Need someone with a 2017 A8 to do an experiment for me...please
10-16-2016, 02:50 PM
#21
Pro
Thread Starter
This is the best breakdown I have seen for the power flow through the 8L90 showing both via diagram and text description how the various ratios are selected. It probably won't help much with your current "project" but maybe some of the information will be useful: http://www.thetruthaboutcars.com/201...-transmission/
10-17-2016, 02:46 PM
#22
Melting Slicks
Thanks to everyone doing this. Like I said, I have the older A8 plagued with the morning lurch. When I saw this in my PDR, in my head I said "BINGO".
I can tell you that when I go from R to D, it does show 4th for a second or two and then slams into 1st.
But while it is allegedly in 4th, it not engaged...the car can roll as if in neutral.
So the difference between the new vs. old A8 is the time it spends in 4th is a nano second, where as mine spends a second or two.
Interesting.
I can tell you that when I go from R to D, it does show 4th for a second or two and then slams into 1st.
But while it is allegedly in 4th, it not engaged...the car can roll as if in neutral.
So the difference between the new vs. old A8 is the time it spends in 4th is a nano second, where as mine spends a second or two.
Interesting.
Last edited by Speedforhire; 10-17-2016 at 02:57 PM.
10-17-2016, 03:29 PM
#23
"A garage shift (GS) is the turbine speed transient commanded by the shift lever movement from Park to Drive or Reverse, from Neutral to Drive or Reverse, from Drive to Reverse, from Reverse to Drive, or from Drive or Reverse to Neutral [1].A usual metric to verify the garage shift comfort is the data acquisition of the fore-aft acceleration on the seat track, but also the shift time should be considered, as well as the clutch energy and the repeatability of the shift feeling for different temperatures and engine idle speed levels.This paper demonstrates the transmission calibration strategies to determine a sensitive and a non-sensitive garage shift and its interactions with the engine calibration.Many factors may affect the garage shift calibration, like hardware controls (software and calibration), hydraulic system (fluid and actuators), clutches (design and friction material) step ratios, and non-transmission factors such as idle control and engine torque signal accuracy [2]. The vehicle’s sensitivity to torsional driveline inputs and the powertrain mounts configuration also influence the shift quality perception."
