96 250 w/ 460 E4OD trans, will never pull any really heavy loads. I'm looking for (don't laugh) a little better MPG. Will switching to 3.55's help with the mileage or not??

Thanks in advance for not laughing at the Newbie to loud....

 

It probably would, but by how much who knows? I would think you might see 1-2 mpg highway better. It also depends on what size tires.

 

I've considered going from 3.55 to 4.10 just for the added "Umph". I'm going back to the taller factory 235/85R-16 (load range E) tires for the added capacity/towing and I think the 5.8L would appreciate the added gear reduction. Drive your truck over and we'll swap!, LOL.

 

If you aren't hauling any heavy loads, then why are you driving around a 5000 lb truck with a 460 in it?

If you really want to improve your gas mileage, buy a car.

 

That's what I have now. I'm going from 285/75 to 235/85 and see if that helps a little. It pulls ok now but in these hills were I live I use a lot of gas doing it.

When I do my SAS next spring it will have 4:10 for sure.

 

I switched to P255/70R16's (~30.5" tall) last fall and the truck really seemed to like the smaller diameter tires. They also rode, drove & handled a ton better than the tall, narrow & stiff factory tires, but the load capacity was not quite on par with my 250HD. Unfortunately, the tires are about worn out now and I plan on doing some more towing & hauling, so it's back to the original LT235/85's. I would love to buy a new set of LT245/75's (best of both worlds) but I don't have the money for new tires right now.

 

It would help with MPGs but not to recoupe the $1000+ to reagear it

 

i have a friend who had 2 separate trucks, both with the 460 engine & automatics...one truck had 4.10 gears and the other had 3.55 ratio...He got an honest 7 mpg better with the 3.55 ratio....the 4.10 truck got 10 mpg and the 3.55 ratio ran 17 mpg. I am looking to do this exact thing with my 89 F350 with a powerstroke/auto implant...The donor truck & the F350 both have 4.10.....I want over the road milage.... I have another friend running a 95 F350 crewcab single rear wheel with the powerstroke/auto...&3.55 from factory...He gets 26.3 running form CA to AZ on the open freeway....

 

I don't see a 460 getting 17mpg. And I certainly can't see a 7mpg difference between the two gear ratios. I could be wrong of course.

 

i didn't believe it till I saw it.....the rear end ratio makes a huge difference....

 

Intresting about the 3.55 giving better MPG. I might have to do more thinking about that swap on my E350 RV/bus conversion with a 460/e4od in it. I was getting 8.5mpg up till start of this year and its now down to 6.7mpg.

I think the engine is getting into it's peak torque range with the 3.55 gears, with 4.10's its running over the peak torque hence poorer MPG

 

Carrying around an RV is a whole different animal compared to an empty pickup truck. I wouldn't expect those numbers. And remember, with those taller gears it's going to take more gas to get the heavier weight moving. Now on long trips on level ground....maybe some improvement over time but probably not enough to get your money back.

 

Unless you find someone like me who has a SRW 3.55 and wants 4.10's.
Then you can just swap the whole rearend and it costs a days labor, some beer and a little money for unexpected problems. Otherwise, I agree. If you went from 10mpg to 13mpg, it would take ~11,000 miles to recoup a $1000 at $3.85/Gal. That's a years worth of driving for some people. The money is better spent on a quality tune-up or on a $800 "beater" Ranger or something that get 2X the MPG.

 

Having an OD trans seems to help equalize the MPG differences between different gear ratios.............as opposed to older vehicles with only a direct final gear. In the Mustang world, most guys go from 3.27 to 3.73 or 4.10 and only see a 2-3 MPG decrease at highway speeds. A lot of them, however, report the same or even better MPG in city driving.

 

Maybe, but I wouldn't tow or haul anything in OD especially not an auto trans. Even a manual trans won't put with that for very long.