axle ratio?

[allczns]

my '94 F350 IDI non-turbo crew, E4OD, 235-16 tires, has 4.10 gears. Typical service is highway driving, no load, just a driver. Thinking of going to 3.54 gears to improve fuel economy. Seems like 3.08 would be a BIG change.
What did the factory offer in these trucks? What do others use?
Winning the stoplight launch is not important to me.
thanks,

 

[Cat_Rebel]

I wouldn't do 3.08s with an auto, you will burn it up doing that. 3.55 gears would help out but that's about as high as I'd want to go. Remember if you went much higher on a crewcab like that without a turbo it will have a hard time getting out of it's own way.
They came with 3.55 gears & the HDs got 4.10s.

 

[Agnem]

Going to 3.54's would be a good move. It will be like having a true overdrive. A ZF in 5th, with 4.10's is equivelent to a T-19 in 4th (1:1) with 3.54's. You have already figured out what ratio's are available.

 

[allczns]

thanks

thanks guys...that's what I was thinking too. 4.10s make sense for a truck that has to work for a living.
Next question...should I be shopping the wrecking yards for complete axles (4wd so have to do both ends) or put new gearsets into my existing axles?
How common are 3.54 gears in the wrecking yard? I assume I have 10.25 Sterling in the rear and Dana 60 in the front...both open.

 

[sootman73]

what happened to your turbo? all 94 came with turbos! im assuming that its not he original engine? what size are your tires. need to have the middle number. the 235 is the width. the second number is not a measurement but a ratio to the width of the tire. i have 3.54's in my truck and can still haul 15,000 lbs around at 60 without making it work. good rpm for highway though i would still like a gear splitter for a second overdrive. what you want to do will make a big difference in the driveability of ur truck for sure! yes you have a sterling in the rear. and i think a 60 upfront if its a solid. im not sure about 350's

 

[suv7734]

what happened to your turbo? all 94 came with turbos!

Just an FYI, 94's were available with three different diesel engines, the 7.3 IDI non-turbo, the 7.3 IDI turbo and in 94-1/2 the PSD DI turbo.

As far as gears go there have been a lot of things tried. Member 'Tonkadoctor' had some 3.08:1 gears in an F350 dually IIRC and he liked the mileage but I can't remember if that was an auto or not. Going with complete wrecking yard axles is an option but can also be expensive if they are needing work done. Taller tires is also an option to effectively change the overall ratio but if you end up getting into a tire that is wider then you will have more rolling resistance... So many decisions.
Overall I like my 3.55's with the 285-75x16's. Even with the C6 I'm still at 2500 RPM at a steady 60 MPH though. I don't tow a lot but when I do it's usually heavy so I take off easy until I get rolling. An overdrive would be nice, it's a lot of money initailly but if you are not doing the work yourself it may be a better option than going to a shop for a front and rear gearset change...

 

[Ironman03R]

In 94 there were 3 engine options, N/A 7.3 IDI, Turbo IDI, and Powerstroke. From my understanding the first year you could only get a PSD with a 5-speed.

 

[allczns]

what happened to your turbo? all 94 came with turbos! im assuming that its not he original engine? what size are your tires. need to have the middle number. the 235 is the width. the second number is not a measurement but a ratio to the width of the tire. i have 3.54's in my truck and can still haul 15,000 lbs around at 60 without making it work. good rpm for highway though i would still like a gear splitter for a second overdrive. what you want to do will make a big difference in the driveability of ur truck for sure! yes you have a sterling in the rear. and i think a 60 upfront if its a solid. im not sure about 350's

no turbo...plain jane IDI...tires are 235-85R16...front axle is solid.
I'll call the local wrecking yard tomorrow re axle prices...may have to wait for the taxman to deliver my refund...

 

[RKOCH]

You would be better off buying a couple of gear sets for a scrap yard is going to charge for a 10.25 alone. And around here you never and I mean never find one of these trucks with a diesel in a scrap yard.

 

[Cat_Rebel]

In 94 there were 3 engine options, N/A 7.3 IDI, Turbo IDI, and Powerstroke. From my understanding the first year you could only get a PSD with a 5-speed.

You're right, the early Powerstrokes (94) were all 5sp.

 

[BigRigTech]

I have a ZF with stock 235/85/16 tires and 3.55 gears....70MPH at 2000rpm....Pulls ok and isn't screaming on the highway.

 

[tonkadoctor]

As far as gears go there have been a lot of things tried. Member 'Tonkadoctor' had some 3.08:1 gears in an F350 dually IIRC and he liked the mileage but I can't remember if that was an auto or not.

It was MEEEEEEEEEEEE

ZF5 tranny, N/A 7.3

Went from 18 mpg with 4.10 gears to 23 mpg on the hwy with the 3.08s but was a dog accelerating or hooked to my flatbed trailer loaded with firewood.

I gave the member here that bought it from me the original 4.10 gears but he turboed it and put 3.73s in it. Last I knew he was pretty happy with that setup.

Now figure your return on investment, how many miles you drive and how long it will take to recoup the initial investment. For most here it would take years to recoup the price of a gear swap unless you are driving 3500 miles a week where a 1 mpg difference will save you $100 a week at $4 gallon fuel........ So if you only drive 14,000 miles a year you will save only $400 a year in fuel on a 1 mpg difference....... Now here's the catch, you COULD possibly make it worse with the wrong combo, what worked for me and my needs may not work for you and your needs..... It's a risk you must decide if it's worth taking.



It's nice now getting the same 22 - 23 mpg (hand calculated, no kidding) with great power too in my "new to me" 2004.5 Dodge ;p

 

[sootman73]

huh never knew that all three were offered. i thought they just put turbos on them and thats it for the idi's in 94. i knew the psd was offered. learn sumthin new every day.

 

[Camarogenius]

Another vote for not going higher than 3.55's.

 

[gnathv]

Gears

I have a 93 Extndedcab has E4OD NA at the time. Changed from 4.10 to 3.55 and it is great to cruise 70mph at 1925 rpm instead of about 2250rpm. 4.10 was about 16-17 mpg, 3.55 bumped it to 18 almost 19. Added used 088 ATS and now just over 22mpg at 73mph (Cruise control in Louisiana, what we call hills most would call speed bumps, pretty flat). Mine is 2wd, change them and enjoy you always have 4 low.