Not understanding LSD - how LSD works

[Mux213]

surfingdrums,

well I'm a bit fuzzy on that one but it has to do with how it locks on acceleration and deacceleration. I believe 1 way only locks on acceleration. Locking on deaccelaration doesn't make sence when you want to keep both wheels gripping the tarmac, locking on deaccelaration in a corner could cause one wheel to loose grip because the other wheel is turning at a different rate and 'pulling' the first wheel to turn at the same rate. That can lead to easier sliding.

2 way means that you have full locking on both acceleration and deacceleration.

1.5 way means that you have full locking on acceleration but parcial locking on deacceleration (the diff does try to match both wheels speeds but it will always allow a difference in speed)

As for other types, you have the method in which locking is achieved.

Our hachi's come with clutch LSDs. This means that there are little clutch plates within the LSD. Think of these as brakes, the more difference in speed there is between the left and right wheels, the more these brakes lock the two wheels together. Note this all happens within the diff so there is no braking of the speed (get yourself a lego technics set, they have an open diff setup that really shows you how it works if you imagine the gears inside being locked by some sort of braking mechanism).

Then you have viscous LSDs, these work just like a viscous coupling in an automatic gearbox. The left and right wheel are linked by a fluid, if both wheels are turning at equal speed the fluid doesn't move, when the wheels start moving at different speeds the fluid start being pumped around. By this pumping the fluid gets friction by resistance build into the system, the bigger the difference in speed between the wheels, the higher the speed of the fluid, the more resistance is build up, the more the fluid resists the difference in speed in the wheels (thus viscous LSD never fully lock, thus viscous sucks for drifting).

Then you have torston diffs or whatever they are called, always forget the name. They work by gearing, I still don't understand how they work exactly. I only know they only work aslong as both wheel still have atleast some grip. The wheel with the least amount of grip will magicly increased the amount of power on the wheel with the most amount of grip. But when one of the wheels looses grip completely, all power to the wheels is lost.
This is why torston diffs are very common on 4wd (subaru is torston if I'm not mistaken) and in rally, they ensure all that grunt doesn't go to waiste.
But they suck for drifting because as soon as you start to slide the wheels will loose power and start gripping again.

There are probably some other types of diffs but the above 3 are the most common.

Atleast the above is the theory as I've understood it, I'm far from an expert so please don't shoot me if I'm wrong cause I probably am