FordExcursions.com Forums
kidhauler
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• St. Louis, MO, USA |
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• Registered on 7/3/2005 |
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• 3 posts |
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 Posted:9/3/2005 15:34 |
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I have a 94 Mustang, took it from 3.08s to 4.10s, and saw a great increase in performance.
As you can guess, my main use of the X is taking my 5 kids any and everywhere.
Why not swap the gears down from 3.73s down to 3.08s, or so?? Does anyone make them?
I know it would be a dog for accelleration, but it already is as I baby the throttle to get 9 mpg?
What do you all think? |
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CHPMustang
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• Plano, TX, USA |
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• Registered on 7/24/2002 |
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• 1,800 posts |
• 1 Vehicle
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Posted:9/3/2005 15:50 |
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The only factory differential ratios I've seen on Excursions from the factory is 3.73LS,4.10LS,4.30LS and 3.73 PegLeg.
I'm sure differential houses may be able to get lower ratios than 3.73 
Bill
2002 Excursion XLT-P 4x4 7.3L Powerstroke Diesel
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Scott Stover
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• Fayetteville, NC, USA |
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• Registered on 4/16/2004 |
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• 354 posts |
• 1 Vehicle
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Posted:9/4/2005 22:14 |
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What would be the mileage increse with dropping from 430's to 373's? Ive thought about it.....especially lately!!
Scott
2000 X 4x4 V-10 4.3 LS
K&N
Gibson Catback
"Custom" Kickplates |
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CHPMustang
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• Plano, TX, USA |
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• Registered on 7/24/2002 |
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• 1,800 posts |
• 1 Vehicle
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Posted:9/4/2005 23:05 |
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Going to a lower gear ratio will force higher RPMs to get the truck to move/accelerate from a stop or low speeds.
Throw a bottle of Chevron injector cleaner in the tank,that'll help out some but can't say how much mileage will change.
Bill
2002 Excursion XLT-P 4x4 7.3L Powerstroke Diesel
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monsta
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• The Big Island, HI, USA |
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• Registered on 1/5/2002 |
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• 1,056 posts |
• 2 Vehicles
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Posted:9/5/2005 02:06 |
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| Quote: | | What would be the mileage increase with dropping from 430's to 373's? Ive thought about it.....especially lately!! |
Let me know.  I've 3.73 and want 4.30. Swap yours and I'll buy the 4.30s off ya.
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In reference to the thread...I, too, have not seen lower (numerically) ratios for the Sterling axle. Usually folks go the other way.
Why don't you just put taller, skinnier tires on it instead?
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Scott Stover
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• Fayetteville, NC, USA |
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• Registered on 4/16/2004 |
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• 354 posts |
• 1 Vehicle
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Posted:9/5/2005 20:34 |
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Ive got Michelin 265's and run 75psi in them, I keep the foot outta the gas, I was just curious what the advantage might be.....I will let ya know Monsta...
Thanks guys!!
Scott
2000 X 4x4 V-10 4.3 LS
K&N
Gibson Catback
"Custom" Kickplates |
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E. Long
 
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• Subscriber since 1/1/2001 |
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• Atlanta, GA, USA |
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• Registered on 1/23/2001 |
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• 2,229 posts |
• 1 Vehicle
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Posted:9/5/2005 21:37 |
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I have been contemplating a gear swap for some time on my PSD X. I would not recommend going from 4.30's to 3.08's.
The lowest numerical value I've seen are 3.55 for the 10.5" rearend in our Excursions:
http://www.ring-pinion.com/content/products/default.asp?vid=3&pid=4
When I owned a '97 F-250 PSD, it had 3.55 gears and I routinely got 17-18 MPG without any mods and without babying it.
Using the online calculators, and assuming the following:
Engine: PSD
Speed: 75 MPH
Transmission ratio: 0.75
Tire Diameter: 31" (265/75R16)
Here are RPM figures based on various gearing (for a PSD):
3.55 @ 75 MPH: 2,164 RPM
3.73 @ 75 MPH: 2,274 RPM (see pic -- seems about right)
4.10 @ 75 MPH: 2,500 RPM
4.56 @ 75 MPH: 2,780 RPM
The pic link above verifies that @ 75 MPH with 3.73 gears, the RPM is roughly 2,250. If I were to drop to 3.55 gearing, my rpms would drop by about 100.
You'll have to do similar calculations based on your RPMs on your V10. I would start by verifying the RPM @ 75 MPH on your V10. Take note of it, and use the calculator link above to enter different values. The transmission ratio value will vary for your situation. You can use these calculators to figure out what your RPM will be with the different gear ratios. Unfortunately, 3.55 is the smallest for the 10.5" rearend.
For gassers, going from 4.30 to 3.73 will be a significant change in mileage. But going from 3.73 to 3.55, it might not be worth the expense. However, for PSDs, dropping 100 RPM in this range is beneficial. 75 MPH w/ 3.55s would be like 70 MPH w/ 3.73s. 70 MPH in my X renders excellent fuel economy, so the expense may be worth it in purchasing 3.55 gearing (front and rear) and any installation.
Whew, long-winded, but hope it helps.
-Eric
'67 Galaxie 500 - 390 FE, .030" over, FE to AOD adapter, disc brake conversion. The Daily Driver.
'00 Excursion - 7.3L PSD, LANDYOT Gen-II Radius Rods, Factory Tech Valve Body, 200K+ miles and going |
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monsta
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• The Big Island, HI, USA |
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• Registered on 1/5/2002 |
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• 1,056 posts |
• 2 Vehicles
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Posted:9/6/2005 14:35 |
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Just a note....
The RPM listed are the same no matter what type of engine it is. It is the tranny, tires size and rear end gears that determine the engine RPM at a given speed
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Scott Stover
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• Fayetteville, NC, USA |
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• Registered on 4/16/2004 |
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• 354 posts |
• 1 Vehicle
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Posted:9/6/2005 20:57 |
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I will have to do that....I appriciate all the help everyone!! Its been a thought but for 1500 in labor and parts...whew!! Thats alot to think about !! Ive gotta get the tie rod ends done and the drag link ends are shot...but thats gonna come at tax time!! Im just not sure what to do!! LOL-But I will play with the numbers and see!!
Scott
2000 X 4x4 V-10 4.3 LS
K&N
Gibson Catback
"Custom" Kickplates |
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