7speed getrag DCT transmission swap.
 

Just a few progress pictures of my ongoing DCT swap in a 92 miata.
Im installing a 7 speed dct box from a 2016 M4, "because i can".
It will fit the BP with a slightly modified Kmiata adapter plate, but pretty much everything else will be custom made.
it will fit in the transmission tunell, and for a 450whp street/trackday car it will be plenty strong, and have a higher top speed/lower rpm for cruising/autobahn driving(200mph miata?)


https://cimg4.ibsrv.net/gimg/www.mia...03a1eed255.jpg
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This will be fun to watch; that box makes the engine look pretty petit!

Following!

Oh my.

This is awesome. Cant wait to see how it puts the power down.

Just curious,what did the trans cost?

I... what? In for seeing how you control the thing...

I have no desire to do this, but i have many desires to follow this

Where does the paddle shifter come from and what in the good Lord's name do all those buttons and switches do??

I presume shifting is solenoid activated and not pneumatic as it would be on a race sequential box. If this ends up costing less than about 11k USD, it would be cheaper than the Quaife QBE6OG.

What's the expected weight penalty?

If memory + a cursory google serves correctly, about 2.2x (~80 lbs for a six spd vs. 82 kg dry weight of 7DCI700) ignoring adapter plates, clutch/pressure plate hardware differences (or lack thereof) and driveshaft length changes.

This is Sofa King cool

Whoa.

Wheres the bee--oh

This is pretty cool. GS7D36SG?

I'm fairly sure you already know this if you're doing this swap, but worth mentioning anyways. Check the fluid pan gasket and the mechatronic sleeve area on it. It's a somewhat common occurrence for them to leak fluid and when/if it gets low enough, the clutch packs can start to overheat. Had a rather long drawn out experience with the 7 spd DCT box years back in my old 135i and learned entirely too much about them.

Paddle shifters are parts for high end gaming rigs, but the paddle and the mounting plate is my own design, machined from 4mm carbonfiber.
One of the buttons with the green light is a Neutral gear button, the other changes page on my dashlogger.
The red knob changes between power level of the engine, and traction control settings, 6 in totalt between 300whp and full wet mode tractioncontrol, low or high power with dry setup tractioncontrol, or full power with no tractioncontrol.

Paddles send a signal to a external transmission control ecu, and gearbox internals are modified. we do not use the BMW TCU unit. all valves and position sensors etc er directly connected to the new standalone unit.
This allows full adjustability of shifting times++ and i still have a clutch pedal (drive by wire clutch) .

It will be as if the car had a race sequential gearbox. Clutch in, select first. and then only use paddles after that. But it also allows a driver to clutchkick if used for drifting, this is not normally possible with a DCT transmission!.
Shifting is also more aggressive than with the stock TCU unit, and clutch pressures are also adjustable.
It will also be able to control a automatic function from my ECU, making it send gear up/down signals, and making this fully mappable aswell.

All seals on the gearbox will be changed Sometorque :)

A used DCT box from a M4 cost us 1000 euro, and the rest of the conversion parts are similar, but not the same as K miata manual swap parts.
The gearbox is TALL and i have had to raise the engine a bit to make this work, but my car is 99% a streetcar, with some trackdays inbetween.
The ratios are typical BMW with a short 1stk. but 3-4-5-6 is the same as the miata 6 speed, but with a 7th at 0.67 on top of that.
For street use ( i also sometimes drive on the autobahn) a gearing to over 200mph is sweet as hell :D and with 450 whp it will still rip through the lower gears.

There are some problems doing this swap, but it helps not having the canbus controlled stock TCU. and installing it in a light and low(relative) power car like a turbo mx5 should make the mechanics of the gearbox pretty much bulletproof.

https://cimg2.ibsrv.net/gimg/www.mia...ecd10eff32.jpg

It will be cheaper. but heavier. but more streetable :)

How much did you have to raise the engine?

Damn! Was expecting it to be way more than that.

