We’ve got yet another NC 6 speed transmission to build caused by the weak OE aluminum bearing plates. Our billet steel replacement is next to it. If you’ve got a higher hp NC, track one, or even just drive it spiritedly, it’s only a matter of time before this gives way.
The stock box has cast aluminum plates that flex and crack which moves both the main shaft and cluster shaft around inside the transmission which causes a lot of issues from being stuck in a gear, popping out of a gear, harder to engage gears, noise, heat, and a big one of shearing gear teeth.
If you track your car, your plate IS tweaked. We see it on transmissions with new plates that run a single race weekend. With these plates, that certainly won’t happen and with our dimension changes, it allows us to set up the transmission settings where it needs to be because you can’t quite get there with the stock plate and shims.
Even if it doesn’t give up completely, the increased free play in the gear stack due to these bending or wearing from the mid main shaft bearing race spinning or slamming in to it, it can cost significantly more during the rebuilds due to damaged gear and hub thrust surfaces.
For the NC MX5 6 speed box, it might just look like a billet piece we had made, but the end product will be steel versus aluminum to strengthen the case and keep the shafts from cracking the stock cast aluminum plate. It will also be sized differently to change and control thrust settings that the stock pieces and shims have a hard time getting to, and retaining. We also have bushing kits for these things that actually work better than the steel Mazdaspeed versions that wear out the aluminum that they ride in. Get these pieces installed, along with our other rebuild tricks, to make your NC handle more power, and last longer! We have data from these transmissions from years of racing the NC and am finally applying what we’ve learned to make some parts. Now we also have a transmission builder who can effective apply our data to his build techniques. This results in fixing heat issues, noise issues, better shifting especially 3 and 4 shifts, significantly more reliable, reducing drag significantly, increasing its power capacity and a few other things. A full list of improvements is available in the listing for built NC transmissions: https://walter-motorsports.com/shop?olsPage=products{78bd25a4e39902761a0e7f42e466794481d9c3fb9c4601a846300725f2f42940}2Fnc-mx-5-built-transmission
