Hard down shift with A8
Thread Starter
Drifting
Joined: May 2002
Posts: 1,546
Likes: 282
From: Back in Nebraska
Hard down shift with A8
I’m not sure if this is normal or not so I’d like to see if anyone else has this issue. I have a 2017 GS with an A8. The transmission is smooth and shifts great. However, when slowing to a stop it will jump from 3rd to 1st without going through 2nd. This causes an abnormal hard down shift. This only happens when stopping. Is this normal or is there a problem with the transmission programming? Thanks!
Le Mans Master
Joined: Jan 2006
Posts: 6,800
Likes: 2,653
From: Down south in Dixie
My previous '16 went from 3rd to 1st with no jumping, and my now '19 is the same. It's my understanding that these tranny's are designed to go from 3rd to 1st so it would be a smoother transition, but I can't say if that's a true fact or not. The A10 in my wife's Mustang GT goes from 3rd to 1st also without any jumping. Even my F-150 with an A6 is the same. You may want to have your's checked. Good luck.
Last edited by Rebel Yell; Jan 5, 2019 at 05:17 PM.
Safety Car
Joined: Aug 2012
Posts: 3,960
Likes: 1,106
Going from 3 to 1 is normal behavior, the only time you would need the 3 2 1 sequence when slowing is if you were manually shifting to use engine braking. But it shouldn't be a hard shift. Get it looked at and it may need to be put back into learn mode by the tech to relearn this shift. These are clutch to clutch architecture transmissions without the slipping bands and overrunning clutches of older automatics and shifts are achieving by precise timing of the release of one or more clutch packs at the same time others are being applied. If the timing is off then rough shifts and shift flaring will result. The controller adjusts apply/release timing and pressure based upon actual shift behavior but if it gets too far off from desirable the correction is so slow (requires a huge number of shift events for that particular shift sequence) that it needs to be forced back into a fast learn mode where the problematic shift is then repeated multiple times.
Team Owner
Joined: Sep 2000
Posts: 25,007
Likes: 2,707
From: Far NW 'burbs of Chicago
St. Jude Donor '13
2017 Z51 A8
Ours also goes from 3 to 1 as we come to a stop. If we come to a complete stop, that works fine. But if we slow to about 3 mph instead of a complete stop, and then get on the gas lightly, the tranny somewhat lurches into 1 because adding some throttle "forced" the shift.
That programming might work fine in an EPA test cycle, but it's kind of a PITA for normal driving.
Ours also goes from 3 to 1 as we come to a stop. If we come to a complete stop, that works fine. But if we slow to about 3 mph instead of a complete stop, and then get on the gas lightly, the tranny somewhat lurches into 1 because adding some throttle "forced" the shift.
That programming might work fine in an EPA test cycle, but it's kind of a PITA for normal driving.
Advanced
Joined: Jul 2010
Posts: 83
Likes: 56
I’m not sure if this is normal or not so I’d like to see if anyone else has this issue. I have a 2017 GS with an A8. The transmission is smooth and shifts great. However, when slowing to a stop it will jump from 3rd to 1st without going through 2nd. This causes an abnormal hard down shift. This only happens when stopping. Is this normal or is there a problem with the transmission programming? Thanks!
Safety Car
Joined: Aug 2012
Posts: 3,960
Likes: 1,106
2017 Z51 A8
Ours also goes from 3 to 1 as we come to a stop. If we come to a complete stop, that works fine. But if we slow to about 3 mph instead of a complete stop, and then get on the gas lightly, the tranny somewhat lurches into 1 because adding some throttle "forced" the shift.
That programming might work fine in an EPA test cycle, but it's kind of a PITA for normal driving.
Ours also goes from 3 to 1 as we come to a stop. If we come to a complete stop, that works fine. But if we slow to about 3 mph instead of a complete stop, and then get on the gas lightly, the tranny somewhat lurches into 1 because adding some throttle "forced" the shift.
That programming might work fine in an EPA test cycle, but it's kind of a PITA for normal driving.
The completely different but still electronic with clutch to clutch architecture heavy duty Allison auto in my GMC pickup also makes some rough shifts if you transition from off throttle low speed coast down back to throttle when the timing is just wrong.
Or as a friend who is a retired LEO put it to me, you aren't supposed to be making "rolling" stops anyway
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