gear box ratio's

[goose]

i have read on here somewhere that if you know how many times round the gearbox shaft turns in relation to the weel
it is possible to work out the ratio and ring and pinion
if so can someone help

car jacked up
gearbox turns
1st gear 8 times per wheel revolution
2nd 4.25
3rd2.5
4th 1.75

your help is appreciated

[Taylor]

Those numbers don't sound right.  They should be higher, like 15, 8, 5, 3.5. 

[goose]

thanks for that

when i have done the exercise i have only had one wheel turning
i have been informed that both wheels need to turn to take into account the diff and ring and pinion

i will repeat the excercise and report new figures

cheers Angus

[Andy]

It is easier if you turn the gearbox input shaft, use a clutch disk and mark a spot.

If you don't know the ring and pinion, start with 2nd gear as these are nearly always 2.06

Rotate the clutch disk and count the turns it takes to make the wheel turn once. Divide this by all the diff ratios in turn till you get 2.06.

Then in the other gears, divide the total turns at the clutch by the diff ratio to find the gear ratio.

[MeXX]

thanks for that

when i have done the exercise i have only had one wheel turning
i have been informed that both wheels need to turn to take into account the diff and ring and pinion

i will repeat the exercise and report new figures

cheers Angus

Hi

If you have one wheel on the ground you just see the half because of the diff.
So you just have to multiply by 2 than you have it.

MeXX