3 replies to this topic

[snowsports1]

Hi here is the spec of my MG Metro engine.

 

Final drive 3.4

Speedo drive worm and pinion 5/17

 

The speedo I want to use has a rev per km of 800. As the speedo reads KM/hr.

 

I don't mind whether the odometer reads km or miles and the dial has both miles per hour and km/hr for speed.

 

What do I need to change the worm and pinion to? the guess works calculator doesn't go to 800. lowest it goes is 1000 TPM for the metro

[MrBounce]

800 turns per KM needs to be calculated in to TPM. Given that each mile is 1.609 KM, multiply 800 by 1.609 which gives you 1287 and a bit. There's a calculation on Guessworks' site for 1280 so that should get you pretty close if not spot on.

[snowsports1]

I have just counted the cable revolutions per 10th of a digit turn and this is 118 so this makes 1180 revs per 1 digit turn for this speedo. The speedo reads kms only, so I want to use my another dial face plate that has both kms and miles per hour. looking at the guess works calculator this doesn't correspond to speedo on there.

[snowsports1]

using a 6/17 speedo drive it looks like the dial will read over by 4% which is close enough. I take it all km and mph speedos are the same in terms of the speed side of the gauge, the odometer is just different to record miles or km distances?