I'd like to use my Mulligan for this question?

[autobonrun]

I know there are questions the rookie diy'ers would like to ask but think they are too dumb. This is mine and I ask forgiveness in advance and I'll use this as a mulligan. Perhaps a mulligan day once a quarter would work.

I'm as interested in understanding how this car works as much as fixing it. In fact the former helps the later. I'd like to know if a 911 does not have limited slip and is driven from one wheel, why is a CV joint needed for the other wheel? Is it merely an added brace to help the semi-trailing arm?

I have a feeling the anwer is obvious and starts off with "Duh".

[emcon5]

Even without a LSD, both rear wheels are still driven. In general terms, an open differential will spin the wheel with the least traction, where a LSD will try and drive the wheel with the most traction.

To be honest, I really don't understand how a limited slip works. I know what it does, but how it does it is a mystery to me.

Tom

[autobonrun]

Originally posted by emcon5
Even without a LSD, both rear wheels are still driven. In general terms, an open differential will spin the wheel with the least traction, where a LSD will try and drive the wheel with the most traction.

To be honest, I really don't understand how a limited slip works. I know what it does, but how it does it is a mystery to me.

Tom

Thanks for the clarification. I started with a flawed assumption that only one wheel was actually driven.

And thanks for not starting with "Duh".

[88911coupe]

Check out www.howstuffworks.com I too was confused about the internal workings of a differential and it has cool animation that show how it works. TONS of other information...jet engines, transmissions, all kinds of things. I get stuck on the site forever looking at stuff.
Later,
Buck
88 Coupe

[beepbeep]

http://www.howstuffworks.com/differential.htm

[autobonrun]

These links are great. I just spent an hour reading the sections. With the complexity of the many systems in a car, it's a wonder they ever get out of the driveway.

For some reason, discussions I've heard about the "drive wheel" gave me the impression that only one wheel did the pulling. From the article, if you don't have LSD, or locking, you have an open differential, and equal torque is applied to each wheel, up to the maximum of the one that is slipping. From this writeup, assuming a car has enough torque, even one with an open differential should leave two streaks from a jump start. I had always thought this represented LSD or Positraction. I don't know if you guys saw the Joe Pesci movie, My Cousin Vinnie, but in it they used this dual tire tread argument in the courtroom.

[beepbeep]

If you really want to read about wierd mechanical devices, check out Torsen differential...

[RarlyL8]

There are several types of "posi" units for a differential.
Some use clutches, some mechanical, some direct (spool).

It is true that an open rear end will pull a posi off the line given enough torque from the engine. I have had two vehicles with modified V8s that would do this.

[Wayne 962]

The limited slip differential does just that - it limits slip when there is bad traction on one of the wheels. With a normal diff, if one wheel is on ice, or on wet pavement, then it might spin when accelerating. This is a function of the 'planetary-style' gea setup in a standard differential.

The LSD works with sliding disks or bands that function somewhat ina similar manner to how automatic transmissions work. They limit the amount of slip that the one wheel (on the slippery surface has), and move that torque over to the other side.

LSDs are best used for racing on autocross-type circuits where one of the rear wheels may have the opportunity to be raised off of the ground slightly by the normal banking of the car. The LSD brings more power to the wheel that is still firmly planted on the ground. Also allows you to alter your sway-bar suspension settings a bit more for optimum handling and balance, since you don't need to be concerns with keeping it super-stiff on the rear end (stiffer on the rear means that the wheel would be less likely to rise).

-Wayne