Speedo & Tach twitch

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RoadScholar

RoadScholar

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When I when through my '75 MK III I sent the instruments out to Nisonger and replaced the drive cables. During fitment I made sure that the ends had the proper square to fit easily into the drives and the instruments and that the cables were lubed with moly grease (Ford, fox body, Mustang wheel bearing grease).

The botton line: The speedo needle gets stable at and above 65 MPH the Tach, which is stable up to 4000 RPM gets a twitchy above 4000 RPM. I notoced that the OE fitment had a few more cable ties than I have fitted on the speedo, but the tach goes straight up.

Any advise?

RS
 
I have 2 Nortons, 1 with a twitchy speedo and good tach and one with the twitchy tach and good speedo. I kinda gave up on making them stable, I think Brian must be right though because both of mine were rebuilt too. Any help guys?
 
Thanks guys.

I was hoping for a fix, but the reality check is just as good. My biggest concern was possible damage to the instruments, the rebuilds cost $165/ea; at least they can be done...

I'll live with the wobble, at least they don't wobble when I'm in the studio at cocktail hour tinkering.

RS
 
I have a feeling that I swapped the heads over onto the wrong cables once to diagnose a tacho problem. As I recall, the ratios are similar enough to get an idea of what's happening. Don't blame me if the clock explodes though ! :)
 
I like this quote from the book advert - "No specialist tools required, just a cycle computer."

If a cycle computer isn't specialist then I don't know what is ! There certainly isn't one nestling amongst my Whitworth open-enders !

Biggest problem with SSMs of course is putting the bezel back neatly without the use of a rolling tool.
 
79x100 said:
I like this quote from the book advert - "No specialist tools required, just a cycle computer."

If a cycle computer isn't specialist then I don't know what is !
Click to expand...


I think there would be quite a few cyclists who may disagree with that? And many classic motorcycle riders also use them as speedometers.

And from around less than £7.00 each, available from any cycle shop (or any branch of Halfords, no doubt?) they can hardly be described as a spcialist tool these days I think?
http://www.jpgelectronics.com/products.asp?partno=L119P
 
I just down loaded an article from the internet on rebuilding Smiths and Jaeger speedometers. I'm hoping that gives me enough info to lube my wacky tachy. I expect the real problem will be the chrome ring.
 
Cookie said:
I just down loaded an article from the internet on rebuilding Smiths and Jaeger speedometers. I'm hoping that gives me enough info to lube my wacky tachy. I expect the real problem will be the chrome ring.
Click to expand...

LINK!!!!!!

Thanks. :mrgreen:
 
It may turn out to be useless. It's based on cars and about all it seems to give you is one type of lubrication this guy uses. The lube points are similar but this seems out of date with the stuff he is using. It does not deal with the case ring or bike specific problems. This would be pretty good for car stuff but I'm going to keep looking.
 
I had some pbs with my clocks last april (garage fire)

Speedo & Tach twitch


and managed to change the glasses and bezels which I found on ebay for £12 a set.

Not having the tools to form over the rims I glued all the gaskets, glasses and bezels together with a thin line of super glue and they are like nearly new.
The twitch most often comes from the speedo cable and gearbox setup, check it with an electric drill on the cable.
 
I have a new cable on mine and i'm wondering if it is long enough to drive the tack properly. That will be the first thing I check tonight.
I'm in the middle of a job on another bike so I'm not putting much time on the Norton.
 
L.A.B.

Thanks, I just purchased the book.

I called to Nisonger this morning and they suggested that the cable(s) may be the wrong length or that the drives may be skipping. I like the ideal of using a drill to check the drives, and I do have the OE cables I can swap in for a cable length check. I was not impressed with the new cables as I had to re-shape the ends, slightly, so that the ends would enter the dirves and instruments. At the time of assembly I also coated the inners with moly grease.

RS
 
Funny you should say that RoadScholar I tried to change my speedo cable and the new one wouldn't screw onto the speedo, bad machining I suppose, in the end I put the old one back on. I'll have to have a word with Norvil.
 
I wouldn't blame Norvil, mine from Mick Hemmings wouldn't either, had to grind it down on the sides, awful job. I think they get them from the same suppliers. Years ago, the bike shops had the tools to make them, I can remember the punch for forming the ends. Never bought a brake or clutch cable that fitted properly yet, always had to alter the inner or outer lengths.
 
This seems pretty silly but so far I'm happy with my basic Norton, but everything I buy for it except the Tri Spark seems to be defective and require modification to work. This would not seem so bad except for the bits I buy for my Hondas screw right on and work.
Since I am old enough to recall buying parts that fit this makes me fussy.
 
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