Tall gears ( 4.11:1) are slow. You use slow gears to go quick.
Short gears ( 2.41:1 ) are fast. Fast gears are slow 'out the gate'.
I had a 2.41:1 on my 78 firebird. It was awesome on the hiway. I could dump it into first gear at 45 MPH and grab a car length instantly. Could leave it in second till near 90! Cruising at 60, I could dump it into second, and pass someone easy.
And I really gotta make a comment on the afore mentioned pozi comment..
Whether or not the rear end is positive traction, either locker, spool, clutch type... has no effect whatsoever on gear ratio. It only effects a tire which is slipping. At speed, a pozi rear feels just like an 'open' rear with exception to the fact that the 'open' rear does not 'pop' when going around turns.
It really surprised me that so many replies didn't catch that..
A little explanation for the dude whom posted the original question: and more that you never knew, and didn't want to learn:
An 'open' rear end has nothing to stop one wheel from spinning. If you loose traction on one side, that wheel will spin, and the other will not. All power will be effectively transferred to the spinning wheel. Not good for getting off the line.
Drag racers prefer a 'pozi' rear end. There are many designs. The detroit locker POSITIVELY LOCKS ( pozi ) the axles together under load. one side cannot slip. There are variations of the locker design. Most engage with a noticable CLUNK. Some can be engaged manually, most function automatically. Most are not street friendly.
Then there are limited slip.. these are often referred to ( incorrectly ) as pozi rears. Limited slip is also varied in design, but mostly they use either cones or clutches to create friction between the axles. They CAN turn independently, but must overcome the friction of the clutches/cones to do so.
OK. so WHY would one want the rear axles to turn independently? Well, if you are driving your car in other than a straight line, it is highly desireable. Why? because in a turn, the outside wheel is moving faster than the inside wheel. Now, if the axles can't turn independently, the outside wheel would 'hop' through the turn. If you have an open rear, as do most passenger cars, ( and my lawn mower ) your turn will feel as smooth as a straight line. BUT.. if you get in the mud ( or wet grass in the case of my mower ) one tire will inevitebly have SLIGHTLY less traction than the other. That tire will spin, and you will not move.
ENTER LIMITED SLIP.. I had a limited slip in one of my firebirds. The clutches were set to about 40 ft/lb. That means, that for the axles to spin independently, there would have to be over 40 foot/pounds of torque differential. This accomplishes several things... When I was stupid enough to put one wheel off the shoulder on my way to california, in the mud.. I was able to just drive away. Had I not installed the limited slip, then I would just spun a tire, and dug into the mud. Another thing I noticed limited slip does for you.. it wears out the inside of the rear tires. RAPIDLY. That rather sucks. And, my particular limited slip, would 'pop' when going into a turn, if I had run in a straight line for a while ( think interstate ) This is due to the gear oil getting slung out from between the clutch discs, so they get real good traction on each other. Then you go into a turn, and they 'pop' loose. Annoying. There are additives you can put in the gear oil which will help with this, but I didn't notice that they actually helped. And finally.. the real reason I put in the limited slip.. the car had a tendency for the rear to move sideways when I punched it. I thought the limited slip would eliminate this.. it actually made it worse.
One last nugget.. the 'spider' gears are what allow the axles to actually move independently of one another. An old dirt track trick ( cheap hot rodding ) was to weld the spider gears, so they couldn't move. Then, so the car wouldn't be 'hopping' through the round track, put a larger tire on the outside wheel.
