So, some of you may have read my "backyard project" post a few weeks ago. I installed a helix up pipe about 3 weeks ago. Since the install I have been experiencing a strange howling/grinding sound every once an a while coming from the passenger side. It only happend while I was turning, and it only happend on the passenger side. I thought that the passenger side bearing was going bad. From what I had been reading, the symptoms seemed to fit the discription of a damaged bearing. So, just to be sure I scheduled an appointment with a local dealer and had them check it out...they said everything was fine and dandy with the bearings, but just to be sure, I took a technician around the block and recreated the noise while he was in the car. He confirmed that it was not bearing noise, but he wasn't quite sure what the noise was. So, they didn't charge me for anything and basicly said, if it gets worse to come back and they would take another look at it...but that the bearings were fine. I was satisfied. Next stop, Grand Muffler to have a resonator welded into my ANSA cat back to hopefully quiet things down until I can afford a decent cat back system. (the ANSA was on the car when I bought it) On the way, I noticed the noise a few more times, but didn't pay it much attention. After the install at Grand Muffler, I was very happy with the resonator, it definately took the edge off of the exhaust note...but, low and behold...a new noise...great, just effing great! It was pretty easy to figure this one out though. The new resonator was bumping up against the chassis and rattling pretty bad at certain rpms...nothing a some extended hangers wont temporarily fix until I can get the cat back. And then it hit me... The original sound that I thought was a bad bearing was infact the downpipe ( another crappy piece that was on the car when I bought it ) The DP is bent in a way that it comes within mm of the chassis, and installing the helix up pipe with the flex section, is allowing the downpipe that extra bit of movement to come in contact with the chassis of the car, the stock up pipe, being a stiffer piece, did not allow the dp to move...when that happens the sound of spooling turbo and exhaust vibrations are magnified and sent into the cabin...which is the noise that I mistook for a bad bearing on the passenger side. This also explains why it only happens while turning because the body of the car twists and the DP comes in contact with the chassis. Does this make sense?
That sounds very logical. I'd test it with the stock up pipe to see if it goes away. If so, you could get a new down pipe but who knows if one or another is going to have better clearances, or you could get some heat wrap and put a little where its hitting. I've had problems with my catback's resonator hitting the chassis due to the stock down pipe residing closer to the chassis than the pre 06 models used to causing the exhaust (which is supposed to fit and 06+) to sit higher along the whole route. Fix: heat up and hammer in any spots on the resonator that are hitting. It's not the best idea but for me extended hangers would make the exhaust hang abnormally low and the down pipe and midpipe might not have connected at all after that...and it was free and the exhaust I have is so damn cheap that i didn't care. (more of a rant... but you could use this to solve one of the problems).
I have had issues with the midpipe section of the dp hitting a driveshaft bracket. When you are in reverse or first start the car up it taps it. Kind of annoying, but not bad, since there is a bracket that its hitting and not actually the driveshaft.
Yeah...I'll just go throw the stock up pipe on there real quick. ;-) I have this same post up on nasioc, and I got a reply from someone saying that the flex pipe should not allow any movement of the exhaust system post turbo. The DP is bolted to the turbo, and the turbo is bolted to the block, so it should not be moving because of the flex in the up pipe. He also reminded me that the stock up pipe has a flex section in it as well. Regardless of why the DP is touching, it is for sure where the noise is coming from. He suggested that I try unbolting the DP and re-aligning it farther from the firewall before bolting it down. The resonator is hitting pretty badly, it is more than just a little annoying here and there. I am not going to keep this exhaust on my car for much longer, and the resonator was just a temporary fix, so I will probably end up hammering it to fit. Thanks
I am hearing the same kind of noise, seems like its comming from the front air vents sounds like something is loose. I checked under there but I didnt see anything loose.
So, I un-did two of the exhaust hangers between the muffler and the DP, and it helped a bit. Now that I know what the noise is, it doesn't bother me as much. Regardless of the knocking on the chassis, the exhaust is still way too loud for my taste. Long run...a Maddad Whisper or Borla Hush.