4.9, E4OD, 3.08's presently. I have 31x10.50x15 tires that are almost new, so swapping to a shorter tire isn't an option. So far, only mods are K&N F.I.P.K. filter kit, Dynomax Super Turbo muffler, and 13* base timing, instead of 10*. What rear gear ratio will give me the best compromise between towing power, and economy. Presently, I get 16-18 mpg's in mixed highway/city type driving. The truck runs excellent, and has plenty of power "empty", but is lacking, when loaded...


Thanks, BOB

1990 F-150, 4.9 Tow Vehicle
1986 Mustang LX 10.45@131
You MUST be FAST,
cause you were FLYING,
When I PASSED YOU!

 

I went from 3.08s with 29" tires to 3.73s and 30" tires. That put me at the engine's torque peak at 65 in OD. There was no loss in fuel economy around town or in mixed driving. My towing mileage actually seems to have improved about 0.5, but that's not really a verifiable difference. I don't have enough pure highway mileage since the change to tell you if there's a measurable difference, but I think it's minimal. With your slightly taller tires, I'd say go for the 3.73s. 4.10 is probably too much gear for a 300 with 30-31" tires.

 

That's what ratio I had in mind. Thanks SR

1990 F-150, 4.9 Tow Vehicle
1986 Mustang LX 10.45@131
You MUST be FAST,
cause you were FLYING,
When I PASSED YOU!

 

[font size="1" color="#FF0000"]LAST EDITED ON 26-Oct-01 AT 10:28 AM (EST)[/font][p]Hey Bob,

Proper gearing really depends on what you're towing. Most trucks that are used for towing an type of serious load don't come with anything less than 3.73s. I have 4.10s in my F250 with a 460 under the hood. I get about 8-10 mpg, not very good, but a great (gasser) towing machine, it doesn't even compare to a diesel though. Axle gearing plays part of the GVWR and GCWR ratings, this is one variable in the equation. Here's some interesting info off of ford-diesel.com from crewzer:

-Rich

 

Rich,
The "load" that is being towed, is in my signature, but we will leave that subject be, OK?;-)

Anyway, with the 3.08's and stock sized 235/75R15 tires that were previously on the truck, it labored up some of the longer, steeper inclines when towing. On level, and near level roads it was fine. I believe that 355's, with the original tires, would have been the answer. Now that I have re-installed my 31x10.50x15's, I'm hoping the 373's will offset the taller tires. Any thoughts?

FWIW, I actually bought a brand new set of 235/75R15 tires for the truck. I removed them because they weren't "XL" or true "truck" tires, even though they were advertised, and sold to me, as "truck" tires. What was happening was I got sway and a general uneasy road feeling when towing with them, and didn't feel safe using them. A buddy bought them for his SUV, and I re-installed my "real truck tires", which makes me feel alot safer than before.

BOB

1990 F-150, 4.9 Tow Vehicle
1986 Mustang LX 10.54@129
You MUST be FAST,
cause you were FLYING,
When I PASSED YOU!

 

Rich, is your 460 carbed or injected? You said you were getting 8-10 MPG...I'm assuming your unloaded? The reason I'm asking is because I'm thinking of going from 3.55's to a set of used 4.10's I have sitting on the shelf. In my 1989 EFI 460 I'm currently getting 11 MPG empty and 7.5 MPG towing 9,000 lb.

Deen Hylton
Ford F250 460 C-6, K&N, Headers, Dual Exh.,Comp. Cams,Shift Kit
Pioneer CD w/Bose Speakers.
Other Passion: Blown 77 Corvette (Sorry Guys/Gals)
How I can afford to Drive the above: 93 GEO Metro

 

[font size="1" color="#FF0000"]LAST EDITED ON 29-Oct-01 AT 11:40 AM (EST)[/font][p]Bob,

No need to beat a dead horse right? :-) I believe the 3.73's will give you the best balance between towing power and mpg that you are looking for. They should compensate for the taller tires. Good call on getting rid of the "swaying" tires, nothing worse than feeling unstable going down the road.


Deen,

My 460 is injected, it's a '95. Indeed the mileage is about 8 loaded and 10 unloaded. Terrible mileage for a truck, but it'll pull just about anything up the hill. The 4.10's are what gives the 460 the torque it needs to move the load.

-Rich

 

Thanks Rich, losing 1 MPG would'nt be too bad if I could pull those long steep hills about 10 MPH faster. Deen

Deen Hylton
Ford F250 460 C-6, K&N, Headers, Dual Exh.,Comp. Cams,Shift Kit
Pioneer CD w/Bose Speakers.
Other Passion: Blown 77 Corvette (Sorry Guys/Gals)
How I can afford to Drive the above: 93 GEO Metro

 

Deen,

I should also let you know I have installed the Banks TorqueTubes exhaust manifolds along with a Flowmaster 3 chamber all on 3" pipe. I also installed a K&N filter and removed the air silencers in the intake tube. This helps drastically with the fuel economy. I also added the Banks TransCommand to help improve the shift characteristics of the E4OD.

So our trucks sound pretty similar, except for the injection and trans.

-Rich

 

Ya Rich, sounds like we've made similar improvements. I think the biggest difference is your overdrive tranny...I have thought about getting a "Gear Vendor" or buying a used E4OD but I can't justify $1,500-2,500. costs to get an additional 1-2 MPG...it would take me YEARS just to break even.

Deen Hylton
Ford F250 460 C-6, K&N, Headers, Dual Exh.,Comp. Cams,Shift Kit
Pioneer CD w/Bose Speakers.
Other Passion: Blown 77 Corvette (Sorry Guys/Gals)
How I can afford to Drive the above: 93 GEO Metro