School me in LSD (1 Viewer)

[FLFJ40]

This vid was posted in chat and I asked a technical question about it, big no no.

http://www.youtube.com/watch?v=DYxUlroameU&mode=related&search=

I thought LSD's were supposed to put the force to the wheel with the most traction, why didn't it work? The video looks like the Dodge has no LSD's at all. Okay class is in session.

 

[Spud]

http://en.wikipedia.org/wiki/Limited_slip_differential

 

[SouthBostonFJ40]

It's bad for you and highly addictive.



Sorry, I couldn't resist.

 

[FLFJ40]

So I guess the Dodge had a Geared Torque-Sensitive Differential? Other than the chances of a clutch diff. suddenly locking up during spinning is there any other disadvantage?

 

[Blue77FJ40]

Don't bother with lsd diffs. Go locker, either auto or selectable, you'll be much happier.

 

[Letsgomoreplaces]

lsd

LSD is a limited slip differential. All they do is LIMIT the SLIP. With an open diff it doesnt take hardly any resistence for the tire w/ the least traction to break loose. Same is true with an LSD, it just takes more to get it to break free. Some use clutches that are preloaded to prevent the spider gears from spinning so easely, some use a helical gear setup that binds on itself and the case to prevent slip. The phrase "transfer power from the wheel that slips to the wheel that grips" is misleading, as all an lsd does is allow power to go to both wheels MORE often than an open diff. LSD's are quite effective and work well for most people, but not great for rockcrawling, as if one tire is on rock and one in the air, the traction difference side to side is too great for the LSD to stay hooked up to both tires. This is where a mechanical locker has an advantage, as they are fully coupled whenever throttle is applied, downside is they can be too noisy for many people.

 

[FLFJ40]

So basicly an LSD is just a locker that slips and how much it slips depends on the amount of preload in the clutches? The advertising out there and convetional wisdom muddies the water quite a bit. So LSD's don't transfer power all they do is slip sooner and more smoothly than an auto locker? What keeps an auto locker from slipping when so much torque is applied to one wheel as in the case of one wheel in the air?

 

[Downey]

(1) the rear diff in the Richmond video was either an open diff (deception), or a broken LSD, because LSD's don't work like that!!!!!

(2) Spud gave the long version, here's the short version. LSD's work on a "percentage of efficiency" where they can send more power to one side than the other, but not to the hideous extent you saw in the Richmond video. Typically the tire in the air could receive 70'ish percent of the power, while the tire on the surface received only 30'ish percent of the power. In the Richmond video, with a properly working LSD the tire on the surface would have continued to propel the vehicle even if it were only receiving 30 percent of the power.

(3) The thing that's really great about LSD's (besides being so incredibly highway managable) is that most the wheelin "most" people do is with both tires on the ground, with some vehicle weight on both tires (I know, exception is extreme rock crawlin), and in this case it really doesn't matter if one tire receives more power than the other because they are both on the ground.

 

[agent orange]

It's bad for you and highly addictive.



Sorry, I couldn't resist.

I was gonna say it is available in small tabs of paper or in liquid form, and can be enjoyable under the proper circumstances.

LSDs can only bias power away from the slipping tire by a certain ratio, aka if you have 10 ft/lbs of available traction to one tire you can only have say 40 ft/lbs to the opposite side with a bias ratio o 4:1. If there was almost no traction to the slipping side, then there could be very little traction to the other side.

Considering that one tire was one a roller with almost negligible resistance, then very little torque could be applied to the other side.