Gear Ratio??? What If????

[Maverick]

i have a 96 1/2 ton 2wd Chevy and i think it has a 3.08 ratio, if i put like a 3.73 in it what could i expect or should i leave it alone????????

[1995C3500]

373 with increase towing capacity and lower mileage basically, its all in what you need the truck to do.

[mudseeker]

higher gears are used in bigger trucks that do alot of towing and off-roading. it would be best to leave it unless you do alot of towing. being 2-wheel i don't think you do alot of mudding.

[75K30]

Are you wanting to lower your gears for a specific purpose? Lower gear ratios ( numericaly higher ) will giver you better acceleratoin, and sacrifice gas mileage (to some degree). The 3.73:1 ratio that you are considering, will up your RPM's at highway speeds resulting in an overall decrease in economy. You will however notice a considerable "seat of the pants" fell in a quick drive from point "a" to point "b". Kinda feels like the truck is makin more power. 3.73:1 complete rear axles (for your truck, no posi or anything) can be found in wrecking yards for not too much cash, and are much easier to change out than a gear set. Try to locate one, so you can "experiment" with the ratio. The worst that could happen is you don' t like it, and you switch it back. Sell the one you just bought, and re-coup some money. If you change gears only, it will be real tough gettin any dough back if you change your mind. Just a thought. do you have any buddies with a truck similar to yours, (with a lower gear) that you can drive to see the difference?

[corey]

Originally Posted by 75K30

Lower gear ratios ( numericaly higher ) will giver you better acceleratoin

That's wrong. Lower Gears (numerically higher) will give you better torque, hence the improvement for towing (and decreased gas mileage). Higher gears (numerically lower) will give you a quicker jump off the line and better gas mileage. I agree that unless you've got something heavy to tow, I'd leave it.

If you do decide to change your gears, you'll also need to change your speedometer to compensate. Otherwise, you'll be doing 70 and it's gonna read 60. Then "the man" is gonna bust you. Not sure how the silverado calculates speed. My old jeep is just a little gear on a cable. Swapped it out when I went to 33's.

[bradrhale]

i disagree. the higher the torque, the more shove off you will get because it is easier to get the vehicle into motion. higher horsepower will give you more top end speed. the lower the gears, the faster off the line. the higher the gears, the faster your car will go once it gets up to speed. higher gears will give you a little better gas mileage but will hurt in stop and go traffic.

[corey]

That's fine. But go drive a 5.3 with 3.23 gears and then drive a 5.3 with 3.73 gears. You'll see which jumps off the line faster (hint: the 3.23). I know, because I drove both 4 weeks ago when I was test-driving prior to my purchase.

Logically, let's assume the transmissions are the same and let's assume a 1:1 transmission gear for 1st gear, for simplicity. One driveshaft has to spin only 3.23 times to get the rear wheels to make 1 full rotation... versus... the driveshaft spinning 3.73 times to get the rear wheels to make 1 full rotation. The 3.23 rearend will complete a tire rotation in less time than the 3.73 would. After 10 full tire rotations, one vehicle will have rotated the driveshaft 32.3 times and the other 37.3 times with the engine and transmissions doing the same amount of work. Does this make sense now? I promise this is the way it is. I've dealt with jeeps for 9 years. Seeing one go from a 3.27 gear set to a 4.56 is a huge gap, and it's very noticeable which set up has the "get-up-and-go" off the line and which one has torque (towing capacity - higher RPMs at slower speeds).

[bradrhale]

the more power you have at the line to put down on your tires is going to decide how fast you accelerate. if your engine is lugging behind trying to turn that rear wheel by turning a driveshaft 3.23, you would want it to turn 3.73 times so that it takes some of the load off. its just like a bicycle man. if you got a 10 speed back, how fast are you going to take off in one of your top end gears like you are talking about?? your not!! its going to take everything you have just to turn the pedals once. but if you put it into of the lower gears, where you have to turn the pedals (driveshaft) more, your going to raise up the front end and take off like a rocket.

[corey]

http://www.webejeepin.com/Gears.htm
paragraph 3 - "Lower gears will move your vehicle slower than higher gears, given the same engine RPMs..."

[75K30]

corey: you are barkin up the wrong tree, that link you posted is correct, but that is based upon simple ratios, not acceleration. If your argument was correct, then drag cars would not have such steep rear end gears. It is this lower ratio ( numerically higher ) that gives the vehicle an advantage from a dead stop. Remember, torque gets it going, horsepower keeps it going. Add a lower gear, and you have created a mechanical advantage, by multiplying the torque. The outcome is a better 60' time, E.T. and miles per hour will stay about the same, only the engine R.P.M. will differ.
As far as your comparrison with the silverados, unless they were side by side, one could not make a decission from the seat of ones pants. All things being equal, the truck with the lower gears (numerically higher) will out accelerate the other...every time.