diff selection

[WalkerContracts]

my friend has a mg midget engined minor with the midget gearbox. what would be the correct ratio diff to fit this car to suit this gearbox and so that will be able to be driven at higher speeds?? any help would be great, thanks

[MoggyTech]

http://www.elitemg.co.uk/used_parts.htm

Quite a choice, and depends what is required, for more relaxed cruising the lower ratio diff is best. I'd go middle road for the best of both Worlds

[WalkerContracts]

will a change in diff make a large difference 4.5 midget diff £40 to £60
4.2 midget diff £35 to £55
3.9 midget diff £100 to £130
3.7 midget diff £145 to £165, which would be the best diff in this range??? will these diffs fit into a minor axle??

[MoggyTech]

If it was me, I would fit the 3.9 diff, but opnions on this matter will vary a great deal. As for the Midget diff fitting the Minor Axle, ashamed to say I can't remember I think so, and someone will be along shortly to either confirm or deny I am losing it

[Willie]

I had the 1275 Midget with the 3.9-1 diff and they were well suited but,
the Minor is heavier than the midget, so you would probably need the
4.2-1 for decent acceleration but the 3.9-1 for less frantic motorway work

[WalkerContracts]

with the midget gearbox and 4.2-1 diff what would acceleration be like? would the top speed be any beta?

[plastic_orange]

I had a 3.7 diff (Riley 1.5 or Wolseley 1500) in a mildly tweaked 1100 minor and it was just fine. Top speed was pretty good, and it cruised well on fast roads. Acceleration was as good (if not better) compared to a standard engined minor.
Top speed depends on whether you believe the speedo - I've had it hitting the stop before (4.22 diff).

Pete

[bmcecosse]

The Midget gearbox has no relevance - they are all straight through drive in 4th gear. Just use the diff he has - it will be fine, and not cost anything!

[WalkerContracts]

thanks for the help everyone. original diff would be best option then??

[dunketh]

Depends on your driving.
I do lots of high speed stuff so I could really do with a 3.7 but I can't afford one.
If money is no problem he needs to decide how he's going to use the car as different diffs suit different driving styles.

[IslipMinor]

What ratio is fitted now? Also where is the oil filler - on the nose of the diff or on the rear of the axle casing?

Is the gearbox a 'proper' Midget one, i.e. closer ratios than the Minor? If it has the later built-in reverse light switch it is, but there were others without.

948 Minors had a 4.55 diff and the 1098 had a 4.22 (LCV were lower).

Which is the most important? Performance or cruising?

I wouldn't use a 4.55 with a 1275 engine, it puts too much strain on the already weak half shafts in the lower gears.

4.22 will give good performance, but higher speed cruising will be a bit noisy. Check the oil filler position before fitting.

3.9 will give reasonable cruising (17mph/1000rpm), but will only fit the later axle casing with the rear oil filler (unless you modifiy/change the casing).

3.7 will give the best cruising, but less quick acceleration (18mph/1000), and same comments about oil filler.

With a close ratio box, a 3.9 is probably about as high as you would want to go, otherwise the initial acceleration will be a bit slow.

Although can be a bit expensive, have you thought about a 5-spd conversion?

[WalkerContracts]

i really want the car for cruisin but still would like good performance. thanks for al the help