Gears

[jtoscano19]

Heyy guys when people say to put in different gears, what does it mean.
I'm hoping someone on here can educate me on this topic...

 

[The Assassin]

Generally speaking, when you upsize your tires, you suffer from loss of power due to the added rolling weight of said tires. In order to make up for this loss of power, people change the gears. The two most common gears are 4.10 and 4.56.


Copied from the internet:

A lower (numerically higher) gear ratio, such as 3.73-, 3.92-, or 4.10:1, provides more low-speed wheel torque, which means it takes less throttle to get the vehicle and the load it’s carrying or towing moving.
More low-speed torque at the wheels is a welcome help when the fishing boat is heavy, the ramp steep, or there’s a slide-in camper or load in the pickup bed in addition to a trailer of one sort or another in-tow.

(Diesels, because of their massive low-rpm torque, can get by with 3.55:1 or 3.73:1 ratios if trailers weigh less than 8,000 pounds.)
Wth a lower axle ratio you can ease into the throttle and the tow vehicle will respond a lot quicker than it would with the “highway” gears that come as part of the standard equipment.
A lower axle ratio also means your vehicle will accelerate quicker when pulling a trailer or carrying a load of passengers and cargo. Roll out from a stop light or merge into fast-moving highway traffic and you want a tow vehicle that gets up to speed quickly. A truck equipped with a lower axle ratio will do just that.
It’s for those very reasons I always buy a new truck with one of the optional axle ratios, typically 3.73s or 3.92s, when the primary boat being towed is less than 21-foot. This is especially true of a vehicle equipped with a V-6 or small V-8.
If I were towing a bigger boat, say a 24-28-foot sport fisherman or center-console, or hauling equipment trailers weighing north of 7,500 pounds,I’d get the optional 4.10s axle ratio if available. When towed weights get above 5,000 pounds, gasoline V-8s need all the pulling help available, and those 4.10s are just the right ticket. Aren’t I concerned about my tow vehicle’s fuel economy being hammered? No.

 

[jtoscano19]

So if I don't plan on getting bigger tires, I don't need to change the gears?

 

[glass3222]

Here is a very old, but good video on how a differential works. These gears would be what you swap out to get a different ratio.

[yt]K4JhruinbWc[/yt]

 

[truckin151]

No you don't need to change them. But if you have a 3.55 rear gear and put in 37" mud tires or larger you'll want them. They will help get it moving and will help with you mpg's as well. If your a speed junky like a lot of us are they are a welcome gain as well as you can speed up quite fast with less gas being pressed. I have 4.56's on mine and I have a 31.5" tire. Acceleration is outstanding and the mpg's went up a bit all around.

 

[NWRQC]

Just to add/clarify. When going to larger tires you don't lose power, you lose power multiplication. Same goes if you go with smaller tires, you don't gain power you just gain power multiplication. If you have a 345hp engine, it still produces 345hp with 31" tires or 44" tires. Gearing doesn't change the power output of the engine, just the multiplication factor.
Think of it like a 12 speed bike, 5 rear gears (transmission) and two front gears (rear end gear). If you look at the front sprocket of a bike you will see one larger gear and one smaller gear. With the larger gear selected, peddle through the rear gears (aka transmission)... riding the bike is ok, hills are a little hard but you can go fast downhill. Now switch to the smaller front gear and peddle through the gears. It's a lot easier to accelerate, but you cant peddle downhill as fast. Same thing applies to replacing the "Gears" in your trucks rearend. From the factory your truck comes with one of the two front gears on the bike. If you want to accelerate faster you can swap it for a smaller gear. If you get larger tires, you can swap the gearing to compensate for the larger tires. The transmission, rearend gears, and wheels are all just torque multipliers or deviders. You need gears to accelerate at a decent pace, or travel faster. If there were no torque multipliers then you wouldn't go very far very fast.
I believe a lot of reverse gears are a 1:1 ratio, meaning that there is no torque multiplication or divsion, you are running off the engines output. Imagine trying to drive around all day in reverse (obviously going forward)...thats why there are gears. I ventured beyond the rearend gears so I probably confused you, along with myself.. Hope some of this makes sense.

Oh if you don't plan to change your tire diameter, you will gain acceleration by changing the gear ratio from say 3:55 to 4:10

 

[The Assassin]

Just to add/clarify. When going to larger tires you don't lose power, you lose power multiplication. Same goes if you go with smaller tires, you don't gain power you just gain power multiplication. If you have a 345hp engine, it still produces 345hp with 31" tires or 44" tires. Gearing doesn't change the power output of the engine, just the multiplication factor.
Think of it like a 12 speed bike, 5 rear gears (transmission) and two front gears (rear end gear). If you look at the front sprocket of a bike you will see one larger gear and one smaller gear. With the larger gear selected, peddle through the rear gears (aka transmission)... riding the bike is ok, hills are a little hard but you can go fast downhill. Now switch to the smaller front gear and peddle through the gears. It's a lot easier to accelerate, but you cant peddle downhill as fast. Same thing applies to replacing the "Gears" in your trucks rearend. From the factory your truck comes with one of the two front gears on the bike. If you want to accelerate faster you can swap it for a smaller gear. If you get larger tires, you can swap the gearing to compensate for the larger tires. The transmission, rearend gears, and wheels are all just torque multipliers or deviders. You need gears to accelerate at a decent pace, or travel faster. If there were no torque multipliers then you wouldn't go very far very fast.
I believe a lot of reverse gears are a 1:1 ratio, meaning that there is no torque multiplication or divsion, you are running off the engines output. Imagine trying to drive around all day in reverse (obviously going forward)...thats why there are gears. I ventured beyond the rearend gears so I probably confused you, along with myself.. Hope some of this makes sense.

