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ok from what i have heard the higher the numbers the more top end, the lower the gears the less acceleration.
Is this true or am i full of sht?
And will they work with a 2002 built in june?
I did a search and didn't come up with much info.

Sorry i didn't really get my point across that clearly. hopefully this edit will help.

[ 11-10-2002, 12:19 AM: Message edited by: jeremydahl1 ]
 

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I was under the impression that 4.06 is the final drive gear, and that will increase acceleration, but decrease top speed, and your cruising RPMs will be higher.

I'm pretty sure thats how it works. My dad wants to drop some 3.73s in to the rearend of his GTO, and I think he was going up in numbers.
 

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higher number=shorter gears=faster acceleration. HOWEVER, your engine will now turn faster for any given speed in a given gear, so you'll not be able to go as fast, and you'll get worse cruising mileage.

as for the technicalities with the gears (final drives, etc) i have an auto, what do i know??
 

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Final drive is the same concept whether on manual or automatic. The higher the number (i.e. shorter gearing), the faster the engine must turn to acheive a certain speed. The lower the number (taller gearing), the slower the engine turns.

EDITED: Removed faulty analysis - see below for better one!

[ 11-10-2002, 06:39 PM: Message edited by: Zoomer69 ]
 

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Dang it! Serves me right for not checking first.

From Car & Driver's November '99 ZTS Sedan test:

3.82 final drive
Gear _ Ratio _ Mph/1000 rpm Max. test speed
1 ____ 3.67 ___ 5.0 ______ 33 mph (6750 rpm)
2 ____ 2.14 ___ 8.5 ______ 58 mph (6750 rpm)
3 ____ 1.45 __ 12.6 ______ 85 mph (6750 rpm)
4 ____ 1.03 __ 17.7 _____ 106 mph (6000 rpm)
5 ____ 0.77 __ 23.7 _____ 106 mph (4450 rpm)

4.06 final drive (my figures w/ speed limiter)
Gear _ Ratio _ Mph/1000 rpm Max. test speed
1 ____ 3.67 ___ 4.7 ______ 32 mph (6750 rpm)
2 ____ 2.14 ___ 8.0 ______ 54 mph (6750 rpm)
3 ____ 1.45 __ 11.9 ______ 80 mph (6750 rpm)
4 ____ 1.03 __ 16.7 _____ 106 mph (6350 rpm)
5 ____ 0.77 __ 22.3 _____ 106 mph (4750 rpm)

Okay... back to the drawing board....

Shorter gearing may actually HELP top speed in our case.

With stock gearing, 4th is too short for anything but a bone-stock Focus, while 5th is too tall as a top-speed gear for anything but forced induction.

4.06 gears won't have a huge effect on stock Zetecs. You'll run out of revs in 4th before you do power. It'll be pretty tapped out in 5th at about 120-125.

4.06 gearing would be helpful on more powerful motors. Shorter even, if your motor can rev. 5th is still a little tall for all-motor Foci, but forced-induction ones will find this about perfect.

With 4.06 gears, 6000rpm gets you 133mph in 5th. 7000 gets you 156, 8000rpm gets you 178.

How about shorter yet...
4.30 final drive
Gear _ Ratio _ Mph/1000 rpm Max. test speed
1 ____ 3.67 ___ 4.4 ______ 30 mph (6750 rpm)
2 ____ 2.14 ___ 7.6 ______ 51 mph (6750 rpm)
3 ____ 1.45 __ 11.2 ______ 76 mph (6750 rpm)
4 ____ 1.03 __ 15.7 _____ 106 mph (6750 rpm)
5 ____ 0.77 __ 21.0 _____ 106 mph (5050 rpm)

Clearly pointless unless you drop the speed limiter. Okay, so you slam into it a lot quicker.

NA motors will love 5th now. 6000 gets you 126mph. 7000 gets you 147. 8000 gets you 168. This would be great gearing for a built all-motor Zetec.

Assuming a stock Zetec maxes out at 125 with its 130 hp (slightly generous estimate), you'll need 212 hp to go 160, and w/ the 4.30 gears make that power at about 7600. That's a little out of reach of a built NA motor, but not much.

Most of use are not going to rev that high. At best, maybe 7000 - 7200 in 5th (about 150). You'll need 187 hp to do 150. Still a little out there, but we're close.

It takes 6700 rpm to hit 140, where you need to make 164hp to overcome drag. The stock SVT motor makes about that much at 6700, as do the stronger all-motor Zetecs.

In all, 4.30's seem about right for lower-revving all-motor guys. Higher-revving ones may want to do 4.40's or 4.50's to maximize top end.

[ 11-10-2002, 08:21 PM: Message edited by: Zoomer69 ]
 
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