RIP DCT? Rebuild or Buy New

Mfan82 · 10-09-2022, 08:38 AM

Any update on replacing the transmission? How did it work out with the mechatronic and vin number recognition? Any advise or confirmation is welcome I'm having exactly the same issue.

r!der · 10-17-2022, 01:42 PM

2015 F80 M3 with 51,000 miles. Having the "same" issue.
Noise from the transmission. It's more of a rotational hum and grinding. Local shop (not dealer) that specializes with BMW and Mini took a look and said it's the DCT transmission (output side) and recommended buying a used transmission and swapping.

Can the existing control unit be programmed to work with a transmission swap?
Better yet, is there a way to rebuild the output bearings?

andrei.m4 · 10-17-2022, 03:38 PM

guys, you don t need reprogram the new gearbox, tcu is a separate part. You move the tcu on other gearbox and just readapt it at first start for basics pressures etc(this also is necesary if you replace the gearbox or oil). You can swap with mecathronic or separate.
PS: TCU is on the mecathronic in a few screws, just unscrew and take out and install it on the new donor gearbox.

andrei.m4 · 10-17-2022, 03:42 PM

Quote:

Originally Posted by Mfan82

Any update on replacing the transmission? How did it work out with the mechatronic and vin number recognition? Any advise or confirmation is welcome I'm having exactly the same issue.

Mechatronic is just a valves bank used to control the pressures for gears, clutches etc, tcu is the computer and you just swap the tcu from old gearbox to the new gearbox(doesn t matter if gearbox is new or second hand is same thing). Tcu is in the same box with mechatronic.

McIntoshMotorSports · 10-17-2022, 03:51 PM

I didn't have time to send the old trans out for a rebuild or diag so found one used with about 30K miles from a crashed CS. Grabbed the FEM for programming and it has been working great since. And yes if you're swapping in a USED transmission that is vinlocked you will need the FEM or DME to reprogram to your current setup. RK Tunes did the programming for me, Farley Eurotech of Natick did the install.

EDIT: The reason I didn't simply do a mecha transfer is because it seemed like a valve issue and not just failed gears or clutches.

Mfan82 · 05-06-2023, 04:46 PM

Hi,

I noticed exactly the same sound from my F80, but it sometimes makes the sound after the shift when accelerating around 3000rpm seconds after shifting in 3rd or 4th. If you put it in reverse same sound but not always.

I had the diff checked just to be sure and it was ok. But this can certainly be the gearbox synchro and or the clutch? When replacing dct do you also recommend replacing the clutch ? The car has 120k km.

McIntoshMotorSports · 05-06-2023, 06:54 PM

Quote:

Originally Posted by Mfan82

Hi,

I noticed exactly the same sound from my F80, but it sometimes makes the sound after the shift when accelerating around 3000rpm seconds after shifting in 3rd or 4th. If you put it in reverse same sound but not always.

I had the diff checked just to be sure and it was ok. But this can certainly be the gearbox synchro and or the clutch? When replacing dct do you also recommend replacing the clutch ? The car has 120k km.

I’m not sure it’s a clutch pack issue, but might be in your case. The noise was always consistent on the original trans; auto 3-4 and manual 2-3 it made the same noise. Ended up finding a broken shift rod once eventually it was opened up but clutches themselves looked great so not sure what specifically caused the failure.

Mfan82 · 10-13-2023, 06:26 PM

Hi,

Transmission replaced, broken shift rod.
Clutch was great but after clutch relearn procedure now very rough shifting occurs and rolling in first gear. Seems like a clutch adaptation issue, any recommendations?

Mfan82 · 10-14-2023, 10:38 AM

andrei.m4 McIntoshMotorSports

Do you know if the clutch relearning needs to be done once or it is recommended to do it again after testing or codes need to be deleted? We Used the standard clutch relearning program (pressure/torque etc) step by step.
It seems rev match is not done and it shifts rough even in d1. Sometimes hesitation on traction and power so I assume this is also torque curve learning related.
Original computer is transferred and clutch from the new gearbox is used.

Gearbox seems fine the sound is gone.
Clutch was like new when checked.

undermine · 12-24-2023, 08:35 PM

Funny those photos are of one of my dct. Check your oil levels with the car jacked in the air or on a lift. You want to use ista for oil balancing you basically rev the engine at about 2k for a minute to bleed out air. You fill it until fuild is streaming out and cap in between temps 30-40 again with it streaming. You press the brake when done with the procedure, it then saves the measurements of the oil level in the trans, run the valve adaptations basically neutral 2500 rpm exactly, just follow the steps hardest part is holding it at 2500, try not to go beyond 2500 when doing this. Gear box adaptations and if you have a good working trans you should be fine after these steps. This is all stuff the dealer can do for you just try to find someone honest.