Oh if you don't plan to change your tire diameter, you will gain acceleration by changing the gear ratio from say 3:55 to 4:10

Great explination!

Sent from my DROID X2 using Tapatalk

 

[jtoscano19]

Thanks guys..so if i keep the stock 20's and change the gears it'll accelerate faster?

 

[TheSatinPumpkin]

From the posts provided i would take it as a yes.

 

[NWRQC]

Just to add/clarify. When going to larger tires you don't lose power, you lose power multiplication. Same goes if you go with smaller tires, you don't gain power you just gain power multiplication. If you have a 345hp engine, it still produces 345hp with 31" tires or 44" tires. Gearing doesn't change the power output of the engine, just the multiplication factor.
Think of it like a 12 speed bike, 5 rear gears (transmission) and two front gears (rear end gear). If you look at the front sprocket of a bike you will see one larger gear and one smaller gear. With the larger gear selected, peddle through the rear gears (aka transmission)... riding the bike is ok, hills are a little hard but you can go fast downhill. Now switch to the smaller front gear and peddle through the gears. It's a lot easier to accelerate, but you cant peddle downhill as fast. Same thing applies to replacing the "Gears" in your trucks rearend. From the factory your truck comes with one of the two front gears on the bike. If you want to accelerate faster you can swap it for a smaller gear. If you get larger tires, you can swap the gearing to compensate for the larger tires. The transmission, rearend gears, and wheels are all just torque multipliers or deviders. You need gears to accelerate at a decent pace, or travel faster. If there were no torque multipliers then you wouldn't go very far very fast.
I believe a lot of reverse gears are a 1:1 ratio, meaning that there is no torque multiplication or divsion, you are running off the engines output. Imagine trying to drive around all day in reverse (obviously going forward)...thats why there are gears. I ventured beyond the rearend gears so I probably confused you, along with myself.. Hope some of this makes sense.

Oh if you don't plan to change your tire diameter, you will gain acceleration by changing the gear ratio from say 3:55 to 4:10

Great explination!

Sent from my DROID X2 using Tapatalk

Thanks, glad it made sense.

Thanks guys..so if i keep the stock 20's and change the gears it'll accelerate faster?

Yes

 

[glass3222]

yes, if you go to 4.56 gears you will be able to accel faster, but you may/will spin easier.

Do you have 4x4 or rwd? If 4x4, you will have to swap both front and rear diff gears which adds to the cost.

 

[jtoscano19]

2wd and how much is it to do the swap?

 

[glass3222]

2wd and how much is it to do the swap?

it varies on location, but I would expect 700-1000

 

[jtoscano19]

that's not too bad...I'd probably do it to spin tires easier

 

[truckin151]

Just swap to a wider tire, it wont completely tame the gears but it will help.lighting them up from a stop is fun, lighting them up at every stop light because your tires don't stick not so much

 

[NWRQC]

Just swap to a wider tire, it wont completely tame the gears but it will help.lighting them up from a stop is fun, lighting them up at every stop light because your tires don't stick not so much

+1 here. wider is good. .
My recommendation is if you go up in tire size, go down(numerically higher) in gearing, or go down in gearing and go wider on tire size.

 

[jtoscano19]

What tires are good? I was looking at the nitto 420's
and what size would be good to spin easy, cuz right now with the stock goodyears its really hard to break them loose.

 

[Prism]

You can also drop your wheel size down to a 17" or 18" wheel(less weight than a 20") which in turn means less rotational mass = easier to move vehicle with less power. This same thing applies to tires too(smaller tire = less weight). If you go with a smaller tire you; in theory; change your overall gearing and that helps too. So if you go from a 33" tire w/3.92 gearing down to a 30.5" tire w/3.92 gearing then those smaller tires help the gearing seem more like 4.10 gearing or a little steeper.

You will notice a difference. I had an 04 Ram with 3.92's and 275/55/20's(about 32" tire) on the factory 20" wheels(aluminum) and tested them against the basic factory 245/70/17's(about 29.5" tire) on the factory 17" wheels(steel) and my truck was consistently .2 sec faster in the 1/4-mile everytime.

 

[truckin151]

What tires are good? I was looking at the nitto 420's
and what size would be good to spin easy, cuz right now with the stock goodyears its really hard to break them loose.

The stock crapyears were the easiest by far to spin. It was like they were never there

 

[jtoscano19]

they do spin but only a little bit