Vibrations at highway speeds

[GM_Fan]

My G8 has had vibrations at highway speeds ever since I bought the car.

I've had it in 3 times and the dealer still hasn't fixed the problem. I've had the tires rebalanced, Road forced balanced, and 1 tire replaced.

I feel it in the steering wheel and I think that it is a drive shaft problem. The whole car vibrates and at 65 -75 mph the mirrors vibrate so much that you can't see out the mirrors.

I'm taking the car in to my dealer. I'm taking the service manager for a cruise. What should I ask the techs to look for? Anybody else have similar issues and how were they solved?

I've seen the threads about re-balancing and drive line boom noise. Anything else to check while it's there?

[MitsukiGT]

Wish i could help, but on mine from day one I have a vibration when I brake, if I remove my hand from the steering wheel while braking the wheel with move by itself back and forth like 5-10 degrees each way. But not enough to stop going in a straight line. It hasn't gotten worse so I never took it in.

So the car only vibrates at that specific mph? A few years ago I had a bad tire that would cause allot of vibration once I got over 35 mph, but you already check that.

[DRCUSTOMPARTS]

If the strut bushings are crushed it will cause the suspension to have excessive movement causing the wheels to hop. Bad strut bushings are a common issue with the G8 so have them check that. Also too much or too little air pressure in the tires can cause vibration.

[-Ray-]

I assume you are going to Reeve's? Ask Erik to ride with you. You just can't go 70 on 31 South.

[GM_Fan]

I assume you are going to Reeve's? Ask Erik to ride with you. You just can't go 70 on 31 South.

Sure you can..but it is ill advised. They might know a back-road where we can open it up.

I think Erik has worked on my car before. Jamie has been good to me the times I've been there.

I might as well plan on being there all day. I want the problem Fixed !

[GM_Fan]

I'm taking my car in Tuesday. The Service manager thinks that the tires are just flat spotted. Are the stockers so crappy that they flat spot and don't smooth out ever? My GTO tires would flat spot if I let it sit all winter and took it out for a drive when it was cold. After a few miles the ride smoothed out and it was fine. This vibration doesn't go away and constantly appears above 60 mph.

I seldom let the G8 sit longer than a couple weeks without taking it for a drive in the winter. Oh well I'll find out more tomorrow.

[-Ray-]

I need to have the recall done on my G8. What time you going?

[GM_Fan]

around 10 am tomorrow.

[99-LS1-SS]

I've never thought about the tires flat spotting. Do you think a road force balancing would be able to tell that or not?

[-Ray-]

Without a doubt Brandon. I'll see you down there Ron. Shouldn't take long for my recall work. We can go to lunch in the Red car. :)

[GM_Fan]

I've never thought about the tires flat spotting. Do you think a road force balancing would be able to tell that or not?

They road force balanced them the 2nd time I took it in. They did decide to replace one tire after I called them on the way home and told them that that didn't fix it. The 1st time I took my car on the Interstate was in the spring when I went to visit Ray. I recall telling him that day I had some kind of vibration going on.


Without a doubt Brandon. I'll see you down there Ron. Shouldn't take long for my recall work. We can go to lunch in the Red car. :)

See you there.

[99-LS1-SS]

IF my car has flat spots I think I've possibly reduced the dimple some.

Since I've already "broken in" my front tires before they rotated them. I felt I should be safe and "break in" the other two tires. I will be posting pictures of that example. I could/should have gone on into third and continued the fun but I looked up in front of me and there was a nervous pedestrian making his way off the road when he heard me coming. I thought I would be polite and let off before I got near him.

[GM_Fan]

Wow I just got back a few minutes ago. About 6 hours including travel time.

The dealer found one tire cupped. There is also the drive line problem as mentioned earlier. I'm getting 4 new tires next week.

[-Ray-]

Good to see you Ron. Thanks for lunch.

[GM_Fan]

Good to see you Ron. Thanks for lunch.



No problem... Let me know when it's cooler and you'll be heading to the track.

[Chewy]

Let the tire smoke commence!

[99-LS1-SS]

Ron, did the tire(s) fix your vibration? My vibration is odd. I know rubber gets softer when it gets hot but it seems like the hotter it is the higher the MPH when the vibration starts. I don't know if it's the tires and/or where the driveshaft mounts to the differential.

[GM_Fan]

They ordered a set of 4 tires for me. I'm getting them put on Aug 19th. They also found a vibration in the drive train.

The dealer did the alignment of driveline. Rotated the shaft 120* twice. The vibration did diminish, but it is still there. A call to the GM Tech engineers found that there is a known problem, but there currently is not a fix for the problem. So I'm SOL until they find a solution.

[Panzer Leader]

GM Fan sorry to hear this. Did they check the balance of the drive shaft? BTW is this drive line alignment problem limited to only the V8s or does it affect all the G8 models?
Hope they gt it seolved soon. Thanks.

[99-LS1-SS]

They ordered a set of 4 tires for me. I'm getting them put on Aug 19th. They also found a vibration in the drive train.

The dealer did the alignment of driveline. Rotated the shaft 120* twice. The vibration did diminish, but it is still there. A call to the GM Tech engineers found that there is a known problem, but there currently is not a fix for the problem. So I'm SOL until they find a solution.

I'm seriously considering doing this. I've already rotated it once.

I wonder if the rubber "bushing" between the driveshaft and the differential could be bad?

[GM_Fan]

There is a problem with some 08s and 09s. Here is info from another thread.




