What final drive should I go for?
Turbo Mini Forums

As title, and what FD's have you guys got?

In the 13's at last!.. Just

Usual response; what do you want from the car?

I want it to...

1: stay in ne piece
2: accelerate like it's possessed
3: Not hit 6000rpm at 40 in forth

Would a 2.95 FD and a clubman gearset be ok?

In the 13's at last!.. Just

I'd go for a 3.1 or 3.2 it seems good for cruising on the motorway etc but its also still drivable round town.

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1/4mile in 13.2sec @ 111 terminal on 15psi

In the 13's at last!.. Just

Sorry if I seem like I'm not listening.

Thing is, I've been offered a box, drops and diff at a good price. It's a standard re-built box with X-pin diff 2.95 FD and S/C Drops.

In the 13's at last!.. Just

What size wheels?

13" unfortunately

In the 13's at last!.. Just

My 998 with the 2.9 sat at 80 at about 4000 with 12's
My other 998 with a 3.1 sat at 80 at about 4500 with the same wheels.

The 3.44 I've got now does seem a little short, whereas the 2.9 was great for cruising but not accelerating. So I'd say 3.2 with the 13's.

Edited by minimole23 on 9th Oct, 2007.

Hi,
I run a 2.95 on 13s with a NA 1380, I'm really pleased with it.
Pulls like a good 'un, doesn't rev its nuts off on the motorway...
Cheers,
Gavin :)

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I thought that maybe I would be less likely to break the lower gears as well. Or am I talking rubbish?

In the 13's at last!.. Just

maybe this will help...

i picked this handy programme up ages ago for gear calcs

here is the calck for that box and a 2.95

Attachments:

130.69kb

2.95 is goof for a road going turbo'd car.

If it's a pure daily like Candice's I'd alwasy say find a 2.7:1, if it's a track based car I'd suggest a 3.1 or 3.2

To my mind a 3.44 or below is going to be a PITA on the raod and you'll probably be tickling the limiter on every decent straight on track days too.

2.95 is a good compromise

Every day is a school day ...........

How fast and how expensive ...... the same question...

Cheers guys

My car is basically fast road, so from the looks of things, the 2.95 would probably suffice.


Next question...

Do you think that the standard box would take 150 nanas?

In the 13's at last!.. Just

I run 3.44 on my non turbo 998, pulls like a goodun but does tend to scream its tits off at around 80.
The box I would of thought would take that bhp, but it depends how you drive he car, how quick an hard the power comes in, and if the box as been built to a decent standard to begin with.
From what I gather from reading up on this myself before having a box built, it tnds to be the diff pin and drops that shit themselves with the power of the turbod motor.
Shane.

You'd need to change to a 4 pinion diff but if it's all built properly you may just get away with 150bhp .... it's about 10 more than I'd be happy with trying though!

Every day is a school day ...........

How fast and how expensive ...... the same question...

As said .... drops become the problem, but by standard box I assumed you meant standard in every way.

Actual helical box should be good for 150 so long as you limit the torque in 1st and don't enter any traffic light grand prixs

Every day is a school day ...........

How fast and how expensive ...... the same question...

Box should be OK, AlexB has been using a completely standard gearbox with 140bananas for some time without incident.

im using a standard box on mine wont be any where near 150 bhp though. made me feel a bit better now, because i was wondering what sort of power they would take.

depends how you treat it, driven carefully should be ok, but like all human beings you will tend to launch at lights ect so may not last as long as you hope for, but would be better with sc drops and 4 pin diff.

on the diff side go for 2.9 or 3.1

always looking for them bigger bunches of bannanas

my experience on this is ,
,the heli box will take around 120 hp no probs 150 bhp itll strip primary gear and 3rd gear in box .

diff ratio wize , the 2.95 is fine for a heli box with the low first gear and daily use ,
for drag racing if you have 150 bhp and your going over the line at 97 mph your only doing 5k rpm ,this is way too low rpm for a good time.

. if you go to a straight cut box ,then the 2.95 with the much higher 1st gear is a bit of a pain specially on 13's ,so id go for a 3.1 or 3.2 ,the latter for better accel ,and the former for a drag road compromise , i have the 3.1 and straight cut box and its good ,better than the 2.95 ,but still a little bit tall in first . phew .

Medusa + injection = too much torque for the dyno ..https://youtu.be/qg5o0_tJxYM

taking into consideration what robert has suggested, how do you think a 1380 with s/c box with on a 3:4 diff running on 10's will run??

Hi,
You'll get there quick enough, but don't go far on motorways
Cheers,
Gavin :)

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WB/EGT gauges. Click here for customers write-up

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Got to say I'm still struggling to work out what final drive to go for in the hill climber (or whether to go for a close ratio box or not for that matter) I've a feeling that I'll end up starting with whatever I've got lying around and go from there.

Any ideas?

Edited by Rob H on 11th Oct, 2007.