On my speedo the 'jumping' was in time with movement of the odometer and was
caused by the input shaft being dry. A drop (!) of oil on each end of the
shaft cured it.
PaulH.
http://freespace.virgin.net/paul.hunt1/
-----Original Message-----
From: B. Schiefelbein <bjschief@acay.com.au>
To: mgs@autox.team.net <mgs@autox.team.net>
Date: 22 April 1999 08:29
Subject: Jumpy Speedo
>Hi List,
>
>I am new to this MG (Midget) DIY so I hope the questions aren't too basic.
>
>Firstly my speedo reads approx 9 mph faster than it should. ie when I am
>actually travelling at 37 mph it reads about 46 mph. I have changed my
>tyres from 145 SR 13ZX to 155/70 R13 75T but I didn't think the change
>should cause such a drastic speed change. The original speedo was damaged
>and the replacement speedo still reads approx 9 mph fast.
>
>Secondly, the speedo needle jumps (or varies across 4 mph) whilst driving.
>I once had this problem on a Datsun 200B and the problem was a filthy
speedo
>cable and cable housing.
>
>My question is... could the worm gear which drives the speedo cable be worn
>(ie the bit where the speedo cable slots into - not the worm itself)
alowing
>the cable to slip occasionally and therefore cause the speedo needle to
jump
>?? .... and....
>
>would this be part of my false reading problem or are the tyres the
culprit.
>(Logically I would assume (<-- yes I know it's dangerous) that if there was
>slippage the speedo would read slower but I ain't that technical.
>
>Any assistance would be appreciated.
>
>Bruce S
>Sydney Australia
>Midget '69 YGN41163
>
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