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Rear axle nut torque setting
Posted: Mon Jul 21, 2008 5:19 pm
by southerly95
Rear axle nut torque setting - anybody know what this is please?
Posted: Mon Jul 21, 2008 6:09 pm
by MoggyTech
No figure quoted in the BMC manual I have, but as the nut has a knock over lock washer I would say tighten until bearings are only just loaded (you will feel the hub start to drag as you rotate it), back off slightly, check no free play, and knock over the tab washer.
Will also depend if 1st or 2nd type axle fitted I would think. I would also guess 45 to 50ft/Lbs would be about right.
Posted: Mon Jul 21, 2008 6:22 pm
by alex_holden
MoggyTech wrote:No figure quoted in the BMC manual I have, but as the nut has a knock over lock washer I would say tighten until bearings are only just loaded (you will feel the hub start to drag as you rotate it), back off slightly, check no free play, and knock over the tab washer.
That's the procedure for a taper roller bearing I believe. With the type of bearing the Minor has you need to get the nut very tight to clamp the inner race securely. If it isn't tight enough the inner race could move and wear the stub axle. Tightening the nut doesn't put any load on the outer race so you won't feel it start to drag as you tighten it. I can't give you a figure though - I just push down hard on the end of my very large hub nut spanner.
Posted: Mon Jul 21, 2008 7:17 pm
by Dean
Mine is just a castle head nut, with a split pin through?
Posted: Mon Jul 21, 2008 10:32 pm
by alex_holden
Dean wrote:Mine is just a castle head nut, with a split pin through?
I'm guessing that must be the very early type of rear axle then, or maybe one off a different car - I don't know anything about those.
Posted: Mon Jul 21, 2008 11:34 pm
by IslipMinor
Southerly,
What model and year is your car? Also which 'rear nut'? The diff flange or the rear axle hub?
The diff flange is 140 lbf. ft., but the two hub nuts have no quoted torque, but need to be very tight as they secure the inner race of the bearing to the axle tube. As Alex says, there is only one bearing, no pre-load or end play, so no 'feel' when it is tight enough.
Don't forget that the LH hub nut has a LH thread.
Posted: Tue Jul 22, 2008 1:24 am
by southerly95
IslipMinor wrote:Southerly,
What model and year is your car? Also which 'rear nut'? The diff flange or the rear axle hub?
The diff flange is 140 lbf. ft., but the two hub nuts have no quoted torque, but need to be very tight as they secure the inner race of the bearing to the axle tube. As Alex says, there is only one bearing, no pre-load or end play, so no 'feel' when it is tight enough.
Don't forget that the LH hub nut has a LH thread.
Thanks Islip, the car is a 65 convertible and it's the nut on the wheel stub rather than the diff flange, I was aware of the LH/RH thread issue thanks. I stopped at 80 lbs torque; the limiting factor is the grip that can be achieved on the very narrow (new) nut even with the correct socket that I have.
There was a small amount of play still at about 20 lbs but that went at the higher setting - it revolves cleanly with no play now.
I wonder if low torque settings cause the dreaded leaking half shaft joint problem as the stub may be fretting against the half shaft end due to excess play? Regards, John