Quote:

Originally Posted by Mfan82

andrei.m4 McIntoshMotorSports

Do you know if the clutch relearning needs to be done once or it is recommended to do it again after testing or codes need to be deleted? We Used the standard clutch relearning program (pressure/torque etc) step by step.
It seems rev match is not done and it shifts rough even in d1. Sometimes hesitation on traction and power so I assume this is also torque curve learning related.
Original computer is transferred and clutch from the new gearbox is used.

Gearbox seems fine the sound is gone.
Clutch was like new when checked.

10-09-2022, 08:38 AM	#45
Mfan82 New Member 0 Rep 5 Posts Drives: BMW M3 F80 Join Date: Oct 2022 Location: Belgium iTrader: (0)	Any update on replacing the transmission? How did it work out with the mechatronic and vin number recognition? Any advise or confirmation is welcome I'm having exactly the same issue.
	Appreciate 0 Quote

10-17-2022, 01:42 PM	#46
r!der Private First Class 12 Rep 102 Posts Drives: 07 BMW 335i Join Date: Apr 2009 Location: SoCal iTrader: (1)	2015 F80 M3 with 51,000 miles. Having the "same" issue. Noise from the transmission. It's more of a rotational hum and grinding. Local shop (not dealer) that specializes with BMW and Mini took a look and said it's the DCT transmission (output side) and recommended buying a used transmission and swapping. Can the existing control unit be programmed to work with a transmission swap? Better yet, is there a way to rebuild the output bearings?
	Appreciate 0 Quote

10-17-2022, 03:38 PM	#47
andrei.m4 Second Lieutenant 113 Rep 291 Posts Drives: bmw f82 Join Date: Mar 2019 Location: Romania iTrader: (0)	guys, you don t need reprogram the new gearbox, tcu is a separate part. You move the tcu on other gearbox and just readapt it at first start for basics pressures etc(this also is necesary if you replace the gearbox or oil). You can swap with mecathronic or separate. PS: TCU is on the mecathronic in a few screws, just unscrew and take out and install it on the new donor gearbox.
	Appreciate 1 Mfan820.00 Quote

10-17-2022, 03:51 PM	#49
McIntoshMotorSports Second Lieutenant 187 Rep 240 Posts Drives: F80M3 Join Date: Feb 2021 Location: LV, PA iTrader: (0) Garage List 2016 BMW F80 M3 [10.00]	I didn't have time to send the old trans out for a rebuild or diag so found one used with about 30K miles from a crashed CS. Grabbed the FEM for programming and it has been working great since. And yes if you're swapping in a USED transmission that is vinlocked you will need the FEM or DME to reprogram to your current setup. RK Tunes did the programming for me, Farley Eurotech of Natick did the install. EDIT: The reason I didn't simply do a mecha transfer is because it seemed like a valve issue and not just failed gears or clutches.
	Appreciate 2 TopJimmy5461.50 Mfan820.00 Quote

05-06-2023, 04:46 PM	#50
Mfan82 New Member 0 Rep 5 Posts Drives: BMW M3 F80 Join Date: Oct 2022 Location: Belgium iTrader: (0)	Hi, I noticed exactly the same sound from my F80, but it sometimes makes the sound after the shift when accelerating around 3000rpm seconds after shifting in 3rd or 4th. If you put it in reverse same sound but not always. I had the diff checked just to be sure and it was ok. But this can certainly be the gearbox synchro and or the clutch? When replacing dct do you also recommend replacing the clutch ? The car has 120k km.
	Appreciate 0 Quote

10-13-2023, 06:26 PM	#52
Mfan82 New Member 0 Rep 5 Posts Drives: BMW M3 F80 Join Date: Oct 2022 Location: Belgium iTrader: (0)	Hi, Transmission replaced, broken shift rod. Clutch was great but after clutch relearn procedure now very rough shifting occurs and rolling in first gear. Seems like a clutch adaptation issue, any recommendations?
	Appreciate 0 Quote

10-14-2023, 10:38 AM	#53
Mfan82 New Member 0 Rep 5 Posts Drives: BMW M3 F80 Join Date: Oct 2022 Location: Belgium iTrader: (0)	andrei.m4 McIntoshMotorSports Do you know if the clutch relearning needs to be done once or it is recommended to do it again after testing or codes need to be deleted? We Used the standard clutch relearning program (pressure/torque etc) step by step. It seems rev match is not done and it shifts rough even in d1. Sometimes hesitation on traction and power so I assume this is also torque curve learning related. Original computer is transferred and clutch from the new gearbox is used. Gearbox seems fine the sound is gone. Clutch was like new when checked.
	Appreciate 0 Quote