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BMW 3-Series (E90 E92) Forum > E90 / E92 / E93 3-series Powertrain and Drivetrain Discussions > N54 Turbo Engine / Drivetrain / Exhaust Modifications - 335i > DCT slipping with lots of Torque? Nope!



View Poll Results: Does your DCT slip and/or Have Problems with 400tq+ ?
I have a DCT with 400tq+ and my clutch slips (I HAVE abused my transmission) 10 17.24%
I have a DCT with 400tq+ and my clutch slips (I have NOT abused my transmission) 13 22.41%
I have a DCT with 400tq+ and NO problems with my transmission (I HAVE abused my transmission) 18 31.03%
I have a DCT with 400tq+ and NO problems with my transmission (I have NOT abused my transmission) 17 29.31%
Voters: 58. You may not vote on this poll

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      09-16-2012, 03:14 PM   #1
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DCT slipping with lots of Torque? Nope!

[Short Story]
I dyno'd conservatively at 460tq and my DCT trans is handling the power like a beast. Clutches grab strong, no slipping.


[Long Story]
Hi guys. I kept hearing rumors about DCT's and their lack of ability to hold large amounts of torque, causing slip and the like. Well, I just wanted to share an experience from the other side. I can only really find one instance of DCT slippage from "having too much torque" l, but I was still nervous non-the-less as I piled on the mods, testing out my 7spd DCT.

Just as a background and to familiarize everyone with my setup: I have a 2012 335is with the DCT transmission. I'm running BMS DCI, AR catless DP's, ETS FMIC, and a Cobb protune done by Jake@ProTuningFreaks. In my tank lies 6 gallons of e85 with 10 gallons of 93 octane.

This is a new map I'm running, and it still in the process of being smoothed out, but I took the opportunity at ///Mpact East 2012 to have my car dyno'd on the very conservative Dyno Dynamics setup they had. Unfortunately, I don't have base numbers to compare with, as I went head first into mods as soon as I picked up the car, but my car read 460tq to the wheels at ///Mpact!!

Needless to say, while doing logs and just driving my car hard for the past few days, I have had no problems with my transmission holding the power, WOT through a gear, or through shifts with sport mode on as well.

I have been running 3 gallons of 85 to my 13 gallons 93 octane for a few weeks prior to this and that wasn't causing any issues either. So far, I have to say, the DCT is working like magic and I haven't seen any problems that I keep hearing people spreading because of one (maybe two) instances of dogged cars with DCT slippage.

I'll update with my dyno graph in a bit. Again, this map is still a work in progress
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      09-16-2012, 03:31 PM   #2
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Parts wear down over time, Im not surprised that its not slipping right away, most cars that had problems were because they were constantly tracked/raced. Let us know how everything holds up!
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      09-16-2012, 03:46 PM   #3
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Quote:
Originally Posted by Beemw335 View Post
Parts wear down over time, Im not surprised that its not slipping right away, most cars that had problems were because they were constantly tracked/raced. Let us know how everything holds up!
+1 it's only a matter of time.
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      09-16-2012, 04:06 PM   #4
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just make sure when doing WOT or aggressive performance runs make sure to be in manual mode / Sport On / DTC off (not completely off)
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      09-16-2012, 05:06 PM   #5
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Interested in the long term effects on the DCT.

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      09-16-2012, 05:08 PM   #6
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Not even a new stock cluch slips on high torque. But however, I remember reading somewhere that the 335is DCT is stronger than the N55 135i DCT.
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      09-16-2012, 05:10 PM   #7
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Quote:
Originally Posted by cstavaru View Post
Not even a new stock cluch slips on high torque. But however, I remember reading somewhere that the 335is DCT is stronger than the N55 135i DCT.
If you have the link can you share?

sorry
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      09-16-2012, 05:55 PM   #8
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Quote:
Originally Posted by Kcyrusm View Post
[Short Story]
I dyno'd conservatively at 460tq and my DCT trans is handling the power like a beast. Clutches grab strong, no slipping.


