It sounds like a flat tire.... but it's not....

[bobmut]

Greetings....
I recently bought my son an '03 Liberty to take to school with him. As soon as I bought it I did the usual stuff: 4 new tires and wheel alignment, brakes (pads and rotors) all around, transmission and differential service... now (4 months later) he says that that it sounds like he has a flat, but the tires are all okay. When I pick up the car it is, indeed, making a "thump, thump, thump" like it has a flat. I checked the lugs (all tight); nothing stuck in the tire; sound get faster with speed. As I drove the car to my mechanic.... it went away. Quieter as I got up to 35 mph or so before it went away. Mechanic says no play in the tire (bearing?).
We've been driving the car and the noise comes back every now and then, but then goes away again.
Oh.. and this all started (suspiciously) after we got the car back from the dealer after service for recall F23 where they replaced the lower ball joint.
I'd love to resolve it before he drives 300 miles back to school after the holiday break.... Anyone have any ideas?
Bob

 

[HoosierJeeper]

Maybe a tire is out of balance?

 

[bobmut]

I would think a balance issue would be constant... or would get worse at higher speeds....

 

[KYLiberty]

Mine made a similar sound when the factory LSD broke.

 

[bobmut]

@KY... did the sound go away for a few days and return sporadically?

 

[KYLiberty]

Heard it off and on at first. Then it became constant.

 

[SeventyGTX]

An easy check would be to jack up the rear, throw some jackstands under the axle housing, put it in gear and gas it up a bit. That is assuming you do have an LSD.

 

[CzarKJ]

Is the sound from the front or rear? Front I'd check for play in cv axles then cv joints on front driveshaft. Rear sound I would check U joints on driveshaft. If it is rotational those could be suspect. I agree with raising it up and spining the tires to see if it binds or makes a noise somewhere but I would do it by hand.

 

[ltd02]

The ideas above sound good to me.

Just a thought though if they don't solve your dilemma, do you feel it in the steering wheel or the seat at all? If you don't feel the vibration in the wheel I'd be inclined to check the rear brakes especially the ebrake. Maybe they weren't set up right. I'm assuming you've got the rear discs with the ebrake inside the minidrum of the rear rotor. Pull the rear rotors off and make sure they are okay. If you do feel it in the steering I'd check that all the front brake hardware is tight.

 

[Birdman330]

Possible flat spot that formed, had one when I bought the KJ. No wheel shake, no vibration but a mind boggling thumping noise coming from the front left. Went away when I rotated the tire despite going over it over a dozen times trying to find the flat spot.

 

[72specialized]

Mine does something similar to this as well. Started about two months ago. I've rotated tires, checked lugs a dozen times. Had it to my mechanic and they couldn't find anything. They suggested the front brake pads were touching ever so slightly to make the noise and a bit of vibration that you can feel in the seat. ???????

 

[ltd02]

Mine does something similar to this as well. Started about two months ago. I've rotated tires, checked lugs a dozen times. Had it to my mechanic and they couldn't find anything. They suggested the front brake pads were touching ever so slightly to make the noise and a bit of vibration that you can feel in the seat. ???????

That is an odd one. I've had some warped front and rear rotors before on different vehicles. If the both fronts were warped I'd feel it in the steering wheel and if it was just one it would also pull when braking. If the rears were warped I'd feel it in my butt. :shrug: