i have a 2015 C7 automatic. i have recently started using the paddle shifters and i have discovered that as i shift down the engine RPM goes up. WAIT i know you are going to tell me that it is supposed to go up. YES, but... it is NOT slowing the car down, the engine rev up and then will start slowing the car down. In other words, the car is NOT dragging the engine to the new gear RPMs.

does anybody know how to disable this??? the dealer tells me that there is NOT rev-matching on a automatic

thank you guys in advance
Manny

 

That is rev-matching. The RPM's increase so the driven and drive gears are turning the same RPM before the engine braking has an affect. Makes it shift smoother and not unsettle the car when down shifting coming into a corner. Really only needed on race track driving when your pushing tires over ~90% traction level.

 

My 2016 Z06 A8 does the same thing and the dealer says there is nothing wrong with it. In paddle mode it actually accelerates on downshift due to the RPMs rising unless you have your foot on the brake. Let's see how many others have noticed.

--Dan

 

Have you tracked the car at all? I am curious how it does when braking, downshifting and turning into a corner.

 

You don't want to disable this feature. If you don't rev match on a down shift, you will slam the transmission, jerk the drive train and unsettle the car's balance if you do this in a turn the result might suck.

Learn that it is normal and you will be much happier.

Elmer

 

Yes I agree with the definition that JD nice gave us. my point is that an automatic transmission C7 is not supposed to have matching according to the dealer and I believe that they do.
I like to know if any of the members have gone through this exercise before.

Manny

 

Dealer is wrong (Surprise!).


Elmer

 

Oh by the way, it's in the owners manual.

 

I've been using manual rev match with automatics since 67 with A 2 speed auto chevele Malibu.I would take it from drive to neutral give it some gas
And drop it down to low.
Since then have did it to all the automatics I've owned.Transmission,drive shaft,rear held up on all of them.

 

Yes, I've tracked it twice and autocrossed a few times. There's no problem when you're already on the brake pretty hard as is the case when going into a corner and downshifting -- at least for me.

Yes, I do want it gone. It serves no purpose when under hard braking and on the street it's just annoying and potentially dangerous having the car lurch forward when expecting it to slow down.

The A8 and A6 before it aren't getting slammed on downshift as the torque converter takes the hit. With proper use of the paddles you make your downshift ahead of the corner and there is no disruption from a gear change mid-corner as can occur in automatic mode.

Drive with the paddles, choose gears as you would in a M trans and you won't have an unsettled car anymore than with improper use of a M car. The shifting of the A8 is much better than the A6 I've raced for ten years. But, the A6 slows down with a downshift unlike the A8 that speeds up -- I suspect due to the rev-matching attempt.

It's not just at slower speeds either. I tested it on the highway and downshifting (without braking) from 4th to 3rd results in an initial slowdown followed by the car accelerating. How can that be correct?

I am tempted to see if it can be corrected in the tune. You do a lot of tuning, I believe. Can HP Tuner address this "feature" as it is not this way in my A6 car?

--Dan

 

Hmm, on my m7, I did have to learn how to suggest to the active rev match that I'm downshifting in order to scrub speed, as opposed to downshift in order to get into power.

When I first got the car, I would learn that a scrubbing downshift would cause a bit of extra power when coming off the clutch, and a slight surge forward, as opposed to slowing down, like I desired. I found that if I was on the brakes, even lightly, when downshifting the surging would be gone - Because I was braking, the car knew I was downshifting in order to scrub speed.

Maybe give this a try, when doing downshifts to scrub speed, also use a bit of brake, and see if you still encounter the behavior.

For those with a manual, this works, but I also found staying on the clutch just a quarter of a second longer allowed a very quick clutch engagement without any lurching (when downshifting to scrub speed.)

 

That's a very good observation. But, there are times when in traffic where I only want to engage a lower gear and not be on the brakes. It's here that it's most annoying. Also, when pretty slow having the exhaust note roar in rev-match gets unfavorable side glances from others thinking I'm some boy-racer. It's just not necessary with the A8 or an M7 for that matter after you've learned to drive.

I'll make the effort to adjust from how the A6 works, as expected, to the A8 behavior of needing some brake for the computer to know what to do. @&^#ing computers!

--Dan

 

You don't have to be hard on the brakes, just enough to let the car know your intentions. I can't imagine a scenario where you're downshifting to scrub speed and there is a reason *not* to use the brakes as well. Maybe if your brakes are hot?

It seems to me that in traffic one should be using one's brakes when slowing down, brake lights to alert the traffic behind you of your intentions.

 

Brakes on enough to turn on the lights will rid you of the dreaded surge. The surge will not happen if you let the car shift down on its own too. But if you are in traffic there would be no real reason for you to be in paddle shift mode anyways. You may also notice that when you shift up under light acceleration it actually shifts like a manual.

 

Not to argue but....




The only time the transmission holds RPMS and tries to keep in the lower gears is when you get the car into puppy mode. Puppy mode is when the car senses that you want to drive in a spirited manner and the car tries to keep the RPMs up to allow you to stay in the power band while the "puppy" mode is activated. If you are talking about the "puppy" mode and it being bad, I flat give up.

BTW, I have the 2014 A6 and it is supposed to work this way. The older A6 trannies might not have had the "puppy" mode.

From your comments in THIS post, you sound like you found "Puppy" mode. Congratulations! Have fun with it!



Elmer

 

I honestly have no idea if this is an argument, a mis-communication, or agreement. What is "puppy mode."

Do you mean paddle mode? If so, yes, I discovered it over 11 years ago and use it all the time. I was the first person to reverse the operation of the right paddle on the A6 to upshift when pulled as it now does properly on the A8.

--Dan

 

Naw, puppy mode is the car's computer trying to help you drive in a performance mode. It keeps the car in a higher revving situation and in a lower gear to give quicker throttle response during turns and sharp maneuvers. Think of a puppy excited to go out and chase a ball or something. Basically the car wants to play.


Elmer

 

Lord. GM builds a decently sporting slushbox and the only people who can afford it hate it.