They're surprisingly cheap since they were/are used on a bunch of DCT-equipped BMW's for the last 8-10 years. I had bought one locally for $1600 about 2 years back that i ended up selling after i sold my old 135i. They're all over the place now for $1300-$1500.

Also helped by the fact that they are difficult to use in anything else than a BMW with the same gearbox. making the marked for used ones because of chrashed cars really small.

That's waaaay cheaper than anticipated! And progress looks great so far!

Holy shit. This is right up my wheelhouse. What trans controller are you using, if I may ask?

In for the engine height as well. My K24 probably can't go any higher.

Can you share more details on the trans controller? What does the trans use for inputs? Are they regular (12V) solenoids that engage particular gearsets/clutches?

This is awesome. I'm surprised that there is little excitement about it here. A Miata with a DCT was in my head for a long time and I was waiting for someone to finally engineer this out.

Can we get more details? Is there another place where you describe your project in more details?

Do you plan on creating a kit once you are done so other people can use this awesome solution?

Please give us more updates.

Nice work man, thanks for taking the time to document it.

Pretty damn slick swap here. Congrats on taking this on.

I want one with the TCU solution please.

I am also curious. As someone who owns a BMW with this transmission, it's my understanding the TCU determines clamping pressure of the clutches by the "torque request" made from the pedal to the DME.

Line pressure vs engine torque is half shift feel (shock vs response) and half durability. You don't want your luxury car slamming gears driving around a city. You also don't want slow lockup at WOT, because you will put a lot of heat into the clutches due to slippage.
It's pretty common to run bench engine dynos with automatic transmissions by actuating the solenoids with 12v power supplies. At work we literally don't even use a TCU sometimes and just have a row of power supplies we toggle to select gears. Assuming this is a race car, you can make this work with fairly crude methods. We've done it with the NSX 9DCT and a slew of 6/9/10 speed torque converter slushboxes.

I knew the first part, but thanks for the insider info on dynos and such!

Have to say, I'm very interested in this. The trans height and need to raise the engine is a concern though. Would be interested to see if any measure could be taken to minimize block relocation.
I can see one of these in Vegas running ST2 at 2350# & 300 average whp with Sonny behind the wheel on 245 A7's. Even if we got our asses kicked, I would love to build it and see it run.

Thanks for sharing Harald.

for a pure race car it might be the wrong transmission mainly because its a heavy bastard. and the ratios for most racecars would need a very tall rear end to keep the top speed down. but for a dual duty car that will see mostly street use and some trackdays i think its a great choice. low cruising RPM, quiet, and capable of handling any power a miata engine can make.

There really is no way of installing this without raising the engine Emilio. as the sump section of the gearbox actually sits a little lower than the BP sump. and that is with a gearbox sump of around 1/2" height.
you could probably make a new sump and save a few mm, but not more.

Here it is installed on the final transmission mount.

https://cimg5.ibsrv.net/gimg/www.mia...52f01b5074.jpg
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Beautiful fab work!

Very cool idea

Sorry if I missed it, but how much did you have to raise the engine?
Any change to angle of engine?

I raised the engine 17mm. a DCT had never been tried in a mx5 so we didnt know anything about how it would fit until we tried :D the angle is still spot on.

https://cimg7.ibsrv.net/gimg/www.mia...ded79fcbbf.jpg
Custom 3" driveshaft made by a friend of mine installed. Perfect fitment:)

Nice
 

Good to see you got this off the ground.

I have the dev firmware for MaxxECU and the DCT wiring harness releases soon, to use the stock mechatronics with clutch kick feature as well. Less expensive and don't have to replace the factory BMW TCU!

Side question: Did you go ahead and replace all the stock seals with the Viton seals and new screws on the pan?

The speculation is the heat from the exhaust and dissimilar materials between pan/transmission/screws + cheap seal material is why they all end up leaking at some point. Not just the pan and the mechatronics seal, the one further up on the box as well.

