So My Current set up is as follows 89 F-250 Supercab Long box 4x4 460efi c6 4.10 gears and 265/75/16's 3" exhaust no cat, k&n Intake. i use the truck mostly for dump/hardware store runs, and hunting in the hills with occasionally hauling a camper or pulling a trailer. I am currently hoovering between 9 and 10 mpg which I know is pretty typical for a 460. My question is a buddy of mine has a 90 with F-250 with 3:55 gears. How much will swapping to the 3:55 improve my mileage? will I notice a huge loss in power by going to a the 3:55 gears.

any input would be great thanks

 

You might see a 1-2 MPG gain on the highway....that's not a guarantee. Probably not worth the effort IMHO.

 

If you combined the 3.55 rear axle with a ZF5 transmission to get the OD ratio then you would really have something, but with the C6 I don't see the axle change having much impact on fuel milage or towing power, I mean it should improve milage a bit but nothing that too dramatic... the big motor is thirsty and that's pretty much the end of it.

 

Regearing probably isn't the correct solution for you unless you drive a lot of miles.

For reference, my '95 with the E4OD and 3.55 gears nets a reliable 11.5-12.5 MPG and on long highway trips can even achieve the 13-14 MPG mark. Regearing front and rear axles will cost you more than you'll save in fuel if you don't drive a lot.

If you decide on swapping gears anyway, the jump from 3.55 to 4.10 gears is large enough to be noticeable. If it's mainly a parts-runner, it probably isn't too detrimental though.

 

Towing will blow goats, My '96 351w with 4.10s will out pull my '91 460 with 3.55s BUT my '91 is my DD so the higher gearing is fine form me and when I tow I just go slower which saves money.


My '96 got 10mpg the '91 gets 10 around town and 13.9 on the interstate going 70mph I've checked into gear swapping if you can't get them cheap i.e. Pick and Pack, then I would get a skinny taller tire.

 

I think you will be unhappy with your towing if you change to the higher gear. Unless you drive 80% or more on the Interstate I would keep that 4.10.

 

If your mileage went up from 10 to 11 with the gear swap, assuming gas is $3350 / gal, you'd save about $32 / 1000 miles. from 10 to 12 mpg would save you about $58 / 1000 miles. So how much would a gear swap cost, and how many thousand miles to pay it off? If it was $1000 / axle (some say it's a lot less than that), it would take 63K miles to pay it off with a 1 mpg bump, 34K with a 2 mpg bump. Tou need to decide if it's worth it.

As to how the truck would work towing, it depends on what you want to tow and how quick you want to be towing it. I used to be plenty happy with the performance of my F-150 (351, E$OD, 3.55 gears, 33" tires) towing/hauling about 6,000 lbs. But that's not 12,000 lbs and I wasn't expecting it to keep up with sports cars.

 

guess i should of put in the comments the gear swap will cost me nothing but some time cuz my buddy with the 3.55's wants my 4.10's

 

not planning on towing anything really big probably just a 20-25' camper. maybe a small boat. nothing over 5-6k lbs

 

IMHO...leave your truck as-is. There is a whole can of worms just wanting for the lid to pop off.

 

Personally, for that kind of use I'd prefer 3.55s, but I know most on here would say it's a dog like that and want the 4.10s. But I do have 4.10s in my current truck and I'm not exactly jumping to replace them. Even if it was "free" I'm not sure I'd bother. But its your time, your money and your truck.

 

Are you planning to swap housings and all? If so that wouldn't be a big deal. I like my 3.55s but they are a little high for HEAVY towing. They do just fine for normal towing.

 

thanks for the info i would just be swapping rear ends and front drop outs pretty easy stuff with an air compressor. I haven't fully decided on the swap yet I love the low end torque the 4.10's give me but hate that my truck is cranking just over 3k rpm at 65 mph.

 

trans swap would be more beneficial.

 

For the way you use your truck, 4.10s are PERFECT.

If you did a lot of highway travel, then I would say 3.55s. but you don't so stick with the 4.10s