3.08 gears
New User
Joined: Feb 2004
Posts: 9
Likes: 0
From: fort lauderdale
Hi DT 466Man
i get the same mpg but want more. the auto trans is probably the culprit. i like what you are doing, hop up that motor. do it now because it wont seem senceable when you have teenagers to feed.
steve
i get the same mpg but want more. the auto trans is probably the culprit. i like what you are doing, hop up that motor. do it now because it wont seem senceable when you have teenagers to feed.
steve
Posting Guru
Joined: Jul 2003
Posts: 2,454
Likes: 1
From: Adams TN
i know what you mean this summer i learned the value of money.
might as well when i put the main rod bearings oil pump head gasket and rings put hedders and a 4bbl.
my parents told me how much it cost to run a house hold with a 16 year old that is 6'3(me) and a 14 year old that is 6'1(brother) and we are constantly eating it cost a but load of money
want to have fun while i have it
might as well when i put the main rod bearings oil pump head gasket and rings put hedders and a 4bbl.
my parents told me how much it cost to run a house hold with a 16 year old that is 6'3(me) and a 14 year old that is 6'1(brother) and we are constantly eating it cost a but load of money
want to have fun while i have it
Elder User
Joined: Apr 2001
Posts: 772
Likes: 0
From: Glen Burnie Maryland
Guys; Ive had 2 different trucks with the 3.55 and 3.08. Mileage is predominately the same 13-15 on Highway and 10-13 city. With 12-12.5 towing. The 3.55 are a better gear for towing light equipment and trailers and wold rather have them over the 3.08's.
The mileage will NOT drop or gain appreciably with a change from 3.55 to 3.08.
The only way to get a lot more mileage is to get a Honda, Toyota, or Nissan car and cut the rear out of it and convert it to look like a truck.
Larry
The mileage will NOT drop or gain appreciably with a change from 3.55 to 3.08.
The only way to get a lot more mileage is to get a Honda, Toyota, or Nissan car and cut the rear out of it and convert it to look like a truck.
Larry
Senior User
Joined: Oct 2003
Posts: 215
Likes: 0
From: Central Coast, CA
I'm with Larry on this one. Evan (85F100SWB) is the only one I've ever read about getting 20 MPG with a 300. I routinely get about 15 mpg with my C4, and 2.73's (that's freeway driving). It gets worse city driving and I run 31" tires. I was really suprised recently how well my truck towed a 20', 2000 lb trailer fully loaded, with the bed loaded as well. Lugging a 300 is rhetorical statement. The 300 is a lugger, it's all about the low rpm torque that sets it aside from any other six all the way up to a 400. Without a cam swap, the move to a numerical ratio rear end gear less than one will have little affect and probably will not be worth the cost. On a side note: I know on a rear like the 9" you might as well consider a full rebuild of your third member when doing a gear swap. You'll have to replace the pinion bearing, might as well replace the carrier bearings as well. IMHO third member work should be done by someone with experience. Not to insult anyone, but a gear swap is something you only want to do once, not twice.
Postmaster
Joined: May 2004
Posts: 2,854
Likes: 0
I bought my 83 brand new, have lots of history.
It's a 300 with 4spd OD manual.
I ordered it with the 3.08 diff....wanted good mileage cause I planned on alot of highway driving. It turns 1600 rpm at 60 mph, that's good for fuel economy.
It's not designed for towing, but when I do, 3rd gear is my high gear, it's geared 1.00 to 1.
It came with "higher" PSI tires ....41 psi. It's a Super Cab and 8 ft bed...more weight.
I routinely got 21-22 mpg, so that's your reference point.
If you've got auto or 3.55 or worn engine or no OD, you can start subtracting.
I CAN tell you that 22 mpg was phenomenol for a pickup in those days.
Nowadays, I spend most of my time ranching...translation, idling, first gear, etc...so I'm getting about 12, but that's to be expected.
It's a 300 with 4spd OD manual.
I ordered it with the 3.08 diff....wanted good mileage cause I planned on alot of highway driving. It turns 1600 rpm at 60 mph, that's good for fuel economy.
It's not designed for towing, but when I do, 3rd gear is my high gear, it's geared 1.00 to 1.
It came with "higher" PSI tires ....41 psi. It's a Super Cab and 8 ft bed...more weight.
I routinely got 21-22 mpg, so that's your reference point.
If you've got auto or 3.55 or worn engine or no OD, you can start subtracting.
I CAN tell you that 22 mpg was phenomenol for a pickup in those days.
Nowadays, I spend most of my time ranching...translation, idling, first gear, etc...so I'm getting about 12, but that's to be expected.
Senior User
Joined: Feb 2004
Posts: 219
Likes: 0
From: Chicago
Well the 8.8 is a lot easer to do then a 9" but it should only be done by some one who has the PROPER TOOLS!!. If you have a no torque wrence, dial indicator, feeler guages, and the right shims do not attempt a gear change. If you set it up wrong you will ware the gears out fast, or worse it will brake on you and leave you stuck someware. I have done it with experenced and think i could do it but you know what i paid to have the gears installed in my mustang cause i did it like 12 years ago.
New User
Joined: Jan 2004
Posts: 14
Likes: 0
From: NH
Another gear ratio available is 3.31 which I have in my 95 F-150 XL 4.9L w/E4OD tranny. It gives me nice pulling power and I also average 18 MPG city/highway. I don't know if this ratio was available in the 80's, though. I highly recommend either 3.31 or 3.55 gears unless you are always travelling straight down the highway with no load.
Dave
Dave
New User
Joined: Feb 2004
Posts: 9
Likes: 0
From: fort lauderdale
I want to thank everyone for their input on gas maliage with the 3.55 rear. i have decided to sell the truck and buy a car to get the higher miliage but dont hate me just yet I have a 91 F-350 that i am keeping. (love that truck) see ya
steve
steve
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