A Diff Ratio Question

[zossy1]

My guess would be 3.9 from watching Stu's video. I don't think it's a 3.6.

[ja9]

It's only fair that I share some of my knowledge about diff ratios.
For the people who don't know their diff ratio, this is how you do it in a couple of minutes.

Mark your tyre with tape or marker pen. Mark your tailshaft in the same way. This unfortunately is a two person job (at least it's much easier). One person turns the wheel 10 times, the other counts the number of times the mark on the tailshaft spins around.

39 spins on the tailshaft = 3.9 diff ratio
41 spins on the tailshaft = 4.1 diff ratio
etc.

[zossy1]

I use this calculator for assessing data on ratios -

http://www.apexgarage.com/tech/gear_ratios.shtml

[RS2000]

That's only correct for a locked diff !

If your diff is open or torsen, keep one wheel on the ground, and double the final calculation.
eg. If spinning tyre 10 times rotates the drive shaft 18 times , then ratio is 18x2/10 = 3.6

Cheers

[hks_kansei]

It's only fair that I share some of my knowledge about diff ratios.
For the people who don't know their diff ratio, this is how you do it in a couple of minutes.

Mark your tyre with tape or marker pen. Mark your tailshaft in the same way. This unfortunately is a two person job (at least it's much easier). One person turns the wheel 10 times, the other counts the number of times the mark on the tailshaft spins around.

39 spins on the tailshaft = 3.9 diff ratio
41 spins on the tailshaft = 4.1 diff ratio
etc.

A good way to get a rough idea.

But bear in mind that you need to make sure the rear wheels both spin at the same rate. (not an issue with a welded diff)

I can't remember the ratios, but off the top of my head if one wheel is fully stationary the opposite wheel will spin at twice the rate for the same input speed. (going off memory here, might be wayyyyy off)

[93_Clubman]

The 3.9 was only on the 10AE and the Heritage models in Australia.

ADM 10AE was 3.6.