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Agree in some cases but perhaps not all. When the flush doesn't help it could be related electrical problems, sensor problems, valve binding, seal leakage, etc. that all have similar symptoms. GM may know but they aren't telling us.
Yep that is what I like about that Tech video. He has worked on 50 DCTs and only two had the same CEL (which as he showed there are well over 100 CEL codes.) AND he said both of those solved with a software update.
It's obvious the DCT is very well protected with many sensors that catch "stuff" before internal failure occurs. Has many things that can cause a CEL. In fact, my observation is very few replacements, sure some with well over 100,000 C8s sold and the forum does not see them all.
It is likely a combination of high lateral Gs and low vertical Gs uncovering the pickup. Fluid won't go to the top of the case in a free fall condition but it could "float" around. The car would have to be pulled down at a faster acceleration rate than gravity can exert for the fluid to go to the top of the case. Remember the video from the moon of the feather and hammer falling at the same rate?
Additionally, there was an explanation (I don't remember where I saw it, maybe someone else will chime in) that the reason the problem was discovered so late was because all the earlier testing was done on OEM tires. It wasn't until they installed track tires capable of higher Gs that they discovered the problem.
And in a track situation I think that may be possible. I have read that the downward force of the rear spoiler (not sure which version) can be 400 lbs. That's about 11.9 percent of the car's weight (3366 lbs). If that extra force is evenly applied to the car (and its not , really), and if my math is right, the result is 1.12g of downward acceleration (if the wheels are off the ground). The fluid in free fall would be accelerating at 32.17 ft/sec^2, while the car would be accelerating at 36.03 ft/sec^2. So, the fluid could float to the top potentially. Of course, in reality, that force is all in the back, so its probably more of a rotational acceleration, but the back end is being forced downward. Having said that, if that was the issue, adding 2 quarts of fluid would not help. All the fluid would still "float to the top" . I still think its more likely lateral acceleration which moves the oil to one side. In that case, more oil does help to keep the bottom covered.
... . I still think its more likely lateral acceleration which moves the oil to one side. In that case, more oil does help to keep the bottom covered.
BTW both the low standard Z51 and high wing are said by Tadge to produce 400 lbs downforce- likely at ~170 mph. Assume the high wing has less drag, he never said.
My first inclination was to blame lateral "g" BUT not what GM has said. Only thing I have found is at 1.3 peak "g" no CEL!
That was very short duration! From the only semiformal statement made at a Carlisle PA Seminar that "It's IF going downhill and turning, where the fluid goes to the top of the case." I consider that means under that combo of conditions it gets away from the fluid pickup. I agree with RKCRLR It probably takes both. Likely found in testing like at the Corkscrew turn at Laguna Seca or similar Tracking with a high "g" turn going downhill.
And in a track situation I think that may be possible. I have read that the downward force of the rear spoiler (not sure which version) can be 400 lbs. That's about 11.9 percent of the car's weight (3366 lbs). If that extra force is evenly applied to the car (and its not , really), and if my math is right, the result is 1.12g of downward acceleration (if the wheels are off the ground). The fluid in free fall would be accelerating at 32.17 ft/sec^2, while the car would be accelerating at 36.03 ft/sec^2. So, the fluid could float to the top potentially. Of course, in reality, that force is all in the back, so its probably more of a rotational acceleration, but the back end is being forced downward. Having said that, if that was the issue, adding 2 quarts of fluid would not help. All the fluid would still "float to the top" . I still think its more likely lateral acceleration which moves the oil to one side. In that case, more oil does help to keep the bottom covered.
That's what Josh said to me. It was lateral grip on race tires and during long double apex type long turns where you're carrying lateral load for quite some time. That lateral load may only be 1.0g instead of peak 1.5g I can hit in small turns but it goes on for 5 full seconds or more. Very different than a fast turn.
Here is what that looks like. This illustration is to scale in arbitrary units. In a 1 g turn with no vertical acceleration - there is 1mg of force down and 1mg (m is the mass of the fluid) of force to the side, so the fluid depth up the side and the fluid width on the bottom will be equal. In order to keep the bottom width covered in a 1 g turn, the depth of the fluid at rest needs to be half the width of the bottom. Of course, in this illustration there is no structure to the bottom. The effect will be different (I think) with a more complex shaped container and baffles on the bottom. So this is just to illustrate how adding fluid helps with lateral acceleration.
Last edited by Andybump; Jun 27, 2023 at 12:19 PM.
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I believe the tech in the video might be Paul Koerner, out of CT. He has been invited to Corvettes at Carlisle PA many times for seminars to standing room only (the tent fills up early for him). If this is in fact him, he is extremely knowledgeable, and I would pay very close attention to what he has to say. IMHO!
