Loud Underbody *Rattle* Defect Found - Easy Fix
 

The (#3) underbody panel that mounts around the exhaust pipe rattles like mad because some of the bolts were designed to hold 2 larger and wider underbody panels together on both sides... instead of just one slimmer unit (#4) attached on the driver side.

http://blog.perrinperformance.com/wp...el-550x368.jpg


This issue ONLY affects FR-S/BRZ/86 models that DO NOT come with the extra underbody panels pictured below...

The North American and entry level models DO NOT get the long wider underbody panels and THAT'S THE PROBLEM!

The (3) bolts on the LEFT SIDE (passenger side) and the (1) bolt on the TOP RIGHT (driver side) are too long and cause the (#3) panel to rattle.

Pictured below: Japanese high end model with the extra panels all bolted together.
http://www.mann-engineering.com/site...nderpanels.jpg

CHEAP FIX: Install a 3/8" washer on each of the above mentioned bolts to fill in the extra void (you cannot simply tighten the bolts any further without installing new washers... the threads don't extend all the way to the bolt head). I personally bought four 3/8" nylon washers (about 2mm thick) from a hardware store and installed one on each bolt... NO MORE RATTLES!

Other option: purchase and install the extra Japanese panels.

Hmm this must be what I'm hearing during first start up

Good find i was having the same noise during start up and accelration at low rpms. I knew it had to be something underneath the car.

I'm not so sure if this is the rattle that some of us hear at low RPM under load - that sounds more like a metallic rattle, this material is some kind of a composite, no?

In any event, I do see what you mean - the bolts are easy to get to without jacking up the car too, so I might look into putting some washers in there. Anyone know what size is best?

Good find! I do not notice it on my car, even when it was up on the rack. But something to keep in mind. I would really like to add the other panels to mine eventually.

Picture shows a 10mm bolt, so I would expect a washer for a 10mm bolt to work fine.

I don't think it's a standard bolt - looks like it has a ring piece between the bolt head and the threaded shaft and it's wider than the threaded shaft. I think we would want the washers to go around that part and not the threaded shaft. I'll yank one off and bring it into Home Depot with me.

yeah, best idea yet. Let us know what you figure out.

neoprene washer perhaps?

Found some 3/8 washers that fit perfectly. I had to double up the one on the passenger side closest to the driveshaft as it was still loose with only one washer.

can someone repost the pictures from the OP?

are you anorexic sti from iwsti?

dafuq..why can't i see any pics?

Hah, I was wondering what that sound was. Usually happens during a cold start, loud rattle for about 30 seconds, then quiets down when the RPM settles. Good find, I'll have to try it.