rearend gears
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Elder User
Joined: Nov 2003
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From: Harrisburg, OR
rearend gears
I've got a 64 f100 292 w manual 3 speed and I'm running 295/50/15 . What would be a good gear ratio to run so that I've got good take off and not whinding 5000rpms when I'm going down the freeway at 70 
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Forgive my lack of knowledge on this issue...but what exactly does gear ratio have to do with power/speed etc...?
My truck is a 240 manual 3 and is running a 3:70. I hear mention of tire size, gear ratio, etc...lost in the newbie world here...
Chad
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From: Charlotte
Hey Chad,
Easy to get lost. Look at it this way. With the right gearing, you can do 8 sec in the 1/8th mile with a Lawn mower engine. (Check out Jr. Dragsters)
Not exactly sure on that tire size, but I bet a 3.25 pumpkin would serve you well. I run a 390 with C6, 3.54 diff and 255/70 15's and hit 3000 at 70.
Easy to get lost. Look at it this way. With the right gearing, you can do 8 sec in the 1/8th mile with a Lawn mower engine. (Check out Jr. Dragsters)
Not exactly sure on that tire size, but I bet a 3.25 pumpkin would serve you well. I run a 390 with C6, 3.54 diff and 255/70 15's and hit 3000 at 70.
Postmaster
Joined: Nov 2002
Posts: 3,447
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From: Littleton, CO
I'll give this a shot but not being an expert myself, maybe some more "experienced" folks will assist. The gearing has a lot to do with how your truck moves. If you have gears that are 4:11 or what I would consider "deeper" (like the 5:56 range)your truck will leave a start line hard and fast, but will max out more quickly. If you have what I call "taller" gears, like 3:70's, your truck will not launch as hard and will take a little longer to wind up, more for say highway driving (but I need to mention most have a 1:1 final drive). Also, the bigger the tire, the more work to move your truck, causing and affect similar to go with "taller" gears.
Let the beatings begin if necessary
--Mike
Let the beatings begin if necessary
--Mike
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Ok, Ok, so it's making more sense...I am actually buying new tires either tonight or tomorrow, and was planning on purchasing 235/75/R15...with my truck info as I posted earlier is there a differerent tire suggested?
Scamardo...what are referring to as a 3.25 pumpkin?
Postmaster
Joined: Nov 2002
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From: Littleton, CO
The 3:25 refers to the gear set in the "pumpkin" or case on the front of the rear axle.
--Mike
--Mike
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From: Charlotte
Yes, Mike is right.
You can get any pumpkin from any Ford 9 inch and use it in your truck to play with. Only catch is, you gotta make sure the spline count of your rear axles match. In other words, if you have 28 or 31 spline axles, then the pumpkin has to match. If in doubt, pull your rear axle and count them.
You can get a used pumpkin at a junkyard for $50 or less.
You can get any pumpkin from any Ford 9 inch and use it in your truck to play with. Only catch is, you gotta make sure the spline count of your rear axles match. In other words, if you have 28 or 31 spline axles, then the pumpkin has to match. If in doubt, pull your rear axle and count them.
You can get a used pumpkin at a junkyard for $50 or less.
Laughing Gas
Joined: Oct 2001
Posts: 957
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From: Winchendon MA
I'm a member of Tapa-kega-brew my self.....
I've posted this link before you should all book mark it.
http://www.parkercarburetion.com/calculators.html
It will let you play with tire sizes and rear end ratios to see rpms at a given speed or visa versa.
44
PS: check out all the calc's there good reference.
I've posted this link before you should all book mark it.
http://www.parkercarburetion.com/calculators.html
It will let you play with tire sizes and rear end ratios to see rpms at a given speed or visa versa.
44
PS: check out all the calc's there good reference.
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Joined: Mar 2003
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From: Mobile, ALABAMA
I was wanting to replace my rear end gears with someting with more bite...mine has 3.08 gears in a 90 F-150 1/2 ton....how does the 3.08 compare to the 3.55's? thats sorta what im looking to put in 'er.....With the 3.08 in it now its great, feels like it wants to lift offa the ground (did some mods to it) but was curious to see how the 3.08's stand up against some other gears...thx
nd4spd
nd4spd
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From: Charlotte
He-he, with your setup, it would run like a scalded dog! My 65 is probably a little heavier than yours, especially with the 390 FE in mine, but I am running a C6 tranny and a 9 in rear. I am sure you can get that gear set in the 8.8 (that is what you have right?) Really depends on what you want to do. Daily driver, red light racer? Concerned about fuel mileage? If so, keep what ya got.
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From: Mobile, ALABAMA
Originally Posted by scamardo
He-he, with your setup, it would run like a scalded dog! My 65 is probably a little heavier than yours, especially with the 390 FE in mine, but I am running a C6 tranny and a 9 in rear. I am sure you can get that gear set in the 8.8 (that is what you have right?) Really depends on what you want to do. Daily driver, red light racer? Concerned about fuel mileage? If so, keep what ya got.
Hell it runs like a scalded dog now...i want it to run like a dog on fire! haha 
