Mechanics

--VIBRATION DURING ACCELERATION

2002 Pontiac Bonneville

Please forgive the length, but it is necessary. I have a 2002 Pontiac Bonneville SE, 3.8L engine. The car currently has 123K miles on it. Since 2005 I have been experiencing a moderate to severe vibration during moderate to hard acceleration, and I would like to better diagnose it so that it can be repaired. Oddly enough, the vibration is more severe when more weight (passengers) is added to the car. Here is a brief history on the vehicle. During the first winter after I purchased it in 2002, I accidentally hit a snow-covered curb at 40mph with my right front tire. The impact dented the rim. I had the local Pontiac dealer inspect the car for damage and all they came up with was a dented rim. There was some slight vibration at highway speeds, but I & the dealership attributed it to the rim, and it is nothing like what I am experiencing today. In January of 2005 I had to replace the wheel bearing for this same tire. Then in May 2005, while on vacation driving in Florida, the vibration started that I am asking about (at this time the car had about 85K miles). It started suddenly and without any obvious cause. The vibration was severe, and it felt like I was hanging onto a jackhammer. At first I thought it was a tire out of balance. But after several rotations & tire balances (even at a Pontiac Dealership in Florida), the vibration persisted. The vibration was so bad that it gave each tire that was rotated to the front of the car a visibly uneven wear pattern (I had to replace the tires later that summer). It wasn’t until I returned home (after driving over 1000 miles with this vibration), that my home dealership found that my right front boot was ripped and the CV joint was damaged beyond repair. They replaced the right front drive axle assembly (notice the reoccurring maintenance on the right front tire). The vibration diminished some, but has continued & progressively gotten worse to this day. I have discussed this with my dealership, and they cannot offer any concrete answers. They told me to drive it until it started getting worse. Since the vibration is only felt during acceleration, the dealership is convinced the cause of the vibration is in the front axles of the car. They say they have no vibration sensors for diagnostics, so they are unable to determine which side. They are quoting me $80 to remove the axle assembly they installed for a visual inspection to see if it is binding, and $300 for a new one. Here are the questions: what could be causing this vibration? Does the dealership’s diagnosis make sense? Do the prices seem fair? And finally, does anyone know of a way to detect vibrations to determine where it is coming from?

Thanks
Zach
Avatar
Zach Attack
September 7, 2007.



I would start on an alignment rack! Any tire store has one.I would say you probably, after hitting the snow at 40mph, bent the lower control arm and or the strut. If the stut bent inside the knuckle it will be hard to see, but the alignment will be off!

Merlin2021
Sep 8, 2007.
Dear Merlin2021,

I am sorry it has taken me so long to respond, but thank you for your reply. I appreciate your input. Anyhow, I Googled the components you suggest and I found similar situations (smacking a curb) with similar suggestions (check the struts and lower control arm). The car has been aligned at least two times since the incident, and it has been inspected at least 3 times, and nothing was ever said. Would these items be self-evident during an alignment or inspection, or would you have to specifically call attention to them? During one of my follow-up visits, I did ask them to see if anything else was bent. They never mentioned anything to me, so I assumed nothing else was bent. Also, the front strut hisses as it is depressed; however, my dealership told me not to worry; that it wasn’t the cause of the vibration. As an update, I plan on submitting another post as a follow up to what I have found. Though I couldn’t personally find anything wrong with the strut and control arm, I did notice that my “replaced” CV joint has ±1/16” side to side movement at the inner joint, which I don’t think is right. We’ll see what the forum says. Thanks again for your time and explanations.

Best regards,
Zach-Attack

Tiny
Zach Attack
Oct 6, 2007.
I seen you questions as well as the respones thus far. I have a 2005 impala with very very simalar problems. As you stated, the vibration gets worse with more people in the car. The dealer has replace both front axels, rotors, as well as other parts, still the problem is not only there but it is getting worse.

Have you found out any more on your issue?

Thanks.

Tiny
Tony Smith
Nov 2, 2007.
Next thing to check is motor and tranny mounts, check the cv axle on the opposite side, is it tighter? If the mounts are weak, the enging can movve ouy of position, and cause the inner tripod jouint to move in ways not intended!

Merlin2021
Nov 2, 2007.