Speedo works OK BUT Odometer will not

[alandorman]

Hi
I have a 1961 Morris Minor 1000 convertible. The speedometer works fine but the odometer won't clock up the mileage. Any suggestions to remedy this problem? Alan

[graham1957]

it may be the digits which have rusted to the spindle or the worm drive which is worn out,if it is a gold face 0 to 90 mph i have a spare one, the small number on the face is "1376" turns per mile and was removed from a early morris 1000. if your interested i can test it before posting at £5 plus £30 for the speedo. the 0 to 90 gold face variety are quite rare as they were only used for about 18 months and then it was changed to a black face speedo!

[jaekl]

The cable drives a worm gear that rotates a small eccentric that operates a pawl that advances the mile wheels. Most likely some teeth are gone from the driven gear. In that vintage I've found two different gear pitches used. All my spares had good gears but were not the same pitch as the one that needed to be replaced. I did find a commercial aluminum gear that was able to be modified to work to replace the worn non-metallic original. It's an easy repair. The hard part is finding the correct part. Of course make sure the odometer set is not overly tight which may have cause the failure in the first place.

[gtt1951]

I had a spare one that didn't "drive" the odometer and I think it was the ratchet hand/pawl that had "jumped" off.
I will have to take it apart again and take a photo of the item that was the fault on that one.
I took the oppurtunity, whilst it was apart, to reset the odometer to 00000.
Of course, to test it was still working after assembly, I had to spin it up with an electric drill - it worked OK, but isn't ZERO anymore.

[MrIan]

I've just been freeing off an old gold face speedo and as said above there's a brass worm gear driving a smaller gear/ shaft assy that operates a cam/ pawl assembly to rotate the odometer. This is independent from the magnetic speedo drive so one can work without the other. On mine the shaft/ cam assy was very stiff and also the number drums themselves. I used WD40 to get everything moving then air dried then very very small dab of very thin oil and all appears well on the drill test so far. Needs to be stripped to check and sort and be careful of the tiny return spring on the speedo.

[chesney]

For reference, the later black face speedo use a plastic pawl gear as opposed to a brass one.

[jagnut66]

it may be the digits which have rusted to the spindle or the worm drive which is worn out,if it is a gold face 0 to 90 mph i have a spare one, the small number on the face is "1376" turns per mile and was removed from a early morris 1000.

Hi,
Is the the standard TPM for a 1098 0 to 90 mph speedo?
Many thanks,
Mike.

[mike.perry]

Standard 1098 with 4.22 diff tpm is 1408 but you may find that it is optimistic. A 4.22 diff seems to be accurate on a 3.9 diff.

[Ufudu]

Here (about halfway down the thread) are some pics what happened to my speedo and how to fix it.

http://www.mmoc.org.uk/viewtopic.php?f= ... 37#p478852