Decided to reuse the ppf as i dont like the available bolt on solutions for holding the diff.
https://cimg2.ibsrv.net/gimg/www.mia...32087f5ee7.jpg
Rear lower miata suspension bushing in a alu tube made to dimension.
https://cimg5.ibsrv.net/gimg/www.mia...9e41e9f3da.jpg
6mm folded alu plate for strength.
https://cimg7.ibsrv.net/gimg/www.mia...a250c7e067.jpg
Even more strength.
https://cimg9.ibsrv.net/gimg/www.mia...51d2fa092c.jpg
Looks clean. And easy to work on.

All welded up.


https://cimg9.ibsrv.net/gimg/www.mia...d46b66fc2b.jpg
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Too bad something so pretty gets stuck under the car! Really enjoying your fab work!

had to make a new downpipe and first half of the exhaust to get it past the DCT gearbox. Its a tight fit, even with the modified floorpan, but it fits.
Heat protetction will be added.
Still have to find a way to route the transmission oil cooler lines and install the thermostat.

https://cimg3.ibsrv.net/gimg/www.mia...20f8fd49bf.jpg
not much room for activities!


https://cimg4.ibsrv.net/gimg/www.mia...76c22e51a0.jpg
Made the downpipe a 2 piece design. with a short elbow on the turbo to make it possible to take it out of the car without having to pull the entire drivetrain out in one big package.
https://cimg5.ibsrv.net/gimg/www.mia...55502dbe33.jpg
https://cimg6.ibsrv.net/gimg/www.mia...67016a84df.jpg

I want your clean subframe. Please include it with the transmission and controller.

This is amazing. In for... wherever this goes.

Very elegant PPF solution.

So when can we all buy the kit?

Sadly way to much custom work for a kit to really be a viable thing. where the 6speed E46 box can be made as a bolt on, this is so far not.

It's ok, you can do it.... We all believe in you.

This is amazing. Absolutely amazing. Almost wanna do this to my car!

So you're using the factory BMW TCU with MaxxECU to flash it, is that correct?

EDIT: MaxxECU appears to be a standalone management unit and isn't a flash, I don't know what's going on.

finished the downpipe and hanger.

https://cimg6.ibsrv.net/gimg/www.mia...c8b26e81de.jpg


https://cimg7.ibsrv.net/gimg/www.mia...51cf228f6d.jpg

No sir.

Håvard here has his transmission retrofitted with new internal mechatronics to openly communicate with his standalone he is using.

The maxxECU folks have cracked the communication to the factory BMW TCM and spoofed it to work with their ECU in any application. I'll be doing one In my TTv8 Volvo.

maxxECU does not work with the M4 transmission for now, maybe at a later point is what i got from the maxxECU guys when discussing my project with them,
But its really cool that the ECU manufacturers start supporting crazy mods like DCT transmissions in older cars :D

It does
 

As of now, both m4 and 335/135 are supported, with a little more work on the m4 needed for clutch pressures. That's the last I remember on the subject. It's in beta right now anyway, the final work is perhaps due with the next version

I agree with you, this opens up so many possibilities. Very exciting.

335/135 boxes, and e92 V8 boxes use different protocols, and also different control from the shifter etc. the messages i got from maxxecu was that this would be tested next winter.

Also, the maxxecu will run the BMW TCU firmware in the gearbox, while this setup just removes it completly and runs all sensors and solenoids directly from a standalone controller.
It also gives the possibility of a "drive by wire " clutch pedal. and tunable shift times/pressures more easily.


here is a video of one of the guys already running the setup im using, in a RX8 with a honda engine.

Any chance your controller is from the "H**" guys? I'm looking at installing it on a customer's RX-8 as well and looking for feedback before purchasing.

Finished the last mechanical part. The centerpart of the clutch delete, with splines. Just some wiring left now and perhaps i can testdrive this setup soon.

https://cimg7.ibsrv.net/gimg/www.mia...cfb79034b5.jpg
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Any update on this? Is it possible to have the engine auto blip on down shifts? How would that work?

That would require DBW.