M-DCT Troubleshooting

NYG · 07-09-2020, 09:26 AM

Has anyone experienced anything similar? This has happened to me twice and it was on a VERY HOT day but on an upshift, the car would not go into gear and would just rev as if the clutch was either slipping or not making contact.

SYT_Shadow · 07-09-2020, 10:48 AM

Odd, hasn't happened to me. You could try overfilling the DCT using the GTS fill method.

NYG · 07-09-2020, 11:46 AM

Quote:

Originally Posted by SYT_Shadow

Odd, hasn't happened to me. You could try overfilling the DCT using the GTS fill method.

Any more info?

F80Speed77 · 07-09-2020, 12:01 PM

Was this on track or on the street?

NYG · 07-09-2020, 12:09 PM

Quote:

Originally Posted by F80Speed77

Was this on track or on the street?

Track

SYT_Shadow · 07-09-2020, 12:28 PM

Quote:

Originally Posted by NYG

Any more info?

You follow the dct fill procedure but instead of having the car level you jack up the passenger side. You can get an extra quart in like that

Haven't had any issues with the dct in the cs just yet. On the E90 dct i have the slonik dct pan which allows for less fluid starvation and overheating, but generally the f8x ones are more robust

NYG · 07-09-2020, 01:01 PM

Quote:

Originally Posted by SYT_Shadow

You follow the dct fill procedure but instead of having the car level you jack up the passenger side. You can get an extra quart in like that

Haven't had any issues with the dct in the cs just yet. On the E90 dct i have the slonik dct pan which allows for less fluid starvation and overheating, but generally the f8x ones are more robust

I was blown away by how much fluid this thing takes. Insane.... I'm surprised it starves too with the dry sump.

M2C AW · 07-09-2020, 01:15 PM

Quote:

Originally Posted by SYT_Shadow

You follow the dct fill procedure but instead of having the car level you jack up the passenger side. You can get an extra quart in like that

Curious...is that a proper / factory procedure for the GTS....written up somewhere...or just a good practice ?

I happen to do this Overfill for the DCT (and also for the differential btw), But only because that’s what I usually do on any car that will see some track use.

M2C AW · 07-09-2020, 01:26 PM

Quote:

Originally Posted by NYG

I was blown away by how much fluid this thing takes. Insane.... I'm surprised it starves too with the dry sump.

Sounds like overheating. Did you happen to check transmission temps ? Have you altered the Transmission coding ?

NYG · 07-09-2020, 01:36 PM

Quote:

Originally Posted by M2C AW

Sounds like overheating. Did you happen to check transmission temps ? Have you altered the Transmission coding ?

No tuning whatsoever and I didn't get any trans heat warnings.

SYT_Shadow · 07-09-2020, 01:46 PM

Quote:

Originally Posted by M2C AW

Curious...is that a proper / factory procedure for the GTS....written up somewhere...or just a good practice ?

I happen to do this Overfill for the DCT (and also for the differential btw), But only because that’s what I usually do on any car that will see some track use.

The GTS has a special banjo fitting that allows you to overfill. Leaning the car over is the poor man's version

nicknaz · 07-09-2020, 07:46 PM

On my e89 z435 I overheated it at Buttonwillow willow (after like 5 laps on a hot super hot day

) and it has similar behavior of not obeying the flappy paddles and just revving without much forward motion.

Is your car modded with power adders?

fanatic1 · 07-09-2020, 08:29 PM

hope you got this sorted out and didn’t shorten your track day too much

kvm-driver · 07-09-2020, 09:10 PM

Happened to me several times over the years, I disregarded it assuming it was a part of the m-dct's personality. Interested if anyone can expand on whats going on the technichal side. Can it have something to do with the crank-hub ?

NYG · 07-10-2020, 07:41 AM

Quote:

Originally Posted by nicknaz

On my e89 z435 I overheated it at Buttonwillow willow (after like 5 laps on a hot super hot day

) and it has similar behavior of not obeying the flappy paddles and just revving without much forward motion.

Is your car modded with power adders?

No mods outside of suspension/pads/calipers/rotors/camber plates.

Quote:

Originally Posted by fanatic1

hope you got this sorted out and didn’t shorten your track day too much

It would happen in the middle of a session, then I'd get it into gear and it would stop doing that for a bit.

NYG · 07-10-2020, 07:48 AM

Quote:

Originally Posted by kvm-driver

Happened to me several times over the years, I disregarded it assuming it was a part of the m-dct's personality. Interested if anyone can expand on whats going on the technichal side. Can it have something to do with the crank-hub ?

No, opposite side. I can't say exactly what's happening on the technical side because I'm not sure as to why it happened but essentially the second clutch doesn't "connect" with the flywheel. I don't know if it's related to the spring/pressure plate/etc.

