Half shaft oil seals

[liammonty]

BMC Minor wksp manual Pt No: AKD530L dated 1968 shows the modification to the hub and it states in section HH.10 'On the rear axles fitted to later cars a modified rear hub with an additional oil seal is introduced'. So I consider that it can be safely assumed that the modified rear hub was introduced around 1967/68. No car/chassis number relating to when the modification was introduced is specified.

So it’s OK to ‘safely assume’ that the modification was introduced around ‘1967/68’ on the basis that a 1968 manual includes it, but we should also assume that it being included in a 1950s manual ISN’T reliable? I’m confused! Assumptions in general can be risky

[philthehill]

The earliest reference I can find to the fitment of the 'O' ring part number ATA7225 is in BMC parts list AKD559 third edition (Morris 1/4 ton van which does not have a publish date) which incorporates and embodies all information issued up to and including parts list amendment No PM/1925.
It states that the 'O' ring was introduced at vehicle C 49801. So if you can work out the date of manufacture of vehicle 49801 it will give an approx date of the introduction of the rear hub 'O' ring.

[geoberni]

The earliest reference I can find to the fitment of the 'O' ring part number ATA7225 is in BMC parts list AKD559 third edition (Morris 1/4 ton van which does not have a publish date) which incorporates and embodies all information issued up to and including parts list amendment No PM/1925.
It states that the 'O' ring was introduced at vehicle C 49801. So if you can work out the date of manufacture of vehicle 49801 it will give an approx date of the introduction of the rear hub 'O' ring.

Well that's easy.
The Original Morris Minor specifies 49801 as being the first Series 3 LCV in September 1956.

I have a copy of the AKD 3574, which is the combined Service Parts List for all LCV and includes the early SII models.
Strangely, it does not mention any introduction point, despite listing 3 different Hub Assembly numbers, none of which coincide with 49801....
All quite peculiar....

Axle.JPG (121.69 KiB) Viewed 1522 times

The Parts List does have some peculiar entries, or rather omissions.
Take Steering Wheel for example.
It give commencement of Steering Wheel 21G 6044 at vehicle number 49801, but doesn't mention what came before it...

[philthehill]

geoberni
Thank you for the information above.
Whilst the September 1956 incorporation date may be correct not all cars were so fitted including mine which was first registered 01/01/1958.
The incorporation dates and commission numbers do not always tally.
Phil

[mike1864]

The nearside on my 56 Series 2 (no rubber ring or groove) often suffered a chronic leak.
It seems OK since I fitted a latter style (S/H) hub, ring and gasket.
Strangely the offside has been OK with the original setup.
Bear in mind there's been a long debate elsewhere on this forum about the importance of the the thickness of the paper gasket.
Can someone advise whether the level of EP90 in the diff is designed to dribble (cascade?) into the hub bearings?

[philthehill]

The thickness of the paper gasket which fits between the half-shaft flange and the hub flange determines the amount of holding pressure on the hub bearing. Too thick and there is the possibility of the bearing moving in the hub. Too thin and there is the possibility of the half-shaft flange breaking. The thickness of the hub paper gasket should be determined by following the instructions in BMC Wksp Manual Section: HH.2.
The EP90 oil from the axle tube is designed to dribble/flow into the hub.

[mike1864]

So this variance presumably arises from the manufacturing tolerances of the housing, the bearing; and even the (interference?) fit between the two.
But ESM don't seem to offer the gasket (DIF150) in anything other than a single thickness.
As it happens, I've collected a range over the years; perhaps 4-12 thou.
But I suspect most people would just fit what they are given.
And then again, a smear of jointing compound or grease would add a thou or two of its own anyway.
I'm not disputing the HH2 guidance, but can only wonder whether there's any record of an actual failure attributable to this gasket being too thick or thin.
Or -as in many other areas - is the Minor more tolerant of such mis-settings than the W/S manual implies?

[philthehill]

You are correct in that the variances occur because of manufacturing tolerances.
I have seen a half-shaft broken out of the half-shaft flange but what caused it to fail is not known.
I suspect that in most cases the tolerances negate the need for different thickness gaskets but if you want to do the job properly then you need the correct thickness of gasket. It is easy to make half shaft gaskets from gasket sheet blanks and I have made many over the years to get the clearance right. I have several ready to fit hub gaskets on the shelf supplied by various sellers and they are not all the same thickness.

[mike1864]

Ever since I was pointed to the HH2 measurements, and now that I too have accumulated a stock of various thickness gaskets, I'll obviously comply with the HH2 instructions next time I'm working around there. Previously such interventions have always been triggered by leaks, not mechanical failures.
Having multiple sheets of gasket paper and the blades/punches/patience to produce gaskets is clearly a superb solution.
But I suspect that very few owners or mechanics do this, and just use the supplied gasket (like I did for 45 years!).
So statistically it's probably the "wrong" thickness gasket currently in 80% of Minors.
So should the owners be worried?
As an aside, if ever I take the rear wheels or brake drums off for any length of time, I refit the wheel nuts (with fat spacers underneath), to maintain the pressure (ie oil tightness) on whatever gaskets and seals are fitted.