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The RS6 isnt a dual clutch, like chassis said you can probably rule that out. Im not sure its the torque coupling either, wouldnt putting it in neutral eliminate the vibration?
The RS6 isnt a dual clutch, like chassis said you can probably rule that out. Im not sure its the torque coupling either, wouldnt putting it in neutral eliminate the vibration?
No, because the torque coupling is spinning any time the rear wheels are spinning.
We are talking about the center longitudinal torque coupling downstream of the transmission, not the torque converter or PDK coupling between the engine and transmission.
Agree with Mootz and Chassis,
the RS6 AWD system layout looks similar to the Panamera Ie how axle goes from transmission forward and how the diff sits on side of engine .
My point is therefore, if it is a similar configuration and no harmonics on the RS6, this brings it back to transmission to axle interface - torque coupling, U joint, or CV joint and not axle layout/ angles.
Chassis, for your info, we are talking about fairly bad harmonic bounce between 57-62mph. Weird part is that the vibration decreases at higher speed but still there. If you drive at 65 and start braking, the bounce is felt through the slowing the car.
there is no change if I change gear and rpm as long as speed is same.
again, therefor not engine nor transmission but (like you said) anything after output shaft ie torque coupling or missing rubber disk in axle, bad U joint,
if I can accelerate quickly from 45-70, then not there
rrd1288 Do you think you can message the Administrator and see if they can change the tile of the thread to something like "Vibration at 57mph"? I think this thread would get more traction.
I just messaged one of the admins. The frequency of the vibration sure didnt feel like a mechanical vibration, it felt more like a really bad tire that was hopping. Like I said my issue is vastly diminished after the rim swap and im happy with the car. They went through tires after tires which were all roadforced under 20lbs, replaced the cardan shaft and in the end the rim swap from the other car helped big time.
I found this, it’s from NHTSA, but I don’t think 971 diesels were sold in the US. Worth asking dealers to check. This could be an issue for all AWD cars, as engine is really irrelevant
I had a long elaborate, albeit windy response typed up. Where it went, i know not. Let me summarize and if this is redundant, i apologize. The router lost connection; people in Florida have no idea what to do when they see a 3 in front of the thermometer, let's blame Spectrum!
I too own a car that originally came from Houston with 20K miles that i bought last summer and it too was very heavily optioned by someone that had to check every darn box. I noticed the vibration since the first day. i agree that it changes frequency with all sorts of ambient conditions. I thought it was either an unbalanced tire or a bent rim - the car had heavy rash under the passenger side rocker so i assumed someone drove it up on a curb. It had a clear bra that was peeling on the left front with a big stain in another part of it, none of which bothered me because that's why it was 45% off.
I installed the tune and the Cargraphic downpipes and the harmonics got way worse and would be felt through the passenger floor. I was able to move a heat shield over as it was definitely worse after my techs installed the downpipes but it reduced what the passenger would feel in the floor. I couldn't feel it in the steering wheel and it therefore didn't feel like a tie rod. I then put new BC wheels and tires on and there it was again. At one point, since it got worse with the downpipes that have less dampening I wondered if it was caused by the drivetrain. The more I thought I knew it was something else, the more dead ends I found.
So...i began to wonder was it the damper that was bent? It definitely has a frequency problem at the speeds at which you all describe. To me it feels like a bell curve at that speed (not as bad above but still there and much less noticeable below that mph) so i was ready to blame the damper's being bent but it wouldn’t behave like that I don’t think.
After reading, on page 2 i was convinced that someone else shared the same theory that i had briefly involving aero, ride height and PASM controllers but then someone else mentioned that they put the thing on the lift and same the front end oscillating at that speed which sort of shoots my theory in the butt. (P.S. you guys have shared some rather sharp, scientific data so kudos.)
Once i got to page 4 i think i was less sure of myself. Either way, can we all agree on the following?
1.) there is an oscillation at a certain speed and it’s significantly worse AT THAT SPEED than it is above and below.
2.) It is not tires or wheels as too many people have changed both without success.
3.) it could be the PASM controller and some aero effects but if someone ran it on the lift and it started jouncing then that kills that theory which sucks because that we can fix electronically with mapping.
4.) we have a bulletin about axle grease but I would think that it would not increase or decrease frequency. (I need to read the information that’s posted though about PASM and speed settings. If it is sitting lower at a certain speed and then lifting slightly, maybe?
I am not an engineer. I am not a dealer tech. I am a person like you guys that has a car that does the same so this is all speculation because I haven’t ever heard of this problem before. I thought it was all alone.
If it’s in the PASM controller, we can make a map with the DSC controller and fix this once and for all.
If there is a certain baseline ride height setting that makes this go away, I can set it with the factory PIWIS computer. I need to go and first ride around with the PIWIS looking at the actual PASM ride height values. If we can confirm that it happens at a certain reported front ride height then we might learn something. You’d hate to find out that you’re riding around on the bump rubber up front and when you go fast enough and the speed then creates lift and makes the front end light and gets back off of the bump rubber the oscillation stops.
