Just got a RX-8 last week. When I have the door open, I can clearly hear less engine/tranny noice when clutch is down. I can drive, but ain't smart with engines. Is that normal? What's the cause?

 

Hit the button labled "SEARCH" and put in "tranny noise".
Its been discussed to death.

 

https://www.rx8club.com/showthread.p...t=tranny+noise

here is a good thread

 

Maybe he already did a search. Most likely "noice" didn't bring up anything! :D

 

Mine has done it since new. They all do it to one extent or another. Its a bit annoying but is actually nothing to worry about. I had to force myself to get used to it. It is caused by the fact that the rotary engine puts a particular type of torsional vibration due to firing order / sequence, into the crankshaft. A 4 cylinder or V8 engine does the same thing and its called fourth order and eigth order combustion resonance. Essentially, every time a cylinder fires, an energy pulse goes down the con-rod and into the crank .Engine people do a lot to try and smooth it out in the crankshaft design and all conventional piston engines have to have a crankshaft balancer and a flywheel on the back end. The rotary engine is somewhat different and it puts out third, sixth and ninth order vibrations. Heres the issue - the flywheel and crank balancer are relatively light and the gearbox (with the clutch engaged) gets quite excited by these orders of vibration which are really worst at engine idle to about 1200 rpm. Hence - when you depress your clutch pedal, you disconnect the engine from the gearbox which then goes quiet. There`s one other issue to top it all off...and that is the design of the gear teeth between the input shaft gears, layshaft gears / output shaft gears is a bunch of crap - the "gear mechanical transmission error" sounds poor and thats something that Mazda should change asap. It would not cure the issue but would certainly help to quieten it all down.

Tom

 

Thanks, guys.