jlutherva

The flanges that connect the crosspipe on my C6Z are hitting the tunnel plate. Is this normal? Can this be adjusted out? Do I need to adjust the connection between the cat pipe and the manifold?

The intermittent rumble is driving me nuts!

Jim

nuck

I had a problem with my 07 which only appeared after I swapped out the Borla axle back for the stocker. A hard rattle from 4-6k rpm in first and second gear, and often but not all the time. Exhaust shop couldn't see the contact area when they went back underneath but when I contacted the previous owner he advised:

"had the same issue looked and looked and looked
It is touching the heat shield where the flanges bolt together at the front of the the cross pipe
If you look you can see where the chevy dealer tried to trim back the flange but that did not work
Calgary muffler finaly found it and tweeked the shield a bit but he said if it comes back to cut an oval hole out of the shield
just above the flange and it won't bother you again
You could try tweeking the shield a bit if you dont want to go to the trouble
They put a floor stand under the area and rested a bar on the stand and pried up on the shield a bit"

I never actually saw the problem with my own eyes but when I flipped this email to the muffler shop they had me bring it in for a "trim". It's fine now and a very simple fix if you are getting what I had.

ChevyCobb

It can be adjusted. Mine was doing that a little bit with stock manifolds and the dealer fixed while it was in for something else. Is yours stock, or have you had anything done requiring removal of any exhaust?

jlutherva

Yes, I had the performance GHL exhaust (H-pipe back system) replaced with the OEM exhaust. I didn't notice the interference with the GHL since they drone anyway and 95% of the time the car was on-track.

The car has stock manifolds, CAT pipes and H-pipe. There's been no engine work so not sure how these pipes got out of adjustment....

Thanks for the input!

Jim

MTPZ06

Not the first I've heard of this. I believe some have loosened the manifold bolts at the heads to pull down on the mainfold/cat assemblies to create more clearance between the mid-pipe and tunnel plate.

nuck

Spoke too soon. My own noise is back However doing a head swap in a couple of weeks so will give me a chance at MTPZ06s solution. Keep us posted jlutherva.

jlutherva

Sorry for the late post on the fix.

I took the car to a muffler shop and they heated the pipe with a high temperature torch and were able to bend it down enough to eliminate the interference.

Jim

AimHigh

got mine right where it needed to be and then spot welded all in place from the flange back.

everything under there is sooo tight on position that you have to get it just right…..then secure.

drove me crazy up to that point but has been good ever since.

Chance Massey

I have a scratching kind of noise when I accelerate hard and I believe it’s the flange touching tunnel under hard acceleration. Did your sound come from the shifter area under the console?