LSDs vs ATB differentials.

[Kozy]

Having a discussion with a friend the other evening about our respective cars, and we got onto the subject of differentials. Mine has an aftermarket Quaife automatic torque biasing diff, and his has a factory clutch type LSD. We both wanted to argue that our respective systems was better, but both lacked sufficient knowledge in the area to come to an informed decision. Anyone want to shed some light on which is the better system? The cars in question are FWD.

[culver]

That actually isn't a question that can be answered easily. Either one could be better than the other and it would really depend on the details of the design. Clutch type difs can be easier to tune for racing applications. They also are commonly designed to be input torque biased like the Quaife. It is possible the factory dif would be better because it was setup and tuned by those who knew the chassis. Then again it's possible the Quaife is better because it doesn't have to meet any of the universal specs such as not scary for a novice to drive, 10 year, 150,000 mile life expectancy (or what ever it really is), slightly cheaper to keep the accountants happy, buyers already have a contract with that manufacture etc.

[khooper]

LSD limits the quantity of slide of the wheel that is trailing traction. Using this will give better traction going to the wheel with more grip.

On the other hand, An ATB differential essentially has a set of worm gears inside use to lock up and exactly transfer torque to the wheel that has the most amount of grip.

[culver]

But both the clutch type and helical gear types are limited slip differentials. Also but can work based on input torque. That is the bias ratio can be a function of torque to the dif with either design. Contrary to popular believe, the worm gear difs are not fool proof. They certainly don't always do the right thing when it comes to torque bias. I know this first had as I have a Torsen 2 in my car.