Sound insulation - rear fender area. Anyone done it?
 

I'm noticing more and more road noise coming up from behind me. It changes with surface so I know it's road noise transmitted through the tires and up the fender cavity. I checked around and don't see any obvious leaks, so I'm thinking of putting some sound insulation back there. Have to pull up the carpet, remove the seats, it's a pretty big job for and old fart like me but would prefer a quieter driving car on long trips. I know it'll add a bit of weight too, I can live with that.

If anyone has tackled this, let me know and if there are any gotchas, or special concerns.

How old are your tires? Old rubber is terribly noisy.

Interesting, I did the opposite and pulled the stock foam insulation out of the fender wells and removed the rear deck carpet when I did the rear seat delete. Less weight and more engine sound was my goal.
But to help you I can say that removing the rear panels was a bit of a challenge and if I do it again I will remove the seats first. It gets very tight in the back of the 996. The trickiest screw was the one at the seat belt slot. Good luck.

Spray can of undercoating in each wheelwell helps.

"Spray can of undercoating in each wheelwell helps."

I wondered if this had any affect on tire noise reduction???

The sound deadening from factory is roughly an inch thick in that area. I doubt anything like dynamat or equivalent would make a difference.

I took most of the carpet out of the back of mine for weight - and there is a LOT of thick, heavy foam on the back of all that carpet. I was amazed at how LOUD it was with the carpet out! So much that I throw the biggest piece back in if I'm driving around town or on the way to the track (then just yank it out at the track). Without it on the highway - it's crazy loud!!

So the only thing I can say to the OP, is take pictures as you go..... there's a lot more pieces than you'd think pulling that carpet out...

yes done it in several cars. buy sound deadening material, usually 12 sq " on ebay. I use about 10 to 12 pieces, use a vinyl base or asphalt base, both about the same. you have to take up rear carpet, seats, side panels, lay them all over all surfaces. You can put in fron floor , wheel wells, where ever you can get to. Crank the car before and as you lay them. it almost doubles the sound deadening affect of the carpets and seats and all stock material

Thank you. Did you do it on a 996 chassis? I guess as expected, this is a massive job. Wondering if I should just wear my earplugs on long trips.

That was the purpose...

Yes, but does it really work??? Would it be worth doing? That is the info I was looking for from someone who has tried it already.

996 and 997

Didn't think to do a before and after Db measurement but "seat of the pants" judgement was/is positive.

Went through 3 tire brands before concluding that all got dramatically more noisy after 8-10,000 miles.