Morris Minor Owners Club

Hi is there any serial numbers etc that identifies the moggy diffs as to what they are. We got two diffs with our purchase but don't know what they are. the engines were 948 and a 1098.

Any ideas or advice please cheers.

The ratio's should be stamped on the case or diff carrier - Something like 9/41 - This will give you the ratio and hence which car they were fitted to. 1098's had a 4.22:1 diff and 948's had a 4.55:1

If you have the nose of the diff facing you, the stamped number is at 1/2 past 12 position, about 1 inch forwards of the flange that has the bolt holes. Large digits about 1/4 tall.

Alternatively, count the number of teeth and divide the big gear by the small gear. (ie: 9 teeth and 41 teeth)

The ratio should also be stamped on the crown wheel, at least it is on my diff (10/39)

cheers for that, will look at them on week end. I've been reading that a 3.7 diff from a riley 1500 fits, would like to look at that in more detail.

Any difference between the original diffs besides the ratios

Later ones are stronger - and don't have filler plugs! Tricky if the axle casing doesn't have a filler plug either!

No filler plug?

Some diffs have the filler plug on the diff, some have it on the axle casing behind the diff. If you have the wrong combination of diffs and axle cases you either have two filler plugs or none at all.
I expect some expert on diffs will be able to tell you where all the filler plugs are.

listerjones wrote:No filler plug?

4.55:1 diffs had a filler plug. Later 4.22:1 diffs do not because it is on the axle casing.

Out of interest how about 5.375, 3.9 and 3.7?

mike.perry wrote:Out of interest how about 5.375 3.9 and 3.7?

5.3 on diff. 3.9 & 3.7 on axle casing.....

Right got it, thanks everyone. any one got a 3.7 for sale by any chance....

listerjones wrote:any one got a 3.7 for sale by any chance....

Noooooo

But keep an eye on ebay - they do come up fairly often

3.9's are cheaper and just as acceptable IMHO.....

Not sure if there is an 'exact' Mini speedo to suit the 3.9 diff. It would need to be ~ 1345 tpm.

mike.perry wrote:Some diffs have the filler plug on the diff, some have it on the axle casing behind the diff. If you have the wrong combination of diffs and axle cases you either have two filler plugs or none at all.

I have the problem of no filler plug

Shouldn't you have the Morris axle in the early Series II? Or have you had an engine transpant?

bmcecosse wrote:Not sure if there is an 'exact' Mini speedo to suit the 3.9 diff. It would need to be ~ 1345 tpm.

I think mine is 1350 but I'd have to check that....

I haven't done enough research on Mini speedos yet. Only got the 1248 and 1376. There were a lot of different ratio diffs on the Coopers etc.
There are 3.444, 3.647, 3.765, 3.938, 4.133, 4.267 & 4.35 to choose from, all with different speedo TPM

The ratios beginning with '4' (and the 3.9) were never fitted to Minis as standard - these are competition ratios only. There is also a 3.1 and a 2.9 - fitted to late model cars - but not with centre 'Minor' type speedos.

That reduces the options then.