Ok, I tried coasting on the way back from the tank fill up. At that time it decided to be quiet.
I just finished a 6 hour marathon wash/clay/polish/wax and will wait a couple of days for clear weather to try it again. I'll try neutral/coast and downshifting when I have a nice thrum going. Thanks, bud!
Originally Posted by waldig
Doesnt change with the speed
Must not be a tire shape / runout issue. It sounds like a resonance that has changed amplitude with increased mass - gas.
It has a period of several seconds but the same noise, sounds to me like a resonance with the exhaust sustem and the tire vibration. You have not reported the coasting in neutral change or lack there of. I suspect that you will see coasting makes it very much lighter in sound.
Try this, please go down the road and change the gear ratio, like go into 4th and maybe 3rd to see the effect of moving the engine speed away from the tire speed. Should make the thrumm go faster or quicker in period.'
Makes me think of Don Knotts and the Thrumm that the fish made to disable the submarines and torpedos. Mr Blimpit or something - your old youll remember.
Enjoy, woody