Might sound like a strange as people would rightly say its a waste of time, but has anyone heard of or attempted to fit an E92 DCT box to the M156 engine.

This has become quite popular in the jap scene and people converting BMWs from SMG to DCT but I do believe it would be a worthwhile conversion on the C63.

Thanks!

 

 

Why would you want to downgrade?

 

If you’ve got 20+ grand lying around to blow experimenting, sure, give it a shot. Don’t see the point really when you can just get a Weistec Bulletproof or Southern Hot Rod Viking trans for a fraction of that which should perform just as well.

Freefall put a Holinger 6 speed sequential in a few years back, and that’s about the only trans performance upgrade that makes sense over the above.

 

if you have that much money to spend on things, i'd recommend you just custom fit a automated sequential race gear box and standalone ecu for your engine.

also...no it won't work. both use completely different communications standards.

 

we can use a gearbox from an sls or gt. Probably take around 40-50k parts and labor to make it happen.

 

Isn't the MCT in 2012+ basically the same? Pardon my ignorance if not.

 

DCT or dual clutch transmission allows for lightning fast gear changes. the DCT does this by have one clutch on opposing gears and when an upshift or downshift is called the clutch of those gears actuate enabling those gears. the problem though, due to this design, DCT transmissions have lower torque handling limits when compared to standard automatic transmissions. their gears and clutches are smaller due to packaging requirements and restraints.

the MCT utilizes a multi plate clutch in place of the torque converter to aid in shift speed while still utilizing a standard transmission with larger gears and larger clutch packs.

but the real question is...with BMW moving to a standard torque converter transmission with their latest vehicles for drivability and torque handling...why would you even bother.

 

totally different. Mct is just a clutch pack in place of a torque converter, still normal automatic transmission. Dual clutch is basically 2 manual transmissions / 2 clutch assemblies doing alternating gears. makes any automatic seem horrendously slow. Not really sure on the handles less torque thing, i suppose the hollow input shaft would be the weak link, but there's only 2 clutch packs to smoke vs 3-4 clutch and brake packs of an automatic since dct uses regular hard gears / cogs like a manual transmission. I haven't heard of any dct failures nor have i seen any. Automatics.... mct, converter... etc... plenty. But also wayyyyyyyyyyyy more of those on the road in Mercedes form that is.

 

The PFL 7G is horrendously slow compared to a double clutch, hence the want to change. Its actually slower than other autos I own.

Its the speed of the change I want, i.e when I pull the paddle I want to reduce the latency in which it responds.

There are many reasons why they're going back to conventional autos but thats not what I'm interested in. My main issue is latency between pulling the paddle and it responding.

 

It's not all joy and happiness in the land of DCT.

Take a number of features of a transmission and create a checksum.
Then you will see that it remains unchanged.
Whereas some features that you think that you are interested in, are greatly improved, some other ones are greatly downgraded.

Here's how a winter morning starts for me in my DCT GLA45 (confirmed as normal by other forum members):
Start up let it stay for 30 seconds, go to back out of driveway, put in reverse:
Accepts and confirms reverse in a second or two, turns the camera on right away.
Doesn't start to move in reverse.
Another second goes, starts to inch. Accelerator has no effect, even floored.
Reverse to drive, accepts drive quickly accelerator has little effect. Start to floor it, then pump it, 2 seconds later slams forward.

Get in line to cross busy street to pick up cup of coffee
My turn comes, I floor it starts to move right away, slowly with little accelerator effect.
By the middle of me crossing the road, when I start to pump the accelerator (in about 10 ft), slams me forward.
Once in the parking lot, as I switch drive-reverse it slams a half second after you floor it.
Once I leave, there's a lag in acceleration and by the third traffic light, comes into its own.

Even in warm weather, the first merger into traffic, with cold transmission, figure you're driving a Trabant for the time being. Most GLA45 forum members had close calls and angry horn beeps.

Mine is a fairly improved one. While I drive in manual, it guesses fairly well what to do with the next shift and doesn't disappoint.

Except:
Turbo cars can be low compression. Especially the GLA45.
Low compression cars start easily but have very little engine brake.
If you're wanting to slow down because a turn is coming, a single manual downshift (with blip), doesn't cut it.
3 are needed and by the second one the DCT goes:
Huh? What? Really?, and by the time you would speak these 3 exclamations, you get your second downshift and then third right away.

Once I cued 4 downshifts, because I was not sure if that damn computer is actually going to actively negate my command and tell me to go f myself.

Then it kinda did so, because it waited almost 2 seconds and then threw all 3 additional downshifts at me.
It's hard to know if one of my downshift commands is going to be ignored and cancelled, or just postponed.
It's like it tells me, you don't need that.

In automatic mode, it can be a lot worse, especially in comfort mode.
In comfort mode with full traction control, it acts like a turbo car of the 80s:
You floor it, nothing ... nothing.. slams you forward.
However, if you let the gearbox do what it wants and only accelerate smoothly, it feels like it surfs a wave of torque, probably lines up the boost and valve and spark advance just so..
Really feels like a V8.

I like the sport plus with traction control almost removed. You get to bundle these using the individual setting.
Then acts like I would expect, but sometimes builds the RPM too much.

And yes, the shifts are snappy, quick and flawless.

 

It would be easier to use the double clutch out of an amg gts. And that car does not have the issues stated above with the 45.

 

Well, the GT S is a transaxle with a torque tube.

Adapting these to a C63 may have its challenges.

Of course, the DCT in the GLA45 is a AWD, transversal-mounted, a whole other different set.

With this said, and on the subject of "DCT is limited, torque-wise",
I took a look in Xentry at the list of settings of the DCT (can't change any, as expected).

There was one called
Front torque limit
The value was 1200, no measurement unit.
Rear torque limit
1200, no measurement unit.
Even if these were Newton Meters, that still means over 800 ftlb, per each of the front and rear, for a grand total of 1600 ftlb that this can distribute.

 

If I was going to this efford, I would just drop a ZF8 in. Honestly my favourite gearbox. TC for comfort and you can't even notice the gear changes, and then lightning fast almost DCT like when you want it to. Tuneable with XHP as well.

 

If I was going to attempt a transmission transplant, I'd opt for a manual and a third pedal... something along the lines of a TR6060 / T56 Magnum. IMHO that would be the only option worth exploring and a real upgrade to the MCT.