[Long Story]
Hi guys. I kept hearing rumors about DCT's and their lack of ability to hold large amounts of torque, causing slip and the like. Well, I just wanted to share an experience from the other side. I can only really find one instance of DCT slippage from "having too much torque" l, but I was still nervous non-the-less as I piled on the mods, testing out my 7spd DCT.

Just as a background and to familiarize everyone with my setup: I have a 2012 335is with the DCT transmission. I'm running BMS DCI, AR catless DP's, ETS FMIC, and a Cobb protune done by Jake@ProTuningFreaks. In my tank lies 6 gallons of e85 with 10 gallons of 93 octane.

This is a new map I'm running, and it still in the process of being smoothed out, but I took the opportunity at ///Mpact East 2012 to have my car dyno'd on the very conservative Dyno Dynamics setup they had. Unfortunately, I don't have base numbers to compare with, as I went head first into mods as soon as I picked up the car, but my car read 460tq to the wheels at ///Mpact!!

Needless to say, while doing logs and just driving my car hard for the past few days, I have had no problems with my transmission holding the power, WOT through a gear, or through shifts with sport mode on as well.

I have been running 3 gallons of 85 to my 13 gallons 93 octane for a few weeks prior to this and that wasn't causing any issues either. So far, I have to say, the DCT is working like magic and I haven't seen any problems that I keep hearing people spreading because of one (maybe two) instances of dogged cars with DCT slippage.

I'll update with my dyno graph in a bit. Again, this map is still a work in progress
Hi KC! glad to hear your trans is doing well with all that torque! hopefully it will hold up!
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      09-16-2012, 07:56 PM   #9
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Quote:
Originally Posted by cstavaru View Post
Not even a new stock cluch slips on high torque. But however, I remember reading somewhere that the 335is DCT is stronger than the N55 135i DCT.
Its the same DCT, with the difference, the DCT mechatronics, which controlls clutch pressure, is programed differently. Thats why on the 135i DCT LC is set at 3k RPMs and the 335iS DCT it is set to 5K RPMS. This also applies to the N65 DCT M3.

Quote:
Originally Posted by Rioter View Post
Hey, i know you probably have more experience than anyone when it comes to racing the iS. Did you notice faster times when turning DTC off but not completely off? I always thought completely off was best?
Yes, all my low 12s ET times were done with DTC (one press) off ie in LC prep mode. I experimented with DTC completely off and it hurt my ET and had clutch slippage. When people do this they use a method of brake launching that results in the clutch slipping also.

I stay away from brake launching and trying to WOT from a dig without using LC.

There is another LC not mentioned in the Owners Manual which can be used for those special occasions at a red light

Sport On
S Mode (Not M or D Mode) {when you launch you can shift manual, dont let the DME shift for you}
DTC Completely Off

"Firmly" Hold Brake Down, Press gas peddle down pass the kick down, release the brake.....off you go with a hell of alot of wheel spin

Use it only once within a period of time, multiple use you will start to experience clutch slippage, or the DME will not allow you.
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      09-16-2012, 11:51 PM   #10
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Quote:
Originally Posted by Beemw335 View Post
Parts wear down over time, Im not surprised that its not slipping right away, most cars that had problems were because they were constantly tracked/raced. Let us know how everything holds up!
Thanks for the optimism, lol!

Quote:
Originally Posted by BuraQ
just make sure when doing WOT or aggressive performance runs make sure to be in manual mode / Sport On / DTC off (not completely off)
I have been doing exactly that, but I would have thought having sport activated would be harder on the transmission since it is shifting faster and harder, no?

Quote:
Originally Posted by BuraQ
Yes, all my low 12s ET times were done with DTC (one press) off ie in LC prep mode. I experimented with DTC completely off and it hurt my ET and had clutch slippage. When people do this they use a method of brake launching that results in the clutch slipping also.

