Just need some thoughts on what you guys are running in ya rear rear diffs ratio wise.

My questioning comes from some experience as follows:

When I did my Cossie conversion (T5 standard box / internals) I put the engine & box into a car that was originally 2.8i and so had a 3.45:1 diff ratio. Now this was not a good combo - the engine was completely standard at this point and with that diff it was like pulling away in 2nd gear all the time and I felt the car could not pull top speed as it did not have the power to pull the gearing.

I swapped to a 3.64:1 ratio diff - from a 2.3 and this made the car completely drivable. This transformed it even with the stage 3 conversion. It behaved on the road and on track. So I am now running Cosworth Saph ratios and its a good combo.

My question is..... I know many people like the 3.9:1 diff ratio. I never tried this as I could not find a 2.0 donor car. The ratio of these was 3.89:1. I have since ripped appart my arse end and now I use Cosworth diffs and so can get what I like to fit.

My thoughts about fitting a 3.9:1 would be that you are always changing gear, 1st gear would literally just get you moving and top speed would be about 90mph. The car is predominantly for track use but thinking of putting it back on the road.

I want to get a Gripper build and would like to know your opinions and experiences with both 3.9:1 and standard 3.64:1 ratios. I don't want the expense of buying say a 3.9:1 CW&P, have it built for it to be crap.

Discuss......