Vibration
Thread Starter
Melting Slicks
Joined: Aug 2006
Posts: 2,409
Likes: 129
From: Fairview Heights IL
Vibration
During mild acceleration I'm feeling a pronounced vibration starting at 2,000 rpm. My local dealership (a good one) diagnosed it as a failed harmonic balancer (72K miles). $1,500 later, I've still got that vibration. It's engine speed dependent, and not noticeable at 1,500 rpm crusing down the freeway. Is there a U-joint or similar part along the torque tube that could cause this?
Cruising
Joined: Nov 2012
Posts: 11
Likes: 0
dealership a good one ?
being out $1500 with a new unneeded harmonic balancer doesn't sound like a good dealership in my opinion but as we all know the dealer usually gets it right the third time
with speed sensitive vibrations I start at the tire / rim area and work from road contact up into the body as it could be any one of a dozen things
good luck - take it back and tell them try try again
with speed sensitive vibrations I start at the tire / rim area and work from road contact up into the body as it could be any one of a dozen things
good luck - take it back and tell them try try again
Retired & lovin' it!
Joined: Mar 2005
Posts: 4,474
Likes: 547
From: Jackson NJ
During mild acceleration I'm feeling a pronounced vibration starting at 2,000 rpm. My local dealership (a good one) diagnosed it as a failed harmonic balancer (72K miles). $1,500 later, I've still got that vibration. It's engine speed dependent, and not noticeable at 1,500 rpm crusing down the freeway. Is there a U-joint or similar part along the torque tube that could cause this?
Pro
Joined: May 2008
Posts: 577
Likes: 2
From: Downriver MI
Vibrations
If it's engine speed dependent then we should all know where to start looking. You should try to explain in a little more detail when you experience the vibration. Is it under load or while coasting or both. Can you sit in your car in neutral and slowly rev the engine and feel the vibration? Post some more information and maybe we can zero in on it for you.
Burning Brakes
Joined: May 2005
Posts: 1,091
Likes: 35
From: Coldville
being out $1500 with a new unneeded harmonic balancer doesn't sound like a good dealership in my opinion but as we all know the dealer usually gets it right the third time
with speed sensitive vibrations I start at the tire / rim area and work from road contact up into the body as it could be any one of a dozen things
good luck - take it back and tell them try try again
with speed sensitive vibrations I start at the tire / rim area and work from road contact up into the body as it could be any one of a dozen things
good luck - take it back and tell them try try again
I had some new tires put on some used rims.
They put them on and said nothing about it.
I drive the car and call then place back and say I think the tires are not Balanced because the car is Vibrating on the HWY.
I take them back and this time they say the rims are bent.
I know I have a C4 but one thing that it does have in common is Leaf springs.
A warped wheel or out of Balance or out of round tire can be felt very easy due to what I believe are Harmonics from the leaf springs.
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Thread Starter
Melting Slicks
Joined: Aug 2006
Posts: 2,409
Likes: 129
From: Fairview Heights IL
As I said, this is engine speed dependent, not vehicle speed dependent. Red has an A6, and under modest accelleration RPMs typically edge past 2,000 in third and fourth gears on its way to 35mph. As soon as the tach reaches 2,000 RPM, the whole car starts to vibrate. Not violently, but I can feel it in the floor, the steering wheel, I can see it in the rear view mirror. It's not a rumble or a screech. As soon as I reach 35 mph and ease back on the throttle, the RPMs drop to 1400 and the vibration disappears. I hope this is clear to those who suggested wheel or tire problems.
Team Owner
Joined: Sep 2000
Posts: 25,005
Likes: 2,706
From: Far NW 'burbs of Chicago
St. Jude Donor '13
So if you sit there in Neutral and slowly rev it to 2000+ rpm, does the vibration occur?
If you increase the rpm well above 2k, say to 4k, does the vibration increase, decrease, or stay the same?
Does the vibration occur if you are coasting at 2k rpm, or only under load?
Etc?
If you increase the rpm well above 2k, say to 4k, does the vibration increase, decrease, or stay the same?
Does the vibration occur if you are coasting at 2k rpm, or only under load?
Etc?
Race Director
Joined: Mar 2010
Posts: 15,996
Likes: 824
During mild acceleration I'm feeling a pronounced vibration starting at 2,000 rpm. My local dealership (a good one) diagnosed it as a failed harmonic balancer (72K miles). $1,500 later, I've still got that vibration. It's engine speed dependent, and not noticeable at 1,500 rpm crusing down the freeway. Is there a U-joint or similar part along the torque tube that could cause this?
