smilence

find that it might be better posting here than the general forum.

I was at button willow raceway yesterday, and it's my 3rd track day so I'm pretty much still beginner. This time I try to use the paddle shift a bit more aggressively so that there are indeed several times that it's close to the red line, and the vehicle refuse to accelerate without me up-shifting.

It's hot, like 103F on the track and in my last 20mins session (there is 1 hour between sessions), and in those last 5mins, the transmission deny my downshift to 3rd gear even at around 40-60mph. And after I come off the track, I shift to D, but the shifting also jerks.I don't know whether that's a sign of overheating since I didn't see anything on the gauge.

The jerk disappears after I fill the gas and the car cool down a while.

While it's worth noting that my gas was low in my last session (in red zone, but still be around 2 gallon left), don't know whether that causes the shift deny, but it won't make sense for the jerking?

5thGear

The rough shift are caused by elevated transmission temperature. Your torque converter was slipping. The car went into limp mode to protect the transmission. That's why it wouldn't go into lower gears
What year is your Car? Z51?
Did you check the transmission temperature at the of the session?
It doesn't matter what ambient temperature you are dealing with. The automatic transmission will overheat at the track. Mine overheated even in 65F ambient at Auto Club Speedway. Check out the threads that I have started on this subject. On the bright side there are solutions to over come this but they are not cheap.

EcoBrick Bob

If you will do a "Search" you will find multitudes of threads & posts on this topic.

smilence

2015 Z51, yeah, i used toolbox to analysis my recording and find the max temp as follows:

water 221F
engine oil pressure 55.1
engine oil temp 277F
transmission oil temp 275F

seems high to me

5thGear

Yep. Your transmission overheated my friend. Again you will find lots of info on this subject on some threads that I have started. Many of us (2015 Z51 A8) have an open case with GM regarding this issue and they have promised a solution. Since the solution had no time table, I have invested in aftermarket solution.

smilence

Thanks, at least there exists solutions, unlike the other issue of AFM failure.But so disappointed that this would happen to z51 which is supposed to be track ready.I mean so many less expensive cars like miata/s2000/brz would not have such problem

sjones

What aftermarket solution did you install? Will a aftermarket transmission cooler affect warranty coverage?

NinjamanZ51

Yes an aftermarket solution *could* affect your warranty. They (the dealership) have to "prove" the modification will create or has created an issue before they can deny a warranty claim though.