Final Drive Help
#1
Posted 19 March 2022 - 07:39 PM
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
#2
Posted 20 March 2022 - 08:46 AM
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.
#3
Posted 21 March 2022 - 03:43 AM
Definitely 3.1
#4
Posted 21 March 2022 - 10:24 AM
3.1 or 3.2. Both are very popular amongst boosted A series boys.
#5
Posted 21 March 2022 - 12:12 PM
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,
#6
Posted 21 March 2022 - 12:54 PM
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.
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