Yes, John, wear is reported in %. See my SD2 thread for all the sceen shots. Yes, PIS is what you listed. But, in a way, it's backwards as it's the point when the clutch just starts to bite when closing.
So how can wear be reported in % if it defined as the difference between new and current clutch closed positions w/o knowing the clutch thickness? Also, how can PIS depend on the new clutch closed position (NCCP) if it is determined by when the clutch starts to grab, probably by looking for some predetermined drag (RPM drop) of the engine. (Note, these are questions I'm asking myself.)
All good insights. I still think that if the car is constantly adjusting as John’s info shows , and you start out with a pick up point that is in the correct range, whether by using the SD or having dumb luck, you should be fine. The amount of miles I do makes it a mute point for me. But I’ll report back the findings in 2048 when I need a new clutch.
Skipp, you better hope it does not end up like your last - maybe that one was not setup with an SD? https://www.ferrarichat.com/forum/posts/145970469/
Here is some more data to confuse the situation more. On my car, the "clutch position as new" is 13.49. Matt has seen others at 17.0, 17.8. So, that's a 4.31mm difference. Could that be the stack up off parts? Or could those values be adjusted values by a tech to have the car pickup better? We don't know.
Again, knowing nothing about F1 but reading the WSM, the WSM clearly states that the clutch control strategies are based on the PSI and the closed clutch position which are updated when ever the car is started or driven and self calibrated. The only reference to the new closed clutch position is in regards to wear. There is nothing that states that you can arbitrarily change the pick-up point. But, perhaps, messing with the new closed clutch position makes the TCU do something it was not actually intended to do. I think this is going to remain a mystery.
That is not entirely true, John. The WSM does state that altering the new closed clutch value will impact the pickup point. And, this has been confirmed by 2 very experienced techs and one of the engineers involved with these systems. Image Unavailable, Please Login
Ok missed that. I will hypothesize that the TCU used the new and current closed clutch positions in the determination of the PIS. Glad I own a 3 pedal and don't have to worry about this stuff. Hey Dave, you have the SD. Why don't you try changing the value in the SD and see what happen when you drive your car. You can always change it back.
I've considered doing just that but decided against it for these reasons: - The WSM states it - Techs have confirmed it - I have better things to do then screw up my perfectly running car
I kinda agree with Dave The way these manuals read you are never sure they have told you everything. Has anyone bothered to check the total stackup tollerences to see how much they vary. This could at least give us a value in which we should all ways be between?
My error. Spoke with Matt earlier and he read this and corrected me. So the PIS is cluth disengagement. The pickup point is on engagement. Matt will hopefully be by to clean up my errors
Wonder about the difference. Where it starts to grab would be independent of torque. Where it starts to slip would not be. I wonder if PIS is actually as you said. If PIS is detected each time you start the car (WSM), how? To find the point of initial slip would imply that there is some torque load on the clutch and as the clutch is disengaged the PIS would be where the torque transmitted through the clutch starts to decrease. How can that be done with the car in neutral and the brake on? On the other had, the pick up point would be fairly easy to detect as once a gear is engaged you could monitor the engine RPM and sense when it first started to decrease due to an applied load, brake on or off, unless you started to roll down a hill. So, if, as per the WSM, you can change the pick up point by changing the NCCP, what is the procedure to do so?
Yes, I understand that part, but how do you tell what RPM the pick up point is at? The answer is not, "you read it on the SD." I'm asking what signals tell the TCU that the pick up point is at xxx RPM. Is the pick up point a minimum RPM where the clutch starts to engage from when you release the break and hit the gas from a dead stop? That's what it sound like to me. In an F1 car, what happens if you are a dead stop on level ground, engine at idle, and you take your for off the brake? Does the car start to move or do you need to raise the RPM a little before the clutch will engage? The F1 owner's manual seem to imply you need depress the accelerator or it won't engage the clutch, and ultimately will shift to neutral after 4 sec. Image Unavailable, Please Login
Thinking a little more about this perhaps when you start the car, with it in neutral, the TCU could cycle through a clutch engagement and record the engine RPM when the trans main shaft starts to spin as the clutch is engaged. I'm assuming the pick up point is the clutch position when the clutch make sufficient contact to turn the main shaft. (Writing before your post Dave)
Yes that is what the sensor under the secondary shafts watches. The computer sees the rpm and also at which rpm the secondary starts to turn
If that sensor malfunctions it uses the previous remembered positions but is jerky, not jerky for disengagement of first but jerky from first to 2 and 2 to 3 etc Its actually quite smooth for lift off
