Mechanical Rev Counter Drive

[mike.perry]

I would like to fit a mechancal rev counter to my Series MM. I have adapted a Series MM speedo by fitting a rev counter face over the speedo face. The MM pulls 15 mph at 1000 rpm so that at 3000 rpm the speedo needle is indicating 45 mph in 4th gear and the rev couner needle indicates 3000 rpm. I would then need to find a dynamo with a rev counter drive and somehow gear the rev counter so that the cable is turning at the same speed into the rev counter as the speedo[frame][/frame][frame][/frame]

[bmcecosse]

Where will you connect this to the engine ??? And I have to ask...why ?

[mike.perry]

As I said, the rev counter drive would be off the back of the dynamo, common practice before electronic gauges. Of course I could always convert the inside of the speedo to electrics but that would be defeating the object of the exercise.
Why? Because I want to!

[IslipMinor]

Mike,

Early Sprites/Midgets/Spitfire/Herald? used a dynamo driven rev counter, but don't know what the engine speed to rev counter cable speed is.

[bmcecosse]

I don't see where you earlier 'said' you would connect to the dynamo..... I do have the Sprite connector somewhere..although sadly not the modified dynamo. Still don't see why you would want to count the revs !

[Declan_Burns]

Mike,
The MG TD also uses a dynamo (C39PV / C39PVA) driven rev counter drive-see photo below. The correction factor on the TD is 2.25:1. Speedograph in Richfield sell the gearboxes for it. If you need measurements/dimensions let me know. The Spridget units were as far as I know C40's.
Regards

Declan[frame][/frame]

[bmcecosse]

Mike - Was that dynamo part added later? I definitely didn't see it before. My apologies if it was always there....

[mike.perry]

Sorry Declan, I seem to have hijacked your topic, I am trying to get it moved

[LouiseM]

Post now split Mike, as requested.