I like the tough ones. You guys have presented some good info. Let’s see how we do.
I had a long elaborate, albeit windy response typed up. Where it went, i know not. Let me summarize and if this is redundant, i apologize. The router lost connection; people in Florida have no idea what to do when they see a 3 in front of the thermometer, let's blame Spectrum!
I too own a car that originally came from Houston with 20K miles that i bought last summer and it too was very heavily optioned by someone that had to check every darn box. I noticed the vibration since the first day. i agree that it changes frequency with all sorts of ambient conditions. I thought it was either an unbalanced tire or a bent rim - the car had heavy rash under the passenger side rocker so i assumed someone drove it up on a curb. It had a clear bra that was peeling on the left front with a big stain in another part of it, none of which bothered me because that's why it was 45% off.
I installed the tune and the Cargraphic downpipes and the harmonics got way worse and would be felt through the passenger floor. I was able to move a heat shield over as it was definitely worse after my techs installed the downpipes but it reduced what the passenger would feel in the floor. I couldn't feel it in the steering wheel and it therefore didn't feel like a tie rod. I then put new BC wheels and tires on and there it was again. At one point, since it got worse with the downpipes that have less dampening I wondered if it was caused by the drivetrain. The more I thought I knew it was something else, the more dead ends I found.
So...i began to wonder was it the damper that was bent? It definitely has a frequency problem at the speeds at which you all describe. To me it feels like a bell curve at that speed (not as bad above but still there and much less noticeable below that mph) so i was ready to blame the damper's being bent but it wouldn’t behave like that I don’t think.
After reading, on page 2 i was convinced that someone else shared the same theory that i had briefly involving aero, ride height and PASM controllers but then someone else mentioned that they put the thing on the lift and same the front end oscillating at that speed which sort of shoots my theory in the butt. (P.S. you guys have shared some rather sharp, scientific data so kudos.)
Once i got to page 4 i think i was less sure of myself. Either way, can we all agree on the following?
1.) there is an oscillation at a certain speed and it’s significantly worse AT THAT SPEED than it is above and below.
2.) It is not tires or wheels as too many people have changed both without success.
3.) it could be the PASM controller and some aero effects but if someone ran it on the lift and it started jouncing then that kills that theory which sucks because that we can fix electronically with mapping.
4.) we have a bulletin about axle grease but I would think that it would not increase or decrease frequency. (I need to read the information that’s posted though about PASM and speed settings. If it is sitting lower at a certain speed and then lifting slightly, maybe?
I am not an engineer. I am not a dealer tech. I am a person like you guys that has a car that does the same so this is all speculation because I haven’t ever heard of this problem before. I thought it was all alone.
If it’s in the PASM controller, we can make a map with the DSC controller and fix this once and for all.
If there is a certain baseline ride height setting that makes this go away, I can set it with the factory PIWIS computer. I need to go and first ride around with the PIWIS looking at the actual PASM ride height values. If we can confirm that it happens at a certain reported front ride height then we might learn something. You’d hate to find out that you’re riding around on the bump rubber up front and when you go fast enough and the speed then creates lift and makes the front end light and gets back off of the bump rubber the oscillation stops.
I like the tough ones. You guys have presented some good info. Let’s see how we do.
I agree with your summary, but I don't think ride height has any influence--at least on my GTS. The oscillation does not change in frequency or magnitude when driving at different ride heights, and remained at the same frequency when tested on a lift. Softer damper settings are sometimes actually ever-so-slightly worse.
I'm comfortable ruling out engine, wheel/tires, and suspension as the source of the vibration.
I agree with your summary, but I don't think ride height has any influence--at least on my GTS. The oscillation does not change in frequency or magnitude when driving at different ride heights, and remained at the same frequency when tested on a lift. Softer damper settings are sometimes actually ever-so-slightly worse.
I'm comfortable ruling out engine, wheel/tires, and suspension as the source of the vibration.
Okay i am back. I wanted to compare notes but you did that. My problem is that when i run the car on the lowest setting ride height wise, it's the worst. When i go to medium or to lift (or i should say when i start at lift and drop down on the interestate) the change in the ride height has the most effect. It's super hard for me to discrern if the damper stiffness exacerbates it or not because you have to be right smack dab in the window. For some reason for me the magical number is between 76 - 82. I took one of my techs with me though so they could feel it and they agreed. I agree with you though that going softer makes it worse.
I read a lot of your posts; your intuition is spot on, i'm just still scratching my head because to me it occured the least when the car was in LIFT mode. I should say though that when i got the car i used the factory computer to lower it another 20mm so my car in the lowest setting sits lower than stock. I can't ignore the fact that you ran the car on the lift though and re-created the problem. I need to try that next, maybe later this week.
