Shake in Steering HELP!

[2009G8GT]

Hey guys, I'm hoping to find some help from our Holden brothers. We have a 2009 Pontiac G8 GT 6.0L that has a shake in front coming thru the steering wheel. We have ruled out the wheels/tires, 3 different sets of wheels/tires and same result. They have turned the rotors and still nothing.

I am hoping maybe there is something you guys know that hasn't made it's way to the GM dealers in the states. Is there an issue with the hubs in the front or maybe the face of the rotor that lays against the hub?

Anything would be helpful!

Thanks,
Rich

[acarmody]

You have tried a tyre alignment right?

[2009G8GT]

Yep, the alignment has been checked with each set of wheels installed.

[UFO]

more info please.
when does it shake?

does it shake straight away upon acceleration, or only when cruising at a certain speed, or only when braking?
is there any shake when turning through a corner, or only in a straight line?
when's it most noticeable? what speed you doing?

is the shake definitely coming through the steering wheel (front wheels), or can you feel it if you rest your hand on the center console (possibly coming from the rear end)?

does the shake change with speed, or with revs regardless of speed?

[mint]

Time to turn to the suspension side of things..

[Bill44]

Even though the car is a couple of years old I'm assuming this is a problem you've had since new, and not as the result of a modification or accident.

Going back a few models I had a new sedan with a front end shake. After 10,000Km of putting up with it and everything balanced, tuned, changed, and twiddled with no improvement, GM suggested that the dealer lift the vehicle on the hoist, loosen off everything in the front end, lower to the ground and (using hand pressure) bounce it up and down a few times, lift up and re-tighten everything to specification. Guess what? NO MORE FRONT END SHAKE!


Apparently something had been fitted/tightened under stress and was causing the problem.

[DynoVE]

dont know if this will help but i had this problem on my new wheels on the freeway, turned out that the wheels were not balanced correctly

[2009G8GT]

when does it shake?
from about 35mph-80mph. more on some streets. worste on concrete
does it shake straight away upon acceleration, or only when cruising at a certain speed, or only when braking?
It no longer shakes when braking because they machined the rotors. shakes anytime I'm driving between 35mph and up.
is there any shake when turning through a corner, or only in a straight line?
straight line for sure. not really sure about curves, but I believe it does if I'm above 35 mph.
when's it most noticeable? what speed you doing?
50-60 mph is prime speeds

is the shake definitely coming through the steering wheel (front wheels), or can you feel it if you rest your hand on the center console (possibly coming from the rear end)?
ONLY felt in steering wheel. No where else.
does the shake change with speed, or with revs regardless of speed?
as speeds increase the shake increases speeds.

[2009G8GT]

Even though the car is a couple of years old I'm assuming this is a problem you've had since new, and not as the result of a modification or accident.

Going back a few models I had a new sedan with a front end shake. After 10,000Km of putting up with it and everything balanced, tuned, changed, and twiddled with no improvement, GM suggested that the dealer lift the vehicle on the hoist, loosen off everything in the front end, lower to the ground and (using hand pressure) bounce it up and down a few times, lift up and re-tighten everything to specification. Guess what? NO MORE FRONT END SHAKE!


Apparently something had been fitted/tightened under stress and was causing the problem.

This is really interesting, there may be something to this as well.

[lease1]

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

Subject: Drive Line Boom Noise and/or Vibration

Models: 2008-2009 Pontiac G8
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The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.

Condition/Concern:
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).
Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.

[2009G8GT]

The feeling is thru the steering wheel only, not thru the seat so the driveline was ruled out.