3.9 crown wheel & pinion in F13

[Mike]

Good idea bad idea?

[tom reid]

4.1 would be better!

[Adam]

Most boxes come with a 3.5-3.7 as standard, so 3.9 will just give a bit more accelerate

[Mike]

Ad, do you know whats in a F13CR as standard chap? I cant be @rsed to go find a haynes manual and check lol

[Adam]

Usually a 3.74

My F13cr had a 3.74, as does my current f15cr box

[mikey14sr]

The F13 I had was a 3.94FD, 5th gear, 40mph, 1000rpm. went pretty well too.