7 replies to this topic

[The Wing Commander]

Okay. Here's a teaser. My speedo is totally inaccurate at the moment, and soon I intend to fit a new gearbox, which will make it even more inaccurate! So, here is my question: ! "How can I calculate my speed by multiplying the rpm by a number?"

diff = 2.95
10 inch wheels
Tyres = Yoko A008

eg, would it be 19mph per 1000 rpm?

[Bungle]

this help ?

[Jammy]

Why don't you fit the correct speedo drive when you fit a new gearbox?

[Guess-Works.com]

The suggestion would be...

A late model 90mph Nippon speedo running @ 1242 TPM, then a speedo take off with a ratio of 6/15

or...

An early center speedo 1280 tpm, with a 7/17 speedo take off

[taffy1967]

Well if you want your speedo to read accurately after the change, contact these:-

Speedy Cables

[The Wing Commander]

Well if you want your speedo to read accurately after the change, contact these:-

Speedy Cables

Thanks everybody for the help! With the gearbox out of the car, I ought to be able to get the speedo to read right, you would think. I have a Nippon speedo 3 clock set, how do I tell which one? And I have a gearbox, how do I know how many teeth? John, you refurbed my gearbox for me, so maybe you might know!
Thanks again
Jeff

[Guess-Works.com]

Remove the speedo from the unit ( two screws ) and on the coloured spindle running front to back, there is a number molded into it... that tells you the TPM of the speedo...

Do I know that ratios which are in the box, sorry can't remeber, however if it's not in the car then it's a simple job to find out, remove the pinion by undoing speedo cable thingy, and count the teeth, the worm could be counted by rotating the gearbox..

Edited by GuessWorks, 26 September 2006 - 04:00 PM.

[Sprocket]

Well if you want your speedo to read accurately after the change, contact these:-

Speedy Cables

Better to get the speedo as close as poss with the speedo gears and then get it calibrated. Calibrating it with the wrong gears fitted is just stupid.