Grinding noise above 60 km/h (Willie)
 

My '05 RX8 makes a grinding noise above 60 km/h. Sound like the wheelbearings are the problem. I was told by the mazda dealer that it is the tyres making the noise. I replaced the tyres and the rims (stock got bent by a small pothole). The noise is stil there and getting worse. The car has only 32k km on it. Any one can help me?

To rule out most of the drivetrain related issues try to see if you still hear the noise with the clutch pushed all the way down.

Is the sound rythmical, tied to rpms or speed? does it happen when not moving (free revving the engine)?
Solving noises over the internet is hard...

Also... Does the noise increase in volume or pitch with speed? Does it change depending on what gear you are in? Do different road surfaces change the noise?

I'll say the wheel bearings.

The title was changed to comply with RX8Club Rules

The noise only start at around 60 km/h. it does not change when the cluch is pressed in, even when going 70 and disengaging the gears the noise is there. It does not increase with engine revs or when changing to a higher gear. When driving on a more coarse road surface the sound of the tyres does dampen the grinding noise. Could the problem be from the car being stationary for long periods? Thanx for the quick response guys

They may be the wheel bearings and yes, leaving the car stationary for long periods may lead to increased wear.
Get them inspected or source a couple of new\barely used ones from shops like Mazmart if your local prices are too high!

Anyway, is the sound "rythmical" like a "tud-tud-tud"?

#50
The sound is continious more like the sound when you sandpaper wood with coarse sandpaper.
I think the dealer will agree this time around that it is the wheelbearings, as the car is out of the warranty period. Gues I'll have to carry the cost now. As long as the 8 runs again like it should, I'll be happy. Great car hey? Also planning to up the hp and torque a bit, but I'm still browsing options.

After you get a quote from the dealer you might want to research other venues to purchase your bearings. Dealers are extremely expensive at times.