Im gonna be putting gears in my truck but i dont know anything about gears so i dont know what to get, I was thinking about getting 4.56 gears but i hear that you get bad gas mileage on the highway? Im currenty running 3.55 stock gears, do you think running these gears with 37's will hurt my tranny? And how much am i looking to pay for the gears and the gears installed??
Gears for 37's or bigger!!!
dod
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Being that it is a 2500 and a cummins, The 37s would look better with 7". A few cummins guys have a simular set up and went with 4:10s
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Do you think I will be ok driving the truck with the 3.55's in it until I got enough money for the expensive gear change.
Has anyone changed their own gears? I have never done gears, but I am pretty mechanically inclined. I plan on installing the DC longarm, sj 7" coil, thuren trac bar, etc. lift myself with the help of friends. I know it would save me a ton of money.
I would also like to upgarde the rear to a locker, or air locker. I am not sure which way to go? Do I need to upgrade the front CAD system to a cable actuator, leave it alone, or uprgrad to air locker?
Has anyone changed their own gears? I have never done gears, but I am pretty mechanically inclined. I plan on installing the DC longarm, sj 7" coil, thuren trac bar, etc. lift myself with the help of friends. I know it would save me a ton of money.
I would also like to upgarde the rear to a locker, or air locker. I am not sure which way to go? Do I need to upgrade the front CAD system to a cable actuator, leave it alone, or uprgrad to air locker?
G
Guest
·You wont need deep gears if you have the CTD. Should be OK with 3:55's and 37's.
As for the gassers, get teh 4:56 or 4:88's if they get out for the 9.25
I personally love 5:13's and 37's
Still get decent mileage
As for the gassers, get teh 4:56 or 4:88's if they get out for the 9.25
I personally love 5:13's and 37's
Still get decent mileage
I have been running 35's with 3.55 gears in my CTD for the last year and it pulls just fine. You're not going to win any races, but I have never felt like my performance was below standard.
I would like to go up to 38" soon, and I have been thinking maybe 4.56 might be worth looking at, though. I hate to spend all that money just to go to 4.10's when the factory offered them in the first place! I had a buddy of mine who put gears in his Chev a few years back and went from 3.55 (or whatever Chev is using around there, and went to a 4.56 with his 35"s and he was actually disappointed with the lack of improvement.... I guess I just don't want to make a change that is so slight I don't notice a big bang for my buck... (gears cost plenty....)
Does anybody have any recommendations for the Dana 60/70 crowd?
I would like to go up to 38" soon, and I have been thinking maybe 4.56 might be worth looking at, though. I hate to spend all that money just to go to 4.10's when the factory offered them in the first place! I had a buddy of mine who put gears in his Chev a few years back and went from 3.55 (or whatever Chev is using around there, and went to a 4.56 with his 35"s and he was actually disappointed with the lack of improvement.... I guess I just don't want to make a change that is so slight I don't notice a big bang for my buck... (gears cost plenty....)
Does anybody have any recommendations for the Dana 60/70 crowd?
when I had my 35's and 3.55 I ignored people who told me to get gears and on the freeway I couldn't hit overdrive and the trans would up shift and down shift and I got crappy gas milage then the tranny blew up and then I got gears and it drives better than stock and my gas milage went up. save yourself the trouble and go with the gears.
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9,594 Posts
A smallblock V8 gas burner will always need more gearing than will a bigblock V8 gasser or diesel, because a smallblock simply doesn't make the low end grunt (low rpm torque) of a big block V8 or a diesel.
If you're sticking with a Dana 44 front axle and 9.25" rear axle, and you want to run 37" tires, I'd put 4.88s in it, if and when the 4.88s come out for the 9.25." People might ramble on about the pinion gear getting small and breaking, which there is truth in that concern/theory, but the reality of it is that the 9.25" rear is pretty tough. I don't know of many people who have broken them because of design problems or actual hardware/material/parts failures. Usually 9.25" failures are due to shock-loading the axle/differential. 4.88s and 37" tires would put you in a similar rpm range (probably a couple hundred rpm more, at most), in all gears, as would the 3.54 (stock) gears and the stock tires, whether the truck has 245/75R16 or 265/75R16 tires on it from the factory.
