Parts Spotlight: 5th Gear NA/NB Miata Transmission Spacer

Inexpensive spacers help keep transmissions in service longer and make rebuilds easier

Part No. 0000-0257-22SP
Racer Price: $51.00

Longtime Spec Miata racers know that NA and NB transmissions have a slight problem under racing conditions – the transmission shaft can twist under the repeated hard acceleration of racing. While it doesn’t affect performance, it can be a big problem when it comes to rebuilds – the gears can be incredibly difficult, even impossible, to remove from a twisted shaft.

Some Spec Miata racers, and those who race the Miata in other classes, found a solution: an old fifth gear, ground down, could serve as spacer in the transmission, strengthening the shaft to keep it from twisting. But you have to have an extra fifth gear, and it’s a lot of labor to grind it down. So the late-Dave Wheeler of Advanced Autosports, who ran a fleet of Miatas for himself and customers, sought a better solution: a custom-manufactured piece that slips onto the shaft and can be a much cheaper and easier option than a modified gear. He found someone to manufacture it, and now it’s available exclusively through Mazda Motorsports.

Approved for use in Spec Miata, the spacer has no affect on performance, though it is intended to increase the longevity of the transmission and make rebuilds easier.

To order, log into the parts store or call (800)435-2508.
Pricing is subject to change.