How Reliable are M DCT Transmissions?

[gr8000]

Originally Posted by SenorFunkyPants

The DCT has an odd pan leak which is easily and cheaply repaired and the software has been solid since a 2010 update.

MTs suffer badly from 2nd synco wear which has already led to numerous replacements similarly clutch wear and broken flywheels.

DCT failures reported in M3post over the last 6 years have been extremely rare (looks like you have only been here a few months), clutch packs equally stand up to a lot of beating.

Fully agree.

Mine is a Jun '08 delivery; no reliability issues whatsoever.

[s85e90]

Originally Posted by SenorFunkyPants

The DCT has an odd pan leak which is easily and cheaply repaired and the software has been solid since a 2010 update.

MTs suffer badly from 2nd synco wear which has already led to numerous replacements similarly clutch wear and broken flywheels.

DCT failures reported in M3post over the last 6 years have been extremely rare (looks like you have only been here a few months), clutch packs equally stand up to a lot of beating.

bad, misleading post/info to any prospective buyer. Yes DCT has proven to be very reliable, but in no way could it ever be as reliable as the simpler manual.

[Craigy]

I shyed away from anything BMW but my internet and word of mouth researching allowed me the peace of mind to purchase a DCT e92 M.

There are very few posts of people who have had transmission failures. There are more people throwing around the $13k replacement cost figure than there are actual failures. The failures that occurred seem to be either due to abuse (heavily modified) or factory defect (replaced within ~10k from delivery under warranty).

Either way, getrag has made some of the best, most reliable transmissions for decades and they make an excellent (the best?) dual clutch box in our cars and I wouldn't have my M3 without it.

[Craigy]

Originally Posted by s85e90

bad, misleading post/info to any prospective buyer. Yes DCT has proven to be very reliable, but in no way could it ever be as reliable as the simpler manual.

Depends on your definition of reliable. Which will withstand more use/abuse and continue to function? Which requires less care and perfection and not be subject to driver error?

DCT appears to have fewer/no true wear parts compared to a manual transmission. No clutches, synchros, etc. that will wear out (theoretically they will wear out, but long after the car is worn out). Because the transmission completes the shift for you, it's a consistent shift everytime and less/no chance for premature wear like a third pedal. Someone who dumps the clutch, rides the clutch pedal, or simply isn't very good at a stickshift will wear out a 6spd faster than they would a DCT.

I know it's a technicality, but the proverbial moneyshift is a quite literal way that a DCT is more reliable than a manual. DCT won't let you complete the downshift. A manual will.

[s85e90]

Originally Posted by Craigy

Depends on your definition of reliable. Which will withstand more use/abuse and continue to function? Which requires less care and perfection and not be subject to driver error?

DCT appears to have fewer/no true wear parts compared to a manual transmission. No clutches, synchros, etc. that will wear out (theoretically they will wear out, but long after the car is worn out). Because the transmission completes the shift for you, it's a consistent shift everytime and less/no chance for premature wear like a third pedal. Someone who dumps the clutch, rides the clutch pedal, or simply isn't very good at a stickshift will wear out a 6spd faster than they would a DCT.

I know it's a technicality, but the proverbial moneyshift is a quite literal way that a DCT is more reliable than a manual. DCT won't let you complete the downshift. A manual will.

mechanically speaking one has more parts and computers working it. My gear shift works via levers, yours works via electronics.

[SenorFunkyPants]

Originally Posted by s85e90

bad, misleading post/info to any prospective buyer. Yes DCT has proven to be very reliable, but in no way could it ever be as reliable as the simpler manual.

I've been here since 2009 - in that time there have been numerous cases of MTs being swopped out but very few DCTs. Then there are all the "MT grind" threads with hundreds of posts bemoaning the weak second gear synco ring.
Given that the number of DCT cars far exceed the number of manuals all point to the DCT being significantly more reliable. The MT may be simpler but its still more likely to break.

[Helmsman]

Originally Posted by s85e90

bad, misleading post/info to any prospective buyer. Yes DCT has proven to be very reliable, but in no way could it ever be as reliable as the simpler manual.

[iuhutch]

2013 N55 135i DCT - FBO and stg1 turbo upgrade. DCT slipping. Talked with Dinan regarding their stage4 flash and Alex @ Alpina regarding anything he can do. The non-M DCT doesnt handle >450tq well at all. Now I cannot even run more than 15psi if WOT shifting through gear above 3rd @ 6500rpms...

