Morris Minor Owners Club

My black minor has an oil leak from the front seal on the diff flange. I have read about needing to pre load the bolt once the new seal has been fitted. Or is it just a case of just tightening up the bolt to a torque ?? I have never done one before so advice would be appreciated.

As you are just replacing the seal you should be alright.
See BMC Wksp Man Section HH3 for details if required.
Mark the prop-shaft & diff flanges to get them back in the same position on reassembly.
Check the torque of the nut before dismantling (should be 140 lb ft) and set the nut to that torque after fitting the seal. I have used this method an several occasions without problems.
Only with the later crushable spacer does care have to be taken - but so long as you do not go above the 140 lb ft you will be alright.
With the earlier non crushable spacer the nut can be undone and tightened up again and again to the correct torque without any worries.
You have nothing to loose and all to gain.
Check the rear axle oil level after fitting the seal as you may loose some oil on removal of the seal.
Phil

The crush washer will already be crushed - so just undo the nut - it may be loose/may be tight - fit the new seal and tighten it back up to what seems reasonable and see how it goes.

Ok thanks men. I will give it a go later in the year. As the national rally is looming and i don't want to tempt fate. It can't be that difficult even for me

You need to make sure that your torque wrench is capable of 140 lb ft.
You do need to torque the nut up correctly - not just tighten till it feels right.
Phil

Very very few people have a torque wrench at all - never mind one that goes that high - i've always managed just fine with 'tight' - and in this case I doubt it matters all that much . I know very well it's supposed to be 140 ft lbf. It's all very well being dogmatic - but the reality is - these are simple Morris Minors, being worked on by 'home mechanics' and frankly as I suggested 'tight till it feels right' (by which I meant not collapsing the washer any more....) will be perfectly ok here. There's every chance the nut may only be 'finger tight' when the prop is removed....which may be why it's leaking in the first place.

bmc
Call me dogmatic - no problem - I just follow the old adage if you want the job to be done properly do it properly.
The only way that you will ensure that the collapsible spacer does not collapse any more is to use a torque wrench.
Even if the nut is loose it will still need to be torqued up not just tightened.
The OP can decide to tighten the flange nut as tight or as loose as they choose - but I will not give advice that I do not follow myself.
Phil

Yep my torque wrench (which is an old school good type, not a digital one) only goes up to 100 lb ft. So i think I'll go with 100 lb ft and it my arms allow it just try tightening it a bit more.

Whatever you do - DO NOT continue to pull on the torque wrench once it has clicked....Change to a T bar and pipe (and certainly not a ratchet) - or breaker bar if you have such a thing, if you want to pull it even tighter.

I did this job a couple of weeks ago with the benefit of an electric impact gun to undo the nut, it did not move with my usual breaker bar.
I also had to use a 3 leg puller to remove the flange once the nut was removed. It was a very snug fit and had to be removed with even pressure on all sides. Trying to drive it off with a block of wood and hammer didn't work at all but the puller only needed tightening by hand to remove it.
Trying to get 140 lbft back on the nut wasn't much fun, get a nice deep socket that won't slip off because it needs a fair bit of effort. I did this by gradually increasing the torque wrench from about 80 lbft to 140 in 10 lbft steps. Would be a lot easier if you have a deep pit or 4 post lift rather than lying under the car.
A good sense of achievement now it is done and leak is no more. Best of luck.

Thanks again. No i would try tightening a bit more with a pull bar