9 replies to this topic

[Vince208]

The speedometer of my 1963 Morris Mini Minor Super has stopped working. It is definitely not a problem with the speedometer cable; the problem is internal to the Speedo itself. Does anyone know the most common problem with these? Is there a spring for example that may need replacing? Thanks

[gazza82]

How do you know it's not a problem with the speedo cable?

[Ethel]

Is the milometer still going?

[Vince208]

That's a great question and hopefully the key. Both the speedo and odometer stopped working just as the odometer was trying to move from 49999 to 50000. Thanks.

[Spider]

I'd suggest unscrewing the cable off the back of the speedo (it should be somewhat easy to access from the engine bay), jack up one front wheel. put the car in neutral, then spin the wheel while looking at the end of the cable, you should see it turn.

If you don't, then it'll be the cable and / or the speedo drive pinion in the gearbox.

If you do, then it's most likely the speedo.

[Ethel]

That's a great question and hopefully the key. Both the speedo and odometer stopped working just as the odometer was trying to move from 49999 to 50000. Thanks.

 

 

That suggests it is the cable, or something very near it in the speedo. The needle is driven directly off the cable via a magnetic clutch/coupling. The milometer is directly driven by a pinion & worm gear that's also directly on the end of the cable.

[mad4classics]

That's a great question and hopefully the key. Both the speedo and odometer stopped working just as the odometer was trying to move from 49999 to 50000. Thanks.

That suggests it is the cable, or something very near it in the speedo. The needle is driven directly off the cable via a magnetic clutch/coupling. The milometer is directly driven by a pinion & worm gear that's also directly on the end of the cable.

It's interesting that the failure occurred at the point where the odometer needs to move 5 wheels which requires a lot more force - this is often where a weakness shows and the pawl in the odometer drops off or the odometer gear strips teeth.

You'd have to be unlucky for an odometer part to fall into the Speedo and jam it up so I would still favour the cable since they both failed simultaneously.

[timmy850]

I would say the most common time for them to fail is when it’s going over to the next 10,000 increment

I’ve had speedos lock up and snap the cable
I’ve had odometers seize but the speed keeps working
I’ve had them make horrific grinding noises

In all cases they normally need a rebuild at the speedo repair shop

[Ethel]

 

 

That's a great question and hopefully the key. Both the speedo and odometer stopped working just as the odometer was trying to move from 49999 to 50000. Thanks.

That suggests it is the cable, or something very near it in the speedo. The needle is driven directly off the cable via a magnetic clutch/coupling. The milometer is directly driven by a pinion & worm gear that's also directly on the end of the cable.

It's interesting that the failure occurred at the point where the odometer needs to move 5 wheels which requires a lot more force - this is often where a weakness shows and the pawl in the odometer drops off or the odometer gear strips teeth.

You'd have to be unlucky for an odometer part to fall into the Speedo and jam it up so I would still favour the cable since they both failed simultaneously.

 

 

Yes, but as the speedo has also stopped, it suggests something closer to the cable, or possibly both.

[Lplus]

As an additional option I had a speedo cable on which the collar clamped on the inner cable slipped so the end of the cable retreated out of the speedo square drive.  It wasn't obvious at first.