i have a 2004 F250 V8 5.4 Triton with 3.73G. Does changing your gears to a 4.30 really help. what are the pros and cons.
I would think that if it does help, it would be on city driving but it would probably hurt you on highway gas milage. I keep hearing that changing gears by far is the best upgrade instead of spending my $$$ on intake and computer chip.
has anyone done this upgrade and were you satisfied. Any info would be apreciated.




Thanks
JC

 

Determining if gears will help or hurt really depends upon the size tires on the truck and what the intended use is. The ratio you have is a very good compromise for the stock tires size and should deliver about the best combination of power and milage, going numerically higher will help power some but it will hurt milage the same amount.

 

Basically for each .25 gear ratio change, the rpms will change by 300

 

This is one of the stupidest things I've heard today. The gear RATIO is just that a RATIO. The gear RATIO will not effect anything on the truck in any other way then as a RATIO.

Going from a 3.73 to 4.3 is a 15% increase, there for everything on the truck will turn 15% faster. If the engine is turning 2500 rpms at 60 mph then the rpms will increase 15% to 2875. That's a 375 rpm increase not the 684 as suggested.

As for gears effecting performance this change will probably slow your truck down. Here's why, the gear ratio increases the amount of torque aplied to the axle as compared to the torque at the driveline by the same ratio. But the truck can only use as much torque as the tires can put on the ground. So if you can spin your tires now then you can't use the extra torque. Conversely it increases engine and transmission RPM by the same ratio making the truck shift more often and sooner, slowing you down.

The only times I would suggest a gear change is 1st if you installed larger tires. In that case change the gears by the same ratio as the increase in tire diameter. 2nd if you are consantly towing/hauling a heavy load and can't spin the tires. In that case a gear change could help the truck accelerate from a stop. But that is the only advantage, everything else is a disadvantage, poor mileage, cost, extra wear on the truck, and the engine spinning so fast on the highway will drive you crazy.

Bottom line spend the money on a good chip from Hypertech they make the best stuff. It's your best first performance upgrade.