Fuel Economy, Hypermiling, EcoModding News and Forum - EcoModder.com - View Single Post - Taller top gear makes a real difference (10%)

1337 · 01-22-2009, 04:14 PM

Big Dave--

My parents have a '99 F-350 diesel, which we use for a winter beater and for plowing. It's a 4x4/automatic model, which is the worst configuration for fuel economy. It has a 3.73 final drive. To swap in a 3.08 final drive like yours, would I need to change the ring/pinion gear in the differentials, or is it a transmission modification?

Multiades--

Yup, that was me on PansyPatrol.com post. I have located a few '92-'94 Protege F25M-R transmissions on car-part.com. Unfortunately, I can't seem to find *just the gear*, and all the junkyards want to sell the transmission as a whole. Do you have any recommendations on where to find just the 5th gear set? Will I also need the 5th gear synchro from the donor transmission?

01-22-2009, 04:14 PM	#42 (permalink)
1337 Now on two wheels! Join Date: Jul 2008 Location: Illinois Posts: 218 [SOLD] Highway Warrior - '00 Protege LX 1.6L Manual 90 day: 35.93 mpg (US) Basic Miata - '06 Miata Touring 90 day: 31.65 mpg (US) Thanks: 34 Thanked 1 Time in 1 Post	Big Dave-- My parents have a '99 F-350 diesel, which we use for a winter beater and for plowing. It's a 4x4/automatic model, which is the worst configuration for fuel economy. It has a 3.73 final drive. To swap in a 3.08 final drive like yours, would I need to change the ring/pinion gear in the differentials, or is it a transmission modification? Multiades-- Yup, that was me on PansyPatrol.com post. I have located a few '92-'94 Protege F25M-R transmissions on car-part.com. Unfortunately, I can't seem to find just the gear, and all the junkyards want to sell the transmission as a whole. Do you have any recommendations on where to find just the 5th gear set? Will I also need the 5th gear synchro from the donor transmission? __________________ 2006 Miata Touring 5MT 2006 VW Jetta TDI 6AT (Sold to buy Miata) 2000 Mazda Protege 1.6L 5MT 2002 Mercedes C230 Coupe 5AT (Water damage, totaled)