Talk Morgan Forums Morgan Sports Cars Classic Morgans (pre-CX) Speedo working, Odometer stuck on 50,000

I noticed when I went out today in my 1972 4/4 that whilst my speedometer is working the odometer is stuck on 50,000 (second time around). Has anybody any idea why that might be and how to fix it, please? I rely on my trip meter for refuelling, as the fuel gauge tells porkies.

Although there is a single cable drive to the clock the spedometer and mileometer have different mechanisms inside the gauge.
You'll probably have to replace it, or send it to a specialist repairer. Melvyn Rutter used to have a gauge repair service (probably still does) alternatively contact Caerbont Automotive in S. Wales.

Speedograph Richfield in Nottingham are another instrument repair company well versed in vintage vehicles.

Put the guage on Ebay. You should get a very good price - there are lots of car sellers who would appreciate a mileometer that didnt move.

As Graham said above, the instrument has two mechanisms within.
Your speedo works so the problem is not the drive cable, nor the speedometer itself.

The odometer is gear driven. The drive cable turns a worm screw which turns a toothed gear. This gear is directly attached to a pawl via an eccentric pivot. Every turn of the gear will pull the pawl once. The pawl turns a plastic (coloured) gear at the end of the odometer wheels.
Everything up to the pawl is pretty robust, mechanically linked and unlikely to be the problem.
Everything away from the coloured gear in the odometer drums is equally robust.
The most fragile element is the pawl and/ or the gear wheel it drives.
i.e
1- The plastic tooth gear can be stripped, or the clip that holds the pawl to the eccentric pivot may have fallen off allowing the pawl to fall from the eccentric.
2 -The spring pulling the pawl to the gear on the wheels may be weak or missing. This may prevent the pawl from touching the gear and thereby prevent any motion of the wheels.
If the odometer is exactly at 50,000 the gear train will have had to push all 5 of the barrels to get from 49,999 and this may have been too much effort for the pawl or the spring.
My suggestion would be to have a look and see for yourself:
- disconnect the cable drive, remove the bulbs and take the instrument out. Once out; an 1/8th of a turn of the bezel should release it and the glass. Two through screws retain the mechanism and face to the back of the case, remove these and the innards will ‘fall’ out as a complete mechanism.
At this stage, the condition of the pawl, spring and drive should be asertainable and will tell you what to do next. If the above are OK all that may be necessary is a number of nudges to get you away from 50,000.
DON’T go further and think it would be ‘fun’ to correct the mileage drums!
Reassembly is as Mr Haynes would say is in the reverse order.

Thanks for the responses. I’ll have a look at it myself and then no doubt send it off to Melvyn to be done properly. He can calibrate the speedo at the same time so that my passenger doesn’t think we are doing 85 mph when in reality it’s only 70.

BTW, when some bits of the car (although it may be only the speedo at this stage) have done 150,000 miles it’s more a badge of honour than something to try to hide😊.

For the speedo; the cable drive has a magnetic element, as it spins it induces a magnetic field in drum to which the needle is fixed causing the needle to move. Unless the magnetic drive to the speedo is re or de-magnetised you can’t alter the amount the needle moves, the speedo will only read correctly at one speed.
Prior to taking your speedo to bits, calibrate the speedo by having a passenger record the shown speed against a GPS device, (satnav or free speedometer App for your phone). By doing this you will see how fast or slow your speedo actually is.
Then pick the speed you wish to the speedo to be accurate at (say 70) and note the speed shown on the speedo (say 85).
When the mechanism is out of the case, manually turn the needle to 85, hold it there and with a fine felt pen put a mark on the magnetically driven drum against a fixed register point on the mechanism.
Release the needle and then pry the needle off the shaft with a couple of tea spoons as levers. Once off, rotate the drum so your mark and register re-aligne, then refix the needle at 70. The speedo will then be accurate at that speed, for the example given the reading will low below that and high above.
You can then remount the mechanism in case without glass, afix the cable drive and repeat the GPS test and readjust if necessary before you button everything up.
And lastly, put the tea spoons back.

It may be quicker and cheaper to deal directly and have the instrument repaired by one of the above mentioned companies dedicated to such.

My tacho gave up the ghost last month one of the last original parts on the car. Current speedo has been round the clock twice and it's the second one!

Whatever the outcome, all of us owners of 4/4s from that era should give Horror a big thank you for the lesson on speedo/odometer workings and adjustment. Brilliant!