speedometer repair?

[tmckeon88]

Has anyone tried to fix a speedometer? I have a 1969 IIA but it has the series III speedometer with the trip odometer in it. The odometers have stopped working and the speedo seems to register a few mph too slow for the actual speed I'm going. I installed this speedo when I got the truck in 1994 and it has probably 125,000 miles on it. I know I can get a new one but it's north of $350 so I was curious about whether there's anything inside I could fix myself on the bench.

Thanks-

[roverp480]

The bezel is attached with a sort of bayonet fixing , so it can be removed by rotating it until the folded over ears line up with slots in the flange on the main case , you can remove the glass and then take our the mechanism. Its possible the pawl is gummed up which drives the odometers . Does the series III speedometer have the same rev's per mile number on the face as the old IIA one . The speedometers change depending on the size of tyre being employed , a standard 109 having a lower number than a standard 88, which affects the accuracy.
I have picked up this from another forum. Series 2A and S1 with 6.00 x 16 tyres have 1500 or 1503 turns per mile ( Which is correct for 6.50 x 16 tyres) . There are 3 main speedometers for Series 3.
1536 tpm for 6.00 tyres.
1408 tpm for 7.50 tyres
1376 for the V8 Stage 1.

[vlad_d]

I ended up getting a gently used one on ebay for about $150. It was a gamble, but I tested it with a drill chuck on a spare Speedo cable when I got it, and it worked good. So, that's always a cheaper option.

There's a guy on ebay selling glass and new bezels (in black matte and chrome) for about $40 which really refresh the look.
https://www.ebay.com/itm/Land-Rover-Series-1-2a-3-Smiths-Gauge-Reconditioning-Kit-Glass-Seal-Black-Bezel-/272473218014?mkcid=16&mkevt=1&_trksid=p2349624.m46890.l49286&mkrid=711-127632-2357-0

I wonder if you could take it to a clock repair old timer? It's basically a bunch of gears.

[roverp480]

I wonder if you could take it to a clock repair old timer? It's basically a bunch of gears.

That's where I take mine in UK. He is an Horologist who also repairs and calibrates mechanical speedometers . http://clockconservation.co.uk/
Here is his short troubleshooting page https://www.magnetic-speedometer-repair.com/troubleshooting.php
I am sure any good clock repairer could clean and lubricate one

[biffidum]

Really stretching my memory here, but I recall the most common problem was a magnet weakens on a spinning device causing a weak or pulsing speedometer. The hack to repair was to slice a piece from a fridge magnet and glue in place. The principle is that the spinning magnets cause a torsional force on a clock spring attached to the needle. I could be way off base here though... haha!

[roverp480]

As you say, its a magnet spinning in a cup, dragging it round against a spring. Faster it goes the more it moves the needle. The magnet and spring have to be correct to get the right readings. I have had faults when the bearings wear and allow the the magnet to get closer to the cup and make the speedometer over read. If oil or grease get in , say if the cable is overlubricated, if will also tend to make the speedometer over read