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MG Midget and Sprite Technical - Odometer Fault

A strange one. My frogeye odometer has just passed through an indicated 91999 miles, however once all the digits eventually realigned themselves it's now showing 02000 instead of 92000.

Odometer now seems to be working correctly albeit that it indicates that I have done an extra 10000 miles.

Rebuild time? - any recommended companies?

Simon
SA Wood

Hi Simon, As no one has pitched in my experience of Midge odometers is that they are a bit ropey.

I had to replace my speedo and therefore odometer just after Christmas and the main mileage is fine however the trip reset isn't wonderful. Sometimes no matter what I do it only resets to 2 miles showing not 0. Its always the same, that is 2, never anything else and when this happens I can't get it to change to 0 no matter how many times I try. When I refill the tank I always reset and sometimes its 0 when I reset but about half the times its 2.

Its put me off resetting the new odometer to the old 'correct' reading as it were in case I break it.

Mine is a 'newer' car (LoL) however this seems to me to be indicative that what happened to you is probably not uncommon.

Shame about not seeing the 999999 miles though, always gives me a smile when my motors do it.

Anyway I may be completely off beam but seems sort of no less than I would expect.

Someone may be along soon to correct me. If nothing else we may then see a definitive answer.

Cheers, Dave

Dave Squire

Could be an indication of tampering in its earlier life....thats just a guess

Prop
Prop and the Blackhole Midget

I can't personally recommend either as I've not had work done by them but my mate reckons speedy is a misnomer although I've heard good recommendations for both

http://www.jdo1.com/

http://www.speedycables.com/
Nigel Atkins

I can highly recommend http://www.jdo1.com/ as above - he rebuilt a Morris speedo for me a few years ago after the internals self-destructed. Reasonable price, fast turn around and it worked beautifully, well calibrated.
Dominic Excell

Not wanting to do any of the recommended businesses out of a job, but the speedometer/odometer units are quite interesting to work on, and not that hard. They have varied a little over the years but the principles are much the same throughout.
Firstly, as far as the odometer is concerned, there is no calibration needed unless you have changed the output gearing (wheel size, or diff ratio, not gearbox as that has no effect). The speedo part can get damaged and give inaccurate speeds, but the odometer is just a mechanical gear ratio so no adjustment needed there.

Each visible wheel of the odometer has a small planet wheel inside that is rotated by gear teeth. The design is pretty obvious in that as the outer wheel turns through 1/10 of a revolution, the inner wheel also turns. When it has turned 10 times it engages a tooth on the wheel to the left and moves it forward 1/10, and so on.

Simon, the likely problem with yours is that the wheels were obstructed with a "foreign body" - maybe a spider egg case or a bit of dirt rather than an alien, but you never know! When the inner gear wheel came around to turn your 1,000 wheel to 2,000, the wheel to the left of it was stuck and dragged round from 90,000 to 00,000.

All it needs is dismantling, cleaning and careful reassembly of parts in the same order. The number wheels are on a shaft with a spring loading to keep them aligned. Generally all it needs is a brush over all the parts with an artists' paint brush. Or one of those puffer brushes sold for cleaning camera lenses. If you use a craft knife blade to open the gap between the wheels you can blow away dust between them without dismantling all those small parts. Don't be tempted to lubricate with anything as that will just attract dust. And don't use any sort of solvent cleaner which will certainly take the white numbering off the wheels! Water-dampened cloth is probably as much as I would dare, but maybe a lens tissue would be OK. Not sure about that!

At the same time you can reset the 02 back to 92 and relive those missing 10,000 miles!
Guy W

Guy,

I like a challenge and I suspect that you may be correct in your analysis. I now have something to look forward to at the weekend!!

Will let you know how I get on.

Simon
SA Wood

if you're taking it apart you might want to overall the whole unit as the specialist do

cleaning/removing rust/repainting the inside of the dial case for better illumination, cleaning the inside of the glass, possibly gently the dial face, possibly replacing the rubber gasket and probably other stuff I can't think of
Nigel Atkins

Yes, I agree. Only reason I didn't mention the other stuff, cleaning etc is that it all seemed a bit obvious!

Refurbishing speedometers is a nice winter evening coffee-table task for the living room. In front of telly, warm log fire and good wife to bring you coffee.
Guy W

...... and a good pair of glasses to find the tiny bits you drop in the shagpile!
Graeme Williams

obvious if you're not totally zoned in on the single task, have you never completed a task put everything back together back in place and fully connected up and tested then realised because you were so concentrated on the one task you missed the opportunity to do other related work whilst it was out and apart

other than driving there are no nice tasks on a car just those that need or want to be done
Nigel Atkins

This thread was discussed between 01/10/2013 and 03/10/2013

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