DIY speedo repairing & re-calibration!

linearaudio · Post by **linearaudio** » Sun Feb 08, 2009 4:58 pm

Speedo stopped playing the game yesterday. Started pulling it apart, then looked on the net and found a wondrous article explaining just how to, also how to recalibrate speedo AND mileometer readings! May help some of you with wayward mile readings! http://www.dur.ac.uk/p.d.kuhlmann/speedo.pdf

Certainly gave me the confidence to carry on and get my speedo working again (dried up grease on bearings)

Post by **nigelr2000** » Sun Feb 08, 2009 7:00 pm

Nice one I have just replaced my old speedo with one from ebay only to find it jerks to the right speeds. Now I have the information needed to service my old one and the new one as a spare. Spot on Linear

Post by **Lukey** » Sun Feb 08, 2009 7:30 pm

Nice find! Is it normal for my needle to oscillate slightly? It's only a very slight wobble, it's been bugging me though.

EDIT: I can't read the pdf because adobe crashes my computer. Put it on memory stick for later.

linearaudio · Post by **linearaudio** » Sun Feb 08, 2009 7:52 pm

One common cause is worn or drying out speedo cable. Try a bit of grease on the inner cable. I'm sure there must be a way of telling by looking at the inner cable when it's getting worn, but never seen any mention anywhere. If in doubt put a new cable on, then dismember the speedo if still a problem. Download the pdf first though!

Post by **bmcecosse** » Sun Feb 08, 2009 10:33 pm

I just swapped my 1508 tpm speedo for a Mini 1248 tpm speedo today - it cost all of £3 on ebay - and the 1248 should tie in nicely with the 3.73 diff to give accurate readings - both mileage and speed. Mini speedo is identical - except for an extra green warning light at the top which I am not using - but could be used if wanted.
Mini speedo has slightly wider side bracket spacing - so these had to be cut and rebent to the correct ~ 5" spacing, and the voltage stabiliser had to be repositioned slightly - both only moments work, and it slots straight in and works perfectly!

linearaudio · Post by **linearaudio** » Mon Feb 09, 2009 5:55 pm

BMC, the point this chap was making was that the "guts" of just about any 1960's ish smiths ( or Jaeger??) are interchangeable, so as long as you find one with the right revolution number, you can swap the bits around, or even build your own ratio by selective gear assembly! Good for you finding a Mini head to suit your application, though. Hope the £3 included postage

Post by **bmcecosse** » Thu Feb 12, 2009 12:17 am

I know they can be swapped around - but what a hassle - especially trying to get the needle back on the spindle, in the correct place. Been there - done that - many moons ago. Think post was another £1:50 but still well worth it!

Post by **wiglaf** » Sun Feb 15, 2009 8:59 am

Thanks, that looks very useful... will keep in mind for when my basic speedo-clean and change of cable turns out not to achieve anything!

Post by **bmcecosse** » Sun Feb 15, 2009 6:13 pm

Here's one on ebay - looks same as mine, but don't know the tpm yet. It's cheap enough at the moment! http://cgi.ebay.co.uk/ws/eBayISAPI.dll? ... 2761.l1259