Undercar rattling after my downpipe installation...

[Chewbacca]

I just did a search on this, but wasn't able to find a definitive answer on why there's a new rattle coming from under my car after my downpipe install.

I just installed an Apex catted downpipe last night.. and while the power increase is unbelievable, I get a really loud and annoying rattling from under my car every time I start moving from a stop.

It sounds like 2 sheet of flimsy metal slapping against each other.

I got under the car after my test drive and checked all the nuts and bolts to make sure they were tight... and checked to make sure that there was adequate clearance around the catalytic converter, too. Everything seems to check out fine.

Is there something I could be overlooking?

Also, I was thinking about switching back to the stock motor mount from my AWR M/T front mount, as I can't stand the vibrations anymore, but would this probably make the undercar rattle louder?

Any help would be much appreciated!

 

[ONRAILS]

Sounds like it's bumping up on the crossmember. Get some kartboy hangers, that should do the trick.

 

[Rawyzf]

It's prolly the mid section hitting the heat shield.

Get some kartboy hangers and the hold up the DP when tighting it.

-Ryan

 

[txrxs]

it's more than likely the heatshield or crossmember, i'm not sure it's been a while since i put mine on. But if i rememeber correctly you can just add some washers and it'll give the downpipe enought room to not rattle. It's been a while though, so i might be wrong.

 

[Rawyzf]

If you are hitting the crossmember, it's more of a cluck. I think he said tin can's rattleing on start up and launch. So...my guess is the heatshield is being hit somewhere. I went through all this about a year ago. Kartboy hangers and a little repositioning did the job.

it's more than likely the heatshield or crossmember, i'm not sure it's been a while since i put mine on. But if i rememeber correctly you can just add some washers and it'll give the downpipe enought room to not rattle. It's been a while though, so i might be wrong.

 

[nate0123]

just lie under the car and shake the exhaust at the midsection and see where it is hitting the heatshield.... then bend the heatshield until you can't make the exhaust hit it.... no more rattle

(yippy)

 

[Aaron]

it sounds like the cross member

 

[NeverSober]

its the crossmember, mine did the samething..........

 

[Chewbacca]

The thing is... I put the two washer spacers in for each of the 4 screws that hold the cross member in place... So there should be adequate clearance with the crossmember. And I DO have the Kartboy exhaust hangers installed as well. We~ird... (screwy)

Anyway... I think I'm gonna get under my car again after work today and try to move the downpipe/exhaust around and see if it touches anywhere. It DEFINITELY is a tin can type of sound. Very very annoying.

 

[Chewbacca]

Okay... went under my car again... and it turns out that the rattling sound wasn't the downpipe at all. It was the resonator hitting against the heat shield.

I took the heat shield off, bent it into a shape that would free up more space for the resonator to move around, and then screwed the shield back in place. No more rattling!

However, now I have a new sound... It's a "clunk clunk" sound that happens when I'm at a stop and slowly engage 1st gear. As I let off the clutch pedal, i hear a "clunk clunk" and feel a couple slight bumps. Could this be my AWR motor mount? Any ideas?

 

[jflo]

what are you feeling the bumps through ? the clutch pedal, through the body of the car, or through the shifter ?

 

[nate0123]

your new sound is the bottom of the shift lever hitting the heatshield... it's bent up a bit too far

 

[Chewbacca]

The bumps are felt through the body of the car. The bumping feeling is very slight... but the sound is kinda loud.

I checked the bottom of the shifter possibly hitting against the heat shield, but I don't think that's the issue. There's about 1cm of clearance so I don't think it's hitting. Besides, if it was hitting the heat shield, I think it'd sound a lot more like a tin can type of rattle. But this is definitely more of a "clunk"... like two solid pieces of metal hitting (almost grinding) together. I might check the motor mounts later.

 

[BMC]

Hmmm, I have the Kartboy hangers, and I used the washers to lower the brace a bit...and I'm still getting rattling too. Time to look at the heat shield. (scratch)

 

[JohnnyB]

I just installed mine on friday. with the kartboy hangers but it still vibrates on the crossmember every now and then.

 

[chowhoundMSP]

reviving an older thread incase anyone else has this problem.

Chewbacca's problem sounds exactly like the sound i had. It wasnt the crossmember, i tested it out, i put 6 washers between it and the frame and pulled on the downpipe and it was no where near hitting, but same sound when driving it.

If you reach up and feel on top of the front of the heat shield on top of the high flow cat, there is a bolt the sticks down from the top of the engine and bangs around on the heat shield, it will slowly dent the shield and after a while the sounds slowly fades and then dies over time.

My sound went away after about a month and when the sound went away, i checked under the car and the dent had stopped getting any bigger, so im assuming it dent in enough to stop hitting entirely.

I hope this makes sense and clears things up for anyone searching about this problem and come upon this old thread.