I stay away from brake launching and trying to WOT from a dig without using LC.
Interesting. I was auto crossing at ///Mpact and my best launches were with DCT single pressed, and brake boosting. I would use left foot to hold brake and gave about half throttle and release brake before the car cut off power. I would get minimal tire spin, modulate the throttle until full grip was achieved. Launch control caused too much tire spin and I wasted too much time modulating the throttle trying to tame it.
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      09-17-2012, 06:05 AM   #11
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Hoping this holds true a year + from now
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      09-17-2012, 11:05 AM   #12
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with one hand i wish u luck that your tranny goes on forever. i know a few guys who very occasionally do WOT with fbo + meth +100 oct launches with zero trannh issues. even i do hard launches but thats very rare.
other problem area is the downshifter in kick down. that shocks the tranny + sudden torque load. try avoiding that from happening.

with other hand i suggest you start saving pennies for an upgraded driveshaft( like DSS) plus a tranny rejuvination ( level 10 or whatever its called)
looking around 6k installed + you may want to upgrade lsd sooner than later. thats another 2K
the harder you push it, the harder the car will hit your wallet
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      09-17-2012, 11:11 AM   #13
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Quote:
Originally Posted by Kcyrusm View Post
Thanks for the optimism, lol!

I have been doing exactly that, but I would have thought having sport activated would be harder on the transmission since it is shifting faster and harder, no?
No not at all...

Quote:
Originally Posted by Kcyrusm View Post
Interesting. I was auto crossing at ///Mpact and my best launches were with DCT single pressed, and brake boosting. I would use left foot to hold brake and gave about half throttle and release brake before the car cut off power. I would get minimal tire spin, modulate the throttle until full grip was achieved. Launch control caused too much tire spin and I wasted too much time modulating the throttle trying to tame it.
and more than likely you had a horrible 60'. Brake and DCT are synced with each other. So when you were holding the brake the preasure to the clutch is being half applied. If you keep doing this type of launch you will over heat the DCT which will lead to slippage > leading to excessive wear and tear.

Its seems you have been moderate at doing this though. Your throttle modulation helps with the strain on the clutches with that type of launching.
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      09-17-2012, 12:57 PM   #14
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lol this is an entertaining topic



"hey guys my 2012 DCT isn't slipping and i just recently installed all the parts and got pro-tuned"



unfortunately, in 0-2 years, you'll need a rebuild. it's not if the clutch packs will slip or not, it's when.
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      09-17-2012, 01:42 PM   #15
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Quote:
Originally Posted by BuraQ View Post
more than likely you had a horrible 60'. Brake and DCT are synced with each other. So when you were holding the brake the preasure to the clutch is being half applied. If you keep doing this type of launch you will over heat the DCT which will lead to slippage > leading to excessive wear and tear.

Its seems you have been moderate at doing this though. Your throttle modulation helps with the strain on the clutches with that type of launching.
I wish I had a way to see my 60' to say one way or the other from the event, but I don't. My impression was that they would have been very nice actually. The car was launching beautifully. I had full grip and was WOT within 10-15 feet if I was to guestimate. I see what you are saying with the over-heating though if the DCT is only applying with half pressure with that method. Sources for that fact would be greatly appreciated!

I did five launches in my autocross runs and 4 of them were with the method I described. Within the number of launches and amount of time I had between though launches, I didn't have any slipping problems, but that's not to say it won't happen later.
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      09-17-2012, 01:58 PM   #16
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Quote:
Originally Posted by BmwECY View Post
lol this is an entertaining topic



"hey guys my 2012 DCT isn't slipping and i just recently installed all the parts and got pro-tuned"



unfortunately, in 0-2 years, you'll need a rebuild. it's not if the clutch packs will slip or not, it's when.
My car has had DCI and tune since after break-in period, so I've got about 4k on my car with "more power." I haven't been running as high torque for as long, but just sharing an ACTUAL experience instead of the perpetuated repetition of "DCT's can't handle upgraded power, they will slip and get damaged eventually."

