LSD and straight line traction (RWD)?

[ian_uk1975]

I've done some Googling, but opinion seems to be divided.

In simple terms, does a limited slip diff (Jag Powerlok, to be exact) help with traction in a straight line compared to an open diff? Is it a significant difference?

I know all about the benefits of an LSD in cornering, so don't need that to be rehashed... just not clear on the straight line aspect. From what I understand, the answer would be 'yes' because when launching the car, it's unlikely that both wheels would lose traction at exactly the same time. This being the case, the wheel that loses traction first would receive more drive through an open diff whereas an LSD would attempt to send more torque to the other wheel to balance things out. Is that right? If so, I could imagine in a real-world scenario, that a RWD car with an open diff could easily end-up fish-tailing down the road when launching hard, whereas the same car with an LSD would just stick and go, or just light both wheels up with the car tracking in a straight line. Sound right?

[TheEnd]

yep, on an open diff, if a wheel spins, the power escapes that way, but a limited slip diff will only allow a certain amount before it locks both wheels together (or comes close to it)

[Richyvrlimited]

ian_uk1975 said:

If so, I could imagine in a real-world scenario, that a RWD car with an open diff could easily end-up fish-tailing down the road when launching hard, whereas the same car with an LSD would just stick and go, or just light both wheels up with the car tracking in a straight line. Sound right?

Exactly what you said, it improves grip even on a straight line, but there's likely to be no fishtailing with the open diff, just you sitting there not moving whilst 1 wheel spins merrily away.

You'll fishtail with the LSD and both wheels spinning tho...

[anonymous-user]

The rear wheels are never equally loaded on a hard launch, because the engine torque has to be "reacted" somewhere. (look at the "twist" in a drag car for the ultimate expression of this fact ;-). But even for a road car, one wheel will be unable to apply the same tractive effort as the opposite side one. Also in the real world, road surfaces have imperfections and varriable friction. A "Stiff" LSD will enable the maximum tractive effort to be applied to the road under all cases. (but as mentioned, when you do eventually overwhelm both tyres, the back of the car is much more susceptable to drifting down the camber etc, as both tyres will be spinning, rather than just one)