10-03-09-001: Vibration/Pulsation/Thrumming TSB (FIX)

[TheOriginalSin]

Dealership just called and surprise surprise my LCA's are bad. After they put these in im thinking I need to invest in some quality aftermarket ones.

[nifong08iom]

I am having this issue, and it's much more noticeable now that I installed my Solo catback yesterday. There is a noticeable boom/thrum at low and high speeds, especially if I set the cruise it almost sounds like a drone (i know its not the Solo doing that ) Are there any updates on this? I gather that it is not the motor mounts that cause the issue but the prop/driveshaft that needs replaced. Is this covered by GM at all costs?

[zepcom]

As we discussed over the phone, try some of the things we talked about. Kinda depends on the dealership and how you approach the issue, as to the answer to your final sentence. I've seen dealers shuffle their hands and say "return it to stock before we touch it" and others who are mod-friendly, and can overlook that you might have an aftermarket setup on there. dod-tuneout is another option, you have to decide what is best for you.

--zep

[nifong08iom]

i tried what you suggested with watching AFM in eng. mode, and you're right. Whenever I set the cruise at 65 on the highway in normal shift mode, the AFM kicks in and goes to Half Active (V4 mode) and I definitely get the vibration or thrumming under the feet and at the wheel. When I put it in Sport Shift and set cruise in M6, there is ZERO vibration and I cannot even hear the exhaust. I will probably be opting for the DOD delete when I get it tuned in a week or so. Loving the Solo catback so far, fixing the tips tomorrow as we spoke about. I do wish the Mach Unbalanced was a bit louder though...You know what that means though right? Kooks Mids w/ HFC coming up next to open her up and give a little more sound thanks again for the chat today! If the DOD delete doesn't help the thrumming/boom issue, I will look into taking it in to the dealer with the bulletin.

[pokey]

Update: ... my experiences, sharing to help the next owner.

As many have already noticed this car is EXTREMELY sensitive to any rotating mass out of balance, suspension problems, etc. When I mean sensitive the driver is not isolated from feeling these issues, minor to major.

As I've owned this car I have progressed from fixing one source of vibration with another becoming more noticeable. Slowly though improving the overall car and my sanity. The following repairs have had the biggest positive impact to removing sources of my annoyance.

- Transmission mount (fix)
- Motor mounts (replace / update)
- Prop-shaft (balance)

Transmission mount:
This was the TSB which originally put wheel weights on the part to stop it from "whining", squealing, etc. in 6th gear on the highway. The weights didn't help my whining to my family / friends but it did seem to fix the car. But WTF? GM.. what kind of fix was that? At least now they have an updated part number which I think I heard means they don't have to use wheel weights anymore.

Engine mounts:
This repair made the biggest improvement to my car. I was feeling more then I cared for, engine vibration through the steering wheel at low speeds around 32 mph under light throttle. At the time I drove mostly in town and this was felt often.

Prop-shaft:
Which brings me to my latest repair my "holy grail" of vibration repairs, the prop-shaft balance. I started this latest adventure as all the rest with the dreaded stop to the dealership. The first repair they completed was to balance the tires at which my service advisor confidently stated "these cars are very sensitive to wheel balance and this WILL fix your highway speed vibrations!" He is right but that wasn't THE VIBRATION I wanted fixed. (needless to say this pissed me off, his confidence and arrogance.. but I gave it a try) He also mentioned GM was no longer doing the TSB listed at the top of this thread. Prop-shaft balance.

Ironically by balancing my tires and eliminating this source of vibration it allowed the prop-shaft vibration to be felt even more. I could now also hear the low frequency pulsating sound with the vibration. My only theory was by eliminating this vibration the other was no longer partially canceled out, like tossing two pebbles in a lake and watching the ripples of water meet. So back I go..

This time I asked to speak to the Service Manager. He was not around so I told the friendly gentlemen who was unlucky to have to help me that I would be calling Pontiac Customer Care but wanted to first speak with the Manager first. (I was polite through this entire process, I'm not the type of person to get mad or show emotion) When I spoke to the Manager he was great! He rode with me, verified the vibration, and said he would call GM.

The GM Engineer...
I was told my Service Manager was working directly with the GM Engineer responsible for this G8 issue. The next repair offered up by GM was to replace the Prop-shaft bushings to the updated Camaro ones. Interesting the Service Manager mentioned they looked the same but whatever..we gave it a try. They were replaced and it seemed like the vibration was still present so my prop-shaft was rotated 180 degrees. Car was then returned to me and I was told this was the only repair GM would authorize, no prop-shaft balance. I was also told that this "was just the normal characteristics of this vehicle" LOL..freaking BS! So off I went.