Could you please enlighten me with some examples and facts, instead of just commenting to be a dick? Of all the searching I did, I had a hard time finding info of actual cars with problems with their DCT's slipping and not able to hold their power. All except for one example of a car thrashed with LC after LC after LC at the track.

All I want to do is add actual examples to the discussion of DCT slipping instead of just he said she said, one example being mine.
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      09-17-2012, 02:46 PM   #17
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Interesting read about DCT abilities from a 700HP e92. Search Google for: M3 DCT Build Journal - World's First BMW DCT Build.

Posting links to other forums is apparently frowned upon.
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      09-17-2012, 03:42 PM   #18
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Very simple, clutch packs need replacement over time. More power/torque == earlier need of replacement.
I'm going to build a Procede/Meth/RB setup with my new '09 DCT. I have budgetted a new upgrade clutchpack for next year. This after my research for the ZF box and the harm tuning can do to a gearbox. I consider the ZF box as stronger then my new DCT box. But we will see.
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      09-17-2012, 06:07 PM   #19
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Might I be bold enough to say you do not even realize it is slipping. Because it may be very little, if you install upgraded parts your time will probably be faster
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      09-17-2012, 06:12 PM   #20
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I agree, had to do quite some research and measurements on my ZF AT to proof slippage.... between the engine, the box and the wheels... it's a slow but progressive process... day by day... at the end only physical inspection can provide evidence...
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      09-17-2012, 06:32 PM   #21
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lol... Look, I understand the whole more power = more wear. All I'm saying is, people keep saying the same thing about DCT's, but where's the evidence???? It's like a game of telephone gone mad, but with everyone saying the same damn thing. I have only found evidence of clutch slip/wear on a DCT car that has been launch controlled 10+ times in a row at a track, creating extreme amounts of heat. Only two cases I could find in existence, and both transmissions were ABUSED. Why is it so hard to believe that the DCT can hold the power and last for more than a year or two max?

I don't want to defend one way or the other, or get offended when someone says XYZ. I just want to see some evidence. There are plenty of e9x M3's with superchargers and I still couldn't find DCT slippage problems. What you are telling me is that because 2 people, who admitted to ABUSING the crap out of their transmissions signifies that ALL DCT's can't handle 400+ tq and will slip or fail. Maybe a poll is in order... asking people with DCT's to come forward and get some actual numbers in order.
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      09-17-2012, 08:07 PM   #22
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Quote:
Originally Posted by rismo View Post
Very simple, clutch packs need replacement over time. More power/torque == earlier need of replacement.
I'm going to build a Procede/Meth/RB setup with my new '09 DCT. I have budgetted a new upgrade clutchpack for next year. This after my research for the ZF box and the harm tuning can do to a gearbox. I consider the ZF box as stronger then my new DCT box. But we will see.
Make sure to get someone to reprogram the mechatronics or else even with the new upgraded clutch pack you will still get slippage cause it will think your still using the stock clutch pack for the specific car it was programmed for.

Quote:
Originally Posted by marcvtec View Post
Might I be bold enough to say you do not even realize it is slipping. Because it may be very little, if you install upgraded parts your time will probably be faster
Oh trust me, the owner will know, torque is diminished, and performance drop will be very noticeble.

Quote:
Originally Posted by BmwECY View Post


unfortunately, in 0-2 years, you'll need a rebuild. it's not if the clutch packs will slip or not, it's when.
Thats interesting, I am 14 months owning my DCT 335iS and have done over 100 launches, 35 in one 90 hot day - recorded and witnessed, and perhaps done more launches than any N54 DCT owner and still running strong.

Have I expereince slippage, yea sure, but the slippage was due to driver error and not understanding how the DCT and its safety mechanisms work
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