2016 Mazda MX-5 Miata: Transmission Noise
by Jason Kavanagh, Engineering Editor on September 22, 2016
Our long-term 2016 Mazda MX-5 Miata has a subtle buzz that occasionally emanates from the transmission.
Not to worry, there's nothing wrong. In fact, it suggests something is very right.
If you let the Miata's engine coast down from high-ish revs while in gear, you will probably hear a light buzz within a certain rev range. Actually, "buzz" is too strong a word. It's more of a "shussssh" sound.
This is classic "lightweight flywheel" gear noise. Many cars that have their stock, heavy flywheel replaced with a lighter one for zippier throttle response will exhibit this phenomenon. Basically, the inertia of the stock flywheel does a better job of soaking up the noise from the transmission's synchronizers.
But our Miata has a stock flywheel. So what's going on here?
It turns out that during the development of this generation of Miata, one engineering team specified a heavy flywheel to ensure the transmission would remain mute under all conditions. Another team reckoned that the heavy flywheel blunted the engine's character and ran counter to the philosophy of a sports car. After some back and forth, it was decided that the latter group was correct, and the lighter flywheel was given the nod. The accompanying "shussssh" noise was considered an acceptable tradeoff in this type of car.
I agree. The sound is hardly objectionable and only crops up in the aforementioned use case. Besides, the kinds of people that would be put off by the noise are also the least likely to drive it in a way that would result in the noise being present. In that respect, the "problem" sort of takes care of itself.
Jason Kavanagh, Engineering Editor @ 14,410 miles