The rx8 started making a worrying noise today, and I was wondering if anybody had any clues what it could be before I take it to a dealer.

At high speed, the car is fine.
Accelerating hard, the car is fine.
There seems to be no correlation between going around corners and the noise.
There doesn't seem to be a pattern when braking either.
At idle I can rev and I don't hear it.

But, when moving slowly, either slowing down, or taking off, I hear the sound - randomly.

It is a "thud" sort of sound, from either directly under the middle of the car (under the gearstick) or midway towards the back (I am pretty sure it is in front of , or near the rear wheels). It is not metallic, and there seems to be no noticeable effect on the steering, gear changing, clutch, cornering, acceleration etc. But it is loud enough and often enough to be very worrying.

Any ideas? Diff? Exhaust popping from a weld near the cat? Suspension?

 

Sounds like one of your
engine mounting brackets might be loose , some guys on the forum reported that the engine mounting brackets on the passengers side have broken .as the welding has been average .

Also could be exhaust mountings . get your car on a hoist and look around .

cheers
michael

 

Ok, I took it to Mazda this morning.

They put it on the hoist, and found the rear left swaybar is broken when it links to the chassis.

Weird. I haven't been hit by anything, and they also can't understand why is has sheared off. I can drive the car until the warranty replacement part comes in, but I shouldn't engage in sprited driving through the hills until after the fix.

 

I had a rear lower control arm shear in two on an Astina SP years ago...

Weird. Mazda Japan were very eager to get the bits back for an inspection.