6 replies to this topic

[burvs]

At some point during the distant 90’s, the original 998 engine in my 1979 Mini was replaced with a 1275. However, ever since the engine change, the speedo has never read correctly, reading about 24mph when you’re actually doing 30mph. I sort of lived with it at the time, but the car has recently come out of many years in storage and I’d really like to fix it. As I understand it, the right thing to do is to change the speedo drive gears but presumably this means getting the engine out and taking the gearbox apart?

 

Do you reckon someone like http://www.speedycables.com would be able to just calibrate the speedo itself for me if I send it to them?

 

Second question… as you’ll see from the attached photo, the odometer got stuck at 70,000 miles, with only the first two digits going round, but failing every time to push the rest fully around. Last weekend I removed the unit from the car and took the face off, and teased around the rest of the numbers so that they are all properly in the 70,000 position now, and I'm hoping that now, next time I hit 9 miles, it will successfully push the next digit to 1 and will continue to just work again (at least until the next 10,000!). If that’s not the case however, is this something that can also be fixed? Would I be better off just buying a replacement new replica speedo (which would presumably still need calibrating)?

 

Thanks!

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[1984mini25]

As I understand it, the right thing to do is to change the speedo drive gears but presumably this means getting the engine out and taking the gearbox apart?

 

Haven't done it personally, but its doable wit the engine in and the radiator out. Although Guesswork's is the guy you want to talk to about the drive gear combos.

[russo]

I've just recently done this. You just need to remove the plastic driven gear by jacking up the vehicle and disconnecting half shaft at universal. You can then get atspeedo cable, disconnect that and then remove the speedo drive gear by removing retaining bolt (7/16 ring/open ender.) Once removed count the number of teeth and you need to fit a gear that has one tooth less than your existing one. Should solve your problem.

[russo]

Here is a link that should also help.

http://www.guess-wor.../Tech/ratio.htm

[mad4classics]

The other option no ones mentioned may be to find a speedo with a TPM value that matches the worm and pinion you've already got, you wouldn't need to re-calibrate it then. There was a good choice of TPM values for the centre speedo, not so much for the two or three gauge clusters.

Just out of interest, it is possible to calibrate a Smiths NEMAG Speedometer yourself, although information in the public domain on how to do this is sketchy at best. You just need a way to drive the speedo through its range, an accurate tacho and a powerful magnetizer. The problem is the odometer, since this is gear driven the only way to correct this is swapping parts.

Word of caution with a magnetizer; At one point while sorting my NORTH Poles from my SOUTH Poles, I managed to re-magnetize my nice compass so that north points to the south. Doooh!

[tmsmini]

If originality and money is not a problem this is an expensive solution in the near future:

 

MINI Electronic Speedometer

Developed as result of repeated requests from customers, we have created an electronic alternative to the mechanical speedometer originally fitted to the original classic mini.

It features a billet case, drive to set function, programmable fuel gauge characteristic, trip and total in the OLED display

The Speedometer is available in MPH & KMH Versions for 90, 130 and 140, 200

Contact us for further information

 

 

It looks like they are updating the pages:

http://www.caigauge....ths-instruments

Edited by tmsmini, 18 March 2016 - 04:01 PM.

[burvs]

Thanks for the great info everyone. I think I've decided the easiest route is just to send it off and get it calibrated. I emailed http://www.speedycables.com who said they will do it and overhaul the odometer while they are at it for a pretty reasonably price.