Wobble right at hwy speeds over bumps

[Helohank]

Hello all,

We own a 2012, 4 door, 3.8 Model Genesis with 141k miles.

Just started experiencing a harsh wobble or “kick” to the right from the rear of the car after traversing a bump on the freeway or at speeds above 40 mph or so. Have only felt the pronouned wobble in BOTH directions, from the rear, while driving within a construction zone on a milled surface. The natural sensation one would normally expect on the milled surface is a much more pronounced wobble. When driving the same stretch of freeway in our MKX, the ride is what you’d expected on a rough freeway surface but wobbling is almost non existent in this vehicle.

Michelin tires replaced about 15k prior to experiencing this issue.

Used fuel tank was installed approximately 4 months ago. (We had fuel sensor issue which was fixed but then had a constant gas odor while parked in garage overnight after that repair. After second visit, dealer stated original tank had a vapor leak requiring fuel tank replacement where they offered reduced price for a used tank). Could the baffling be faulty in the used tank?

Shocks and suspension all original. We just recently started hearing slight creaking sound when going in/out of driveway while crossing gutter trough between sidewalk/driveway and road surface (3”to 4” hump from road surface up to driveway surface). Could any of the suspension components be bad?

Your feedback and expertise is appreciated. Thank you in advance.

Helohank

 

[Gunkk]

Possibly a bent control arm.

Saw this on a 4.6 that had been hit in the rear at the top of the tire. The back end would "bump steer" as a result. Dealer replaced the UCA and the problem was fixed.

 

[homeofstone]

Never seen a post here about a fuel tank needing to be replaced. Fuel tank filters and fuel pumps and filters but not a fuel tank, seems odd to me. Wobble cause - May be loose bolt if or bad bushing. Get it checked maybe by a good alignment shop or dealer.

 

[EdP]

We own a 2012, 4 door, 3.8 Model Genesis with 141k miles.

Just started experiencing a harsh wobble or “kick” to the right from the rear of the car after traversing a bump on the freeway or at speeds above 40 mph or so.

Shocks and suspension all original. We just recently started hearing slight creaking sound when going in/out of driveway while crossing gutter trough between sidewalk/driveway and road surface (3”to 4” hump from road surface up to driveway surface). Could any of the suspension components be bad?

See the first line I quoted. Time to see a good suspension shop. You are beyond the typical life of some components.

 

[Helohank]

Thank you everyone! Great feedback. We will have all suspension components inspected as this seems to be the area you all are pointing to.

 

[Helohank]

Looks like your suspicions where right with the suspension. Dealer states worn rear control arm bushings and sway bar bushings excessively worn need replacement. $1,100. Does this sound right? They said bushings come as a component part making them more expensive. (Had this dealer, in the past, try to replace the driver’s side seat carriage assembly for $1,800, when all it needed was a $34 slide limiter which fixed the problem of the seat getting stuck at times)

And the really bad part..... even after 7500 mile rotations, the 50k Michelin tires I put on the car a year ago were just about destroyed with only 17k miles. Passenger rear was close to bald. The two fronts looked the best, but if I had to guess, I would have said they had about 45 k miles on them. Ugh!!!!

Thanks again for your insights.

 

[EdP]

Looks like your suspicions where right with the suspension. Dealer states worn rear control arm bushings and sway bar bushings excessively worn need replacement. $1,100. Does this sound right? They said bushings come as a component part making them more expensive. (Had this dealer, in the past, try to replace the driver’s side seat carriage assembly for $1,800, when all it needed was a $34 slide limiter which fixed the problem of the seat getting stuck at times)

And the really bad part..... even after 7500 mile rotations, the 50k Michelin tires I put on the car a year ago were just about destroyed with only 17k miles. Passenger rear was close to bald. The two fronts looked the best, but if I had to guess, I would have said they had about 45 k miles on them. Ugh!!!!

Thanks again for your insights.

Don't know if it is a fair price but dealers are not known for thrift. You may want to look around for a shop that does suspension work and the like.

That type of component can cause tires to wear fast and uneven. The so called 50k tire should at least get you 35k.

 

[Helohank]

Thanks Ed. The original set of tires and first replacement Michelins got us to 123k. We drive her pretty easy. Anyway, yes I will shop around. Lower control arms on line were anywhere from $100 to $600 a pair. Not sure if I was comparing correctly but definitely worth investigating and shopping this job.

Thanks again sir!!