E30 Zone

Hi guys . Just finished my m52 conversion , cars been built for country lane and track work focused , went for a shorter box and a 3:91 medium case diff ..
The car goes through the gears like a motorbike which is awesome but it literally runs out of gearing at 105/110 mph , oops , slightly misjudged it, my bad .
My Diffs soon to be going for a good overhaul and I'm considering changing the crown wheel and pinion from it's 3:91 down to a 3:15 .. How much difference would it make roughly to the top end ? Are we talking 5mph or 20mph ? I know it more tech than that but just ball park .. Many thanks guys

It would change it by 3.91/3.15 = 1.241, funnily enough.
At the revs. it now needs to go at 105 MPH, it will be going 130.3 MPH, if it can still get to those revs.

3:15 would be perfect for the M52, there was a thread earlier on my M52 car, Barry said it would be a good compromise.

There is a guy called Martyn Copleston on the Facebook page who can do you a graph of MPH/RPM for the gears if you want

Jim

That sound exactly what I'm after .. Thankyou so much guys ..