Greetings,

I've never rebuilt a transmission, but I do have the documentation from Mazda to do so on the 6 speed that comes on the series 1. I don't have much knowledge on even how they work beyond theory, so this question may come off as silly but, what makes the series 1 6 speed unreliable for high horsepower applications? Is it lower quality gears or just a design flaw?

I'm assuming this can't be done easily and it's not a simple matter of replacing lower quality gears with better ones, otherwise I would have heard about this before. But is it possible to rebuild the aislin transmission with higher quality parts?

 

It does not really work that way. The trans is designed for a certain input torque range (its also used in the S2000 and MX5 to give you an idea) with the goal of minimizing drivetrain losses, which means shafts and contact surfaces are as small as they need to be to still function forever living in a stock MX5/S2K/RX8. Those things are hard to change just by replacing parts (or at all?). So its not design flaw or quality, its that this trans is the wrong tool for a high-power job. Conversely, you would not want our 150lbft of fury pushing through a beefy transmission that could take more power, and incur more losses and carry more weight as a result.

You *can* buy aftermarket gearsets, but they tend to cost more than most RX8s. I am not aware of any specific ones for the 6-speed, but in general what you are buying is still further reduced drivetrain losses, faster shifting and different ratios at the expense of more noise and rougher engagement. Not really stuff you want in a street car.

So, yeah. If you are going for big power, its easier to plan on a trans built for that

 

the S2k trans is based on the overall Aisin AZ6 design platform, but it’s far from being similar to the RX8 S1/MX5 NB version. Just stating this because them being same/similar is a long-standing perpetuated myth.
.

 

Interesting, did not know. Thanks Team.

 

Gotcha, that makes sense. I just wonder where the weak points are, and if there is any way to rebuild and circumvent that. The S2 transmission has comparable weight and size, yet is apparently much better than the S1 trans. Why and how is that?

S1 6 speeds are so cheap people are practically paying to get rid of them, if they could be turned into something useful with some modification that would be helpful to reducing the costs of many builds.

 

yeah, that’s a good thing

I own about 10 of them now, 4 are busted. So just run them until they break, then rinse and repeat is my motto now 😆

 

I’m not aware of anything being interchangeable between them anyway. The S2k being 300 - 400 lbs lighter is a benefit to trans life