For a V10 or bigblock V8 truck (whether it be a Ford, Dodge, or Chevy), you don't "need" quite as much gearing. You could get by, probably, with 4.56s and 37" tires, maybe even 4.10s, depending on what kind of wheeling you do. A V10 or bigblock V8 makes a lot more low rpm torque and, therefore, doesn't need as much rpm, necessarily, to make its power and stay in its power band, depending on the engine combination (cylinder heads, camshaft, intake manifold, etc.).
A diesel will get by with less gear than will a small block V8 or big block V8 or V10 because a diesel has a narrower rpm range than does a gasser, AND a diesel builds the bulk of its power (torque) at relatively low rpm ranges. The 6.0 Powerstroke and Duramax, though, have torque curves that are quite a bit higher in their rpm range than does a Cummins, though. With any of the aforementioned diesels, 4.10s would probably be fine and a Cummins, being it makes the bulk of its torque curve in the 1400-2200 rpm range, could probably get by with something like a 3.92 gear with 37" tires.
Keep in mind that there's more to a lot of these axles than simply buying gears, as well. In Dana axles, there's splits in the carrier between certain gear ratios, so you'll either have to buy a different carrier (i.e. the D44 front will need a different carrier if you switch from 3.54 gears to something like a 4.56 or 4.88) in addition to the gears.
EDIT: Also, a lot of people, incorrectly, a$$ociate lower rpm as meaning better fuel mileage. This is not always the case. As everybody has mentioned, if you leave the 3.54/3.55 gears in your truck and put 37" tires on it, the engine has to work harder to accelerate the truck from a stop. Why? Because it has to accelerate a tire with a significantly greater circumference and that same tire also weighs a great deal more, so there's more rolling resistance. If all you do is change the tires, you've effectively reduced the gear ratio (i.e. from 3.55 to 3.08, or even lower probably, for example). The engine has to work harder to accelerate the mass/truck, which means it's burning more fuel. At the same time, because you've effectively reduced the gear ratio, it'll be turning lower rpm for a given speed in all gears (as compared to what it turned with the stock tires), which might put the engine at an rpm range below its power curve, so even though it's turning fewer rpm, it's having to work harder (burn more fuel) just to maintain that engine rpm or speed. On top of that, you have reduced the gear ratio enough so that overdrive in the transmission is useless. Bottom line: lower engine speeds (rpm) does not always equate to better fuel mileage. People, these days (the era of overdriven transmissions) are afraid of turning an engine some rpm. They hear "4.56/4.88" gears and they cringe, even if you tell them you're going to run a 35"+ tire. 20 years ago, few trucks had overdriven transmissions (3 speed automatics and 4-speed non-overdriven manuals) and guys wheeled them up and down the highway with 4.10 and 4.56 gears (3/4 tons and 1 tons) with 31" tires all day long with no problems at all. Granted, not having overdriven transmissions, they didn't get quite the fuel mileage some of the trucks, today, get (whether the trucks today are a study in fuel efficiency is open for debate), but those trucks saw 3000+ rpm up and down the highway regularly with no known failures, with respect to the engines. The engines in our trucks (318s, 360s, 302s, 351s, 460s, 305s, 350s, 454s, etc.) are, basically, the same as what has been put in Chryslers, Fords, and Chevys for 30+ years, save for some updates.
Guys told me I was nuts, 10 years ago, for putting 4.10 gears in my street/strip, daily driver Mustang, with a 5-speed overdrive and 26" tall tires on it. They said I'd get terrible fuel mileage, etc., etc. I never had a problem and it got very marginally less mileage than it did with 3.73s in it.
