Car: 1995 Lexus GS300
Noise characteristics: a sound like a coin in a clothes dryer. The noise is intermittent at near-constant speed.
Prior to the issue:
Yesterday: DIY installed new brake pads on front wheels; did break-in (aka bedding-down).
Today:
0) Drove 60-70 mph for 20 minutes with no noise whatsoever.
1) Installed new tires on the front wheels with balancing (at an auto care center; I do not blame them: installing new tires seems straightforward; could they leave a coin inside the tires; could they break the car floor when lifting it? I doubt it. I think they did a good job);
2) Then installed two pins (supporting the brake pads, see attached image) on the front driver-side wheel. We forgot to install them yesterday. Note, the dust boot for the sliding pin (see attached image) has been replaced with a new one. We used a bit of silicone sealant to make the boot to seat on the torque plate.
3) Later was driving 30-40 mph and made a sharp turn with hard braking.
4) Finally, we went to highway 60-70 mph, it's the first time the noise has been heard.
Images: https://postimg.cc/gallery/Q3SVBVq
Where: driver's side - exterior; the noise is perceived to originate from the rear wheel, could be the front wheel.
Extra:
Car does not shake.
Steering wheel does not wobble.
The lug nuts are not loose.
Does not matter if brakes are applied or not.
Mileage: 250k.
OBD1 codes relate to catalyst oxygen sensors (have been for at least 2 years).
Transmission: automatic.
I heard exactly the same noise from a random car passing by on a highway about a year ago.
Two people did the brake pad replacing job, and we are pretty confident that we did everything right except for one dust boot sealed to the torque plate (guys usually recommend to hammer the boot onto the torque plate) (see attached images). I do not think it could create such a loud clunking noise.
Questions: Any potential reasons of the noise? Any DIY way to diagnose the problem?
Excellent question presentation, especially for a new member with 2 posts. (I have no idea the answer but this is a great example of a good forum question). Good luck!
yeah ... this is a textbook example of how to ask a question LOL. Well done.
I know right! It was my first thought, too..
We finally identified the culprit: it was the balancing weights installed on the inner side of the wheel rim. The weights rubbed against the rotor cover/plate.
See linked images below:
https://postimg.cc/gallery/ncHR3qy
We used a grinder to remove a layer of the surface of the weights until we saw the bare metal.
Good work.
(I call it the backing plate)
Whack your cat hard & check if you can reproduce the rattling noise.
I hit the catalyst, muffler, and other exhaust parts but could not reproduce the noise.
I found a video with the same noise sample from a bad CV joint (it was recorded when turning):
https://youtu.be/NKFGkKxCFow?t=368
However, in my case, the noise is
1) intermittent;
2) heard only at high speeds;
3) heard when driving straight (no noise when I turn);
4) car or steering wheel do not shake.
Could a bad CV joint produce such a loud sound in my case (when driving straight)?
Could it be the transmission (it sometimes does not shift into the 4th gear; there are 4 speeds)?
Remove the wheels and make sure you don't have loose items like nuts, bolts, weights, rocks etc. trapped between the rim and backing plate. Or just take it back to the balancing place and they can probably help you out.
Try taking of the air filter cover and see if something is rattling around in there, or, the exhaust manifold heat shield. or the catalytic converter heat shield.
