F1 differentials

[kang]

During F1 practice this last weekend, there was a segment on the steering wheels. They showed three knobs on the wheel and said they were for controlling the differential, but didn’t give any more explanation than that. They also mentioned that these came into play after the removal of traction control. I’m thinking that they have some variation of what we usually call a limited slip differential, and these knobs control the amount of slip under acceleration and deceleration (braking or over run) (like varying it from 80/60 to 60/40 or whatever). That would explain two of the knobs, what about the third? What does it do? Plus, even if I’m right, that just explains what two of the knobs do, not how they do it.

Does anyone know more about these real-time adjustable differentials? What do these three knobs do and how do they do it?

http://en.wikipedia.org/wiki/Limited_slip_differential

On another note, I was under the impression that limiting the slip during deceleration (braking or over-run) was useful in preventing trailing throttle oversteer. This article seems to imply the opposite: “An inexperienced driver can easily spin the car when using a 2 way LSD if they lift the throttle suddenly, expecting the car to settle like a conventional open differential.” I thought a limited slip helped prevent spins when you lift throttle suddenly, by preventing the outside wheel from spinning way faster than the inside wheel, thus keep the car on a straighter line that if the outside wheel were able to spin as fast as it could.

[masraum]

I think the deal with not having as much lockup for deceleration is that when cornering, if you have a high % lockup and then let off when cornering both tires will have a greater tendency to want to slide resulting in TTO.

[Aerkuld]

Is this any help...

http://www.f1technical.net/articles/30

I know that several of the things on the steering wheel will not be there anymore, but the diff settings may be somewhat relevant.
There is one switch for diff function selection, then a second button for 'diff +' and another for 'diff -' which would account for three differential controls.

[johndglynn]

I was talking to a Brembo guy at Silverstone today about the Super Touring cars, the huge front discs and motorcycle rear discs they used and Audi's differential braking systems. Fascinating conversation and I found this interesting link when I got home.

[Eric Coffey]

Originally Posted by kang

Does anyone know more about these real-time adjustable differentials? What do these three knobs do and how do they do it?

AFAIK, the new F1 diffs are electronically controlled and hydraulically actuated. So, there are tiny hydraulic pumps that vary the pressure on the diff clutch "plates". The 3 different settings (dials) are for corner entry, mid-corner, and corner exit settings. There may also be +/- buttons for overall sensitivity/strength.

[kang]

Interesting articles to read….

I was wondering if there was some sort of hydraulic pumps varying pressure on the clutch plates. That was the only thing that made sense in my mind. I don’t know how the diff knows when it’s in corner entry, mid corner, or corner exit. Perhaps there is an accelerometer someplace that detects this. If the accelerometer detects braking while turning, it’s in corner entry, coasting while turning means mid-corner and accelerating while turning means corner exit. It could even detect straight line accelerating or braking, and apply a very high level of lockup in those cases.