3:73 vs 3:55 Gears - Ford Mustang Forum
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post #1 of 27 (permalink) Old 01-11-2012 Thread Starter
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3:73 vs 3:55 Gears

Ok I have a 1989 Ford Mustang Gt five speed and right now I have 2:73 gears and I am looking to switch out the gear with a 3:55 or 3:73. Ok I know that there are millions of threads on here about this I have looked at them but I am still undecided. This is my daily driver car I go to school and will be going to work with the car then college here soon. I am worried about the gas mileage compared between the two. Also how much worse will my car get on gas if I get a 3:55 or 3:73? I honestly don't drive much on the highway right now but I half to think of the future about college and so forth so on. The school I am looking at is about 20 miles away from my house.

Thanks for all replies:nogrinner
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post #2 of 27 (permalink) Old 01-11-2012
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You have to make your pick. I've had 3.55s, 4.10s, 3.73s, and of course 2.73s in my car. I like the 3.73s best. The gas mileage will be very similar for 3.55 verses 3.73. The two ratios are only about 5% away from each other. Use this calculator, you've gotten my input:

Ford Mustang: Mustang Tech: Calculators & Decoders: RPM Calculator

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post #3 of 27 (permalink) Old 01-11-2012
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you've read the millions of threads and your still undecided....really. if you are that worried about gas mileage just leave it alone!
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post #4 of 27 (permalink) Old 01-12-2012
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If youve read the threads answered by most of us already then why create another? run the gears you have or 3.73 pretty simple if you ask me. Guys with a t5 and 373 are still getting 25+ on the hwy. Plus you will get better city mpg USUALLY doesnt really make much difference.

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post #5 of 27 (permalink) Old 01-12-2012
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Nobody can really give you an answer on what is acceptable mpg or what rpm you like to cruise at. The calculator will help and so will tire size influence what the final ratio will be.

2014 V6 Deep Impact Blue Mustang, Borla Type S, 2.73 (Uughh need 3.73)
1989 Sonic Blue Mustang LX Coupe, 349 ci,
392 rwhp 424 rwtq....Mustang Dyno
"There are three kinds of men. The one that learns by reading. The few who learn by observation. The rest of them have to pee on the electric fence for themselves." -Will Rogers-
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post #6 of 27 (permalink) Old 01-12-2012
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Motive Gear F888614 - Motive Gear Ring and Pinion Sets - Overview - SummitRacing.com You want these. Stop it with that mamby-pamby 3.55 and 3.73 **** and nut up with a real gear set!
post #7 of 27 (permalink) Old 01-12-2012
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No you dont you want these.

Ford Racing M-4209-F373N Ford Racing Ring and Pinion Sets

and Northern Auto Parts: Home has the install bearing set.

When the green light drops...
The Bullsh!t stops. :shiny:
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post #8 of 27 (permalink) Old 01-12-2012
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Or these.....

1979 - 2004 Ford Racing Gears & Differentials

2014 V6 Deep Impact Blue Mustang, Borla Type S, 2.73 (Uughh need 3.73)
1989 Sonic Blue Mustang LX Coupe, 349 ci,
392 rwhp 424 rwtq....Mustang Dyno
"There are three kinds of men. The one that learns by reading. The few who learn by observation. The rest of them have to pee on the electric fence for themselves." -Will Rogers-
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post #9 of 27 (permalink) Old 01-12-2012
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Quote:
Originally Posted by spdjnky_42 View Post
If youve read the threads answered by most of us already then why create another? run the gears you have or 3.73 pretty simple if you ask me. Guys with a t5 and 373 are still getting 25+ on the hwy. Plus you will get better city mpg USUALLY doesnt really make much difference.
I've got 3.73's on a mild 91 GT and it doesn't pull 25+ MPG. Expect to get 17-20 in mixed driving, and maybe 22 on the Highway if you are lucky.

If you are truly worried about gas mileage, don't change gears. The difference between 3.73 and 3.55 will be negligible. I like the 3.73's, and have heard plenty say they wish they had skipped the 3.55's from the start. First gear is pretty short, though.
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Quote:
Originally Posted by 74stang2togo View Post
Motive Gear F888614 - Motive Gear Ring and Pinion Sets - Overview - SummitRacing.com You want these. Stop it with that mamby-pamby 3.55 and 3.73 **** and nut up with a real gear set!
yea, matt. those would be PERFECT!
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yea, matt. those would be PERFECT!
I knew you'd see it my way!
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6.14's lol...i didnt even know they made those

those would be good if you have a short track..like 60 feet

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I think those would only be good for burn-out contests.

When the green light drops...
The Bullsh!t stops. :shiny:
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ive had 373's in my old fox body but it had a 4 cyl tranny so first gear was useless but 2nd and 3rd wher fun

if its not broken dont fix it,95 mustang gt 5.0bbk x pipe no cats flowmaster 40 series 2 inch drop zone kit cold air intake pistol grip shifter v3 sc kit trick flow heads gt 40 upper lower intake 90 mm mass 42 injectors 397 whp 415 torque
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My dads 07' gt has 3.55s from the factory.
25mpg on a good day.
1st gear is PERFECT for launches and bumper to bumper traffic. Second can be used as first in most cases too. 3.55s have my vote.

1998 GT - CAI, trickflow intake, 3.55 gears, O/R x-pipe, flowmasters, short throw shifter. 145k miles
1995 GT vert - 1 of 36 5.0 Appx. 450,000~ factory motor miles *totaled/parts car* RIP..
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