Wilburwm

lol, I just bought a rear end from caliper to caliper off a 98 z28 to put in my 89 Trans Am. I did it cause I got it for a trade that ended up costing me nothing.

Now from what I have been told, the new rear end's gear ratio is 3.73:1 and the old one is 2.73:1.

I was told that that means that the gear has to turn 3.73 times for the wheel to turn once.

So what is the better one to have? Sounds like the new one is gonna eat more gas, but give me a higher take off speed. But the old one is gonna be better on gas and give me a higher top speed.

I new to rear ends and am just trying to learn. What do you guys know?

Thanks,
Wayne

IHI

iTrader: (1)

Since you have the OD tranny now and are sticking with an OD in the future, if in fact you do have a 3.73, you scored big time over you old cogs. You will definatley have more out of the whole which is a big plus when running the stop lights & 1/4 mi. drags. You will lose a little mpg, but that should not even affect the results you'll get from the smile you'll be wearin once your done. The easiest way to see what ya got, especially since it's out of the car, is to remove the rear cover. There will ne 2 numbers stamped into the ring gear on the outside edge, divide the second number by the first number and that's your gear set.

joshp14

First of all, you have to obviously know that the driveshaft goes into the differential. The driveshaft turns a pinion gear, which it turn, turns a ring gear. This ring gear is connected to the axle which in turn, spins the wheels.

When someone says "I have three forty two gears," this means that the differential gear ration is 3.42 to 1...meaning, like you said, that the driveshaft has to turn 3.42 times in order for the wheels to turn once.

There are many many different gear ratios. It gets kinda confusing because when you have 4.10 gears, you have low gearing (numerically higher), and when you 2.73 gears, you have high gearing (numerically lower).

The higher the number (numerically) means that you will have quick off-the-line movement, will be running higher RPM's at higher speeds, and you will comsume more gas, and your top-speed is reduced.

The lower the number (numerically) the slower you are off-the-line, you have lower RPM's at higher speeds, causing better gas mileage, and a increased top-speed.

If you have a 6-spd tranny, you can take advantage of both off-the-line quickness, and top end because the gearing in the 6th gear of the tranny drops your RPM's significantly. (I run 1600 RPM at 80MPH in my 95 TA and I have 3.42 gears )

So what you have said in that little paragraph is true and above is the explanation why. Hope this helps...

Josh

Wilburwm

Perfect! Thanks! They should make a rear end that can change, lol. Cause now I want both, lol.