If you're sticking with a Dana 44 front axle and 9.25" rear axle, and you want to run 37" tires, I'd put 4.88s in it, if and when the 4.88s come out for the 9.25." People might ramble on about the pinion gear getting small and breaking, which there is truth in that concern/theory, but the reality of it is that the 9.25" rear is pretty tough. I don't know of many people who have broken them because of design problems or actual hardware/material/parts failures. Usually 9.25" failures are due to shock-loading the axle/differential. 4.88s and 37" tires would put you in a similar rpm range (probably a couple hundred rpm more, at most), in all gears, as would the 3.54 (stock) gears and the stock tires, whether the truck has 245/75R16 or 265/75R16 tires on it from the factory.
For a V10 or bigblock V8 truck (whether it be a Ford, Dodge, or Chevy), you don't "need" quite as much gearing. You could get by, probably, with 4.56s and 37" tires, maybe even 4.10s, depending on what kind of wheeling you do. A V10 or bigblock V8 makes a lot more low rpm torque and, therefore, doesn't need as much rpm, necessarily, to make its power and stay in its power band, depending on the engine combination (cylinder heads, camshaft, intake manifold, etc.).
A diesel will get by with less gear than will a small block V8 or big block V8 or V10 because a diesel has a narrower rpm range than does a gasser, AND a diesel builds the bulk of its power (torque) at relatively low rpm ranges. The 6.0 Powerstroke and Duramax, though, have torque curves that are quite a bit higher in their rpm range than does a Cummins, though. With any of the aforementioned diesels, 4.10s would probably be fine and a Cummins, being it makes the bulk of its torque curve in the 1400-2200 rpm range, could probably get by with something like a 3.92 gear with 37" tires.
Keep in mind that there's more to a lot of these axles than simply buying gears, as well. In Dana axles, there's splits in the carrier between certain gear ratios, so you'll either have to buy a different carrier (i.e. the D44 front will need a different carrier if you switch from 3.54 gears to something like a 4.56 or 4.88) in addition to the gears.
EDIT: Also, a lot of people, incorrectly, a$$ociate lower rpm as meaning better fuel mileage. This is not always the case. As everybody has mentioned, if you leave the 3.54/3.55 gears in your truck and put 37" tires on it, the engine has to work harder to accelerate the truck from a stop. Why? Because it has to accelerate a tire with a significantly greater circumference and that same tire also weighs a great deal more, so there's more rolling resistance. If all you do is change the tires, you've effectively reduced the gear ratio (i.e. from 3.55 to 3.08, or even lower probably, for example). The engine has to work harder to accelerate the mass/truck, which means it's burning more fuel. At the same time, because you've effectively reduced the gear ratio, it'll be turning lower rpm for a given speed in all gears (as compared to what it turned with the stock tires), which might put the engine at an rpm range below its power curve, so even though it's turning fewer rpm, it's having to work harder (burn more fuel) just to maintain that engine rpm or speed. On top of that, you have reduced the gear ratio enough so that overdrive in the transmission is useless. Bottom line: lower engine speeds (rpm) does not always equate to better fuel mileage. People, these days (the era of overdriven transmissions) are afraid of turning an engine some rpm. They hear "4.56/4.88" gears and they cringe, even if you tell them you're going to run a 35"+ tire. 20 years ago, few trucks had overdriven transmissions (3 speed automatics and 4-speed non-overdriven manuals) and guys wheeled them up and down the highway with 4.10 and 4.56 gears (3/4 tons and 1 tons) with 31" tires all day long with no problems at all. Granted, not having overdriven transmissions, they didn't get quite the fuel mileage some of the trucks, today, get (whether the trucks today are a study in fuel efficiency is open for debate), but those trucks saw 3000+ rpm up and down the highway regularly with no known failures, with respect to the engines. The engines in our trucks (318s, 360s, 302s, 351s, 460s, 305s, 350s, 454s, etc.) are, basically, the same as what has been put in Chryslers, Fords, and Chevys for 30+ years, save for some updates.
Guys told me I was nuts, 10 years ago, for putting 4.10 gears in my street/strip, daily driver Mustang, with a 5-speed overdrive and 26" tall tires on it. They said I'd get terrible fuel mileage, etc., etc. I never had a problem and it got very marginally less mileage than it did with 3.73s in it.
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