WRC Testing

[OldF]

Reading this again it looks like there’s a lot to test with the active centre differential also.

“We experimented with lots of different options, during rallies mostly, as tests were too short to do any real work on it.”

“When I approached the apex of the corner, I came on throttle and I needed a smooth transition from brake mode to acceleration mode, which did not upset the car, but applied strong pressure on the front diff to help pull the car into the apex, a relatively strong and specific pressure on the center diff to keep the car neutral, a smooth rising pressure on the rear diff for traction but not too much so as to prevent excessive oversteer. All that depended on the speed of the corner.”


What kind of mechanical construction (open differential, planetary differential) did the centre differential have in the past?

[janvanvurpa]

Reading this
again it looks like there’s a lot to test with the active centre differential also.



What kind of mechanical construction (open differential, planetary differential) did the centre differential have in the past?

Oh OK this I know something of..
You understand how normal multi-plate LSD works right?
Half the clutch plates are splined to the case, the other half are spline to side gears In center diff half spline to input shaft, half to output shaft,,

Then in normal LSD there is some kind of spring, sometimes a series of small coil springs (think of any motorcycle clutch) but often a cupped saucer like spring called "Belleville Spring" or Belleville washer. This pushed plates and disc together making the two sets "locked" together and establishing diff "pre-load"..or "break-away torque" .that is how much torque needed to begin to allow the plates to slip some.....

In active diffs there was again discs and plates like we are used to in our own rally diff but instead of a spring to force them together there is hydraulic force or I think somebody even truied compressed air a million years ago..
The hydraulic force is of course able to be regulated as so the diff can go from zero pressure--able be "open" (input shaft turning at whatever speed and output shaft not turning at all) progressively all the way to complete 100% lock up (input shaft and output shaft turning exactly the same speed)
And of course it is a bunch of wheel sensors---like ABS sensors---counting rotation on all the wheels and probably input and output shaft rotation---and this goes to a computer that has a program or "map" done by some guy who certainly never ever sat in a rally car but is a genius engineer, and this decides how to lock up--progressively--or unlock (open on decel into corner).

Very expensive and incredibly costly and arbitrary to amass the foundational information to allow the "injur-near" to decide the MAP---(or said another more cynical way, to allow the injur-near enough information to decide what he belives the driver should like)..
If it was good, it worked. If it was not good--well maybe you read the blog from Warmbold from this very forum when he talked about driving all the way to Poland and then car was undrivable and after paying so much for prep and confusion it tuirns out that somebody had simply forgotten to LOAD a diff map..
Oh well sh1t happens.


Whn "active" diffs were not allowed or simply too insanely expensive work was don on the ramp angles of the pressure rings inside the normal cluth plate diff and this allowed different rates of lock up and lock up on drive direction and open or near open on coast/decel something like this:

Or like this:


This works anywhere so this is what EVERYBODY has been using since active diffs were WISELY banned

[dimviii]

https://www.youtube.com/watch?time_c...&v=S-mHX75n6K8

[aykutbilir]

https://www.youtube.com/watch?time_c...&v=S-mHX75n6K8

realy question is iternity/0x2=Yaris WRC? )


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[dimviii]

have we seen a diffuser at previous tests at c3?

[dimviii]

Traxx - WR is Free ‏@Traxx_WiF 20

@VolkswagenRally testing Polo R #WRC 2017 engine at high altitude

[N.O.T]

have we seen a diffuser at previous tests at c3?

yes

[Lundefaret]

As expected, the aero-development is gaining traction (pun intended.)

[Toyoda]

Still no Hyundai...Intersting how different the C3 and Polo and Yaris spoiler solutions are.

[Eli]

where were Citroen testing, was it Finland?