Thread: Explain gearing, posi traction etc...

Tweet

I will add a couple more things that will help explain. cars have differentials so they can go around corners better. GOing around a 90 degree corner, the inside wheel of a vehicle travels a lot less distance than the outside wheel. If the wheels were connected with a solid axle and tried to get through the corner at the same speed, one or both of the tires would have to slip to allow for the difference in distance. The differential allows the wheels to turn at different speeds. This is a good thing, except when one of the tires loses traction. When that happens the differential allows the spinning tire to take all or most of the power and the other tire just sits there. ( a one tire fire!) To remedy this, several different designs were developed, some use several clutches, others use gear combinations and others still use a ratcheting system. They are known by many names including positraction, Trac Loc, Detroit Locker, limited slip, True Trac and sure grip. These systems allow one tire to turn faster than the other, but they apply resistance to the event to reduce the chance for one wheel to spin wildly while the other barely moves. AS Techie said, since Granny does not often spin her tires, well most anyway, she does not need to spend the extra money for the traction device. You on the other hand love to smoke 'em so it is worth the extra coast for you.

Now the gear ratios. They work like a lever. The lower the gear, the longer the lever. If you need to move a heavy weight easily, you use a longer lever. It makes moving it easier, but you have to move the end of the lever further. A strong person may be able to move the load with a shorter lever. In the case of a car, if you want to make it easier to move, you use a lower gear (numerically higher). The trade off is, you will need to turn the motor more times to move the same distance. A big motor like your Pontiac 455 has lots of torque that come in at a fairly low RPM, so like the strong person, it may not need too low a great to get moving. Also a big motor has a lot of rotating mass that makes very high RPM dangerous, for the motors longevity at least. But that is a whole new topic. Bottom line is a posi traction with 3.23-3.55 gear ratio and 4 speed should snap your neck real good with that big Poncho pushing it. If you decide to go with an overdrive transmission, then you can go to an even lower gear maybe 3.42-3.90 and still have low RPM for freeway cruising. Hope that helps

Pat