Loud clunking underneath driver's side area: suspension, chassis, or wheel related?

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I had new tires, Bridgestone Potenza's RE71r, mounted on to stock rims at Tire Kingdom. I drove home, under 50mph, city roads, for about 10 miles.

The following morning I install a front sway bar and drove without the under panels (SU00301383 and SU00304761). Handled great, when I drove it through some low speed twists for about 10 minutes. It was exactly what I wanted, but I noticed a ton of clunking coming from underneath the driver side area of the car once I went on a straight at speeds above 55mph.

I'm thinking oh no, it's probably from the loose bolt (SU00300036) that attaches the sway bar bracket to the driver's side reinforcement plate, (SU00301225). The threads of the bolt and inside of the hole where the bolts go into in the reinforcement plate have been stripped bare during the installation process. Replacements are on there way to me right now. Everything else was tightened and torqued down to specs.

Anyways, I removed the sway bar, endlinks, and reinf plates. I kept the oem skid plates and covers off.

I drive again to work without the following items: sway bar, oem end links, reinf plates (SU00301224 and SU00301225), oem skid plates/covers (SU00301383 and SU00304761).

The clunking is still there! It becomes violent and apparent at over 55mph just like it was with sway bar and related parts still attached.

So via process of elimination, it probably did not have to do with the sway bar and related parts.

Is it related to ventilation or sound deadening due to the covers being off? I'm not sure. At one point the clunking went away and more wind noise entered the cabin. Has anyone driven without those covers at 55+ mph and had similar issues?

Has this happened to anyone? Could it be related to my new tires, perhaps they didn't mount or balance them properly?

Diagram with part numbers for reference - http://www.trademotion.com/parts/201...iagram=8615205

and

http://www.trademotion.com/parts/201...iagram=8615030

[mav1178]

Are your wheels torqued down properly?

[ryoma]

Are you sure it's a clunking and not the wind caught under your car due to no under tray?

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[roddy]

Have you also removed the 3rd section of shielding under the car? The front 2 bolts that hold it to the body also hold the back of the 2nd undertray. If that 3rd piece is still there, and you didn't put the bolts back in, I'd bet it's flapping around under there once you build up some speed.

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Originally Posted by mav1178

Are your wheels torqued down properly?

I haven't checked but I'll be checking before I leave work.

Originally Posted by ryoma

Are you sure it's a clunking and not the wind caught under your car due to no under tray?

It's highly possible. I'll put on that tray again tonight.

Originally Posted by roddy

Have you also removed the 3rd section of shielding under the car? The front 2 bolts that hold it to the body also hold the back of the 2nd undertray. If that 3rd piece is still there, and you didn't put the bolts back in, I'd bet it's flapping around under there once you build up some speed.

I did not know that the back 2 bolts of the 2nd undertray also hold the third under tray, because I never really looked at that tray. That's a dumb move on me. I'll put the car up and attach the OEM undertrays to see if the sounds go away.