Re: Drivetrain noise & rumble on acceleration from low vehicle speed - DI CTS4 (AWD)

Rab: I have nearly 3,000 miles on my CTS4 with DFI; took delivery on August 28. No noise/vibration on acceleration.

Keep us posted on what you find out.

 

Re: Drivetrain noise & rumble on acceleration from low vehicle speed - DI CTS4 (AWD)

I haven't hit her hard yet as I am at 450 miles or so. Really have babied her so far. Should be there in the next week and will start to hit the gas a little harder. I'll let you know if I hear anything.

 

Re: Drivetrain noise & rumble on acceleration from low vehicle speed - DI CTS4 (AWD)

Rab can you leave me a PM with a phone number I can reach you at to discuss your issue. I am the AWD development engineer for the CTS and would like further information and may be able to provide you with some resolution. The transfer case operation should be totally quiet during operation and imperceptible to the driver regardless of whether it is distributing torque to the front axle or not. And just for clarification, the AWD controls are designed to apply torque BEFORE wheel slip occurs for optimal traction and control.

 

Re: Drivetrain noise & rumble on acceleration from low vehicle speed - DI CTS4 (AWD)

Rab can you leave me a PM with a phone number I can reach you at to discuss your issue. I am the AWD development engineer for the CTS and would like further information and may be able to provide you with some resolution. The transfer case operation should be totally quiet during operation and imperceptible to the driver regardless of whether it is distributing torque to the front axle or not. And just for clarification, the AWD controls are designed to apply torque BEFORE wheel slip occurs for optimal traction and control.

jjab4444, thanks for your post. Your comments regarding normally quiet operation of the transfer case have convinced me there is something wrong with my vehicle. In retrospect I have noticed occasional episodes (2 or 3 times per day on average) of varying levels of drivetrain noise & rumble since day 1, particularly when accelerating from a stop, and especially so accelerating while exercising a hard turn (such as at an intersection, or exiting from a parking lot). Perhaps the problem lies with the limited slip differential rather than with the AWD transfer case? It's definitely a drivetrain issue, wherever the noise & rumble is coming from.
I've sent you a PM, with my phone number info. Looking forward to discussing the issue with you.
Thanks,
Rab.

 

Re: Drivetrain noise & rumble on acceleration from low vehicle speed - DI CTS4 (AWD)

Are there any others with CTS4's experiencing similar episodes of gear noise and rumbling/vibration on mid-to-high accelerations with the vehicle at relatively low vehicle speeds (0 - 15 mph) ?

I can honestly say that my defective CTS does not have this issue. Although I did try and listen for it today, but it's tough since the car accelerates and the tone of the exhaust make it hard to hear if it does.

I test drove my replacement CTS and I didn't pick up on anything odd like this, but then again I didn't push it hard since it isn't fully broke in yet. Hopefully next week I'll be in that one. I'm just trying to get GM to make the wood steering wheel and shifter to disappear from that car to make it identical to the one it's replacing.

 

Re: Drivetrain noise & rumble on acceleration from low vehicle speed - DI CTS4 (AWD)

Rab,
I have about 1200 miles on my CTS4 and there is absolutely no noise generating form either end of the drive train. I wouldn't even know that there is an AWD system in the car it is so transparent. All I know is that full throttle acceleration feels very strong, and very quiet, except for the nice growl coming from the exhaust. I hope that you get that problem fixed so you can enjoy the full potential of that great car. Good luck and keep all of us updated.

 

Re: Drivetrain noise & rumble on acceleration from low vehicle speed - DI CTS4 (AWD)

What a great forum...

I haven't beat on the car yet to tell but in normal driving I haven't noticed anything..

Good luck Rab and follow through with the offer for a possible solution/resolution..

GM's listening..

How cool is that?

 

Re: Drivetrain noise & rumble on acceleration from low vehicle speed - DI CTS4 (AWD)

What a great forum...
I haven't beat on the car yet to tell but in normal driving I haven't noticed anything..
Good luck Rab and follow through with the offer for a possible solution/resolution..
GM's listening..
How cool is that?

