I got a 5 speed rx8 transmission that i try to swap to the FD .I swap the bell housing and the rear shaft housing to rx8 transmission every think fit perfectly only issue is where the speedometer sensor plug in the output shaft of rx8 where you put the speedometer plastic gear on is 1/2 an inch lower then where the FD out put shaft.So from what i hear people say a 5 speeds rx8 transmission can be swap to an FD is not true.

here an fd transmission you can see the plastic gear speedometer through where the sensor plug in.

This is rx8 transmission with FD rear shaft housing on the speedometer gear is like 1/2 an inch off i put the speedometer sensor in it but there no contact of the gear to the sensor.

 

You have to swap the FD speedo gear over.

Yes, this is possible, I have seen it in person

Dale

 

Left is an FD transmission right is the RX8.You can see that where the speedometer seat have a different height. Yes i did swap the speedometer gear of the FD to the rx8 output shaft is on the shaft in the picture. So i don’t think is an easy swap to do so i thing we have to change all the gear of the 8s to the FD main shaft.

 

This is odd. I swapped a 5 speed Rx-8 trans into my FD and did not have this problem and had another friend who did the same thing. Where did you get this transmission from?

 

I got it down in southern California place call JDM Motor Import I think there are in Long Beach CA.

 

it will sell on RX8Club in a heartbeat if you decide to bail.

.

 

Is the rx8 5 speed stronger?

 

The RX-8 5speed is just the FD box, so yes.

 

Maybe there are differences with S1/S2 RX-8's?

Do you know what year that RX-8 5 speed is from?

A number of people have done the mod and the RX-8 shaft was identical to the FD's, just need to swap the speedo gear.

Dale

 

So it's the same, or is it stronger?

 

the RX8 version has added synchros that the FD version didn’t

Mazda had to narrow the gears slightly to fit them in, technically could be considered weaker because of that. However the previous owner of the car I bought from him was really beating on it hard when RX8 3rd let go. Making high torque below 5250 is usually what’s going to do that. He then switched out the S362SXE with an S369SXE and it shifted full boost to occur around 5300 rpm. So the engine can make the same or higher HP with less torque from 5250 rpm and higher.

I’d be surprised if they changed it on the S2 version. There’d be no reason to do that unless it was a manufacturing related reason. The EU version had a different 3rd and 5th ratio, but I’ve never seen or heard of one being imported from there to North America and it being bought from a California importer is most likely making it a JP model. They typically will list the model year though; S2 production began in the 2009 MY.

I was referring to you bailing on the RX8 5-speed. The importers have cut back on selling the trans only because nobody who knows any better wants the low power RX8 engine that it comes on, by itself. They then end up sitting on the engine or cutting the price way back to move it.

I lucked into a low mileage RX8 5-spd from a local JDM importer with a $350 cash on the spot offer on a Saturday afternoon just before they were about to close several years ago. I don’t think they ever brought in another RX8 since then. There’s not any engine advantage at all JDM vs NADM and they just don’t sell like some of the other more popular JDM engines.

Because unlike on a 13B, a Renesis engine is all about rotor sealing when it comes to optimizing the rated power output. The repositioning of the intake ports to extreme early opening coupled with zero intake-exhaust overlap relies totally on the long intake draw and no leakage past the rotor seals to pull in as much intake air as possible. I’ve been saying for many years now that despite the similarities, the Renesis is technically a different engine compared to a 13B because of this.

And both the rotors and rotor housings should always be replaced on a rebuild, and the center iron possibly too because the divider in the shared siamese exhaust port is susceptible to fatiguing and coming out. The exception is if the rotors are EDM’d deeper for full depth RX7 apex seals, especially when combined with Iannetti ceramic seals. Then you can get multiple rebuilds out of them as per the Formula Mazda race cars that were making around 235 whp with blueprinted Renesis engines and those mods on factory ports (never port a Renesis much past just cleaning up the sharp edges and rough casting marks).

The shallow Renesis apex seal was a mistake by Mazda imo. Think of it as a hole in the ground for putting in a fence post. The shallower the hole, the easier it is to rock the fence post back and forth to wallow the support hole out. It’s a lot harder to do that with a deeper hole. 160 - 180 whp RX8s are the norm due to excessive blowby on the rotor seals. When you get it right then 220 - 230 whp is what can be expected. Well, sorry to go off-topic on that. Kind of passionate subject for me.

 

No i have no idea what year rx8 it from.

 

I'm thinking about it .Not sure what i'm going to do yet.

 

Do you have the rx8 5 speed bellhousing still ? I need it for my Cosmo.

 

Yep still got it.

 

Just saw your reply I'll message you

 

Did this speed sensor gear location issue ever get resolved? Alternatively, has anyone else that's attempted this swap run into the same issue? I'm looking to get an Rx8 box for my car but don't want to end up in the same position.

 

Hello @lexxs , was the speedo gear location issue ever solved? I’m currently stuck with the same problem as well.

 

No ,only thing that would work is swap all the gear to FD transmission main shaft.

 

The solution I came up with was not a simple one. Car is not yet running so it is still unproven but everything went together as is should. The difference in position on the shafts is 0.690". So i pocketed out the tail housing for a plug that then got welded in. After welding we put it back up on the mill to recreate the speed sensor provisions in the altered location. If you are going to do this, be careful not to make your plug too big as it can interfere with the shift linkages on assembly.

 

FD main shaft PN:

R50317221C to 01.04.2001
R50317221D from 01.04.2001

RX8 5 speed main shaft PN:

R50317221D to 01.05.2005
R50317221B from 01.05.2005

This suggests that the late FD shaft and early RX8 5 speed shaft are the same. This could explain the difference that lexxs was seeing. Perhaps an early RX8 trans is needed for the RX7 swap?

 

Pictures of the work needed to make this adjustment.