Gearing for the 5th gen 4runner

I want to Regear my 5th gen 4runner. Are 488 the way to go? I just lifted my truck and installed rock sliders and my gas mileage it pretty bad. And I’m planning to put my mods on it.Maybe regearing it would do the trick.

 

At this point, i do not think anything you do will give you back your gas milage, if you play you pay.

 

Did u increase tire size?
A differential has three major purposes, one is to change the direction of the energy transmitted through the spinning drive shaft 90 degrees to the axles...the second is to distribute the power effectively to each axle, the third is gear reduction....
Gear ratios are designed from the factory to distribute the energy in the form of torque made by the engine to the wheels in the most efficient way possible, meaning, the most revolutions of each wheel at a given circumference/per unit of fuel burned. So with the goal of overcoming inertia, friction and aerodynamic resistance; so that the vehicle can achieve an effective rate of acceleration and speed in order to be useful.
The transmission facilitates the most efficient portion of the torque curve of the engine to be used over and over in each progressive gear to increase the speed of the wheels. The differential along with the transmission distribute the engines torque curve effectively to the wheels while mechanically sharing the job of gear reduction and allowing the mechanical components to be of a size and shape that is practical for the automotive application. The laws of physics dictate that mathematically there is a magic number for efficiency that is a combination of the gear reduction in both the transmission and differential to match the torque curve of the engine to achieve a set of performance specifications. If the size and torque curve of the engine, the gear ratios in the transmission to match the engine, and the wheel size, are the constants in the formula for efficiency, then the differential gear ratio is the variable. If u change the tire size, the gear ratio will have to change to maintain the highest level of efficiency. If it is not adjusted to balance the equation, then the mechanical system or (drive train) has been altered from its most efficient configuration, and so will be altered the amount of energy in the form of torque required to achieve the given level of performance, and thus the fuel consumption value will be affected. Conversely, if the fuel consumption per unit of overall wheel travel is to remain constant the performance will be affected. The differential is an accessible place in the system where small incremental adjustment to the overall equation can be achieved to effectively alter performance and efficiency while maintaining design shape and function of the rest of the system.
So... yes, changing the gear ratio can bring your system back into an efficient configuration, just keep in mind that anytime u change any variable in the system there is always a trade off. The trick is finding the right adjustment to achieve the desired effect on performance. By adjusting the gear ratio you may regain the torque and acceleration u lost with the increase in tire size as well as allowing the engine to operate back in the most efficient part of its power curve. Or in effect rebalance the equation! Good luck!

 

Well said.

 

Damn @Samson72 i didn’t think I’d get a physics lesson coming to 4runners.com this morning

 

Thanks for that reply Sam. I going to regear

 

How bad is your gas mileage suffering after just lift and sliders? My mpg loss has been minimal with tires, lift, sliders, skid plates, roof rack, and a few other mods. Maybe I don’t drive enough to notice how bad it really is.