Well, I finally managed to take some video to record the sound for the problem I've been having with my car.
It's a weird rattle that seems to come about after a small warm up. I can hear it the best with my windows down with the revs around 3100 rpm. Usually when downshifting.
I took it to the dealer Wednesday and got it back today. When I called on Friday they told me it seemed to be located around the steering assembly, but they hadn't pinned it down yet.
When I talked to the mechanic today, he seemed to think it came from the exhaust, but when I peer under and listen, it seems to be coming from in front of the resonator. Since it's an aftermarket ALTA exhaust, they couldn't inspect it. I plan on doing a more detailed inspection this weekend, but for now, I took a few videos (at night, so there's not much to see) to see if anyone might have any insights as to what the sound may be.
The first video is under the car from the drivers side. That's where you can hear it the most.
http://www.youtube.com/watch?v=hplEYmtjVUM
The second video is from the rear about 12 inches from the exhaust tip. It's more faint on this one, which makes me skeptical that it's the exhaust, though it could just be other exhaust noises covering it up.
http://www.youtube.com/watch?v=tZxpMl5wDqA have a clue?

 

I don’t have the bandwidth to see/hear your video but here is the short version of things to look at. The heat shields overlap behind the pre-cat and are fastened with one screw; it can be held together without the screw secured in the body and allow the shields to resonate at a particular rpm. It’s easy enough to press the screw into the hole and fasten. Also the shields can vibrated against each other so if you get under the vehicle and rap with the finger you can find the most troublesome spots and bend them to reduce contact or bend, pressing them together. A curved heat shield is located above the steering rack which can contact the header; I created clearance on mine with a pipe, it had an obvious groove from contact with a header weld. Tighten all the fasteners which have been R&R in the exhaust install. The usual culprit is the exhaust hangers on the center pipe striking the center channel heat shield. There are so many possible sources; you’re on the right track by taking a look for yourself.

 

Sounds like excellent advice. It seems like it must be more than that if my dealer couldn't find the problem in 6 days and they had never heard the sound before, but who knows? They could have just missed it. Thanks

 

i have the alta sportone also. i had the same rattle and still encounter it under "very spirited" driving.

the initial rattle was coming from the resonator (the can closer to the shift box) touching the heat shield. jack it up on stands and bend the shield back... protect your shiny, pretty exhaust by placing a rag between the exhaust/pipe and the prying tool you decide to use.

now, the rattle that comes back after spirited driving... here's my theory:
the rear hanger (not the one next to the battery, the other one...) is on a swivel exhaust mount versus a fixed rubber mount. i think it wobbles and the exhaust rubs up against a heat shield somewhere else. i don't worry too much about this rattle since i only hear it after very spirited driving. it goes away very quickly.

 

shinka: Thank you again for your purchases as well as for your comments here. I apologize if you feel we don't listen or aren't helpful when questions or concerns arise. The best way to resolve any issues is to call first, e-mail second and post last. We are in the office from 8-5pm m-f and some Saturdays as well. If we are unable to answer the phone leave a message and e-mail tech@altaminiperformance.com for these concerns or sales@altaminperformance.com for product pre-purchase questions.

Regardless, there are several areas to check most of which have been mentioned by fellow forum members above. However, if the rattle developed suddenly then it is unlikely to be contact with a heat shield, etc. unless something has broken to now allow it to hit any portion of the exhaust system. Still check those areas first. Finally, rap the actual muffler body itself to listen to see if noise is coming from that too. While unlikely there may be a defect that has developed within the muffler and we will replace that under your warranty.

We look forward to hearing from you with the conclusion to the mystery of the noise.

 

I don't think you're not helpful, since I haven't contacted you yet.
I was waiting to inspect the thing up on jacks myself before coming to you guys with my concerns. I'm hoping to resolve heat-shield possibilities first before pointing to the exhaust directly. Though it seems that if it were a heat shield, my dealer would have noticed.

 

Since the rattle seems to be coming from under the shifter area and during downshifts, you may want to check the area where the shifter cables exit the shifter box. Those cables have an aluminum wrap around them, and if the wrap is loose, it can bang against the heat shield that's directly under them and cause the rattling. Mine's come loose several times, and so far, I haven't found a good way to secure them and stop the rattling (which generally occurs only when I'm starting off from a start in 1st gear).

HTH!

 

Interesting. Does yours sound similar to mine at all?

 

Yes, that metal vibration rattle is exactly alike - albeit, there are many situations that may cause that, but you may want to have your dealer investigate the aluminum wrap on the shifter cables. As stated previously, mine occurs mostly when I'm starting from a full stop in 1st gear, and I've never observed the rattle occur while revving at a standstill, but at the very least, it'll eliminate another potential cause. When chasing rattles, you definitely need to rule out as many variables as possible.

 

Indeed. Thanks, I'll look into that.

 

Well, I think I managed to fix it. It appears that the gasket between the resonator and muffler parts of the parts had kind of disintegrated.

We were able to cut a new one from some gasket material from O'Reily's and I haven't heard it since.

 

shinka: Glad you found out what the issue was. If you want please e-mail me your mailing address and I can send you a replacement if you choose.

Thanks again!

 

That would be great. E-mail sent.

 

Done!