4.10 vs 4.56 gears

[Bird]

When I first retired, I had a 1988 C3500 Chevy, single rear wheels, 350 engine, 373 gearing. My fifth-wheel trailer was barely under 10k pounds. The truck did the job; not good, not bad, but the temperature gauge ran too high. With a brother selling Chevrolets, Buicks, and RVs at the time in a small town overstocked dealership, I got a good deal on a 1989 one ton dually, 454 engine, 4.10 gearing that did a good job towing; however, it was a 3-speed (no overdrive) transmission. So after a few months, I had a Gear Vendors overdrive installed. Now that was a real pleasure to drive. It didn't help the gas mileage much when towing, but it did give me a substantial mileage increase when not towing. But you'd better plan on keeping a vehicle that you add the Gear Vendors to because it ain't cheap. Camping World is one place you can have them installed, and the cost will run a minimum of $2500, possibly over $3000.

 

[JerryG]

I have never had 4.56s. I have had 4.33s and have a truck with 4.10s now. I wouldn't want anything lower than 4.10s unless I have a real high overdrive. The F150 that I have now has 4.10s with an automatic an overdrive. The mileage is awful and RPMs are on the high side when cruising down the highway. It does pull great though. If I was going to keep a truck for a long time and needed more pulling power, I would go with the Gear Vendors overdrive. That way you would have the best of both worlds.
Gear Vendors under/overdrive transmissions the most awarded auxiliary transmissions.
Edit: I didn't notice that Bird had posted the link.

 

[RobJ]

I have a Ford SD LB CC 4x4 with 315's. it has a 3.73 and a v10. Only thing i tow is the tractor maybe a few times a year, atv in the back sometimes. To make towing easier I turn off the OD. Not to bad towing then. In OD it's constantly downshifting.

 

[Builder]

I have a Ford SD LB CC 4x4 with 315's. it has a 3.73 and a v10. Only thing i tow is the tractor maybe a few times a year, atv in the back sometimes. To make towing easier I turn off the OD. Not to bad towing then. In OD it's constantly downshifting.

I had a bunch of Ford's with the 4 speed 4R100 trans. Man, what a pile they were. Most of the Ford trannies didn't make it past 75K without needing a rebuild for a mere $3,000. I used to turn the OD "off" to try to help the trans last longer, but that meant you had to run in 1 to 1 and guzzle even more gas than with O/D "on".

 

[RobJ]

I had a bunch of Ford's with the 4 speed 4R100 trans. Man, what a pile they were. Most of the Ford trannies didn't make it past 75K without needing a rebuild for a mere $3,000. I used to turn the OD "off" to try to help the trans last longer, but that meant you had to run in 1 to 1 and guzzle even more gas than with O/D "on".

I'm not sure of your point, sounds like my 1 to 1 with no OD is less rpm's than a 4.56, just cheaper than replacing the rear end. And pulling my tractor I get 9.5-10 doing 65. 14 at 65 empty. You still not over that N80 thing?

BTW to the original poster, if you go from a 3.73 to 4.56 you might also have to change the carrier because of the size of the gear. I'm not exactly where the cut off is on the 2.

Good Luck,
Rob

 

[Builder]

I'm not sure of your point, sounds like my 1 to 1 with no OD is less rpm's than a 4.56, just cheaper than replacing the rear end. And pulling my tractor I get 9.5-10 doing 65. 14 at 65 empty. You still not over that N80 thing?

BTW to the original poster, if you go from a 3.73 to 4.56 you might also have to change the carrier because of the size of the gear. I'm not exactly where the cut off is on the 2.

Good Luck,
Rob

Robster,

The point I was trying to make is that having to run in 1 to 1 (O/D off) sort of defeats the purpose of having an O/D transmission in the first place, since you yourself said yours is "constantly downshifting" and "easier to drive with it turned off".

Perhaps having a numerically higher geared truck like 4.10 or 4.30 with an O/D that you can actually use may be better for towing for the O/P. Then angain, based on my experience with Ford, it wouldn't surprise me if they made a transmission that needed to have a feature disabled so it would run right.

I never had anything to get over with the N80 thing. I just think it looks great in my signature. I get lots of PM's saying "way to go" I wonder why they do that?

 

[wkpoor]

BTW to the original poster, if you go from a 3.73 to 4.56 you might also have to change the carrier because of the size of the gear. I'm not exactly where the cut off is on the 2.

I have already researched it and the saginaw in my truck will except up to 5.38's with out a carrier change and it is a full floating rear end. It is basically the same rear end as the 350 truck, cutaways and motorhomes without the dual tires.

 

[john_bud]

If you change gears, you wil limit your cruizing speed on the highway. 4.10's and you will want to run at 60-65. 4.56 and you will want to run at 45-50. You don't have a large enough gas tank to run 75 with 4.56's! Seriously.

I would look into hopping up the engine some with headers, loose dual exhaust, K&N air filter and maybe a programmer first. Increasing low end torque may give you better road feel without swapping R&P. If that does not work, it's not wasted as those things will yield better fuel econ as the engine screams it's way down the freeway.

jb

 

[Builder]

If you change gears, you wil limit your cruizing speed on the highway. 4.10's and you will want to run at 60-65. 4.56 and you will want to run at 45-50. You don't have a large enough gas tank to run 75 with 4.56's! Seriously.

I would look into hopping up the engine some with headers, loose dual exhaust, K&N air filter and maybe a programmer first. Increasing low end torque may give you better road feel without swapping R&P. If that does not work, it's not wasted as those things will yield better fuel econ as the engine screams it's way down the freeway.

jb

John,

I run 4.30's up to 85-90 with O/D on, 4.88's up to 80MPH with O/D on and 5.38's up to 70+ with O/D in a manual trans. As long as he has an O/D gear in his tranny, he should be fine with 4.10's or 4.30's.

If his "drive" gear is 1 to 1 then he should avoid anything numerically higher than 4.10's, IMO.

 

[RobertN]

BTW to the original poster, if you go from a 3.73 to 4.56 you might also have to change the carrier because of the size of the gear. I'm not exactly where the cut off is on the 2.

On many differentials, 3.73 and taller(ie 3.55, 3.00) use a smaller carrier, while lower gears(ie 3.90, 4.11,4.27) use a larger carrier.

If you can change gears without changing carriers, then the price is not to bad($500 around here). If you have to change the carrier, then plan another $250-500 or more, depending on what you want.