Help with new ratios and diff for Renault un1 box.

[stuart]

1stly sorry but this isn't a gt40 car related question but is about the gearbox some of you run.
I have a car I built using the Renault un1-13 gearbox out of a 21 turbo, it is mated to a cosworth 4cyl 2l turbo currently around 400bhp mounted in the back of a Renault 5 gt turbo.
It weighs around 1000kgs, has 235 40 17 rear wheels, revs to 7500 and I hope to up the power to 480-500 after the box is done.


I'm having a new gearbox made (not from Gto or mach1) at the mo and have the option of changing 1st, 2nd and 5th gear ratios.

What do other cars use and find good?
I currently run a STD Renault un1 box
I think 1st and 2nd need to b longer cos they are over so quickly at 400+ bhp
so was thinking if they are longer it means I get a chance to use the gears, hit about 40 in 1st, 70 in 2nd, then STD 3rd and 4th for quick midrange and a longer 5th for motorway cruising/top speed
I prob wouldn't want any more than 160/170 in my car tho lol.

Also I'm getting a plated Salisbury diff made
what sort of ramp angles, clutch packs... Would b best for mainly road use and a little bit of track and 1/4m use?
Cheers

 

[DBLDREW]

At the bottom of this page GA46; Emco Gears, Inc.

There is a excel spread sheet you can download that lets you put in your tire diameter, final drive ratio and each gear ratio and it will show you the speed per rear/rpm along with the rpm drop between gears. That way you can play around with it and figure out what will work best for your set up.