Morris Minor Owners Club

I wonder if the '800' is Turns per Kilometre - or still the usual TPM. If TPK then = 1280 TPM which will be good with a 3.9 final drive.

Interesting Roy............I have a 1275 plus a Midget 3.9 dif

I am sure Mike Perry will enlighten us as he requested the info from me? So I am sure he can explain

ok will be in the garage.....this coming week so will trace that light green wire.

Now another problem need to fit this hazard switch too

need to know what wires go where

When I started this list I expected about a dozen different speedos. I am now up to 30 serial numbers all with small differences, and I have not seriously started on Mini or KPH speedos.
The TPM four fig is the turns per mile of the cable so the lower the TPM fig, the higher the diff gearing. This works on the 948, 1098 and 1275 diffs as they all have the same gearbox gear/pinion ratio, 5/13. The normal TPMs are 948-4.55 = 1504 and 1098-4.22 = 1408. I have found that with standard 155/14 tyres and the 3.9 diff the 1408 TPM speedo reads accurately to within 1 mph, meaning that it overeads by a conciderable amount on a 4.22 diff. Note tat the 1098 LCVs use a 4.55 diff.
The Series II has a different gear/pinion ratio not listed in the workshop manual so the speedo TPM of 1000 for a diff ratio of 5.375 does not fit the above system.
If anyone knows the gear/pinion ratios for a Series II or Series MM please let me know.
I have not collected enough info on KPH speedos to be able to state if it is a TPM or TPK figure. If anyone has a Minor with a KPH speedo please let me have the info.
Meanwile Russ it is a case of suck it and see

Thanks Mike...............that told us Roy

All that is well known......... - and it 'must' be Turns per Kilometre on that speedo since 800 Turns per Mile would not suit anything....

so with a 1275, plus 3.9 diff will be accurate Mike?

Managed to get into the garage today and located that light green wire and wired it to the speedo, mounted the hazard unit so will wire that soon

RussLCV wrote:so with a 1275, plus 3.9 diff will be accurate Mike?

That depends on what size tyres are fitted.
Just to throw a few more calculations into the pot, as previously noted the 948,1098 and MG1275 boxes have a gear/pinion ratio of 5/13. A scan through the Mini MK1 Workshop Manual finds gear/pinion ratios of 6/17 for manual box and 7/17 for auto box on 145/10 tyres

A 1249 Mini speedo is accurate for both miles and speed in a Minor with a 3.7 final drive - on 155 tyres. So your readings won't be far wrong.

what about 185s on the rear!

Need full details of size, eg 175/80/13

[frame][/frame]
Wiring instructions for hazard flashers

off the face of the speedo followed by the 4 fig TPM, for my speedo application chart.

The 'TPM' (turns per mile) for this speedo is 1280. The 800 on the face is turns per kilometre. So multiplying by 8/5 (1.6) gives 1280. Simples! Oops--we aren't allowed to say that.

Don

mike.perry wrote:[frame][/frame]
Wiring instructions for hazard flashers

Many thanks Mike

Tyre size is 185 14 or I can use a 165 x14

Would need the section height of each tyre. 185 tyres need 5.5" rims. 165 will be fine on 4.5" rims.