[Mk2] [Turbo] Do I Have An LSD?

[matt_mr2t]

Afternoon every one. One thing I can never ever remember is what ways your wheels spin when you have an LSD.

I "think" it's opposite directions = normal diff and same direction = LSD?

I've had the car 4 years and never checked this. Took it for the MOT the other day and noticed when the inspector was spinning both my wheels (rear obviously) spun in the same direction.

Does this mean I have an LSD? It's a rev2 GT Turbo.

If i do, what benefit is there? It still seems to sling the back out with little provocation!

[Mike]

bu88er, I cant remember. I think that if they move together regardless of direction you have an LSD.
My Rev 2 GT has an LSD and I think they were standard on Rev 2 GT's

[Tom G]

LSD optional on rev2s, wheels spinning the same way when moved by hand = LSD. Benefits are improved traction since power goes to both wheels if one of them spins... this also means the back can be easier to step out under acceleration (as I found out last weekend )

[matt_mr2t]

So better traction = the back end stepping out?

That's like saying it gets dark when you turn the light on?

[C50]

So better traction = the back end stepping out?

That's like saying it gets dark when you turn the light off?

dont you mean dark when you switch the light on?

[mishadbull]

An LSD limits the ammount of rotational difference between the wheels. Imagine parking the car on a surface that has a very low coefficient of friction under one wheel and a high coefficient of friction under the other. In a car with an open diff when attempting to drive off the torque generated by the engine will chose the path of least resistance and the tire with a low friction coefficient will spin without the car moving.

However if the car was fitted with an LSD then the diff would limit the amount of low friction wheel spinning by forcing the wheel with a high friction coefficient to rotate and the car would pull away.

Now suppose you are in a corner and have planted the throttle. The inside tire has less traction due to wight transfer away from the inside of the corner. In an open diff equipped car the inside tire will spin up and the car will go around the bend in a relatively normal fashion.

In a car with an LSD due to the more equal distribution of torque, if the amount of torque is high enough then BOTH wheels can and will brake loose. This will cause the car to over steer, or drift.

Now at any given time there is a small variance in traction available to each wheel. In a hard launch condition the open diff car could spin one wheel resulting in a slower start due to transmitting power into heat and noise (the wheel spinning)

In the LSD equipped car the wheels will want to move together and the launch could be quicker due to BOTH wheels 'pushing' the car forward rather than just one.

For a much more in depth discussion:

Click HERE

Mike

[matt_mr2t]

So it's good for getting me off the line but bad at keeping me on the road in the twisty bits?

[mishadbull]

Only if you provoke it. Remember to brake BOTH loose will take more torque then one. Say at 25% throttle you can spin one up in a corner then with an LSD it would take say 40% throttle to brake both loose. This means you could go through the corner at 30-35% throttle and thus go through faster without any spinning of wheels.

Mike

[matt_mr2t]

So it's all about finding the point where it lets go.

Bit like these modern hypercar really. They inspire too much confidence, when they finally let go you tend to die

I think I'll just stick to taking it easy.

[mishadbull]

Best thing to do to learn your car is do some sort of airfield type track day. Bruntingthorpe, Bedford the like. These offer a great chance to give it some abuse with a small chance of hitting anything. Most offs happen into grass as there are no walls.

Mike

Like this one:

IMOC Trackday

[Razor04]

Afternoon every one. One thing I can never ever remember is what ways your wheels spin when you have an LSD.

I "think" it's opposite directions = normal diff and same direction = LSD?

I've had the car 4 years and never checked this. Took it for the MOT the other day and noticed when the inspector was spinning both my wheels (rear obviously) spun in the same direction.

Does this mean I have an LSD? It's a rev2 GT Turbo.

If i do, what benefit is there? It still seems to sling the back out with little provocation!

Heres how to tell if your 2's got an LSD (the easy way) open the bonnet, below the windscreen on the driver side you will see engraved the following: 735/E153. if the last digit before E153 is a 3 or a 5 the car has LSD, (E153 means: transmission heavy duty manual). if you dont have a 3 or 5 before E153 you aint got LSD cappiche? better than spinnin wheels around tryin to suss it.

[matt_mr2t]

Well the wheels have already been up and spud

[RobCrezz]

Do all Rev3 turbos have a LSD?

[mr2lad]

So to summerise, an LSD's purpose is to ensure that both wheels get an even amount of torque/power whatever the conditions, the aim being the car is always being propelled by two wheels, as it 'should' be? (even though in extremis, this may be less forgiving?)

[RobCrezz]

So to summerise, an LSD's purpose is to ensure that both wheels get an even amount of torque/power whatever the conditions, the aim being the car is always being propelled by two wheels, as it 'should' be? (even though in extremis, this may be less forgiving?)

It only locks both wheels to the same speed after it detects a certain amount of slip, hence "limited-slip". They arent locked totally or you would have real problems going round low speed corners as the outside wheel needs to be traveling faster than the inside wheel as it has further to go.

[mr2lad]

So to summerise, an LSD's purpose is to ensure that both wheels get an even amount of torque/power whatever the conditions, the aim being the car is always being propelled by two wheels, as it 'should' be? (even though in extremis, this may be less forgiving?)

It only locks both wheels to the same speed after it detects a certain amount of slip, hence "limited-slip". They arent locked totally or you would have real problems going round low speed corners as the outside wheel needs to be traveling faster than the inside wheel as it has further to go.

I'm with you. You know your stuff

[RobCrezz]

So to summerise, an LSD's purpose is to ensure that both wheels get an even amount of torque/power whatever the conditions, the aim being the car is always being propelled by two wheels, as it 'should' be? (even though in extremis, this may be less forgiving?)

It only locks both wheels to the same speed after it detects a certain amount of slip, hence "limited-slip". They arent locked totally or you would have real problems going round low speed corners as the outside wheel needs to be traveling faster than the inside wheel as it has further to go.

I'm with you. You know your stuff

Haha not really, know a bit of theory, but im a pretty useless doing anything mechanical! lol

[matt_mr2t]

I understand pretty much everything about cars bar limited slip diffs.
It's like some kind of magic happens between the wheels.

[RobCrezz]

I understand pretty much everything about cars bar limited slip diffs.
It's like some kind of magic happens between the wheels.

More info here if you are interested mate.
http://en.wikipedia.org/wiki/Limited_slip_diff

[Lauren]

I reckon Matt that the LSD on the tubby makes it more likely for many to crash. If there no LSD there would probably be less accidents.

However if you know how to exploit an LSD then its a fairly big advantage over an open diff. It means that you can steer the car on the throttle far more accurately, however of course this takes skill.

Learn how to do it on a track and then it won't catch you out on the road.