CanAutM3 · 07-11-2020, 06:19 AM

Quote:

Originally Posted by NYG

No, opposite side. I can't say exactly what's happening on the technical side because I'm not sure as to why it happened but essentially the second clutch doesn't "connect" with the flywheel. I don't know if it's related to the spring/pressure plate/etc.

DCT clutches operates opposite to normal MT clutch, where in DCT springs keep the clutch open while hydraulic pressure clamps it closed.

Have you fixed your shifting technique? I saw in your track videos that you wait until acceleration at track out to downshift instead of downshifting during braking before corner entry. The resulting clutch slip could be putting more heat in the gearbox...

NYG · 07-13-2020, 08:25 AM

Quote:

Originally Posted by CanAutM3

DCT clutches operates opposite to normal MT clutch, where in DCT springs keep the clutch open while hydraulic pressure clamps it closed.

Have you fixed your shifting technique? I saw in your track videos that you wait until acceleration at track out to downshift instead of downshifting during braking before corner entry. The resulting clutch slip could be putting more heat in the gearbox...

So far so good. Ran LRP on Saturday in ridiculously hot temperatures and went 100% on all laps. No issues.

fanatic1 · 04-04-2021, 10:54 AM

Resurrecting this

This has been happening at an increasing frequency and dealer found nothing, fluid level good. Also noticed the engine oil temp slightly above 250°F when this starts happening.

Stock tune and ambient above 75° F is when it seems to start the issues.

BW suggested redline DCT fluid, fixed the issue in their GT4s. Others have suggested larger cooling radiators.

Just confused why this would start happening now when the weather isn’t even hot yet.

07-09-2020, 09:26 AM	#1
NYG Brigadier General 10743 Rep 3,690 Posts Drives: Audi R8 Join Date: Feb 2017 Location: Brooklyn, NY iTrader: (0)	M-DCT Troubleshooting - Not going into gear after shift Has anyone experienced anything similar? This has happened to me twice and it was on a VERY HOT day but on an upshift, the car would not go into gear and would just rev as if the clutch was either slipping or not making contact.
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07-09-2020, 10:48 AM	#2
SYT_Shadow ///M Powered for Life 11490 Rep 10,329 Posts Drives: E90M/E92M/M4GTS/M4GT4/X5M Join Date: Sep 2010 Location: Greenwich, CT iTrader: (2)	Odd, hasn't happened to me. You could try overfilling the DCT using the GTS fill method. __________________ DIY: S65 Rod Bearings E9X PFC Z54 BBK on F8X BK harness bar + seats: fit 6 tires in an M3 do88 Cooling Goodies GTS Twins: GTMore project
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07-09-2020, 12:01 PM	#4
F80Speed77 Grid.Life 325 Rep 383 Posts Drives: BMW M3 Join Date: Aug 2019 Location: Pittsburgh iTrader: (0)	Was this on track or on the street?
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07-09-2020, 07:46 PM	#12
nicknaz Lieutenant General 3187 Rep 10,509 Posts Drives: C6Z Join Date: May 2008 Location: NorCal iTrader: (0)	On my e89 z435 I overheated it at Buttonwillow willow (after like 5 laps on a hot super hot day ) and it has similar behavior of not obeying the flappy paddles and just revving without much forward motion. Is your car modded with power adders?
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07-09-2020, 08:29 PM	#13
fanatic1 Captain 1019 Rep 859 Posts Drives: 2019 M4 CS Join Date: Sep 2010 Location: Encinitas/San Diego iTrader: (1) Garage List 2019 M4CS [0.00]	hope you got this sorted out and didn’t shorten your track day too much
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07-09-2020, 09:10 PM	#14
kvm-driver New Member 10 Rep 17 Posts Drives: 2017 f80 m3 zcp Join Date: Jan 2016 Location: Marina Del Rey iTrader: (0)	Happened to me several times over the years, I disregarded it assuming it was a part of the m-dct's personality. Interested if anyone can expand on whats going on the technichal side. Can it have something to do with the crank-hub ? __________________ [B]17 F80 M3 Comp Silverstone Metallic \| öhlins r/t \| mpe \| vrsf downpipes \| 473 to wheels
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04-04-2021, 10:54 AM	#19
fanatic1 Captain 1019 Rep 859 Posts Drives: 2019 M4 CS Join Date: Sep 2010 Location: Encinitas/San Diego iTrader: (1) Garage List 2019 M4CS [0.00]	Resurrecting this This has been happening at an increasing frequency and dealer found nothing, fluid level good. Also noticed the engine oil temp slightly above 250°F when this starts happening. Stock tune and ambient above 75° F is when it seems to start the issues. BW suggested redline DCT fluid, fixed the issue in their GT4s. Others have suggested larger cooling radiators. Just confused why this would start happening now when the weather isn’t even hot yet.
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