[m3ray]

Originally Posted by iuhutch

2013 N55 135i DCT - FBO and stg1 turbo upgrade. DCT slipping. Talked with Dinan regarding their stage4 flash and Alex @ Alpina regarding anything he can do. The non-M DCT doesnt handle >450tq well at all. Now I cannot even run more than 15psi if WOT shifting through gear above 3rd @ 6500rpms...

Certain DCT owners don't seem to want to acknowledged this, but good that there is some validation from a first hand owner.

Seveal DCT owners with SC's stated it did not slip and a stock DCT could handle all the torque you could throw at it, but we know better don't we

http://www.m3post.com/forums/showthr...+power&page=20

[iuhutch]

Originally Posted by m3ray

Certain DCT owners seem to not want to acknowledged this, but good that there is some validation from a first hand owner.

Several DCT owners with SC's stated it did not slip and a stock DCT could handle all the torque you could throw at it, but we know better don't we

100% validated. Here is even a log of my slippage!

Seems that any 2012+ N55 with DCT without a DME flash slips. Piggybacks are great for power on a new vehicle but I know now the cons of this type of tune. the DME itself still reads 4-5psi when I'm running 16-19psi and the clutch packs are definitely not happy!

[Sinful]

DCT is reliable enough
MT is reliable enough

[Tracyis300]

i talked to a BMW technician that has been working on them for 17yrs, and he has never had a M3 DCT come in from having problems or having to be replaced.
I do know that there are some owners on forums that had some issues, and got it replaced. But the majority of them where still in the break-in period or a half year in. So pretty much "things go wrong" and "not everything is going to be perfect" but from what i have seen and heard? I would say the DCT is strongly reliable.

[Denk]

I want my, I want my DCT. No prob's with DCT or 6mt, personally I prefer DCT with the S65, sublime she is.

[SenorFunkyPants]

Originally Posted by iuhutch

2013 N55 135i DCT - FBO and stg1 turbo upgrade. DCT slipping. Talked with Dinan regarding their stage4 flash and Alex @ Alpina regarding anything he can do. The non-M DCT doesnt handle >450tq well at all. Now I cannot even run more than 15psi if WOT shifting through gear above 3rd @ 6500rpms...

Interesting but not really relevant to M3 DCT (given this is an M3 sub forum).
Clutch slip is a non issue for stock M3 DCTs.

[m3ray]

Originally Posted by SenorFunkyPants

Interesting but not really relevant to M3 DCT (given this is an M3 sub forum).
Clutch slip is a non issue for stock M3 DCTs.

How can it be a non-issue when it’s the same DCT transmission all around Your statement makes no sense.

If you throw enough torque at a DCT, it will slip, period. Just so happens that its the tuned turbo engines which make that much torque.

[tdott]

Originally Posted by m3ray

How can it be a non-issue when it’s the same DCT transmission all around Your statement makes no sense.

What does a modded FBO N54T making 50% more torque than stock have to do with the reliability to stock M3 DCTs?

The discussion was never about how much torque it can hold without slipping.

[m3ray]

Originally Posted by tdott

What does a modded FBO N54T making 50% more torque than stock have to do with the reliability to stock M3 DCTs?

The discussion was never about how much torque it can hold without slipping.

The initial discussion wasn't but the last few posts have been. Go back and re-read them. Slippage on a stock DCT for either s65, n55, or n54 is a non-issue. When you tune the torque up, it is.

[tdott]

Originally Posted by m3ray

Go back and re-read them.

When you tune the torque up, it is.

Yea, it was settled a while back. No one brought it up again since iuhutch and his FBO 335is did.

Originally Posted by dmppdx

Since the OP was not saying he was gong to subject them to more that stock torque, your conclusion is irrelevent since there are many other factors that will make a transmission fail not related to just how much torque is applied to it.

[phrozen06]

[da jemster]

Wow...I'm not even half of that.

[JB135MDCT]

Originally Posted by modkrazy

There's a guy with a new manual F80 that won't shift into reverse. Both transmissions have their gremlins, overall the DCT would be rated as extremely reliable, being far far less commonly reported than even bearing failures. The manual would be much easier to repair, certainly, but there is already data and guides out there for DCT repair/replacement. They actually aren't that complex inside.

I must be search stupid . Where can I find these repair guides?

[maloo]

Has anyone attempted to rebuild a failed DCT vs. replace?