1996 Ford F150 4.9L (300ci) I6 5MT 4x4

[Christ]

Originally Posted by Big Dave

I think since I did my 3.08 gear mod, 3.08s have become very rare in the aftermarket. For bigger trucks using Dana 60s or 70s or Sterling 10.25s, 3.55 is about the limit these days.

I think with the advances in transmissions and engines, the longer rear end gears aren't really desirable for most applications anymore, where large tire diameters and 5/6 speed transmissions are available, as well as higher revving engines with more power available.

[Milwaukee]

15w40 Delvac 1300 in 300 during extreme winter you are hurt engine.

Use 5w40 diesel oil.

13 mpg it must be mistake.

Check brake to make sure it not drag.

I wouldn't use steel flatbed it heavy than you think. I have one on F250 it weigh more than normal bed. Use aluminum flatbed would be much better.


Did you add vacuum gauge that what make huge difference in mpg

You need scanner to check codes in computer. They don't turn on engine light but codes hide. My 95 F250 don't have engine light on but drive awful.We hook to scanner it show lot errors codes after fix some sensors then work great.

[Milwaukee]

It pop up to me

Did you have vacuum gauge on that now? That explain why you get 13 mpg.

I don't know if you would listen me for again. Put 3.08 you would notice vacuum gauge drop 10 or less while you touch gas pedal it more like you have geo metro with 3 cylinders that struggle to 80 mph while your foot is smash on gas pedal all times.

[Christ]

Originally Posted by Milwaukee

15w40 Delvac 1300 in 300 during extreme winter you are hurt engine.

Use 5w40 diesel oil.

13 mpg it must be mistake.

Check brake to make sure it not drag.

I wouldn't use steel flatbed it heavy than you think. I have one on F250 it weigh more than normal bed. Use aluminum flatbed would be much better.


Did you add vacuum gauge that what make huge difference in mpg

You need scanner to check codes in computer. They don't turn on engine light but codes hide. My 95 F250 don't have engine light on but drive awful.We hook to scanner it show lot errors codes after fix some sensors then work great.

It's not extreme winter here, winter's almost over. I'm in PA, not Antarctica. It's getting back into the 40's and 50's here every day already. I put 1qt of MMO in with it, which thins it out pretty good as well. It's just to clean the crap out of the engine, I'll be changing it out after a couple tanks of fuel run through.

13MPG is no mistake, I had a massive fuel leak. I actually got less than 13 MPG. It was closer to 5 MPG.

Brakes aren't dragging, I just had to pinch the back brake line b/c there was a hole in it. I'll have to fix that this week as well. Only front brakes right now.

I have a scan tool, the only code is the heated O2 sensor heater circuit.

The front passenger side axle shaft (the "floating axle" on the IFS setup) is so loose I can actually wiggle it in a 1" circle inside the hub. I have a feeling the axle bearings in the front are done for. I'll have to check when I rip into the front end.

[Christ]

Two days of cold and rain. Miserable. Don't want to work in that crap, so I've been inside organizing my brain.

Not getting very far.

[Milwaukee]

Post your specs and gas mileage - Ford Truck Enthusiasts Forums

[Christ]

Anyone know how to make a gear splitter?

I need a gearbox that's 1:1 and 2:1, and then I can scrap the whole gear swapping idea altogether, cuz I'll be able to halve my RPM's for any gear I'm in.

Only need something to go somewhere in the rear drive line, doesn't necessarily have to bolt to the transmission at all.

And before someone recommends GearVendors, or a similar $2,000+ solution, don't bother.

I'm looking for a REAL solution.

Any ideas?

[Big Dave]

I've talked to literally hundreds of truck guys. Bigger diameter tires actually reduce MPG.

The reason is increased rotational moment of inertia. RMOI goes up with the square of the radius. Big tires are OK if you go long distances at a constant speed, never slowing down or speeding up.

I don't drive that way.

[vskid3]

Offroaders use dual transfer cases or "doublers" to further reduce gearing. They usually take the low range section of a transfer case and attach it to the existing transfer case. You could do the same, but reverse the add on. The only problem is you wouldn't be able to shift it on the fly.

[comptiger5000]

Vskid - A doubler setup is actually a good idea for that type of use, as long as the reduction isn't too big. It allows you to gear the axles taller and still have somewhat lower gearing when needed.

Also, taller tires will help highway mileage, as long as they don't hurt aerodynamics or rolling resistance much. They will hurt city mileage a bit, however, due to increased weight.