Hello everyone,

I have a 2006 TL 5AT, bone stock. I've had it for a year and put about 20k miles on it, now it's sitting at 78,500 miles. Everything is fine until recent, when I started to feel this excessive bumpiness (excuse my lacking automotive lingo) in the ride quality. I've read up on a thread relating to vibration pass a certain speed/rpm but I don't think that applies to my case.

This bumpy feeling is not as harsh at lower speeds (< 25 mph) but it's uncomfortably rough at speeds higher than that. The slightest ripples/cracks/crevices/bumps would give the feeling of driving over rumble strips, not as violent but uncomfortable. I drive on a 7-mile stretch of road that's newly paved and the asphalt is as smooth as can be, and you'd expect a smooth ride but it's not. I can even feel a very unsettling bump when i drive across cross-walk paint lines at intersections. It feels like there's either no give in the tires or the suspension.

I have Dunlop SP Sport 8000 235/45ZR7 (max pressure 44 psi) summer tires on stock wheels. They have 20k highway miles on them with good tread left (at least 60%), no abnormal wear, rotated every other oil change, 35 psi in all four. My car is garage kept. I noticed the problem when it started getting cold out. I'm not sure if it's the tires, suspension, or something else.

That sums up my problem. Any feedback and/or advice will be greatly appreciated

Thanks

 

Don't know what temperatures you're experiencing in the area, but those tires like any summer tire with the soft compound, will harden as the temperature drops.

 

^ if its not that, then the wheels could be out of balance causing a rough ride

 

Yeah, summer tires will "flat spot" overnight when it's cold out, though I remember this going away after a mile or so, as they heated up. I ran them at 32PSI cold.

Definitely could be a balancing issue as VQPower37 has mentioned, or even a bent rim. Do you recall hitting any larger potholes or a curb?

I can tell you that my TL was horrible on the highway when my front axles were going bad - lots of vibration. Smooth as butter since replaced. Any "creaking noises when you turn at low speeds?"

Make sure it's not something simple (and dangerous!) like loose lug nuts.

Though not only the rough ride, you mention that you can feel every little imperfection in the road - and that sounds like another issue altogether. And I'm not sure about that one.

 

put it on the lift and ck the steering parts- bushings etc
Inspect motor mounts- look for oil traces on front and rear mounts
ck shocks- same ck for oil traces on them

drop psi a few more and see how it does