Vibration while accelerating

Tiny
SMURFMAN
  • MEMBER
  • PONTIAC GRAND PRIX
GTP, 113,000 Miles, v6 3.8 super charged
At about forty five to sixty mph only while accelerating or holding the speed at say fifty five. I have a vibration, that acts like a tire out of balance, either that or the wheel is going to fall off.

The vibration is almost invisible at sixty five to seventy mph.

The worst vibration comes while accelerating from forty to forty five mph while corning to the right only, that is where the wheel feels like it is going to fall off. To the left, it is not really apparent.

At higher speeds sixty to seventy and hitting a corner, the vibration becomes more of pulsating that can be felt.

Most of the vibration is not felt in the steering wheel, but rather my legs, not so much my "backside", as I have heard that with some vibrations steering wheel is the front end, seat is rear end.

I was reading some posts about CV joints, could this be what I am looking at?

I was starting think transmission, but it really runs well and responsive all other times.

I thought spark or timing, my plugs and wires were replaced last summer (12,000 to 1,000 ago), timing, I was not sure (there is a muffler noise, towards the front, I have not looked into, perhaps a hole in a pipe, but it is not overly loud) as for timing, it really idles well, runs with good speed and the super charger kicks in as expected.

Any idaes, or troubleshooting - much appreciated.
J
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Friday, April 20th, 2007 AT 10:56 AM

9 Replies

Tiny
NICKYD01
  • MEMBER
Your first thought is most likely the problem. You say the vibration changes with speed. That tells me that it is not an engine or transmission problem at all. If you had warped rotors it would vibrate upon braking. The other possible problem could be tie rod ends but the tie rod ends will occur most likely more steady and on braking. It would be a good idea to have your tires balanced at a cheap price to find out if that is the problem or not.
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Friday, April 20th, 2007 AT 10:47 PM
Tiny
DATAPACKS
  • MEMBER
Hi Smurfman.

Did you ever figure out what this vibration problem was?

I am having the same problem exactly. So far the GM dealer diagnosed it as a front bearing. That cost $500.00 and was wrong. The Goodyear dealer diagnosed it as a bad tire. That cost $500.00 and was wrong. Mr. Transmission thought it had to do with the engine and suggested I change the Mass Airflow Sensor as the check engine light was on and that was the reason it was on. That cost $550.00 and was wrong but was needed anyway. It started leaking a little antifreeze at the center head and cylinder head at the back bank so a friend recommended his mechanic. He did turn out pretty good and he changed the intake manifold, supercharger and valve cover gaskets. That cost $700.00 and did not do anything for the vibration. This mechanic thought the engine was sucking air threw the bad gaskets and figured the vibration would be corrected with this repair as well. It didn't, Although I have full supercharger boost back that I did not even realize that I had been loosing. I have also had the front control arm bushings changed and the front end all checked out. Apparently it is okay. The brakes pads, rotor, calipers and flex lines were all changed within the year and have less then 20,000 on them.

As you can tell, I have $2,200.00 invested in trying to solve this vibration and all I have managed to fix are a few others things. It actually puts me in a bad mood just driving it. I would really like to destroy it and collect the insurance but I do not have the demeanor for that.

Please share you experience with me!

Bill
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Tuesday, February 5th, 2008 AT 7:00 PM
Tiny
NOBODYHOME923
  • MEMBER
Your axles could be the source of your problem.
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Wednesday, March 11th, 2009 AT 2:19 PM
Tiny
ROCKERPALUZA
  • MEMBER
Did you found the actual cause of this problem?
I have the same prob here.
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Monday, March 29th, 2010 AT 2:07 AM
Tiny
MSCHILLINGII
  • MEMBER
Most likely CV axles. I am having the same problem that is what it is. It will keep getting worse and worse until they are replaced. I did both front bearing and mine still does it.
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Monday, July 5th, 2010 AT 2:21 PM
Tiny
DAVE'S BIG BACKYARD!
  • EXPERT
A bad CV joint will make the whole car shake under torq this is one of the in board joint on the CV axle, sometimes it will not do it until it has been driven for a while.
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Tuesday, April 5th, 2011 AT 11:22 PM
Tiny
RICK57
  • MEMBER
2000 GTP. Having the same problem. Wicked shimmy making it un drivable and unsafe at freeway speeds. It is not side to side more like a bounce up and down on freeway speeds over fifty under load on acceleration. Smooth as silk when it not under load or in town. Broken motor mounts will cause this problem as well. Midus in Redding California worked on my problem but still it is unresolved. Changed motor mounts, tie rods and all four struts plus a fluid change in brake system costing me. $2,375.00. I brought it in for this problem and they fixed everything else but what I brought it in for. Midus said it was a list of possible things. Torque converter sticking, Supercharger belt system vibrating and some reasons even an idiot would know better. But the bottom line is they just wanted to take more of my money. Hell of a way to get return business I would say. Part changers. Not real mechanics that work the problem those days are gone.
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Thursday, September 22nd, 2016 AT 12:20 PM
Tiny
CASEY JARVIS
  • MEMBER
Did any of you ever get anything figured out on what the problem is? My 2000 Grand Prix GT does the same thing. I have changed the inner and outer tie rods. I have new motor mounts. I have new transmission mount. I had the front end checked out. My tires have been balanced and I have had it aligned and I still have the vibration when accelerating. It is more like a thunk vibration with tire rotation I guess, but it does not do it all the time. It does it every once in awhile but it i's bad when it does do it and it is daily. Please help.
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Tuesday, May 1st, 2018 AT 3:26 PM
Tiny
ASEMASTER6371
  • EXPERT
Good morning.

To the person with the original question.

From your description, it could be a shutter from the torque converter clutches. This is a common issue often misdiagnosed as a suspension issue.

To confirm, go to a parts store and ask for the additive for torque converter shutter. It is in a red tube. Get two of them. Add them to the fluid and drive it. It takes about twenty five miles to take effect. It puts a coating on the clutches in the torque converter and stops the slipping of the clutches.

If it does stop, it is a temporary fix as the torque converter is the failure and will need to be replaced.

Try this and let me know.

Roy
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Wednesday, May 2nd, 2018 AT 4:45 AM

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