[Artood2s]

Hi all,
I’d like some help trying to identify a noise that I am hearing from the rear of the car, so that when I take it to the dealer I can point them in a direction. 2018 SS 1LE with 5k miles (have owned car since 4K). Only mod is an axle-back Borla Atak exhaust.

• From what I can tell, the noise is not evident until the car gets up to operating temperature. When cold, no noise.

• Noise doesn’t seem to be engine speed dependent. Does not change or increase with higher revs.

• Sounds like a metal on metal rattle and sometimes a squeak when going over bumps.
• No noise when stationary, and when rolling it is pretty constant (but not rhythmic).

• I searched the forum, but didn’t find anything matching all of the above.

Have been putting off going to the dealer since the FM/AM radio is just static (Bluetooth and Car Play is fine so I just dealt with it), but I don’t like strange noises :(

Thanks,
Art

[JD_]

Since you mentioned the only mod being the Borla axle-back, I would start there. Get under the rear of the car and make sure all the mounts/clamps are tight.

From there I would check to see if there were any loose items underneath the mat that covers the air compressor and flat kit. Maybe something has worked its way loose.

After that, check the battery compartment to see if there is anything loose in there.

The noise you are describing definitely seems like something isn't tightened down properly.

JD

[LS3JM]

I agree with JD.

[Artood2s]

Thanks. I’ve already checked the trunk and underneath area. The “computer” on the left didn’t have any screws holding it down, but it also didn’t make the noise I was hearing. I wedged a piece of foam between it and the frame just in case. Everything else was fine. I also got under the car and checked all the main bolts. Nothing seemed loose and the blue marks were all aligned. I’ll double check the exhaust clamps just in case. It’s definitely heat related since it only occurs once the car is up to temp. My main suspect is a heat shield since the rattle does sound like thin steel hitting something. What throws me off though is that the sound is only present while in motion (wether in gear or not). If it was exhaust related, I would think it be noticeable even when stopped and revving the engine.

I also thought it could be debris in the brake cover or suspension arms, but again, it only occurs after it is up to normal temperature. Very strange.

Art

[oOKhanhOo]

I have this same weird rattling too. It much more noticeable go slow 15MPH or less going over small bumps. I've yet to find what this noise it. It sounds like it coming from the rear driver wheel. It's definitely not the NPP exhaust for me, I've changed to AWETuning track exhaust and the same noise is still there. Currently at 10,500 mileage. Notice the sound a year ago.

[Mov Ov3r]

Could also be the wheels not tightened to spec as another "clicking" noise, however from my understanding this comes from the front wheels when turning.

[Artood2s]

Ok. So now I’m even more perplexed, but maybe it could be some clue to all of you. I noticed the past few days that if I give it a little more throttle coming from a full stop, the noise greatly diminishes to the point I sometimes don’t hear it. However, if I’m just creeping along, or start slow off the stop, the rattle is clearly audible (now even with the windows down; before it wasn’t). This is especially the case when going over speed bumps. In that instance I even hear a squeak in line with the car moving up and down when the rear goes over it. Again, I don’t know if it does it when cold, but I only notice it once the car is up to temp.

Could it be the rear end or differential? I have an appointment at the dealer Tuesday morning, and would love to be able to provide them with as much info as possible so they don’t come back to me with “we were not able to reproduce it” bs.

[TrackClub]

Id change diff fluid (for the main "pumpkin" only and not a "diff service" which takes it all apart and costs a few hundred bucks). If it hasnt been done, it is a good idea to do it anyway as part of break in.
Just a suggestion. Cheers!

[Artood2s]

Originally Posted by TrackClub

Id change diff fluid (for the main "pumpkin" only and not a "diff service" which takes it all apart and costs a few hundred bucks). If it hasnt been done, it is a good idea to do it anyway as part of break in.
Just a suggestion. Cheers!

Have a ballpark on how much the fluid change should cost at the dealer? Don’t want to be gouged.

Thanks
Art

[TrackClub]

Originally Posted by Artood2s

Have a ballpark on how much the fluid change should cost at the dealer? Don’t want to be gouged.

Thanks
Art

I think it is about $80-100? If they quote ya $300+ it would be a full "service" which is not needed. Cheers!

[MakCamaro]

I have the exact same rattling noise since the first day I bought the car. It is noticeable at low speeds, especially when I go over small bumps. It sounds like it's coming from the rear driver side. It sounds indeed as if a heat shield is hitting something. I have the stock exhaust on the car.

I took the car to the dealer a few days ago, they kept it for a few hours, drove it up and down a few times, they even went over small speed bumps. They could hear the noise but they could not identify where it comes from. So they gave it back to me.

I would be certainly very interested to find out what this noise is, so I will keep watching this thread.

[TrackClub]

My baffles started to rattle early on and pulling a fuse to lock them open fixed it. Obviously this only applies to stock exhausts but may be worth a try.
Cheers!

[MakCamaro]

I have this rattle whether I pull fuse 51 or not.

[Whitespeed]

Rattling from the dual mode exhaust valves was quite common and the Bora Atak uses those valves. They are inside the tail pipe, so you won't see anything loose externally, but if you look down the outer tailpipes, you will see the valve inside. That's where I'd start looking.

Nigel