Diff ratio

[MartinClan]

Can anyone remind me of the standard diff ratio from the standard 2.5 E30. I seem to remember it is 3.9?

I think I will have to change mine in the medium term as it is whining well. Couldn't here it when I drove the donor - but then I wasn't sitting on top of it with only 12mm of plywood for sound insulation.

I don't want to change the ratio to something higher (EDIT - lower? what I mean is I don't want a ratio with a lower number) as the car is already quite "long legged" with the 16" wheels and large tyres.

Robin

[Patrick]

Tourings like my donor came with a 3.91 - other had lower ratios.

I'm using a larger rolling radius on my wheels so the 3.91 is not quite as aggressive as it is on E30 size tyres. I have a spare 3.91 open diff but it makes a noise too.

I've double checked the standard / sport gear box situation. As far as I can tell on E30 these both had a 1:1 4th gear and an overdrive 5th. Only gears 1, 2 & 3 are different.