Hi everyone,

First of all, sorry (not sorry) in advance for those of you who don't like V8 swaps or "automatics". I wanted to share the project I've been working on over the last year or so.
I just finished swapping a BMW DCT from a 2015 M5 into my twin turbo LS FC. It's a 7 speed double overdrive transmission that is electronically shifted and clutched. There's no longer a 3rd pedal and the car drives pretty well on the street, but shifts super fast.
Some might not be aware that this has become a somewhat popular swap over the last year or so. To make the swap work, you need a bellhousing/flywheel adapter, the standalone transmission controller (only a couple of options currently), an ECU that can communicate with the trans controller, new driveshaft, and trans mount.

The adapter kits use a splined hub adapter that bolts over the flywheel. There are no external clutch hydraulics, it's all controlled by electronics inside the trans.

I used an HTG transmission controller. It's a standalone "GCU" that gets wired directly into the transmission and communicates with the ECU to see things like engine RPM, throttle position, etc.

The GCU takes a lot of tuning to get driving nicely. There are several maps and it's quite different than tuning an ECU.

So far, I've put over 300 miles on the car this month with the DCT and am really enjoying it. I'm only making around 500whp/500wtq at the moment on 7psi. The stock DCT clutches are usually good for up to around 650wtq in the heavier BMWs. I'm hoping I can get away with not having to spend $$$ on new upgraded clutches.

Here’s a short video of the DCT in action:

 

Good stuff...subscribed for updates! And good to see another successful DCT conversion out there. (There's a similar thread in the 3rd Gen section further detailing the items required for install.)

 

thanks for sharing!

 

This might be one of the coolest FC's I've ever seen. Recently I've been thinking about buying a F80 M3 and I've been reading and watching videos about how fast that DCT shifts....but I never could've imagined seeing one in a FC. Obviously it would be better with a rotary (had to slip it in somewhere HA) but this is an awesome build nonetheless. So tell us, what gave you the idea to embark on such a journey, and what have you learned that probably would've saved you some time/money in the event you had to do it again?

 

Thanks! Quite a compliment. I saw some videos last summer of people in Europe ripping DCT cars around a track and it just sounded so good. I had a nice T56 Magnum and twin disk prior and wasn't happy with how much the car got unsettled each shift. It made the car feel slow because the delay between 1-2 was as long as you were in first lol. The DCT is insane. No interruption in power and just instant shifts. It also has decent (and improving) street manners. I need to make a more compliant trans mount bushing. What I have now conducts a lot of noise. Prices for DCTs have gone up substantially since I started a year ago. I paid $800 for my F10 ( cheapest and least desirable DCT because it's harder to package). Now they're $1500+ and the smaller F80 trans are $3k+. I'm pretty happy with the swap so far.

 

What transmission controller are you using?

I'd love to have a DCT in an RX-7.
Hell, I'd love to have a DSG in my B2-chassis VWAG product. Which would be fitting since the first DSG was in the Audi S1 E2 rally car, which was B2 chassis based.

 

So whenever you decided to pursue this route, was there a lot of information out there or you felt like you could tackle it? I can't imagine the euro guys driving a lot of LS DCT swapped cars. And yeeeaaaa...thats how things tend to go when they're popular. Look at the prices of RX&'s in the past year lol

 

I'm using the HTG. My ECU (MaxxECU) has integrated DCT control over CAN, but it only works with the older E-series DCTs, which have a 1:1 7th gear. Not ideal for an LS. Id actually like to put even longer gears than my 3.55s, since 1st gear is a useless 4.8:1 and 7th is .67. The Magnum I had prior was .50:1 and cruised so nice. The Maxx also uses the stock BMW TCU and firmware, which is somewhat limited, but also probably easier to set up out if the box. The HTG currently requires quite. Abit of tuning, but apparently they're releasing a closed loop firmware in the near future.

 

There was one guy state side with a twin turbo LS E90 making serious power that kind of paved my way for what I bought and installed. His car is way more powerful than I'd ever go and he's had fairly good luck. A few part issues that are probably due to him not having much mass at all on the flywheel. The DCT adapter kit I have was designed to only work with a stock automatic flex plate (4lbs). I knew that wasn't going to work for me so I designed up a modified stock LS1 flywheel and had it machined to fit inside the adapter plate. It weighs 25lbs and has pretty damn good street manners. It drives better than my sprung hub twin disk T56 clutch, anyways.

 

I love this idea but the gear ratios aren't ideal for me, its a bunch of overdrives and with myself being non turbo wankel power still, its not going to fair well for acceleration so I'm still better off going with a sequential at that point.

but again this a race car though.

I do love this DCT stuff, its neat but I haven't quite found the right fit for my needs yet. looks killer for a street car with that much torque

 

The E90-era M3, 335i, 135i, and Z4 all came with a 1:1 ratio 7th gear short-ratio set. If I still had the rotary, that's what I'd go with, likely with a longer diff ratio. Considering I can make 600wtq from 3500rpm+, the wide ratio is definitely a better match lol.
I still need to do quite a bit more tuning to get the car to drive as smooth as I'd like. The GCU manufacturer offers remote tuning for 500 Euro and continued support, but since my car is parked for the winter, I'd rather wait till spring to get it tuned on whatever the most current firmware is. They're releasing beta version updates of the firmware nearly every week.

