buzzmasters

Need some help please....new guy here, recently purchased a 2003 996TT, seal gray/black with only 11,500 miles. Have had local shops do a workup on it, with X73 suspension, TRG droplinks, Europipe Stage I Quiet, GiroDisc 350mm rotors, Pagid Yellow pads, GT3 brake cooling ducts, stainless steel brake lines, Motul 600 brake fluid, Tarett rear toe control arms and locking plates. The shops have done a great job and the car is ready for DE in a couple of weeks..... excellent handling with X73 alignment specs, and extra wheels are ready to go with Michelin Pilot Sport Cups. Had to sort out a few minor issues along the way, mostly due to 'garage queen' status of the car not being driven enough over the years, and it is tight and nice now, running great.

The last minor issue is a harmonic noise, kind of a 'wah, wah wah' noise that only happens when warmed up and while holding a constant speed between 2300-2600 RPM. If the RPM is slowly increased, the frequency of the 'wah, wah' increases as well, which makes me think it is some kind of harmonic frequency in the drive train somewhere, maybe a fastener not quite tightened down, or something similar? I do not believe it is exhaust drone, as the frequency of the noise changes with RPM, and it does not occur under harder acceleration, only at a consistent speed with a relatively fixed (neutral) throttle setting, and only in the tight RPM band of 2300-2600.

Anyone out there had or heard of a similar issue? It isn't a major issue, but rather a minor annoyance I would like to solve if possible.

Thanks for any inputs.

Buzz

...attached a few marginal pics...will do better as soon as the weather clears up!

Dock

Wheel bearing(s) or tire(s) (although at least your rear tires look OK) causing a harmonic with the sound the Europipe is producing at the 2300-2600 RPM range?

As my two front wheel bearings got progressively worse they produced enough sound to create some wild harmonics when mixed with my Europipe sound output.

Land Jet

It's the Europipe. I got the same thing when it was installed on my car. I even emailed Stef and he said not to worry about it. I guess it beats the constant buzz some of the other systems out there have.

buzzmasters

Thanks for the insights. The tires are brand new... I had wondered about the old tires being an issue, since the noise was there with the old tires as well (they were the original Pirellis, if you can believe it!). The noise was there before I had the Europipe installed, and is now perhaps a touch louder than before. ....hmmmmm. The wheel bearings occurred to me, too....I'll have them checked out. Thanks again.

buzzmasters

Dock --

Did the noise go away totally after replacement of the front wheel bearings?

PAULUNM

I'm thinking front wheel bearings as well. My car had a bad bearing at 20k miles.

Dock

Yes.

The harmonic noise initially sounded just like the sound that I get when my tires reach a certain wear point; the worn tire noise and the Europipe output at certain specific RPMs causing the harmonic. But slowly the sound got worse and went past the point that I thought would be generated by the tires becoming more worn and thus creating more noise. The front wheel bearings were in fact shot, and after replacing them the harmonic noise disappeared.

LVDell

Very nice Buzz....welcome aboard

buzzmasters

....might as well have the bearings replaced, as the 'most likely solution.' Thanks to you all !

BostonDuce

Buzz, can you elaborate on the GQ issues?

BD

buzzmasters

BostonDuce --

Left front ball joint dried out and had to be replaced; clutch switch that engages at the end of its travel had to be adjusted, otherwise I had to push way too hard to get the switch to engage to start the car; GT3 brake cooling ducts had to be trimmed to avoid rubbing near full wheel turn angle when backing; brake fluid hadn't been replaced in six years; eight or nine-year-old tires; exhaust tips had pitting and a bit of corrosion due to its previous life on the east coast - replaced them; fueling door had a sprung latch; battery ready for replacement. Engine appears to be in great shape, makes proper boost. Replaced most all of the fluids. Installed EVO diverter valves as a preventive measure. Quite pleased with the car now that the minor items have been corrected.

Buzz

Land Jet

I had Pirellis on my car when I bought it. They make a lot of road noise. My tire guy told me Pirellis have a belt shifting problem.

Kevinmacd

A good way to check the wheel bearings is get to the speed you are hearing the harmonics, then make a turn left then right. A good sharp sweeper would be ideal, This will load the bearings differently. If the harmonics goes away or changes as you turn, then I would say it's a wheel bearing, if not probably exhaust.

buzz737

Kevinmacd -

Thanks, I just got back from a trip, and I'll go out and do a test run on some sweepers as suggested.

Buzz

PAULUNM

When I had a bad wheel bearing, this test did not work... Sound remained the same regardless of which way I was turning.

I think the best way to determine if it's a wheel bearing- pop it in neutral when coasting at a decent speed. If the noise goes away, it's your exhaust. If the noise remains, wheel bearing.

Just my $0.02