T3 Speedometer Question

[Fireflyr]

I have a '77 T3 with a '75 instrument/dash installed.  The speedometer is way off, reads 100 mph when going 65 mph from what I remember.  Is there a difference in internal gearing between the two years or should they work?  The needle seems to jump around a lot too.  Any help would be appreciated and no, I don't have the T3 gauges.

[unclepete]

I have a '76 T-3 with a speedo that looks very much like yours .
When I first got it , the needle swung wildly and averaged a reading about 10 + mph fast .
I sent my instruments to member Wirespokes for cleaning and lubrication , and got them back reading with a steady needle and the speedometer calibrated very close . ( speedo indicates 70 at 67mph ) Cost was very reasonable .
When an instrument needle swings wildly , it is asking to be serviced . If you wait til something breaks , it will be much more expensive to remedy ]

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The tach arrived reading about 2k . Turned it upside down and gave a light tap , and it stops on the peg .

[Fireflyr]

Thanks Unclepete, I sent him a PM.  I'd hate to break anything.

Pat

[wirespokes]

I'm still learning the ins and outs of Guzzi gearing and how the speedometers relate to all that.

i'd maybe have you do a check involving counting the number of turns the speedo cable makes over a distance or 1/100th of a mile.

On second thought, I've worked on my own T3, so can double check and compare to yours. I'd assume your 77 would have the same gearing. And then I could determine if the T speedometer is geared right for your bike.

I also think Guzziology has that data.

Another question - does the odometer read correctly? Over a ten mile stretch, or even a 100 - is it accurate?