The bushings...
Interesting enough the bushings did change the feel of the car on the highway, the vibrations were not gone only different which made me believe we were in the right spot to fix. I called my Service Manager and politely mentioned I would be calling Customer Care. I also mentioned I still felt the prop-shaft needed balancing, that maybe it was "within manufacturing spec / tolerance" but for this car balanced tolerances had to be Perfect.

The prop-shaft...
So finally we come to my holy grail of repairs. I called Pontiac Customer Care/Service politely reviewed my experience and after a few phone calls was told GM would in fact authorize the repair. Took a little over 3 weeks for the balance to be completed, sent back and car to be returned to me.

The results...
Interesting my results are (what sounds like) the same as or similar to what SpeedRacerX mentioned earlier. My drive line vibration caused by the prop-shaft is basically 99% gone. No more pulsating vibration with sound. I do though HAVE other vibrations still present, around the same speeds 65-75mph. These could be anything, tires, rotors, something else?? So, sadly I'm not 100% vibration free and probably never will be. Would I do it again! YES!! Being a former Machinist I could not handle knowing I had component out of balance, and that GM's answer was to put different bushing in place to dampen any vibrations caused by the imbalance. If it worked though I would have not pursued the prop-shaft but for me it did not.

My advice..
If you have similar issues do what you need, to be happy with your car. If you feel your prop-shaft is in need of balancing and the dealership can't (won't) help you, call customer service. And I think what helped me was remain polite...these people are just doing their job albeit not very well sometimes. Will I pursue this any further, no. I will live with it as I'm getting closer to change the car anyway. Tires, brakes, rotors, bushings etc.. Maybe even some exhaust work to give the car a reason to resonate / vibrate!

Thanks to WickedMom, Charlie, and all the moderators / regulars on this forum for your help through the last 3 years!

I hope this helps.. any questions let me know / pm me. Good Luck!

[MongosG8]

Sorry to bring up an old thread people but I'm desperate for some answers.

I'm not receiving good service ..as usual from the dealer.. might try another dealer but I'm having this issue and its pretty noticeable IMO.
The dealer is blaming it on my camaro wheels but that's impossible because I had them road forced and everything was in check just recently.

Feeling the vibration and it is exactly like Jess mention. Pulsation, vibration same area etc.

Do you think I would be better off just purchasing the dam thing myself and having a pro instal it for me? It seems like I'm going to beat my head into the ground convincing the dealer that this is the issue I'm having. Seems like they think I'm full of it when I mention this old bulletin and looked at me like I had a third eye on my forehead.

Would love to have some advice ..Jess would love your opinion plus all you other experts out there!


..Bueller ..Bueller?

[-Ray-]

Ask to borrow some stock wheels and take it back.

[WickedMom]

You could just buy it, if you can get it... Or ask the dealership to use the NVH tester.... Like they are supposed to...

But.. This issue would of been since the car was new, not a developed issue.

Sent from my SAMSUNG-SGH-I317 using Tapatalk 2

[MongosG8]

Ask to borrow some stock wheels and take it back.

Ray .. I still have my stock wheels.. they are in storage. Thought about this earlier just to throw them back on for shits and giggles and see what happens.

You could just buy it, if you can get it... Or ask the dealership to use the NVH tester.... Like they are supposed to...

But.. This issue would of been since the car was new, not a developed issue.

Sent from my SAMSUNG-SGH-I317 using Tapatalk 2

Jess .. I actually asked a friend of mine that works for a Chevy dealer upstate if he could price one out. I also asked if the Camaros would work.
He suggested to me that he will ask his service manager if they can service my G8 ..If they can he will bring it to work and have it looked at ..he even said ..to get something like this replaced from GM is going to be like pulling teeth.

Its not like my G8 has a lot of hard miles.. it only has 18k on it ..it still needs to go through puberty. LOL!

[ikarus]

Just bought my GT with 38k miles and put about 3k on in two weeks (had to drive it 2100 miles across country back to where I live), and I have felt this pulsing vibration the whole time. I could live with it I guess, but I'd rather get it taken care of - I just have a bad feeling trying to get it fixed at a generic GM dealer in Las Vegas is going to be like trying to pet a badger.