Thread: Mysterious Noise - 02 GTP Coupe

Just bought this car last month, and as they say on Wheeler Dealers, "we are still getting all the mechanical bits sorted." New tires and struts made a huge difference and the car rides nice now. New sway bars with links and bushings are on the horizon but not an immediate need.

So the weather has been nice and I have been driving to work with both windows down. I have noticed this noise over the past couple weeks and am struggling to find the origin. You know when you drive past a parked car or similar and noise is reflected back towards you, so it sounds like it's on the passenger side. It's more noticeable with the passenger window down vs. just the drivers window. It's not a squeak per se, but sounds more like a high-pitched grinding like a dry bearing. Can't hear it at all with the windows up.

The noise is most noticeable when cruising about 40-ish on local roads. It's a steady kind of fingernails-on-a-chalkboard chattering screech. Can't hear it at highway speeds, not sure if it goes away or is covered by wind noise.

Shifting to neutral while rolling at 40 and revving the engine does not change the noise, make it louder, or make it stop, which would say it's not a belt tensioner or anything engine related. Turning the wheels left to right and carving down the road doesn't change the noise either which would say it's not a wheel bearing (I've never heard a wheel bearing make noise anyway but you never know.)

I read this may be a vacuum leak, but I have not been able to make the noise happen when the car is parked.

The last variable is that the noise comes and goes, it's not always at the same volume and will fade in/out while driving along.

Any ideas????

I should add mods made before I bought the car:

3.4 Pulley
Wizaird intake
ZZP tune
MSD wires
AL104 plugs
Power Log front manifold
3" downpipe
U-bend and resonator delete
Hi-flo cat

I would bet it's that stupid tab on the backing plate on the front brakes......Jack it up and look on the bottom of the rotor.

It's been a fun day, makes me wanna say F my life....so I jacked up the right front and the wheel has so much play in it when you grab it it's ridiculous. Obviously the wheel bearing is toast. I knew I was getting close on front brakes, so I figured this would be a good opportunity to do pads and rotors up front when I changed the RF hub bearing. Fortunately Advance had everything in stock with a 22% Labor day coupon, so got got a Moog bearing, ceramic pads and HD rotors for $225.

Was a great day in the sun, a few cold ones, and feeling good that the job was done and the noise was fixed. Had to get the loaner axle nut socket set from Advance since I didn't get my set out of the storage pod on the last trip.

Now for the test drive....not only is the noise louder, but I have a BAD vibration at 70+. FML. The axle dlidn't look bad, no tears in the boots, etc., but it had a small amount of lateral play. I'm thinking it has to be the axle, what else could be making the noise and vibration . I bought a new axle nut and torqued it to specs. Applying the brakes while staying in the throttle at 40 didn't make it go away, plus brakes are new so not thinking it's brakes.

Going to order an axle and see if that's it. Any thoughts/ideas/comments appreciated.

Yes, it was inspected less than a month ago when i bought it. NY still allows inspections by independent shops so degree of thoroughness varies vs state inspection centers like NJ, not sure how it is in MD. I agree you would think they would have caught the wheel bearing. Brakes still had enough to pass. I miss living in Louisville where KY repealed vehicle safety inspections as unnecessary....

Anyway, I need some help checking my logic here....before I had a slight vibration above 70 along with the mystery noise. The loose RF hub bearing would have explained the vibration above 70 and the noise. Now with a new RF hub bearing, the noise is worse and the slight vibration has turned into a loud thumping above 70 mph. One thing that is consistent is that the noise doesn't come on until around 40 mph.

I thought maybe the RR hub bearing could also be bad, that would allow for the continued noise...BUT...would not account for the vibration going to a thump when I changed the RF hub bearing. Possibly a bad CV in the axle is making the noise....and maybe the play in the hub bearing was offsetting some of the play in the axle. So now the hub is tight and is forcing the play in the axle to be contained entirely in the axle, changing the vibration to a thumping sound?

Whatever it is has to related to the work I did to cause the vibration to get worse, and what else turns up front besides the hub and the axle? Possibility I got an out of round brake rotor?

Vibration could be axle. The noise I'm still betting on what I told you earlier.

OK for all of you who bet on the axle...correct! Right axle changed and noise is gone. Never heard an axle make a noise like that but live and learn.

Now for the stumper....car only had a slight vibration at speed while it was making noise., Now new hub bearing, axle, and front brakes and getting a thumping vibration that gets worse with speed. What is causing that now? Seems like eliminating the worn parts with play would solve the vibration not make it worse....ideas? I was expecting the new axle to fix the vibration too. Unless the other one is gone too....maybe my romps reading KR trashed thge axles?

Could a bad alignment cause a vibration at speed? Since the shop that did the alignment didn't catch the bad wheel bearing its likely they had the wheel off position when they did the alignment.

Tires are brand new, less than 500 miles on them

Bad axle took out the other side.

Originally Posted by koRnhead

Bad axle took out the other side.

What's that mean?

I think what he means is that the vibration from the bad axle and bearing on one side may have worn out the drivers side wheel bearing assembly as well.

Yup. Pretty straight forward. The bad axle you replaced shook so bad it ruined the other side as well.

Never heard of that but nothing is off the table right now. Next up is to have the tires re-balanced and an alignment. Stay tuned.