cobalt

Cool

You will be much happier with the 40/40.

alfredhu

Hi cobalt:

What is the difference netween 40/40 & 20/100? Why Cup car go for 40/40?

cobalt

There are probably quite a few here that can explain it better than I. But here is a relatively simple approach:

Two units were offered either the 40/40 which offers 40% lock up acceleration 40% lock up deceleration vs the 20/100 which offers 20% lock up acceleration with 100% lockup deceleration.

Because these cars have a heavy rear weight bias handling is helped by locking the rear differential under acceleration and deceleration loads. Varying locking values will help improved traction, less slip of the tires, either in a straight line or turn in adding additional stability. As the lock up is increased on deceleration it helps to keep the car from turning in more quickly than desired say if you were to lift slightly into a turn this will keep the back end more stable or planted.

Many early 930's were known as widow makers because the factory did not supply an LSD standard. Lifting into a turn at high speeds we all know will transfer the weight forward. Without an LSD the tires continue to rotate allowing the back end to come around more quickly since there is no resistance between left and right rear tires which spin freely with an open differential. As you increase the lock up between 40 & 100% this creates a resistance between the 2 rear tires limiting the amount of free spin in turn reducing the amount of turn in created by the shift of weight and an open differential. The turbos suffer from this more so than the C2's because of the added power and additional weight of the turbo which resides mostly over the rear wheels.

IMO the 100% is to much. The rear is far more stable than the earlier 930's but at a price. The car is very difficult to turn in when under hard deceleration. In order to get the car through tight quick turns you must be on the gas or the turbo 20/100 lock up will cause tremendous understeer. The 40/40 is much more balanced. Although I find that it might be a little to low on the decel side. I would think for these cars something closer to a 40/60% would be ideal.

So if I didn't butcher this and someone has some better clarification please add. But I think this should explain it somewhat.

alfredhu

Hi cobalt:

Thanks for your detail explaination! Here is a reply from the factory:

"I just got some message from our region office in Singapore.
They double check the type again and find your car is categorized as a Cup-car.
But it can be used as a 911 Cup or 911 Carrera RS.
Therefore, they would like to know which one is your preference. Please let me know.
In addition, for the color of Ruby star, it's translated from German "Sternrubin".
It also can be translated to Ruby Stone Red.
Please let me know what is your preference.
Thank you for your waiting and so apology again!"