the hub outer away from the inner when its assembled on the axle case, if you can't, you just need to grind back the halfshaft inner edge of the sunwheel gear, these gears are really generously sized for the job they have to do, and losing a 1/16" of width hasn't caused any issues when I've  done this. This grinding really needs to be done with a toolpost grinder in a lathe, or in a proper grinding machine.

Thanks Stuart, that's a great tip