 

ahh I was looking at the m5 one when i was taking a look into it, i'll have to see what the smaller one does. that ZF gearbox is no joke and if I can drop several lbs off my clutch with this setup thats pretty big from whats been done

 

the price in the used market on these seems to have skyrocketed, hate to say it but I wish more BMW owners were totaling out their cars to help bring the DCT cost down.
.

 

The M5 box had a much larger bell housing. (largest of the DCT), but is currently the least expensive because it's the hardest to package. There are 3 different bellhousing DCTs - E90 M3 V8, Inline 6 (older 135/335/Z4 and M2/3/4), and F10 M5 V8. All the DCTs have the exact same clutch pack and internals, besides some having close ratio and wide ratio. The wide ratio M2/3/4 are the most expensive.

I'd done the math comparing the TII clutch flywheel, and trans to the DCT and I think it was +40lbs. It's nearly weight neutral compared to my T56 Magnum and super heavy flywheel and twin disk (60lb assembly!). I have a friend who is using just the flex plate as a flywheel and his car revs like a IMSA car lol.

 

A lot of the super short first gears with DCTs is so they can pull from a stop without a ton of clutch slippage. Given that shift time is not exactly a liability, it does make a lot of sense. The short gearing is not necessarily the best for acceleration since you asymptotically reach the engine's ability to freerev, although I suppose one could program in a short shift to 2nd.

DCT tuning gives me the *******, because it has to be SO calibrated with the e-throttle and engine inertia and 3d torque map in order to get those nice seamless shifts up and down that make one such a mind blowing experience to drive.

 

You could also argue that a poorly tuned DCT still drives better and shifts faster than a dog box with a 5.5" Tilton and super light flywheel lol.

 

Agreed and the lower cost of the earlier short ratio box is leading me in that direction; a super quick shift is just the flip of a paddle finger away rather than all that foot and arm commotion. F1 drivers probably get a good laugh and eye roll whenever they hear someone going on about taking the skill and talent out of driving. No, the skill and talent is just refocused towards other priorities to go even faster still. Faster is the goal.

Except for drifting maybe
.

 

I was a DCT believer when I rode in a friend's Evo X and we were hauling *** around a tight course and he ran out of 1st about 30 feet before a braking zone. Upshifted to 2nd for about a half second then downshifted back to 1st without missing a beat. I was torn between "Woah" and "I GOT to get me one of THESE"

 

That's a great way to put it. Driving a stick shift you kinda realize how staying in one gear changes how you take certain corners or when you'd stop or start accelerating. With the T56, the delays between gears upset the chassis and also kind of punctuate the pull and I'd usually end up lifitng at the end of a gear. The DCT you can basically accelerate as long as you're comfortable and it's seamless and the car stays more planted. But at the same time, if it spins and I click the next gear or two, it gains ridiculous wheel speeds nearly instantly and wants to swap ends. I can stab the throttle in 1st and just click the upshift paddle like I'm playing Street Fighter and within seconds I'll have 20mph front wheelspeeds and 120mph rear wheelspeeds lol. It's both entertaining and terrifying.

 

I like twin clutch transmissions so much, I bought one.

It came wrapped in a GTI. The car is waaay faster than the numbers suggest. Instant torque at any speed, lightning fast shifts, and healthy BLAP when you upshift under load and the computer pulls all the timing...

This is the coolest thing ever and I want to DSG all the things!

Thread relevant: Do you have any kind of damper between the engine and trans? I was reading about a BMW DCT swapped turbo S2000 and they kept having problems with the flywheel bolts backing off. Apparently a lack of give between the engine and trans was causing the harmonics to attack the weakest point between the two.

 

Congrats on the GTI. It's pretty cool how nearly uninterrupted power can make something slowish feel way faster on the street.
Like the BMW DCT and 8HP, MaxxECU can control the earlier VAG DSGs for free . DQ250 and DQ500. There are a few different places making adapters for them for retrofitting.

I've not had issues with harmonic for DCT + V8. I originally had a solid input spline hub with a heavy custom flywheel. It weighed 25#.
When I ditched the HTG DCT controller for MaxxECU, I sold my trans and adapter and bought a new one.
Domiworks (best DCT adapters out there) commonized all their DCT kits by making a 2-piece sprung hub that has one sprung, splined hub for all BMW DCT and an aluminum hub that's specific to each engine. So now I have a sprung hub.
TBH, I can't tell a difference, other than my rotating mass is less now and it revs like a race car lol.

I think a healthy majority of people breaking clutch baskets from engine vibrations are 4 cylinder cars, long stroke Honda K-series stuff being possibly the worst.
I would LOVE to do a DQ250 or DQ500 AWD DSG swap into an Evo or some kind of light hatchback. Or RWD in an MR2.