3.7 / 3.9 anyone? - Ford Forums - Mustang Forum, Ford Trucks, Ford Focus and Ford Cars
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post #1 of 32 (permalink) Old 02-06-04, 07:25 PM Thread Starter
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3.7 / 3.9 anyone?

hey all,
just looking for ppl who might have have had diff gears around 3.7/3.9 :1 ratio
in thier car and what they think. im getting mine overhauled on monday but because it is a 2.92:1 (highway diff) the hemisphere has to be replaced to get up to 3.08 or 3.45 so i may as well go higher. any expirience with these would be helpful,
cheers

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post #2 of 32 (permalink) Old 02-06-04, 08:58 PM
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Re: 3.7 / 3.9 anyone?

i've got 3.7's in my fairlane. i wouldn't recommend it for the daily driver, unless your car has overdrive. my car car also has small tyres 245/50/14's (approx 23 inches tall) and at 120km/h i'm doing about 4 grand. it really depends what you use your car for and what you want it to do.
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post #3 of 32 (permalink) Old 02-06-04, 10:41 PM
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Re: 3.7 / 3.9 anyone?

What engine/gearbox? What sort of driving? You do not have to replace the hemisphere to go from 2.92 to lower ratios. It is 2.77 that has the different offset hemisphere.

If you're not driving a manual you're really just steering.
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post #4 of 32 (permalink) Old 02-07-04, 02:25 AM Thread Starter
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Re: 3.7 / 3.9 anyone?

well , my cars a 6 cyl eb falcon S. has standard 5 speed b.w. so i take it that 5th is like overdive. also, the guy from the shop said i will have to change hemisphere so maybe he's after my money? he did mention a 3.7 would drive around 100km/h @ about 4000 rpm , so thats worse again. its a daily drivin car so i dunno bout revin it out hard just to get to work n bak. he is recomending 3.23 gears but said its obviously my overall choice. i asked him for worst case scenario he says $600 if everything is replaced, extra 400 for lsd, the other thing he mentioned was 3.7 gears are hard to find and says they only find em in skylines so i dunno? what u think.
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post #5 of 32 (permalink) Old 02-07-04, 06:39 AM
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Re: 3.7 / 3.9 anyone?

5speed and 3.7gears will have you reving at 2400rpm@100kmh and 2850rpm@120kmh.

Ive been described as a vault of usless random knowledge.

Ill take it as a complement i think.............
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post #6 of 32 (permalink) Old 02-07-04, 06:46 AM
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Re: 3.7 / 3.9 anyone?

Walkinshaw - those RPM figures are pretty damn good, cuz Rollin has 3.9's and i no he aint anywhere near 4000rpm at 120k's

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post #7 of 32 (permalink) Old 02-07-04, 06:59 AM
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Re: 3.7 / 3.9 anyone?

3.9 would be

100kmh @ 2500rpm
120kmh @ 3000rpm

This is for a tyre diamer of 645mm.

Ive been described as a vault of usless random knowledge.

Ill take it as a complement i think.............
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post #8 of 32 (permalink) Old 02-07-04, 06:29 PM Thread Starter
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Re: 3.7 / 3.9 anyone?

well, that aint too bad, alot beter than the guy rekons. at the moment my 2.92 does like 1600rpm @ 100km/h. only doin 3500 @ 180km/h, so i dont mind if i lose some top end. he still doesnt have 3.7 gears though and rekons there hard to get, is this true?
should i be goin somewhere else, monday 8 o'clock im booked in so there aint much time
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post #9 of 32 (permalink) Old 02-07-04, 10:39 PM
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Re: 3.7 / 3.9 anyone?

You defineately do not have to change the hemisphere. 3.7 are not hard to get, but I would not recommend them. I would go 3.27 with a std T5, and 3.45 if you have the 3.28 ratio first gear box.

If you're not driving a manual you're really just steering.
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post #10 of 32 (permalink) Old 02-07-04, 11:29 PM Thread Starter
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Re: 3.7 / 3.9 anyone?

k, cheers for all the help guys, let ya know what happens monday or tuesday.

cheers
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