Morris Minor Owners Club

hi all
fitted a 1275 midget engine and gearbox and going to fit a 3.9 diff what speedo should i use to get the speed roughly right??
or ignore and use a gps style speedo??
Stu

I had a 3.9 diff, 145 radial tyres and 1098 gearbox I found
TPM 1375 was accurate.
Regards Win

I used a SN 4421 800 from a mini after fitting a 3,9 diff. . You need to experiment with the pointer setting to give a reasonabley accurate (in my case) kmh reading.

Not forgetting Odometer accuracy ( if you're bothered ? ) .

John ;-)

I fitted a 3.9 diff only to find that the standard speedo is now accurate. Check it in comparison to a sat nav before changing anything.
Regards
Declan

many thanks for the help guys
forgot to say i have a bronze speedo in the morris
but as some have mentioned ill try with the standard one and see how it goes

Declan_Burns wrote: ↑Mon Apr 11, 2022 11:16 am I fitted a 3.9 diff only to find that the standard speedo is now accurate. Check it in comparison to a sat nav before changing anything.
Regards
Declan

Totally agree - I found just the same when I replaced the 4.22 diff in my old Traveller with a 3.9 one, in that it was far more accurate afterwards than it was when it was as standard!

our one with standard diff overreads by about 10% so 4.22 to 3.9 would make it just about right.

My 1275 is on a standard box and 4:22 diff, with 14-inch minilites and 65 series tyres.

I had my speedo calibrated when the engine was built, 30 years ago, and it's within 2mph of my GPS speed on Waze or whatever...

When I change the diff (or possibly go Ford 5-speed, I'll have it done again...

With the number of constant-speed zones and speed cameras these days, it's money well-spent...