Morris Minor Owners Club

I have recently had the diff rebuilt on my Series II owing to a lost tooth on the crown wheel. In order to rebuild it the diff place had to source a spare MM style diff ( My early Series II has the split case axle with a 5.375 ratio. I originally thought it was 4.55 but now know it was 5.375). What effect on driving will the lower ratio 4.55 have? I know it will throw my speedo out but I believe it should also make cruising less "revvy". Is this the case?

David,
Just check the speedo with a sat nav. I found that after changing the diff on the 1098cc from 4.22 to 3.9 and I'm using 145 tyres, that the speedo is now actually spot on.
Regards
Declan

Thanks Declan not too worried about the speedo as I can put a couple of discreet marks at 60k and 80k using a Sat Nav. More interested to see what effect on the revs of the engine at 80k or 50mph. Previously the little 803 was working quite hard - Hoping the lower ratio will ease things a bit!

Hi David,
I've just put a 4.55 diff in my 803cc (replacing the 5.375). In all honesty it's made very little difference. 3rd gear becomes more usable and the revs drop slightly, you may get another 3 mph or 4 mph more when cruising along but not much more. I'm debating whether the 4.22 diff would have been a better choice - a lot of people say it wont cope with it but from what I've seen it may be worth a try.
Simon

Hmmm. It will be interesting to see if there is much difference in mine being the older axle.

Here are a couple of pics of the job. Almost done, just have to refit backplates, brakes and bleed.





I do notice that the diff seems to be pointing downwards a little, but I am assuming this is just a result of the car being so far up in the air.

Also, re: Roy's favourite method of bleeding the brakes by gravity. Thought I might give this a try. I assume the bleed nipple needs to be lower than the the level of the master cylinder (ie: closer to the ground) for this to work?

Are there many different ratios available for the split case axle? I thought the 4.22 was only for the later banjo axle?

I learned recently from Mike that the MM's had the 4.55, but the early series II's had the same back axle but with a 5.375. The series II changed to the Banjo type axle (still at 5.375) at the same time as they changed to separate front hubs and drums in Oct 53. My car is July 53.

One of the most annoying things on my car is how many seemingly matching parts differ from later cars. The Front locating pin which holds the front end of the springs is a case in point. My original had a damaged thread, so ordered a new one from EMS. On arrival I found the circular disc on one side thicker and larger than the original, and the thread at the other end a 3/8, larger than that on the original. After raiding my backup engine for a head stud bolt I fitted the pin only to find due to the larger disc it doesn't seat fully into the openning on the chassis plate. Having tightened everything up it seems to be OK but I would prefer the correct part which clearly isnt available any longer.