Moss Motors, Ltd

I have a 67' 3000 just got it on the road after 20 years in a garage,

The speedometer and tach don't work.

I purchased a new speedometer cable, and I know that it goes directly to the tranny case (I think thats what it's called)

I also have purchased a new right angle drive. Hopefully this will get it working, my next problem is that I can't find

anything about the tachometer. All I know is that it doesnt work. The workshop manuals I have say nothing, and I can't find any resources.

How does the tach operate? Where are the cables connected to and from? Any help or advice is much appreciated.

Here's some info that is relevant to all Smiths & Jaeger branded tachometers of the 60's & 70's (Assuming it is electronic, rather than mechanical).

http://www.classictiger.com/techtips/motach.html

They are fixable, if you have a little electronics experience, or there are businesses e.g. Nisonger, who will repair, recondition and calibrate the gauges for you.

Hope that helps,

Ed

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I want my MGB

Thanks Ed, just what I was looking for.  I have a box of old tachs for my midget and they all failed right after I installed the Pertronix ( in the distributor) Ign.  That site explains why... I always suspected the switching was more efficient (or spiky) with the Pertronix than the points.

I am currently running one of the later tachs( MG Midget), the ones that have an Op amp? It uses a single wire from the distributor, like most tachs do.  Any info on those tachs?

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-Michael

Hi Michael,

 I'm unfamiliar with the later types of tachometer.

From reading around, I learned that the current sensing tach, with the wire loop pickup sensor, designated "RVI" will not, in most cases, work properly with electronic ignition systems. You need the "RVC" type, which has a direct electrical connection from the distributor-coil circuit point to a terminal in the back of the gauge, these sense voltage, not current.

I think it's possible to substitute the inner workings of a later gauge for the earlier type, with a few modifications and recalibration, but have never tried this.

Otherwise there are some kits and advice available to do this, one of which I found here:

http://members.shaw.ca/tsmit/tachmod/tachmod.html

Otherwise a Google search on Smiths tachometer, RVI, RVC will turn up some useful information.

Cheers,

Ed

 

 

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I want my MGB

Thanks!!

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-Michael

No problem!

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I want my MGB

I've got similar problem with a '64 TR4 that I recently purchased.  The tach isn't working, and the speedometer isn't calibrated correctly -- says I'm going 100mph when I doing 60, and 60mph when I doing 30!  The manuals, however, don't have anything on calibrating the speedometer.

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--Bill

jmswms,

Here's a link that describes everything you'll ever want to know about the spedometer... http://home.comcast.net/~rhodes/speedo.pdf

BUT...When you write that your speedometer indicates 100 mph when you're going 60, could it actually be saying 96.5? The reason why I ask is because that would be correct for kilometers per hour! 30 mph would be 48.2 kph.

Perhaps you have a Canadian market speedo?

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On their death bed, nobody ever said, "Gee I wish I'd spent more time at work!"

'68 Sprite 1275
'76 Midget 1500

good catch davey - the very same thing went through my head....

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I want my MGB

Thanks for the link--everything I ever wanted to know about speedometers! Actually, the speedometer does say "MPH" -- so it doesn't look to be a Canadian model. An interesting question though, is when they started using "KPH" instead of "MPH" in British (and Canadian) cars.

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--Bill