5 replies to this topic

[A1111j]

Hi everyone
I am in the process of rebuilding my gearbox I was wondering what final drive ratio I should go for? it is going to be my daily drive and I go on the motorways quite often. I currently have 3.44 final drive. my engine spec is.
1293 turbo T2 turbo with 7.5psi boost
a plus primary gear
37-29 teeth drops gears
I am going to be fitting minispares heavy duty gearset with these ratios
1st 2.583
2nd 1.644
3rd 1.250
4th 1.0

[absx2]

If it was mine I would go for a 3.1 ratio, it was used on the Rover carburetor Coopers and your spec will pull it quite nicely. 

[Hpal]

Definitely 3.1

[Steve220]

3.1 or 3.2. Both are very popular amongst boosted A series boys.

[mini13]

I ran a 3.1 in mine and liked it, but 1st is quite long, and in traffic can be a bit tedious as you have to slip the clutch a bit. fine once your moving though.

 

Im swapping to a 3.44, but that's mainly as I'll now be running a motor that will rev much higher,

[Ethel]

I'll guess with 7.5psi you're looking for a bit of refinement & reliability over all out performance?

 

3.4 will give better acceleration and be a bit kinder to the gearbox. You should have plenty of torque to run a 3.1,3.2  or even 2.9. You'll might be able to red line them in top too, but you'll be well into licence losing territory, unless you do track days.

 

If it's a rebuild & you've already driven it, you'll have an idea of where it's on the curve rpm wise so have a play with Guess work's gear calculator to see what best matches the revs to the tarmac you drive.