Hello, this is my first post so please be gentle. I tried looking around but couldn’t find anything exactly addressing this.

I have a 2005 4-speed AT (with the Manual option). Is it possible to swap the 4-speed AT to standard transmission without have to do a 6-speed engine swap? Meaning a 4-speed MT? And if so, would a 4-speed sequential gearbox be possible as well?

I appreciate any knowledge, I understand I am ignorant🙏

 

The low power cars (4port) in the EU and Japan came with the 5speed transmissions.... so yes you could convert. It's not as simple as just adding the transmission though as there are a lot of interconnected electronics to deal with

 

So even though as an AT it’s a 4-speed you’d still swap to a 5-speed manual? In theory. Without swapping the 4-port engine.

 

The OEM manual options that could fit are 5 speed manual or Series1 6 speed or Series2 6 speed manuals

There are adapters for numerous other aftermarket.options... but they get.more complex and complicated as you would need to fabricate both transmission and diff mounts and drive shafts etc..

 

There hasn't been a 4-speed manual transmission since the late 80s. Outside of the US the low-power engine came paired with a 5sp manual, so that would be the closest/easiest to what you're proposing. But, its a terrible idea either way. Bolting up the trans is the easy part, after that you get to figure out how to operate the clutch and get the engine computer to understand what happened. It's massively not worth it, you're better off to sell your car and buy a 6-speed manual car with the high power engine. It will be cheaper and you'll have fewer headaches.

 

An automatic transmission and manual transmission work very differently. YouTube has a ton of video explaining their principles, so no, you can't turn an auto into a true manual with 3 pedals without replacing the transmission itself.

Trans swap is possible in that, if you have enough money and knowledge, you can pull it off, but things can go very, very wrong. Here is an example of a manual swap that went pretty wrong. Granted, it's not for an RX-8, but this is just to show you the risk involved. Honestly, I don't even know if most shops will even attempt to tackle a project like this since modern cars have a lot of electronics that will have to be swapped out. The key cylinder works differently between manual and auto as the manual trans has a button you have to push in to turn the key to OFF to pull it out, while auto trans just requires you to be in P; there is no button to press. ECU will also likely differ.

Sell the 4-port 4AT and get the right combination you want. It will be cheaper and easier.

 

Thank you all for the knowledge, I appreciate it. I now fully understand. Thank you again!