JB, this is a great forum. Thanks for your comment.
I'm not really stressing on this noise & rumble issue, as I know it will eventually get sorted out... and the problem is not detracting from the basic enjoyment of my new CTS4.
BTW, I'm not beating on my car! I'm just asking a little more from it following the break-in period. :bouncy:
Yes, it is very cool that GM is listening at this forum. (Did I mention to you that I had worked at GM for 21 years, until year 2005? Will not elaborate on this further here, but will speak of it in a PM sometime).

 

Re: Drivetrain noise & rumble on acceleration from low vehicle speed - DI CTS4 (AWD)

DavidL / Pucks / imrf / bobelew:
Thanks for your posts. From yours and jjab4444's comments I've concluded there is almost definitely a drivetrain issue on my CTS4. Hopefully it will get sorted out before too long. Looking forward to a telephone conversation with jjab4444, and later the specific diagnosis and corrective action at the local Cadillac dealer. Will keep this thread updated with any & all developments.
Regards,
Rab.

 

Re: Drivetrain noise & rumble on acceleration from low vehicle speed - DI CTS4 (AWD)

I too am experiencing a rumble in the drive train which I attribute to the AWD system. In my case it is most apparent (quite noticeable actually) btwn 40 - 60mph. Now that I am attuned to it, I can also detect it at highway speeds. My vehicle does have the performance package. I mentioned this rumble to the dealer, who has not yet run heard of the issue. First noticed this the 2nd day we owned the car. Getting more pronounced now. Have about 300 miles on the car. Hope it does not get worse as I really like this vehicle.

For what it is worth, I have been very into cars for many, many years, including racing SCCA formula cars. Have owned Porsches, Jags (the older, real Jags), Austin Healeys and many GM models, both performance and luxury.
This is a very satisfying car to drive. If they can fix this, a couple unwanted window/door wind leaks, I'll be another happy customer.

 

Re: Drivetrain noise & rumble on acceleration from low vehicle speed - DI CTS4 (AWD)

Jut wanted to provide an update to the forum regarding the drivetrain vibration/rumble issue on my AWD CTS.
Note that the problem is entirely torque-induced, and will only occur after the vehicle has reached normal operating temperature. When the car has been sitting oustide for hours with chilly ambient temps, the vibration/noise problem is completely absent for the first couple of miles of driving following engine start-up, regardless of how much throttle I use.

I brought my CTS4 into the Cadillac dealership for inspection of the problem on Monday Nov. 12th. At is turned out my car sat outside for about 7 hours (8:00 am till 3:00 pm) before anyone looked at it. It was about 3:00 pm when someone finally took it for a test drive for a total distance of about a mile. During that short drive, the service guy never got the car up to temperature, and the vibration problem on acceleration never happened for him, which is understandable.
When the car arrived back at the dealership, they put it up on the lift and loosened and then torqued all the bolts in connection with the crossmember for the AWD transfer case. This operation was done as a way to 'relax' the original positioning of the AWD transfer case (i.e. in so doing hopefully shift it a few more millimetres away from any hard point on the underside that it could be making contact with when the driveline negotiates high torque).

Unfortunately that didn't work. It's now Tuesday, and the torque-induced vibration problem remains. On the way to work this morning (after about 3 miles into the 8 mile drive) I could cause the vibration & staccato rumble to occur virtually anytime, by pressing 5/10ths or more on the accelerator.
I'm going to stop by the dealership later today and bring the service manager for a road test in my CTS4. I want him to witness this problem first hand.

Forum member jjab4444 has been extremely helpful with information in connection with this issue, and we are presently communicating off-forum to resolve the problem.

I will post a further update in a few more days.

