2006 Sonata Wheel well noise

Just back from a 1200 mile trip on which we passed 10 k. Its a 6 cyl
and I know this may not sound right but in the flatlands of VA and DE
we were getting 28 mph (spiked up to 29 once??) at 60-65 with AC on
low, no kidding (or at least thats what the trip computer said). My
questions concerns annoying wheel well thumps that we heard peridically
thru the trip. Sounded like a peice of soft debris being thrown up
into the well. While I was driving I did not notice any debris behind
the car on the road when I heard it. Although I imagine it is possible
it was some foriegn object I wondered if this might be some type of
thermal expansion (we were coming and going from extended wooded areas
into open sunny farm lands) on the roof or some other part of the car.
Anybody have something similar going on?..............Doc

 

Welcome to the Ka-Thunk club Doc. :\

If we're talking about the same sound, I hear it mostly on rough streets
while driving slowly. Sounds like it's coming from between the rear wheels.

One owner stated his dealer told him it was a shock mounting pad issue, and
would be addressed by Hyundai. Heard nothing back on it so far.

Another owner stated his emergency brake cable was loose, and rapping
against the floor pan. He could see a slight mark against the undercoating
where the cable was hitting. He secured it with a zip tie, heard nothing
back on it so far.

Personally, I slid underneath my car and hit against the fuel tank bottom
with the heel of my hand. It made a very familiar sounding "ka-thunk" sound,
even with the lightest bump. I just don't know if that's it or not. If I had
a lift, I would stuff things in there and try to stabilize it. If's and
but's!

Bottom line, if it's the noise I think it is, it should be brought in to
your dealer for resolution. *


*I brought mine in, but the dealer was too busy that day, a huge
thunderstorm came up with power blinking, and I just wanted to go home.

 

Update on the K-thunk. Below is an update from an owner I mentioned in my
previous post.

Begin Quoted Text:

Just an update.
We put 600 miles on the Sonata this weekend with about half being interstate
and the other half being rough roads. We had no more thumps. Actually the
front suspension was louder than the rear. At one stop I reached up under
the drivers side rear wheel and cut the zip tie off the brake cable since
that was the side that had the most marks on the under body. Guess what,
thump was back. I put a new zip tie back on it and no more thumping. Good
enough for me, until I can figure out a more permanent method of keeping the
cable off the body. Good luck people with your thumps in the night.

End Quoted Text


It sounds pretty promising, but I can't believe it's that darn simple!

Anyone else have news from dealers or personally investigating the noise?

 

I had a 2000 and 2002 Sonata with the same problem. It turned out to be
the rear suspension / shocks ; it was very annoying and happened all
the time. Got the District Hyundai Mgn involved and in an attempt to
make it better, he had oil filled shocks put on and it greatly improved
things. Also, consider adding some 3/8" thick insulation roll from J.C.
Whitney.com above the wheel well plastic liners to muffle noise ; it
worked out well on other cars ive done. You have to remove the wheel
then the Liner , but its a pretty easy job. Then glue some insulation
roll down after cutting it to size. Also put some in the cargo area
under the carpetting on the inside of the vehicle .

 

Is the wheel well plastic?

Matt

 

Hmmmm... if the waxy undercoating was applied under the wheel well, I wonder
of the sound mat would even stick? If not, maybe just some of that foamy tar
undercoating would help deaden the noise a lot.

I know the sound deadening mat would help some, but the metal foil coating
is most effective when oriented toward the cabin, right? In other words, it
would work best if you could apply it to the wheel well from inside the car.
Oy, I bet that would be a major job...

 

Bob, dont know if it would work or not but if you wanted to do it from
inside the car why couldnt you drill some small holes and use that spray
foam insallation, you know the kind that swells up when it drys. It would
seep into the hard to get spots before it drys then all you would have to do
is cut off the excess where you drilled the holes and touch it up with black
paint and a small brush or a black magic marker.

Tunez

 

'Is the wheel well plastic?
Matt'

REPLY: The Liners are black plastic inside the wheel well, and, from
looking underneath the car...it appears the wheel well itself might be
fiberglass as the floor looks to be.

 

Yea, I thought of it right away. I've used that expanding polyurethane foam
for lots of things. Tip: Don't get it on your hands unless you like the way
it looks!

I think my car is quiet enough until I get on some extremely rough roads.
All I need to do is kill that "k-thunk" noise in the rear. I would rather
remove the noise than to isolate it, but I will if I have to.

Note to Dave: Sorry for the e-mail. I pushed the wrong button. :\

Another note to Dave: Would you consider doing a "how to" with pictures?

 

'Another note to Dave: Would you consider doing a "how to" with
pictures?
--
Bob'

REPLY: Bob, If it were 'rocket science' id be pleased to, but, on a
difficulty scale of 1 to 10....adding 3/8" insulation matting above the
plastic wheel well liners once you have them removed, is about a 1.8 .
Its even easier for adding it underneath the cargo capetting / cab floor
carpetting. About all you need is a screwdriver, pliers, small socket
wrenches , silicone glue , sizzors, and the insulation roll . Jack up
the car and remove one wheel at a time , then look to see how the
plastic wheel well liner is held on , then remove it taking your time.
Clean up the top of the liner before you cut to size the insulation mat
, glue it on, then re-install the liner. (dont forget to put the wheel
back on too

Dave

 

Hey Dave.

Ya, I know it's not rocket surgery.

But,,, sometimes finding and deciding which screws to remove can take hours.

You're saying to stick the Dynamat to the plastic fender liner? Have you
found that to be truly effective?

The manufacturers could easily and cheaply done the same thing. Makes you
wonder!