95 F250 4x4 5.8L 5sp. The thing I don't like is If I use 1st gear I'll roll the truck about 5 feet before I have to shift. If I start in 2nd gear it does ok but there is a little bit of clutch feathering. I don't want to wear out the clutch and I hate using 1st gear. I was thinking It might need to have the gearing changed in the diffs. How can I tell what I have in there now and what I should change it to? Are there numbers on the diffs I can read and translate? Would putting say a 3:73 in as opposed to if it has 4:11's now, improve the mpg? Any thought's are appreciated.

Thanks.

 

Look at the sticker in the door jam, then go here

Ford Door Sticker Decoder .: Articles

 

Thanks, I'll check it out. I never really looked but there may not be a sticker on the door jam. Any other way to get the numbers if the sticker is missing?

 

If you really are only moving 5 feet before needing to shift to 2nd...then you should be starting off in 2nd. I've never driven a ZF5, so I don't know how the ratios are. A gear swap is an awfully expensive solution to a minor inconvenience.

When I had my Cummins, I was in 4th gear by the end of the intersection.

 

It's not just the shifting, If I have to drive the truck to work it's about 34 miles round trip. That 34 miles cost me $20.00. Basically that 5 gallons of gas at $4.00 a gallon. That's about 6.8 miles to the gallon. That's a lot of gas.

 

If the door jamb decal is missing crawl under the truck and look for a tag hanging off one of the rear diff cover bolts. The first few numbers on the tag are the gear ratio.. you may have to remove the bolt to see all the numbers.

With a ZF manual trans the gear ratio you want for fuel milage is 3.55, but you can get the same result by simply installing larger tires(33" or 35") as long as you remember to recalibrate the speedo.

 

ive never heard of a 351 getting less then 8 mpg and running correctly... you might want to check that out. my brother LITERALLY stomped it from stop sign to stop sign for an ENTIRE tank and averaged 8mpg. his truck is a 1990 F150 ECSB 4x4 351W/E4OD and we believe 3.55s.

 

Figure out why your fuel economy is so bad and fix it before you go doing anything else. Your MPG numbers should be 10+ with a 351 running empty.

 

Looks like this decoder doesn't have info for my truck, unless I'm just not using it right. The sticker on my door reads Axle 39 and springs are 65F.

 

Running stock 235/85/16.

 

Well I pulled the air filter earlier today and I noticed that it has some oil on it, Im thinking I might be getting some blow by. The truck only has 128k on it, but it's been worked...It's lifted with extra springs and arch. It has custom DMI bumpers front and back, with plow frame & pump incorporated into front bumper. If I remove the bumpers, I'll probably lighten the truck by 400 - 600 pounds. This is no speed demon, I have to use the right hand lane when leaving a red light because it just doesn't get to speed that quick but it'll haul anything you put in it or hook to it and never groan. It'll pull a house down if you want it to, but it'll also run at 70mph if it's on the freeway with no problems.

If I could get 10+ in town driving, I'd be like a kid in a candy store. what should I be looking at first? Plugs, wires, Timing?

 

Yes all those things. Fresh oil, air cleaner, tire pressure, cap and rotor. What size tires are you running?any chanc you odometer is off? I'd be epe ting at least low teens probably better

 

According to my 1995 Ford manual axle code 39 is a 3.55 gear ratio (non-limited slip).

 

Not knowing much about gear ratios, is that a good road gear? Like I said, it cruises 70mph no problem just kind of slow coming off a light. I can live with starting out in 2nd gear so that's no biggie.

I plan on looking at plug, wires cap, Rotor if it has one, the oil only has about 1000 miles on it. Would a clogged PCV valve cause oil in the breather? Last time I had blow by it was on an old 68 500 fastback and it was blowing out of the dip stick as well. The truck isn't doing that.

I'll also check to see if maybe the brakes are dragging, I have to replace the right upper ball joint anyway and the steering gearbox is making the whirring sound so I don't know if it's wore out or can be adjusted either. If cost get's to be prohibitive then I'll offer it up for sale to one of you guys or I'll just part it out and send the rest to the scrapper.

 

3.55 gears are a reasonable compromise assuming stock height tires. I had a 1992 F350 4x4 with 5.8L/E4OD combination. The tires were stock height, but wider. It also had 3.55 gears. It was a marginal performer when towing anything. I had seriously considered 4.56s, but my long term plan did not include keeping it for an extended period.

Oil in the airbox is definitely a sign of a plugged or faulty PCV.