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MG Midget and Sprite Technical - Sticky Speedo

Out on my first real run today, one of the issues I had was the speedo seemed to get stuck at ~40 mph.

Once I was able to stop, I rummaged about behind the dash and the needle dropped back down to zero. Once underway and up to 40 it got stuck again.

Seems to work OK under 40-ish.

Thoughts?

Cheers,
Malcolm
M Le Chevalier

"I rummaged about behind the dash and the needle dropped back down to zero"

It sounds like the cable might be exerting some unwanted pressure on the mechanism.

Does the cable go straight onto the speedo or do you have an angle drive? Some 1500s did.

Dave O'Neill 2

If I remember rightly, it has an angle drive Dave.

M Le Chevalier

I had exactly this problem after a speedo was delivered through the post. The needle had moved slightly on the spindle and was just touching the dial at the 40mph position. THe answer is to take the glass off and ease it forward a gnats.
Graeme Williams

OK, thanks Graeme, this speedo has been through the post too so I will check that. If it is, thanks for the heads up, that is one of those things I would never have thought of.

Cheers,
Malcolm
M Le Chevalier

Me neither, hope it's a good call.
If not, erratic speedo can sometime be the route the cable takes which can cause it play up - suspect you may know that already!
Jeremy Tickle

Just to conclude on this, speedo was still sticking. Worst of all it happened when I arrived at MOT yesterday and despite much shuggling it would not go back to zero! The mechanic came out to see what I was up to and I had to act all innocent and hope he wouldn't notice what was wrong! ha ha :-D

Disconnected the cable and it was still stuck (so not a cable fault). Eventually after a lot of tapping and shaking it slowly dropped back down. Phew :-)

Just had it to bits on my coffee table. Turns out there was some dirt on the back of the "drag cup" so the mechanism/needle wasn't able to move freely.

A scoosh or two or three of electrical cleaner has cleaned things up and it is moving freely again, so hopefully problem solved.

A useful reference for speedo repair:

http://obswww.unige.ch/~wildif/cars/docs/Smith-jaeger_speedo_repair.pdf

Only problem I had was I knackered the "trip computer" reset arm trying to get the knob off to get the speedo out of the casing. Oh well, I have never used one anyway!

Cheers,
Malcolm

M Le Chevalier

I use the trip as a cross ref for the fuel gauge which has at least a gallon in it when it goes off the scale and stops just below Min.
As mine is a day car doing different journeys each day I do need to keep a careful eye on what's available in the tank while not stopping more than I need to. (Embarrassing call out the AA man story who lives a couple of villages away has happened).
I have a 7 gallon tank (eat your heart out the rest of you with the 6 gallon one) and I get between 30 and 36 to the gallon depending on the music being played at the time. I therefore work on where the needle is and what the trip says for this tank (set to 0 on fill up).
Dave Squire

Another update. Still sticky. Bugger.

Will just figure out speed from revs/gear ratios for now whilst I determine what to do next speedo wise. Don't tell plod ;-)

Malcolm
M Le Chevalier

This thread was discussed between 17/11/2015 and 29/11/2015

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