I was unsuccesful at being able to see the live values in the Air Ride control unit because it would only show the deviation from stock. I wanted to be able to see the ride heights change so that i could see data that supported my claim that it wasn't as bad at the higher height. I will say this, we did notice that the accumulator pressure up front seems to bounce around a lot more than it does in the rear. I think i need to put my car back to stock ride heights to make sure i am playing with the same setup.
I am not saying it's not a ride height issue - i am just trying to make sure i didn't worsen this problem by making the car lower. I know that others haven't but maybe with the different wheels and tires, ride heights change and that's why others have reported it being worse or better but still not gone.
I need to spend more time noodling.
Last edited by BGB Motorsports; 12-27-2022 at 03:05 PM.
Sorry, i was under the assumption that someone saw this happen on the dyno, which is what i was going to do...strap it to the rollers and see if she changes mapping at the magic speed number.
BGB, Interesting your worst effect is at 76-82 while most others are in range 57-63mph. My worst is if I accelerate moderately to 55, set cruise and go up 1mph every 15/20 sec to 63mph.
from post 18 above from Mootz “ I took the car to a private mechanic. They put the car on the lift and accelerated to 57 mph. The front end shakes. Their suggestion was to return to the dealership have them check/replace the front axels/differential.“
I went to my Indy mechanic to check if he could make some checks but he only have a 2wd dyno.
mine is going to shop Monday for the famous rear spoiler ED. I’m bringing a list for them to check while there took look for obvious problems, ie CV joints, suspension components etc. Do a real Euro NAP inspection with a crowbar.
BGB, Interesting your worst effect is at 76-82 while most others are in range 57-63mph. My worst is if I accelerate moderately to 55, set cruise and go up 1mph every 15/20 sec to 63mph.
from post 18 above from Mootz “ I took the car to a private mechanic. They put the car on the lift and accelerated to 57 mph. The front end shakes. Their suggestion was to return to the dealership have them check/replace the front axels/differential.“
I went to my Indy mechanic to check if he could make some checks but he only have a 2wd dyno.
mine is going to shop Monday for the famous rear spoiler ED. I’m bringing a list for them to check while there took look for obvious problems, ie CV joints, suspension components etc. Do a real Euro NAP inspection with a crowbar.
Funny, I performed the same procedure, "accelerate moderately to 55, set cruise and go up 1mph every 15/20 sec to 63mph". Like minds! I have no vibration in the 76-82mph range.
I sometimes feel a slight hop or oscillation at about 31mph while driving through my neighborhood, but not all the time. I know if I feel that hop driving down my street, it will be a shake show once I get on the highway.
The car was tested on a lift not a dyno. Although the suspension hung, the CV angles were not excessive. Extreme angles on rotating CV joints can introduce their own vibrations, but the geometry was good in this case. If the CV angles were causing a vibration they surely would have been present below 57mph, and would not have cleared up at speeds in excess of 63mph. The correlation of the speeds at which the oscillations occur (57-63), both on the road and on the lift, further reinforce the theory that the drivetrain is where the oscillations originate.
Very enlightening thread. I had a '17 Panamera turbo as well (bought from the original owner with 5K miles) but other issues started happening around the 25K mile mark. Sold it soon after. Not as many pain points as OP here but nice to know if I get into one again.
BGB, Interesting your worst effect is at 76-82 while most others are in range 57-63mph. My worst is if I accelerate moderately to 55, set cruise and go up 1mph every 15/20 sec to 63mph.
from post 18 above from Mootz “ I took the car to a private mechanic. They put the car on the lift and accelerated to 57 mph. The front end shakes. Their suggestion was to return to the dealership have them check/replace the front axels/differential.“
I went to my Indy mechanic to check if he could make some checks but he only have a 2wd dyno.
mine is going to shop Monday for the famous rear spoiler ED. I’m bringing a list for them to check while there took look for obvious problems, ie CV joints, suspension components etc. Do a real Euro NAP inspection with a crowbar.
Keep in mind that my car is lowered another 20mm from factory via the PIWIS computer and i am on different wheels and tires so speeds might be slightly different. Having said that, the air suspension documentation i have for the Cayenne from 2011 that i think is still the same closed loop system we have today has two stages of changes of ride height at speed; one is 50mph and the other is 80mph. It's probably different for the Panamera but unless we are wrong, the premise is the same.
I am not ready to rule out a wheel bearing or a vibration in the drive train but can we all agree that those that have a feel for this can attest to the fact that it does in fact change frequency with a change in ride height? Some of said that changing the PASM dampening affects it but before we get into motor mounts in the lower control arms, wheel bearings or drivetrain parts, trying to lay the whole Air Suspension accumulator thing to bed.
PASM AIR SUSPENSION FOR MY 2011
Last edited by BGB Motorsports; 12-28-2022 at 02:10 PM.
12-21-2022, 08:46 AM
