23 replies to this topic

[Sprocket]

Any body know the turns per mile on the Nippon Seiki clock set so i can double check i've selected the correct speedo gear ratio.

I've had the thing apart and there is nothing that resembles the correct sort of numbers.

I was under the impresion that it was some where around 1280 turns per mile

Any help would be apreciated

MS

[Guess-Works.com]

It depends on the car they were fitted to, but then ones I have are 1242 (90 mph three clock), I have a speedo for a later MPI which is 1300. The only way to be 100% sure is to count the teeth on the odometer drive and work it out..

Just Noticed something which I had never seen before... but on the pinion drive from front to back there looks to be the tpm molded into the drive... see photo.. but cant see this on the later MPI speedo..

Edited by GuessWorks, 31 May 2006 - 07:49 AM.

[icklemini]

From memory - it 1248 (got it in my note book at home - i'm at work!)

another way to check is to wind the speedo on (counting the turns) for 1/10 of a mile, then multiply the number of turns it took to do that by 10.. (or if you're really keen - wind it for a full mile!)

TTFN,
Dave

[Sprocket]

It depends on the car they were fitted to, but then ones I have are 1242 (90 mph three clock), I have a speedo for a later MPI which is 1300. The only way to be 100% sure is to count the teeth on the odometer drive and work it out..

Just Noticed something which I had never seen before... but on the pinion drive from front to back there looks to be the tpm molded into the drive... see photo.. but cant see this on the later MPI speedo..

Genius

Shall check mine out

So 1242, I'll see where im at with the drive i have.

Edit:

Yup, just checked, its pretty dam close with a speedo drive ratio of 3, either 15/5 or 18/6.

Thanks people

[Sprocket]

Checked mine to day as you say Mr GuessWorks and it says 1300.

SO

There are more than TWO speedos with different T/M. which is not what Minispares or a number of speedo gear calculators would lead you to believe.

Judging by this, for any one else, DO NOT go off what any of these calculator programs say unless you have the actual speedo turns per mile, # of teeth on both the speedo drive spindle and pinion as well as the final drive ratio. Wheel size is pretty much indifferent unless you change from 10s to 12s or vice versa. This will give you the information to determine what needs changing using a specific program.

Maybe this should be pinned in the FAQ as it does seem to be a topic of conversation these days.


EDIT:

I have evidence so far that there are three I'll update as soon as i know any different.

1242 t/m
1280 t/m
1300 t/m

[miniboo]

o dear lord no i thought i had cracked it.

Mine is a similar age to yours MS so i might well have the same as you.

did you find it on the speedo where Guessworks showed in the pic?

If it is it looks like i will be taking the dash out...again.

[Sprocket]

o dear lord no i thought i had cracked it.

Mine is a similar age to yours MS so i might well have the same as you.

did you find it on the speedo where Guessworks showed in the pic?

If it is it looks like i will be taking the dash out...again.

Yup

You guessed it

[Sprocket]

Speedo drive ratio combinations available.

You will find that the five tooth spindle will give a high ratio, which means the speedo will require lesser turns per mile. As far as I am aware, there were no Minis fitted with these.

I have a Metro box and it has a 17/5 speedo drive, meaning that the speedo/ wheels of the metro were totaly different to the Mini and if it were to be used on any of the Mini speedos, it will read wrong.

15/7 = 2.14
16/7 = 2.29
17/7 = 2.43
15/6 = 2.5
18/7 = 2.57
16/6 = 2.67
17/6 = 2.83
15/5 = 3
18/6 = 3
16/5 = 3.2
17/5 = 3.4
18/5 = 3.6

[retrodan]

i had a 998 speedo cable and speedo but with a drive than came with my new med g/box and now its runs 12-15 mph slow!!!

[miniboo]

Speedo drive ratio combinations available.

You will find that the five tooth spindle will give a high ratio, which means the speedo will require lesser turns per mile. As far as I am aware, there were no Minis fitted with these.

I have a Metro box and it has a 17/5 speedo drive, meaning that the speedo/ wheels of the metro were totaly different to the Mini and if it were to be used on any of the Mini speedos, it will read wrong.

15/7 = 2.14
16/7 = 2.29
17/7 = 2.43
15/6 = 2.5
18/7 = 2.57
16/6 = 2.67
17/6 = 2.83
15/5 = 3
18/6 = 3
16/5 = 3.2
17/5 = 3.4
18/5 = 3.6

I have a 17/5 aswell and it reads well under, at least 10mph

still not quite sure what i need so will have to take the dash out.

[Guess-Works.com]

I was building an FAQ, but as you say there are varied TPM's for speedos, the problem I was having was relating them to a vehicle type, year of manufacture etc, as I don't know the origin of the ones I have..

So far I have a list of 1/2 a dozen or so, I find a good place to find the information is trawling through the autojumble @ shows..

The old central smiths speedo's have the tpm just under the odometer

[icklemini]

There are more than TWO speedos with different T/M. which is not what Minispares or a number of speedo gear calculators would lead you to believe.

Judging by this, for any one else, DO NOT go off what any of these calculator programs say unless you have the actual speedo turns per mile

add to this the general inaccuracy of some gauges hence why i suggest:

another way to check is to wind the speedo on (counting the turns) for 1/10 of a mile, then multiply the number of turns it took to do that by 10.. (or if you're really keen - wind it for a full mile!)

doesnt take that long really....

TTFN,
Dave

[miniboo]

Look at this for a post revival....BUT

My car speedo reads in km/h and it says 820 on the face. so i think that menas 820 turns per km.

NOW then..... with a bit of maths i have worked out that 820 TPKM equals I think...1320 Turns Per Mile.

does anyone else agree?

so if i have a 3.44:1 FD what speedo drive cogs will i need?

Also what about when i change to the 2.76:1 FD i have?

Thanks..sprocket and GW

[redhotmini]

add to this the general inaccuracy of some gauges hence why i suggest:

hence why they are called gauges. if they were supposed to be accurate they would be called instruments.

[Guess-Works.com]

Yep, 1320 had the same questions raised by moke owners in Aus'... they have 800rpKm speedo's

If it's in rpKm then multiply by 1.609344 to get TPM