I would like to get a case started for you in my system. I would like to offer our assistance to your dealership to help get this resolved. I cannot guarantee anything at all, but I would like to look into the options available.
Please PM me with your name, address, phone number, VIN, mileage, and the name of the dealership you are working with.
Thanks,
Kelly J.
Chevrolet Customer Care
Thread Starter
Melting Slicks
Joined: Aug 2006
Posts: 2,409
Likes: 129
From: Fairview Heights IL
So if you sit there in Neutral and slowly rev it to 2000+ rpm, does the vibration occur?
If you increase the rpm well above 2k, say to 4k, does the vibration increase, decrease, or stay the same?
Does the vibration occur if you are coasting at 2k rpm, or only under load?
Etc?
If you increase the rpm well above 2k, say to 4k, does the vibration increase, decrease, or stay the same?
Does the vibration occur if you are coasting at 2k rpm, or only under load?
Etc?
Based on this limited diagnostic, I think I would have to rule out the torque tube assembly and focus on the A6 transmission, the differential, or either semi-axle.
What do you thihk?
Race Director
Joined: Sep 2007
Posts: 16,557
Likes: 2,106
From: Peoria/Phoenix AZ
C6 of Year Finalist (performance mods) 2019
Jim -- I just went out and ran a couple of quick tests. Stand still and revving gently, there's no vibration up to 4,000 rpm. When I put it in gear and start moving, as long as I'm accelerating enough to bring the RPMs to 2,000+, the vibration is very clearly felt. When I let up on the throttle, the A6 allows it to shift to a higher gear and the engine speed to drop.
Based on this limited diagnostic, I think I would have to rule out the torque tube assembly and focus on the A6 transmission, the differential, or either semi-axle.
What do you thihk?
Based on this limited diagnostic, I think I would have to rule out the torque tube assembly and focus on the A6 transmission, the differential, or either semi-axle.
What do you thihk?
I'm experiencing a significant vibration that starts about 4000 under load and seems to diminish around 5000. Mine started immediately after I swapped torque converters, so I'm pretty sure of the cause. I haven't yet figured out how to resolve it. If I cure mine, maybe it'll help in your diagnosis.
Thread Starter
Melting Slicks
Joined: Aug 2006
Posts: 2,409
Likes: 129
From: Fairview Heights IL
Also try each gear in sport mode using the paddles to stay in gear.
I'm experiencing a significant vibration that starts about 4000 under load and seems to diminish around 5000. Mine started immediately after I swapped torque converters, so I'm pretty sure of the cause. I haven't yet figured out how to resolve it. If I cure mine, maybe it'll help in your diagnosis.
I'm experiencing a significant vibration that starts about 4000 under load and seems to diminish around 5000. Mine started immediately after I swapped torque converters, so I'm pretty sure of the cause. I haven't yet figured out how to resolve it. If I cure mine, maybe it'll help in your diagnosis.
). Not sure what that tells me. I got a Chuck/CoW A6 tranny tune at about 20K miles, and had the fluid changed at 50K.
Race Director
Joined: Feb 2013
Posts: 12,687
Likes: 224
From: Nazareth, PA.
St. Jude Donor '17
hopefully it's not the cow tune, since i've been kicking the idea around to have mine done. but would that make sense 50k miles later? anyone out there have the cow tune and boost without any problems? 
oh, i also have the a6 tranny by the way. any input is most welcome, even from chuck himself. thank you.
oh, i also have the a6 tranny by the way. any input is most welcome, even from chuck himself. thank you.
Race Director
Joined: Sep 2007
Posts: 16,557
Likes: 2,106
From: Peoria/Phoenix AZ
C6 of Year Finalist (performance mods) 2019
I just tried sport mode with paddles. The vibration that began at 2,000 RPM really comes on at 4,000. This occurs in both 1st and 2nd gears (no, I didn't try for 4,000 in 3rd ). Not sure what that tells me. I got a Chuck/CoW A6 tranny tune at about 20K miles, and had the fluid changed at 50K.
). Not sure what that tells me. I got a Chuck/CoW A6 tranny tune at about 20K miles, and had the fluid changed at 50K.I too had a CoW tune, but dumped it after a short while, due to multiple concerns.
Thread Starter
Melting Slicks
Joined: Aug 2006
Posts: 2,409
Likes: 129
From: Fairview Heights IL
This just started happening within the last three or four weeks, so the mileage at the start was probably just over 71,000. As far as the A6 fluid level is concerned, no one. My garage floor is spotless, so there's no leak.