#PIC4989: Drive Line Boom Noise And/Or Vibration - (Oct 2, 2008)


Subject: Drive Line Boom Noise and/or Vibration


Models: 2008-2009 Pontiac G8
There may be a either a boom noise or vibration and in some cases both a noise & vibration detected in a very few 2008 & 2009 G8's. This condition may be detected by customers at speeds of 55-65 MPH on either 08 or 09 G8's. The noise could be described as a low frequency boom or moan noise (not a whine) coming through the body. The vibration is generally felt in the seat or the floor pan. The condition could be caused by either a misaligned center support bearing assembly or the prop shaft mounting to the differential yoke.

Recommendation/Instructions:
The prop shaft center support mount is slotted left to right and can be adjusted by loosening the bolts which are accessible through holes in the metal shield between the prop shaft & the floor sheet metal. After loosening the center support bolts you can use a pry bar between the prop shaft & floor to adjust the center support. If the alignment isn't correct the prop shaft will usually "snap over" into proper location with very little input.

If the condition is both noise & vibration felt through the floor, re-indexing the prop shaft to the differential yoke may have to be performed:

•Mark the relative alignment of the propshaft, rubber coupling, and differential in the original position.
•Number the nut and bolt pairs and their hole in the rubber coupling which join the rubber coupling to the differential (silver) and the nut and bolts which join the propshaft to the rubber coupling (black).
•Remove rubber coupling from differential and propshaft, ensure the nut and bolt pairs are kept together.
•Re-assemble indexing the rubber coupling and silver bolts clockwise (relative to differential), and the propshaft and black bolts counter clockwise (relative to differential).

[GM_Fan]

GM Fan sorry to hear this. Did they check the balance of the drive shaft? BTW is this drive line alignment problem limited to only the V8s or does it affect all the G8 models?
Hope they gt it seolved soon. Thanks.


I asked about checking the balancing of the shaft. The dealership said they will have to send it out for that. That is something that can be tried, but we'll have to try the new tires first and go from there.

[99-LS1-SS]

There is a problem with some 08s and 09s. Here is info from another thread.




#PIC4989: Drive Line Boom Noise And/Or Vibration - (Oct 2, 2008)


Subject: Drive Line Boom Noise and/or Vibration


Models: 2008-2009 Pontiac G8
There may be a either a boom noise or vibration and in some cases both a noise & vibration detected in a very few 2008 & 2009 G8's. This condition may be detected by customers at speeds of 55-65 MPH on either 08 or 09 G8's. The noise could be described as a low frequency boom or moan noise (not a whine) coming through the body. The vibration is generally felt in the seat or the floor pan. The condition could be caused by either a misaligned center support bearing assembly or the prop shaft mounting to the differential yoke.

Recommendation/Instructions:
The prop shaft center support mount is slotted left to right and can be adjusted by loosening the bolts which are accessible through holes in the metal shield between the prop shaft & the floor sheet metal. After loosening the center support bolts you can use a pry bar between the prop shaft & floor to adjust the center support. If the alignment isn't correct the prop shaft will usually "snap over" into proper location with very little input.

If the condition is both noise & vibration felt through the floor, re-indexing the prop shaft to the differential yoke may have to be performed:

•Mark the relative alignment of the propshaft, rubber coupling, and differential in the original position.
•Number the nut and bolt pairs and their hole in the rubber coupling which join the rubber coupling to the differential (silver) and the nut and bolts which join the propshaft to the rubber coupling (black).
•Remove rubber coupling from differential and propshaft, ensure the nut and bolt pairs are kept together.
•Re-assemble indexing the rubber coupling and silver bolts clockwise (relative to differential), and the propshaft and black bolts counter clockwise (relative to differential).

I've done both of these....to no avail.

I guess I'll index it one more time....

[Mike P]

What kind of tires are they giving you?



...




They ordered a set of 4 tires for me. I'm getting them put on Aug 19th. They also found a vibration in the drive train.

The dealer did the alignment of driveline. Rotated the shaft 120* twice. The vibration did diminish, but it is still there. A call to the GM Tech engineers found that there is a known problem, but there currently is not a fix for the problem. So I'm SOL until they find a solution.

[GM_Fan]

There is a noticable difference in the reduction of the vibration already.

The engineers at GM know of the problem. So if the above "fix" doesn't work, we'll have to wait on plan B. Who knows how long that will take.

There is a noticable difference in the reduction of the vibration already.

[GM_Fan]

What kind of tires are they giving you?



...

4 more stockers I would guess. I have the Summer only tires.

[99-LS1-SS]

Does or did you guy's vibrations get worse with speed? Mine starts to shake the mirrors at around 70 mph and then gets worse the faster I go. Is this what you guys are seeing to?

[GM_Fan]

Does or did you guy's vibrations get worse with speed? Mine starts to shake the mirrors at around 70 mph and then gets worse the faster I go. Is this what you guys are seeing to?

Yep!

[VT_Hokie]

Thread from the dead!

I realize that this thread is 2.5 years old but I was wondering if this ever got resolved for you?

I just had my lower control arms replaced, rotors resurfaced, new brake pads, alignment, and as soon as I got on the highway and hit the 75-80 mph mark the whole car started shaking like a banshee.

I want to take it to another local dealer and see what they can do for me, but I was wondering if you guys knew of any fixes for it that have come up since this thread was started?

[99-LS1-SS]

Mine was the driveshaft. I took it to the dealership that I bought the car from and they sent the driveshaft to Michigan to get re-balanced by a company up there. It fixed my vibration.