 

Re: Drivetrain noise & rumble on acceleration from low vehicle speed - DI CTS4 (AWD)

Final update: Problem solved!!! :bouncy:
The issue of driveline vibration & thumping noise on my CTS4 during times of mid-to-high load/rpm/acceleration (i.e. high driveline torque) was resolved yesterday at the dealer.
In consultation with GM Tech, the dealership's service folks succeeded in eliminating the torque-induced vibration/noise problem by shimming the AWD transfer case crossmember down slightly, using a 1/8" alignment shim on each side of the transfer case crossmember.
It appears the stack-up of powertrain tolerances (together with vehicle chassis manufacturing tolerances) on my AWD CTS allowed the transfer case (and/or the transmission case) to momentarily 'ground out' on the driveline tunnel anytime the powertrain was loaded up... (but only when all of the powertrain components would reach normal operating temperature).
Kudos to my dealer and the GM product support network in getting this issue resolved on my car. They did a great job. :thumbsup:
On the way home from work today I managed (as usual) to bury the accelerator once or twice (maybe a few more times than that.. ).. and instead of hearing episodes of driveline vibration & noise, all I heard was the sweet sound of the engine doing its thing. Hey, you gotta love it.
What a great car this new CTS is.
:spin:

 

Re: Drivetrain noise & rumble on acceleration from low vehicle speed - DI CTS4 (AWD)

I'm happy for you
It's nice to hear some good comments about the CTS besides your dealer
Thanks for the update as well because I believe such returns will be a good future reference when people do a search about similar problems with their car

 

Re: Drivetrain noise & rumble on acceleration from low vehicle speed - DI CTS4 (AWD)

I'm happy for you
It's nice to hear some good comments about the CTS besides your dealer
Thanks for the update as well because I believe such returns will be a good future reference when people do a search about similar problems with their car

Cadillacboy, thanks. One of the greatest things about this forum is the sharing of very useful information. I've received plenty of great information from many members here, so I like to return the favor where I can.

An update to my last update: I received an email this morning from the dealership's service manager, who thought to write me and provide a further explanation of their findings. I've pasted in below the text from his note:

Dear Mr. ("RAB"):
I thought, for your interest, you would like a copy of the pictures sent to GM regarding the repair we completed on your 08 CTS. The shims we ordered-in from Lansing were in fact already installed on the propeller shaft on your vehicle. Our technician installed shims above the crossmember mount for the transfer case to stop the transfer case from rubbing the inner floor driveshaft tunnel when flexed under acceleration. The noise(s) you demonstrated to me on our test drive was the reverberating of the transfer case itself hitting the top of the driveshaft tunnel and carrying down the rear axle shafts of the vehicle.
Please do not hesitate to contact me if you have any questions or concerns.
Sincerely,
Service Manager
Cadillac-Hummer of London / London Motor Products

Finally.. in my previous post in this thread I had somehow neglected to make special mention of member jjab4444, who is the GM AWD development engineer for the new CTS. jjab4444 and I have communicated several times over the last couple of weeks regarding the driveline vibration issue on my vehicle, and the information & assistance provided by him has been outstanding. A big THANK YOU to jjab4444 !

:cheers:

 

Following. Am curious

 

[QUOTE="BlackDiamondCTS_Coupe, post: 17969674, member:

I have some video I can send. Not sure how to though. Anyway, it sounds to me like the knocking is coming from the driver's side front. It only does it in gear.

 

YouTube, then upload to the site.

 

Check your rear driveshaft. Unfortunately, there are a few things on these cars that could cause that sound. Read my 2010 AWD - Rear driveshaft at transfer case flange: Bolts sheared & am attempting to repair thread as a cautionary tale and a way to help you know where to look. But it could be so many things - front diff, rear diff, transfer case, center driveshaft bearing, front axle, a wearing cv joint etc.

Does it occur in reverse? Have you tried the same tests with traction control off and/or with the AWD fuse pulled?

 

Check your rear driveshaft. Unfortunately, there are a few things on these cars that could cause that sound. Read my 2010 AWD - Rear driveshaft at transfer case flange: Bolts sheared & am attempting to repair thread as a cautionary tale and a way to help you know where to look. But it could be so many things - front diff, rear diff, transfer case, center driveshaft bearing, front axle, a wearing cv joint etc.

Does it occur in reverse? Have you tried the same tests with traction control off and/or with the AWD fuse pulled?

I have to keep my awd fuse out, otherwise I get the crab walk at slow turns. I don't think it does it in reverse, but I'll definitely check today. All my abs,TC,stabilitrack...lights are on as of about 3 wks ago. Scanned and code was passenger rear speed sensor.