Not understanding LSD - how LSD works
08-04-2006, 09:41 AM
Post: #1
Not understanding LSD - how LSD works
another newb question but hey, I roll ina stock SR5. why is an LSD good for drifting? I thought the technology was invented to prevent tire slip instead of inducing it? I understand what it is and why it works, but can someone explain (without flaming) why it is so much better than an open diff?

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08-04-2006, 09:47 AM
Post: #2
Not understanding LSD - how LSD works
Because the tire slip it prevents is that of the inside rear tire, which during cornering is almost lifted of the ground. All power goes to that wheel easily slipping it, but the outside wheel doing all the work stays nice and planted and gets no more power->no slide/no acceleration

A wheel to steer the front of the car
A pedal to steer the rear
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08-04-2006, 11:27 AM
Post: #3
Not understanding LSD - how LSD works
I see Thumbs up!

1971 Ford Mustang
1984 Hachi-Roku

http://www.club4ac.com
slowest AE86 club on the net Smile
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08-10-2006, 07:13 PM
Post: #4
Not understanding LSD - how LSD works
sorry i dont understand. Huh
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08-10-2006, 07:27 PM
Post: #5
Not understanding LSD - how LSD works
hamsupjai,

Very simply put, when cornering your inner wheels and outer wheels turn at a different speed. So if both your wheels would be directly connected to your engine and turning at the same speed you would have a problem.

This is why they invented a normal differential, it allows the wheels to turn at different speeds, this maximises the effectiveness of both wheels. The problem with a normal differential is that when one of those two wheels no longer has grip for whatever reason (it lifts of the ground or when drifting) then that wheel that does not have grip gets all the power and the wheel that does have grip doesn't get any and that means no power is transmitted to motion.

So this is where LSD comes in. During cornering it allows the wheels to turn at different speeds just like a normal diff, but when one of the wheels starts to loose grip, and the speed difference between the two wheels increases, the LSD starts to lock the two wheels together. This way the wheel that has the most grip still gets power.

Depending on the type of LSD defines how this effect is produced and in which situations it works best.

Greetz,

Bastiaan "mux213" Olij

Moved down under, no more hachi Sad
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08-13-2006, 04:14 AM
Post: #6
Not understanding LSD - how LSD works
oh thanks mux that makes a lot more sense now because no hachi kinda confused me a bit there.
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08-13-2006, 09:57 AM
Post: #7
Not understanding LSD - how LSD works
then what is the difference between a 1 way, 1.5 way, and a 2 way? what other kinds of LSD are there?

1971 Ford Mustang
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slowest AE86 club on the net Smile
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08-13-2006, 11:29 AM
Post: #8
Not understanding LSD - how LSD works
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 amBig Grin

Greetz,

Bastiaan "mux213" Olij

Moved down under, no more hachi Sad
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09-13-2006, 11:53 AM
Post: #9
Not understanding LSD - how LSD works
Put some info about this in the technical thread and pointed to this thread so unsticking this.

The info is in the suspention part of the tech FAQ, not entirely correct but had to put it somewhereBig Grin

Greetz,

Bastiaan "mux213" Olij

Moved down under, no more hachi Sad
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09-13-2006, 11:56 AM
Post: #10
Not understanding LSD - how LSD works
Howstuffworks.com is a great source in understanding how stuff works (Duh..! Big Grin )!

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

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