Vibration sound on compression mode of engine

[trossit]

Hi Forum,

I have a strange problem with my 2012 V6 6sp Camaro. If I am in 2nd gear and aggressively accelerate to about 4000 RPM and then abruptly let off the throttle there is a vibration sound until the RPMs come down to about 2000 revs, then the sound goes away. The intensity of the sound varies at times but it will consistently make this sound. It sounds kind of metallic but at times can sound like air rushing just on the other side of the firewall. Has anyone experienced this with their Camaro? Exhaust? Heatshield loose? Engine cowl loose? Something else?

Thanks

[cawengr]

Could be your Dual Mass Flywheel bearing going out. How many miles are on the car ?

[trossit]

Originally Posted by cawengr

Could be your Dual Mass Flywheel bearing going out. How many miles are on the car ?

The car has 72,000 miles on it, I am the 3rd owner. The first 2 owners babied this car. I will try to post a recording of the sound today. Never heard of a Dual Mass Flywheel bearing. Note, its a manual transmission car.

Thanks

[cawengr]

https://yourautomaster.com/dual-mass-flywheel/

Read up on it, there is a bronze bearing that keeps the two masses turning, Could be that when you back off with the clutch engaged it's forcing the mass backwards where it doesn't want to go.

If you were the first owner with 72,000 miles the flywheel and clutch should be OK but being the third I would think there has been some spirited driving going on,
I have a 2011 CTS 3.6L 6sp manual and I replaced the clutch at 75,000 miles and it still had about 1/4 life left on the clutch plate.

[trossit]

Originally Posted by cawengr

https://yourautomaster.com/dual-mass-flywheel/

Read up on it, there is a bronze bearing that keeps the two masses turning, Could be that when you back off with the clutch engaged it's forcing the mass backwards where it doesn't want to go.

If you were the first owner with 72,000 miles the flywheel and clutch should be OK but being the third I would think there has been some spirited driving going on,
I have a 2011 CTS 3.6L 6sp manual and I replaced the clutch at 75,000 miles and it still had about 1/4 life left on the clutch plate.

Cawengr,

That is a great article on the DMFs, thanks! I was reading in another article some modify their flywheel to a single mass type. I did make some recordings today with my cell phone but was unable to attach the m4 audio files to this site. It was clear that after a cold start up the noise is much more pronounced than after warm up by about 2x. There are some cases after warm up when it makes hardly any noise at all. I think you are on the right track, something I never considered. This 2012 Camaro is my first experience with hydraulic clutches, I have always had the mechanical type in my other muscle cars of the 60s and 70s. I have a question, my clutch feels like it engages at the very end. It has been like this way ever since I got it at 57,000 miles. Does your V6 Camaro behave this way....clutch engages towards the end? It could also be I am almost out of clutch but its never slipped on me that I could tell. I have also noticed in the last 1000 miles there is a very slight chatter sometimes if the clutch engages too quickly from a stop.

My plan is to take my Camaro into the $$$dealership$$$ on Monday for them to look at it and change engine oil. Your responses are appreciated.

Thanks
TR

[cawengr]

My CTS clutch engages about half way up. Hydraulic throw out bearings are OK vs linkage but the DMC (Dual Mass Clutch) is a real issue. The DMC does take away the gear rattle and allows a soft take up but it's life is limited. I was tempted to replace it with a standard flywheel but I chickened out. I had to have m DMC replaced about a month after the dealer originally changed it for a vibration issue at 2,000 rpm, the dealer ate the cost of replacement but i'm sure GM got hit with the labor and parts cost.

[trossit]

Originally Posted by cawengr

My CTS clutch engages about half way up. Hydraulic throw out bearings are OK vs linkage but the DMC (Dual Mass Clutch) is a real issue. The DMC does take away the gear rattle and allows a soft take up but it's life is limited. I was tempted to replace it with a standard flywheel but I chickened out. I had to have m DMC replaced about a month after the dealer originally changed it for a vibration issue at 2,000 rpm, the dealer ate the cost of replacement but i'm sure GM got hit with the labor and parts cost.

Until you mentioned it I have never heard of DM flywheels. i also thought flywheels were a one piece item. I am assuming the the higher horsepower engines on the SS and LS-1s also have the DMC units? I am thinking the horsepower would eat these things up quickly. How is the backlash in your IRS rear suspension? Sometimes I worry how durable that set up is as well. In my V6 Camaro, if I am at parking lot speed in 1st gear and push the clutch in quickly I will sometimes I hear a clunk from the rear end....not sure if this is normal backlash. It never shows backlash if the clutch is fully out. Does your V6 Camaro behave this way too?