[MONT1LE]

I took a look around repairprocedures.com and found #18-NA-172 - Rattle Type Noise Heard from Rear of Vehicle - (May 16, 2019).

The fix recommends modifying the right rear exhaust control valve actuator by cutting off a leg from the control actuator. Has anyone done this?

I cant find the epoxy fix on the repairprocedures website. Perhaps this one supersedes it?

[LT4Greg]

This might be the fix now! I never thought it was that much of a issue anyway! My 2016 SS had the rattle and I’m sure my ZL1 does too but it’s not a concern to me at all.

[MONT1LE]

Well I just did this fix and it appeared to work! Whoooooooo!

The second pic shows the exhaust side. Still processing why this fix worked but man, it was like an itch I couldn't scratch! It was driving me crazy.

[Trochoidal]

Well look at this nice fix! I’m saving this PDF in case this “itch” needs to be scratched. Thanks!

[arpad_m]

Thanks a lot for the info, I'll save it for future reference, too. A bit unfortunate that the fix requires reducing structural strength, but it's just a valve controller, it may not matter much.

[cmitchell17]

I've had high temp rtv silicone on the ceramic pin on the valve flap for about a month now and I don't hear the 1800 rpm part throttle rattle anymore. I tried epoxy 3 times and the 1800 rpm came back within a week everytime. I'm still pretty sure I have a rattle noise at cold start sometimes and at wide open throttle but it appears to sound a little different so hopefully this fix is for this rattle.

[DIYguy]

Actually, this makes sense to me.
Disclaimer- the following is only a guess on my part because my car has a spring loaded set of flaps and no motors (1LT/LGX).

With the tabs remaining on both sides of the motor output it might center the flap shaft in its bushing (where it passes into the pipe) and allow the other end's tip inside the pipe to move around loosely.
With the two tabs removed as shown, the torque that the motor provides to open the flap would only be applied from one side.
So as a result, and because of the springs, it will likely bias the shaft (and internal tip) against one side.
This should reduce unwanted clearances.
With reduced clearances I would then think that it shouldn't rattle.

On mine I wired the spring-loaded flaps permanently open long ago.
I felt that they were only causing unnecessary back pressure and were perhaps responsible for a bit of mid-range surging.
The improvement was immediate, though subtle.
The output sound didn't really change because on my car the flaps are ahead of the muffler.
So I didn't expect it to be noticeably louder (and did not want it to be).
Then I put large hose clamps around them to bias them firmly into the pipes and eliminate any remaining clearances.
So far so good.

This is the basis of my thoughts.
However it may only be a crazy one, IDK.

[cmitchell17]

I just did mine, I haven't had a chance to really test it out, but the exhaust sound may sound a little cleaner?

What I am really wondering about is why does the procedure only say to do the right side? I only did the right side, but I am tempted to do both sides? I removed my AFM valves and actually modified one of my extra AFM actuators, but they look like identical parts.

Any your explanation sounds perfectly plausible to me as well, the only thing is when the valve is completely shut is there rattle? If it is completely shut the electric motor couldn't be providing a unbalanced torque to force the ceramic pin tight to one side.

[Scargoes]

It is possible that when the valve is closed, only one arm of the actuator was touching the valve and minor movement of the valve caused a intermitent contact situation with the other arm. Thus causing a rattle noise.

[cmitchell17]

Originally Posted by Scargoes

It is possible that when the valve is closed, only one arm of the actuator was touching the valve and minor movement of the valve caused a intermitent contact situation with the other arm. Thus causing a rattle noise.

Wouldn't the one side still be intermittently contacting and still vibrating? I just did the same to the left side even though the procedure only says do the right side. I still feel like there is a rattle type noise at WOT though. I have my valves set to close at WOT in your mode, and if you're right about the contact then I'm still getting a rattle. It may also be me mistaking the raspy exhaust note for a rattle.

[Riker]

I wanted to add that I have had the rattle for a while now (nearing 3 years of owning the car) and the dumb locktite epoxy fix worked for only a week.

Had the dealer perform this fix and I am two weeks in with no issue. This looks promising.

[Corbu]

I can confirm this works. I've had the epoxi done for nothing but after the above fix the rattle is gone. The only thing is I like the sound with the fuse pulled more so I guess I have to install a Mild to Wild control box if I ever want to go stealth.

This should be a sticky for a while > The DEFINITE and permanent rattle fix !

[MosaicX1LE]

I did this on my V6 with NPP, and so far so good. No more rattle. I only did the passenger side since I haven't had an issue on the driver side.

[BradfordCamaro]

Hmmm.
I might do this.
3 year rattle as well....