I just had some brand new Crawford HFC's installed by a buddy of mine who runs a performance muffler shop. I notice, now, at WOT and when decelerating odd noises. A majority of the noises emanate from right below the gas pedal and there are vibrations that accompany the sounds (at times).

I was curious to know if there are any know fitment/clearance issues with the new Crawford HFC's? And if not, I noticed that when comparing the underside of my car to Adams @ Crawford Z his brackets face inward while mine face outward. A subtle difference but something that my prove to be the culprit.

So, suggestions?

 

See thread thread, including my post, and a post later by TheLastSpartan.

https://my350z.com/forum/intake-exhaust/251768-emergency-shim-the-m-brace.html

Basically, I had vibration with crawford HFCs, and I added washers above the M-brace to add space between the HFCs and the brace. While you're down there, you should also check the heat shielding on and around the cats (there is some on the underbody of the car), to make sure it has enough clearance so it isn't vibrating.

from the thread:
Yep.. used washers under the 4 M-brace bolts to make about 1/4-inch gap, to prevent the exhaust from vibrating against the brace (which is attached to the chassis). Crawford high-flow cats and stillen exhaust here.

 

Thanks for the reply and suggestion.

But the sound is actually emanating right near the gas pedal not anywhere near that 'm' bracket. After spending the amount of money for the Crawford HFC's I was hoping the application of a mallet would be the last case scenario.

Ug.

I'll take some pics. once it's on the lift and maybe that will shed some light.

*Below* is a pic of the Crawfords on another Z, I believe Adams. His brackets are facing inwards. Now mine on the other hand are facing the opposite direction. I'll switch them Monday and maybe apply the mallet to a couple of areas......

 

Hmm ok.. I guess I'd inspect where the manifold bolts to the cat (did you use a new gasket?), while you're swapping the bracket. If it was hitting the M-brace it would probably be obvious when you look at it (if the gap is less than 1/8 or 3/16 of an inch or so). Also when it hit the M-brace, for me, I could feel the vibration in the seat and chassis.


Also, you may give doug @ crawford a call, he may have some ideas on what to check.

 

Sounds like a plan!

I'll follow up with the, possible, solution..

 

Once we put the car on lift, immediately I saw the left cat was directly resting on the heat shield. We took a crowbar and bent it in as you can see with the pic below.

Result: Fixed the rattles and cabin noise!

Hopefully this post will help others if they have similar issues.