would this be a suitable upgrade for my morris 1000 diff?

[JaneHibbert]

hello i saw this on ebay and was wondering if it would fit my standard morris 1000. am i right in thinking this would give me greater speed for fewer revs of the engine?

any help thankful for!

http://www.ebay.co.uk/itm/differential- ... 19d72f487c

[bmcecosse]

It will fit, but unless you boost the engine power it will struggle to pull it.

[Bazzalucas]

I use a 3.7 with a 1275 in my MM, and it is ideal. I think that anything less powerful would require a lot of patience.

[rayofleamington]

Hi Jane,
I almost agree with Roy on this one.
The 3.7 diff is 'too tall' far a standard car in most people's opinion (including the opinion of those who have never tried one). The 3.9:1 diff is a better compromise but often they are sometimes more expensive due to being a bit more sought after.

However I ran one of these on my 1098 pick up and despite a fairly clapped out engine it was fine. It really struggled on hills and you were down to second gear on any half decent hill but on the flip side it was fine on main roads & motorways.
I certainly never had an issue on both MMOC Lands-end to Orkney rallies and also got one of the best MPG's.


I'm not sure how much you know on the technical side. In general a taller diff will reduce your acceleration and give bigger 'steps' between gears but much lower engine revs at high road speed. A low diff will make the engine revs scream at high road speed, but give excellent acceleration, good gearing for hill ascents and poor mpg at high speed. The 'best' diff is a compromise (happy medium) between all things and depending on your 'normal' drive then you want a bias towards taller or shorter.In the 50's people spent a smaller proportion of time at high speed cross country (there were less roads to do it on!) therefore the standard diff is biased too short compared to today's cars.

If you've got a standard 948, then this would be far worse. For a happy running 1098 you could be fine unless you drive in a hilly
area very often (Bath, Derbyshire, Lake district etc..)

[bmcecosse]

Crikey... 160 pounds!

[rayofleamington]

The last 3.7:1 I bought was £50 + delivery (I collected as it's heavy!)
the last one I got rid of was free (was still in the pick up when I passed it on) and later it sold for a lot of £££ IIRC.

Maybe that's just what people are prepared to pay these days!

[bmcecosse]

I have to say - at that price it's really not worth it........although obviously still very much less expensive than a 5 speed box. It could be considered as an investment......the way prices are rising!!

[JaneHibbert]

I think at those prices Ill stick to a standard diff unless a 3.9 comes up cheap!

[bmcecosse]

Good thinking.......

[David W.]

My 59 Morris with the 948 engine came with a 4.55 differential. I am now running a 3.9 and have no problems. BUT, I am in Florida, USA, where there are no hills.
An important consideration is the gearbox you are running. In my smoothcase, the first gear ratio is 3.62. The resulting overall ratio of 14.1 is low enough for starting from a complete stop. With the ribcase, first gear is 3.2, for an overall ratio of 12.5 in first. That will make it more difficult for the engine. The 3.727 differential would result in first gear overall ratios of 13.5 (smooth), or 11.9 (rib).
Another consideration is the fact that your speedometer will be wrong.

[bmcecosse]

My first gear is still low enough - no problem there, but it is essential to get up some speed before going for second gear on an uphill start........ The low ratio FD exacerbates the gaps between the ratios.... My second gear is good for a genuine 50 mph - but probably the revs are unwise for the 1098 engine.........

[Roni]

The first gear ratio is the same for both smooth and ribbed gearboxes. Second gear is different. A 3.2 first gear would suggest an MG close ratio box.