Yes, considering the 3spd has no overdrive.

 

so the 2.75 gears were basically setup just to be driven on pavement or a gravel road? how do you know if you need a gear swap?

 

I'm really liking the idea of having someone like this 75F350 guy around for all those important things that sometimes get overlooked. That was quite the post! So what do you think the 351-400,460 class of 4X4's run for RPM's at highway speeds assuming they run 4:10's or 4:56's I love the idea of having a butt load of torque for the offroad/working part, but how bad do those things pound down the dino-juice running rear ends that tall?

Sorry Dr. Dirt, didn't mean to interrupt, we posted pretty close to one another...

 

Believe it or not having a proper gear ratio is pretty decent on mileage.
See, with the numerically lower gear numbers. (higher ratio) the vehicle has to work harder to accelerate thus minimizing efficiency.
Remember 10 speed bicycles? Try to pedal one up a hill using the high gears. Real tough on the legs right, and it uses quite a bit of energy. Cant go real fast up hill either. So, click the shifter and create a mechanical advantage, and not you turn the pedals much easier and can make some progress. While the pedals are turning faster, (more rpm) they are much easier to turn, and progress is easier to achieve. While you still might be turning the pedals more, with the mechanical advantage, you still use less energy.
The same is true for your engine. Even though the engine spins at a higher rpm while at cruise speeds, the thing does not require as much throttle to accelerate, and the vehicle feels light because it has to use less energy to get going, and to stay motivated.
There is a threshold, and this can be reached, but I seldom see vehicles running ratios in the 6:1 range, but even these ratios are not that extreme when we take into consideration the added weights of 4x4's and large tire diameters.

A 3:1 ratio would net just over approx 2500 rpm. at cruise speeds.
In order to obtain the same overall ratio with w 35" tire, one would ave to install a 4.10:1 ratio. This would make the overall ratio the same, so step it up one size and run the 4.56's and every engine that tries to turn this combo will perform better.
Sure a larger or higher horsepower engine an do it with a different ratio, but the better ratio will always be the better performer.
Will gas suffer? Yes, but this is so minimal, and if the vehicle is ever driven around town, or on anything other than level surfaces, the ratio with a mechanical advantage will be better every time.

 

Awesome, thats the simplest anyone has made gearing sound. I think thats the first time I've heard anyone use the bicycle analogy. So does this apply to newer fuel injected vehicles too? Would swapping the 3.55's out of my Dakota for 4.10's drop the fuel economy at all(or much)? I know people who swap gears in their Dakotas and say the throttle response and off the line acceleration was affected WAY more than any engine mods did. P.S sorry for the Dodge mention but this seems to be a general performance type thread....

 

because the "other truck" is light you will gain acceleration advantages far more than any little bolt on engine mod. You probably will not sacrifice in overall mileage.
This 3.55 to 4.10 ratio change will only change the rpms by a little over 400 rpm.
Wanna save some gas????? Slow down. Yup, instead of cruising at 75 or 80, slow down to a reasonable speed, and save gas.
The acceleration advantage will blow you away, or at least the guy next to you.
Cool part is that you cant see gears, so this is a little speed secret. Keep the other guys guessing. They will never see you coming, and if they are not properly equiped, they will only see tailights. Yours!!!

 

I have to say, 75F350 has hit the nail on the head. I did that with my '77 F150. Changed the gear ratio from 3.5 to 4.56 and was taking everything, and I mean EVERYTHING, off the line at the dragstrip. Funny part was everyone thought I had this huge V-8 under the hood. Nope, just a little 300 six. Gear ratio is everything, and more.

 

you have a excellent point so will put in new gears wich i dont have the slightest idea on how to do so what ratio should i run

 

More like it's made for all highway driving without heavy loads (i.e. a F100). You get low RPMs and better fuel economy while driving on the interstate, but you will fall face first taking off a dead stop. Since you have a manual, it's slightly better in that regard.

It's how you want it to perform that will affect the decision to stay with the current gearing or swap out.

75F350 and 3004me give good examples.