diff and final drive
Turbo Mini Forums

hi,
im currently working on my gear box but have a few things im stuck with.Im having my central oil pickup pipe fitted soon and i was going to fit a different final drive because i will be doing a fair bit of motorway driving .im using the standard gear ratios (3:2.1 i think)What final drive would you recomend?

i have a hardy spicer diff from a cooper s.would you recomend putting this in or somthing else.

cheers

If in Doubt, go flat out !!!

Any motorway driving and you need to be looking at a 2.7 (mpi), 2.95 (cityE) or 3.10 (998 a+ 12" wheel) IMO


Some Numbers:

10" wheels (13's are little different - speeds will be higher / engine revs lower (SLIGHTLY)
Metro Ratio's (3.64, 2.18, 1.42, 1.0)

First thing - let's look at what it'll do in second gear.

Assume 6200rpm redline (shift)
3.44: 47mph
3.21: 50mph
3.10: 52mph
2.95: 55mph
2.75: 59mph




Let's now look at what the engine is doing when 'cruising' ie 80mph in Fourth.

3.44: 4850 RPM
3.21: 4525 RPM
3.10: 4370 RPM
2.95: 4158 RPM
2.75: 3876 RPM




Now, lets assume we're in 4th pootling along at 65/70, then you need to overtake someone (a common speed to need to overtake). So, you punch down to third, and stamp on the loud pedal. Basically - you want third to comfortably take you well past the 'slower' thing, before having to shift up (so both hands are on the wheel ideally, and your mind on overtaking - not when the revs are going to run out).


6200rpm redline in 3rd (before shifting into 4th)

3.44: 72 mph
3.21: 77 mph
3.10: 80 mph
2.95: 84 mph
2.75: 90 mph


As you know - having a turbo - with tons of midrange torque, you don't need to scream the tits off the engine to make torque (which is what is accelerating you). Let the turbo do it's job and make torque to accelerate you in a lower gear, leaving 4th for cruising.


2.95 is the optimum for a 'roadie' IMO. Not so magic around Combe mind!

D

Edited by turbodave16v on 9th Jan, 2006.

cheers dave thats a big help. i think i will stick with what you sugested. have you or anybody used the evolution 4 pin diff?

If in Doubt, go flat out !!!

Alot of users on here run the minispares x-pin diff (evolution as it is now known) and it will take pretty much anything the turbo a series can throw at it. Top piece of kit.

And heres a superb gear calculator JF has just posted which may be of interest to you.
http://www.turbominis.co.uk/forums/index.php?p=vt&tid=7415

Edited by T3Tone on 11th Jan, 2006.

-MINI CLUBMAN 1380 TURBO-