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The Rodding Roundtable

Motorhead Message Central => Rodder's Roundtable => Topic started by: Daveyboy on November 30, 2006, 04:53:30 PM

Title: Rear end gears? ford 9 inch
Post by: Daveyboy on November 30, 2006, 04:53:30 PM
Ok i am getting numbers all over on this.
But this is what i have. Hope some one can help me.
I have a
350 sbc
700r4
ford 9 inch
Rear tires are 30 inch tall
I want to run 80mph on the freeway but still be good out at the st lights
What gears do i need and what rms would i have at 80mph
I would like to run 2400 to 2700 in OD
thanks Dave
Title: Re: Rear end gears? ford 9 inch
Post by: Dave on November 30, 2006, 05:12:26 PM
Quote from: "Daveyboy"Ok i am getting numbers all over on this.
But this is what i have. Hope some one can help me.
I have a
350 sbc
700r4
ford 9 inch
Rear tires are 30 inch tall
I want to run 80mph on the freeway but still be good out at the st lights
What gears do i need and what rms would i have at 80mph
I would like to run 2400 to 2700 in OD
thanks Dave
]
Well Davey I dont have an OD tranny but im running a 350 stock with an edelbrock 600 and 285/70/15 tires and a 300 gear 350 turbo and i get over 20 miles a gallon.  Id bet you could run a 350 gear and in O/D get close to the same milage but have the kick when you need it. Now ive never actually checked the milage I just know its really good so im guessing 20 at least. I can drive way too long till i need fuel.  
Dave
Title: Re: Rear end gears? ford 9 inch
Post by: rumrumm on November 30, 2006, 05:21:22 PM
Quote from: "Daveyboy"Ok i am getting numbers all over on this.
But this is what i have. Hope some one can help me.
I have a
350 sbc
700r4
ford 9 inch
Rear tires are 30 inch tall
I want to run 80mph on the freeway but still be good out at the st lights
What gears do i need and what rms would i have at 80mph
I would like to run 2400 to 2700 in OD
thanks Dave

I have a 700R4 with a  lockup converter, and  I have 3.89 gears in my 9 inch rear with 30 inch rear tires. I run at those rpms at 80 mph. 3.89 gears is what you want.
Title: Re: Rear end gears? ford 9 inch
Post by: Dave on November 30, 2006, 05:51:51 PM
Quote from: "rumrumm"
Quote from: "Daveyboy"Ok i am getting numbers all over on this.
But this is what i have. Hope some one can help me.
I have a
350 sbc
700r4
ford 9 inch
Rear tires are 30 inch tall
I want to run 80mph on the freeway but still be good out at the st lights
What gears do i need and what rms would i have at 80mph
I would like to run 2400 to 2700 in OD
thanks Dave

I have a 700R4 with a  lockup converter, and  I have 3.89 gears in my 9 inch rear with 30 inch rear tires. I run at those rpms at 80 mph. 3.89 gears is what you want.

Ok I stand corrected :!:
Dave :!:  :arrow:
Title: Rear end gears? ford 9 inch
Post by: Daveyboy on November 30, 2006, 07:10:34 PM
What rpm are you running at with the 389s at 80mph?
Title: Rear end gears? ford 9 inch
Post by: 37fordcoupe on November 30, 2006, 07:25:05 PM
Daveyboy


I'm running a 383 Stroker with 700R4 16.50 X 17 X 31"tall tires with a 430 gear and at 80 MPH running about 2600/2700 RPM's


Darrell
Title: Rear end gears? ford 9 inch
Post by: 1FATGMC on November 30, 2006, 07:26:04 PM
Quote from: "Daveyboy"What rpm are you running at with the 389s at 80mph?

Fat Cat has a calculator that will answer your questions here:

http://www.roddingroundtable.com/tech/articles/calc1.html

c ya,

Sum
Title: Rear end gears? ford 9 inch
Post by: rumrumm on December 04, 2006, 09:40:21 AM
Quote from: "Daveyboy"What rpm are you running at with the 389s at 80mph?

Between 2400-2500 rpm according to my tach. That calculator is a good way to determine what you want to run for rear gears with a particular transmission.  It is how I determined that I wanted 3.89's.
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