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RWDboy Forums Junkie Location: South Australia Registered: July 2002	Re: whats a LSD? Tue, 09 March 2004 01:40 Quote: does your text state what happens when traction is lost in an open diff, or is it just assuming it isnt? what does it say about LSDs or locked diffs? Okay okay...I was going to drop this, but yes the book does state stuff about locked diffs and limited slip (quaife/torsen/viscous you name it) if you read up in this thread bit you'll see that I've already quoted it as saying locked diff's torque distribution varies according to numerous factors. Now, I think people are forgetting (or maybe never learnt, I dunno) Newtonian physics...well at least I think it was Sir Isaac Newton who came up with this, but the statement pretty much says 'Any action will have an equal and opposite reaction' this could be worded that 'Any force will have an equal and opposite reacting force'. In this case we are talking about the FORCE at the wheel (yep - torque is a FORCE, well pretty much anyway). Locked diff example : So, you are punting around a corner and lets say one wheel is up in the air, or even just spinning up due to loss of traction - call it "wheel A". 'Wheel B' is still on the ground gripping perfectly. Sometimes the easiest way to measure how much force something is receiving is to plot it's reaction using Newton's laws. What is Wheel A doing? Answer : Pushing a car. What is Wheel B doing? Answer : Spinning a little bit in the air, pushing nearly nothing at all. A little more indepth : Firstly, rotational acceleration occurs with the application of a force (ie torque), that is when a wheel is spinning up faster and faster, it must be receiving torque. Now wheel A and B will always rotationally accelerate at the same rate due to the fact that they are locked togetherm this means that they always travel the same distance as each other. Wheel B is having to push the car forwards using the friction between the road and the tire...it is doing alot of 'work' -> work has dimensionality of mass, length^2 and time^-2. Wheel B is pushing the mass of the entire car, over the same length (due to the locked rotational velocity of the two wheels) and over the same period of time as Wheel A...meaning that Wheel B is CLEARLY doing alot more work because Wheel A only has to rotate itself and isn't pushing anything but air (alot less *mass* than Wheel B has to push forward). Work is also equal to Force * Length = so if the length is the same (due once again to the locked rotational velocity) then if Wheel B is doing more work than Wheel A, it must be receiving much more FORCE than wheel A to balance out the equation. Torque (a 'twisting' moment/force) is that force. It is entirely true to say that wheel B is getting far more TORQUE than wheel A -> so this is the argument that a locked diff does not distribute torque evenly....especially when a wheel is off the ground or slipping (when it is slipping, it simply means that the tractive effort of wheel A is less due to the lower co-efficient of friction between road and tire, meaning that wheel A is still doing less pushing - ie less work - ie less force - ie less torque). As for open diffs distributing torque evenly? Okay that's a complex thing to argue...it theoritically does, but here's another quickie. When you start spinning up 'one' wheel does the engine suddenly start to rev up? Yeah it does. Force and torque don't disappear, it's impossible...the amount of torque that the diff applies to the wheels will *definitely* diminish when one of them loses grip, but it is still evenly balanced between the two! What happens to the rest of the torque you ask? Well it just so happens that it acts on the crankshaft/propshaft/everything (edit) ***That is wrong*** the energy actually is being used to work against gas compression and expansion etc etc, but the effect is the same, the engine starts speeding up! (/edit) else causing the engine revs to rise. The torque stops acting on the diff, and starts acting more on the engine. Here's a couple of links to some physics tutorials that may or may not help clear things up. A very math's like torque tutorial A slightly clearer explanation of torque A list of physics tutorials that the second link is from The final link has some links to explanations of rotational motion etc etc. When you have read and understood these principals and what torque is and how newtonian physics works, then you can continue this 'argument'. [Updated on: Tue, 09 March 2004 01:48] [Report message to a moderator]

	Subject	Poster	Date
	whats a LSD?	crayz legz	Sat, 06 March 2004 07:40
	Re: whats a LSD?	Intensevil	Sat, 06 March 2004 07:56
	Re: whats a LSD?	crayz legz	Sat, 06 March 2004 07:57
	Re: whats a LSD?	Cool1	Sat, 06 March 2004 09:38
	Re: whats a LSD?	mrshin	Sat, 06 March 2004 10:20
	Re: whats a LSD?	crayz legz	Sat, 06 March 2004 11:08
	Re: whats a LSD?	crayz legz	Sat, 06 March 2004 11:15
	Re: whats a LSD?	HYP04A	Sat, 06 March 2004 11:23
	Re: whats a LSD?	Fattony	Sun, 07 March 2004 17:27
	Re: whats a LSD?	HYP04A	Sun, 07 March 2004 21:07
	Re: whats a LSD?	RWDboy	Sun, 07 March 2004 21:21
	Re: whats a LSD?	Norbie	Sun, 07 March 2004 23:20
	Re: whats a LSD?	RWDboy	Mon, 08 March 2004 04:22
	Re: whats a LSD?	RWDboy	Mon, 08 March 2004 04:55
	Re: whats a LSD?	oldcorollas	Mon, 08 March 2004 07:48
	Re: whats a LSD?	justcallmefrank	Mon, 08 March 2004 05:58
	Re: whats a LSD?	RWDboy	Mon, 08 March 2004 06:36
	Re: whats a LSD?	Hot Celica	Mon, 08 March 2004 06:44
	Re: whats a LSD?	RWDboy	Mon, 08 March 2004 06:50
	Re: whats a LSD?	Hot Celica	Mon, 08 March 2004 07:02
	Re: whats a LSD?	ed_ma61	Mon, 08 March 2004 09:26
	Re: whats a LSD?	GOT_M.I.L.F.	Mon, 08 March 2004 12:18
	Re: whats a LSD?	THE WITZL	Mon, 08 March 2004 12:27
	Re: whats a LSD?	RWDboy	Mon, 08 March 2004 12:45
	Re: whats a LSD?	Norbie	Mon, 08 March 2004 13:30
	Re: whats a LSD?	T APLUS 22	Mon, 08 March 2004 14:38
	Re: whats a LSD?	RWDboy	Mon, 08 March 2004 13:48
	Re: whats a LSD?	Norbie	Mon, 08 March 2004 13:52
	Re: whats a LSD?	RWDboy	Mon, 08 March 2004 14:20
	Re: whats a LSD?	T APLUS 22	Mon, 08 March 2004 14:33
	Re: whats a LSD?	Zhyr	Mon, 08 March 2004 22:02
	Re: whats a LSD?	HYP04A	Mon, 08 March 2004 22:24
	Re: whats a LSD?	ae95	Mon, 08 March 2004 17:29
	Re: whats a LSD?	RWDboy	Tue, 09 March 2004 01:40
	Re: whats a LSD?	Seadog	Tue, 09 March 2004 04:35
	Re: whats a LSD?	Seadog	Tue, 09 March 2004 04:56

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