Quote:
Originally Posted by bradleyland
Yep. Drifters take it one step further though, because they're not concerned with slow speed handling. They just run something called a spool, which has no differential gears at all. It has a mounting place for the ring gear attached to a solid rod, and female splines for the axles to slip in to. Here's a giant one from a truck:
http://image.4wdandsportutility.com/...easurement.jpg
Drifters usually run spools, which introduces another effect that actually makes the rear end very loose.
As you increase the amount of lock, you can also end up with something called scrub. People call it different things, but scrub is when your tires skid during turns because the amount of differential resistance exceeds tire grip. This only happens with certain types of LSDs though, and you don't usually see them in use on street cars (more often off-road). The one from BMW isn't going to scrub at all. In a race car, you really don't want scrub, because it reduces rear-end grip in tight corners.
A tire loses grip very quickly once it starts to skid, so the scrub that occurs with a spool will actually cause the rear end to be more lose than if you had an open diff. Drifters love this side effect though, because it makes it easier to get the rear to step out.
The other place you see spools and unsophisticated LSDs that scrub are in off-road vehicles. My dad has an old beater Suzuki Samurai with a spooled rear end. It's a beater truck for out at the ranch (in Central Florida). It is amazing how much more you can drive through (mud, sand, etc) with a spooled rear end, but when it comes to turning around, it's a nightmare. The front tires just want to slide. When you're driving on dirt roads, you have to be careful too, because it will snap oversteer on you at medium speeds. Sure is fun though  |
Brilliant writeups, Bradley. Thx for posting.