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MG Midget and Sprite Technical - Mechanical Tac drive

Problems with my Frog tachometer.
No, it's not the dynamo gearbox!
First I found that the little squared inner cable connector at the top end was loose. It was supposed to be crimped to the inner flexi thing but it was just turning freely. The crimp wasn't effective so I soldered it on.
That worked, for about 50 miles but now the tach will only go up, where it then sticks showing max revs achieved for the journey. Then when I stop the engine and tap the dial it drops to zero again. Presumably something amiss now inside the tachometer, which I will need to open up and investigate.
Any suggestions?
GuyW

I don't suppose that by soldering the end on it has changed the length a bit and causing the cable to load up on the end of the tacho shaft, might be worth undoing the cable nut a turn or two and see if that helps, if it does you could run a little spacer washer inside the nut-------maybe
William Revit

I once had a faulty cable that was too long and made the tacho erratic. After decades of struggling with this unreliable system I changed to an alternator and electronic tacho. I have two spare cables which you can have for nothing if you want.
Les Rose

Thanks for that offer Les. I think that you - and Willie - are right onto the problem.

I soldered the little squared end back onto the end of the cable. I found it really hard to get the inner cable sufficiently clean to take the solder, despite washing it thouroughly in a whole succession of oil solvents. The spiralled wire of the cable seemed to act like a wick and as soon as heat was applied to the end with the torch it drew more oil up the cable to contaminate the soldered end. Upshot of this was getting a lump of too much solder on the end and having to file it back to profile, and I think that is where the problem lies. Its now still a bit too bulky and is snagging on the ferrule nut or cable outer.

For now at least I am sticking with the out dated design. Call me masochistic, but I like having a dynamo and cable drive! So thanks for the offer of cables - message me on GuyAT followed by weller -lakes and the normal UK ending.
GuyW

My cable and dynamo system has performed ok. Yes I needed a new cable a few years ago and I am on my second dynamo and drive but hey not bad for 45 years of ownership! I only changed the rev counter as the original was stolen! Perhaps I am just getting too old and set in my ways............
Bob Beaumont

Thanks Les. Tachometer drive cables arrived yesterday. And sun came too to put the icing on the cake! (Mixing metaphores a bit there!) 😂
GuyW

This thread was discussed between 28/03/2022 and 03/04/2022

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