How problematic is VW's 7 speed DSG?

[Fels]

  On 12/29/2016 at 9:44 AM, Yuan said:

I am always quoted and cited in these VW or mechatronic failure discussion threads.

Haha... This proves that you are a successful example.

[Detach8]

  On 12/29/2016 at 5:48 AM, Fels said:

The mechatronic is a complex unit of precisely manufactured parts. It is a combinition of electronically managed, mechanically executed and hydraulically resultant unit to operate the engagement of the release bearing to push/relief the disphragm spring to press on or relief the clutch disc to the pressure plate which is connected to the in this case... The correct input shaft either hollow or solid. And to engage/disengage the correct synchronizer to the intended input shaft, including parking gear lock etc. The mechatronic transfers the oil into the different oil routes to ensure the pressurisation of the intended route to actuate the right solenoid to achieve this. As such, the complicated and diversed component comes from a hugely divided source. So no one knows for sure exactly where and who made what part unless you have the PPAP documents and the allocated incoming inspection list batch identifiable one by one. What I think is that part of the APQP had been compromised leading to the failures. However, unless we get to see the 8D/CAR documentations involved, no one can tell for sure what rectifications were carried out and if the evaluation worked. I attended a symposium in Germany that showcased many products including this LuK clutch. My opinion is that the clutch itself is nothing wrong. It's a further evolution of the existing matured diaphragm spring actuated dry clutch assembly to fit a dual input shaft transmission. Chances for such a simple principle to go wrong is slim.

 

The failures have been known to involve mostly the mechatronics and replacement of that helped to re-mobilise the car. This is known in the market.

 

But the unanswered questions that involve this problem is overwhelming. We don't know how or what we can do to not get ourselves stranded. Thus the best idea is to shun this gearbox.

 

So in this context it has nothing to do with whether the clutch is dry or not. Like you said the clutch itself is not the problem. To summarise what you said, mechatronics is the actuator for the clutch and the gear. Hence I draw from your lengthy writeup that the conclusion is that LuK makes unreliable mechatronics, and Borg Warner, VW, and even Porsche's PDK are all OK. Is that what you are saying? How about adding transmission oil coolers like what people do with ATF for track applications.

  On 12/29/2016 at 8:42 AM, Fels said:

There's also the issue of heat dissipation. The oil in the wet serves 3 primary functions. Centrifugal force stabilization, actuation and cooling. The dry however seems rather ambiguous on the cooling part. One of the participants during the symposium in Germany asked the presenter about this and the reply was mind boggling. In summary, Unlike the wet counterpart that has much more oil to help cool the transmission, the dry version has much lesser. This in turn accumulates more heat leading to more wear and tear in the system. The oil becomes more easily contaminated with worn particles. So I advised one of of bros to shorten his oil change frequency to 30k. It helped to postpone the inevitable failure to 70k. He's still surviving but looking to change his car. The worries of getting stranded is no joke. I'm not in the gearbox industry but i don't think we need to be there to have the same questions.

 

So, still the same old opinion... too many unanswered questions. Better don't take the risk.

 

At the end of the day, it is maintenance. Oil change in transmission is often ignored... as with ZF's "lifetime fill" oil, it is still recommended to do an oil change every 50K or so. I am curious how many 7DSGs have not had their oil from factory changed.

 

As for heat, it really depends on how the transmission was driven. Drivers with some knowledge and knowing not to slip the clutch (e.g. hold gear 1 longer in some situations) should be able to reduce the tendency for heat to build up.

Edited December 30, 2016 by Detach8

[Fels]

  On 12/30/2016 at 1:56 AM, Detach8 said:

So in this context it has nothing to do with whether the clutch is dry or not. Like you said the clutch itself is not the problem. To summarise what you said, mechatronics is the actuator for the clutch and the gear. Hence I draw from your lengthy writeup that the conclusion is that LuK makes unreliable mechatronics, and Borg Warner, VW, and even Porsche's PDK are all OK. Is that what you are saying? How about adding transmission oil coolers like what people do with ATF for track applications.

 

At the end of the day, it is maintenance. Oil change in transmission is often ignored... as with ZF's "lifetime fill" oil, it is still recommended to do an oil change every 50K or so. I am curious how many 7DSGs have not had their oil from factory changed.

 

As for heat, it really depends on how the transmission was driven. Drivers with some knowledge and knowing not to slip the clutch (e.g. hold gear 1 longer in some situations) should be able to reduce the tendency for heat to build up.

 

 I don't know how did you get that conclusion.

LuK made the clutch. I didn't say LuK make mechatronics.

The reliability of the mechatronics is a subjective issue. But given the high breakdown rate and questions unanswered on how to avoid that, it is best to shun the dsg7 dry.

The mechatronics managed shifting governs the transmission actuation. You cannot slip the clutch deliberately on your car if you run on a dsg 6 or dsg7. They are all managed by the programming.

[Detach8]

  On 12/30/2016 at 4:54 AM, Fels said:

 I don't know how did you get that conclusion.

LuK made the clutch. I didn't say LuK make mechatronics.

The reliability of the mechatronics is a subjective issue. But given the high breakdown rate and questions unanswered on how to avoid that, it is best to shun the dsg7 dry.

The mechatronics managed shifting governs the transmission actuation. You cannot slip the clutch deliberately on your car if you run on a dsg 6 or dsg7. They are all managed by the programming.

 

You can reduce how much it slips, because the transmission tends to shift quickly to gear 2 while the engine RPM would be still low and it has to slip the clutch to prevent stalling. By not inching forward in traffic or holding on to gear 1 for longer periods, e.g. up an incline in many shopping center carparks, you prevent the transmission from slipping the clutch excessively. When people drive manual cars, they don't tend inch forward in traffic or slip the clutch while going up slope -- or at least I don't do that. It's not only bad for the gearbox but generally tiring to be holding the half-clutch all the time. The problem is the general expectation that a DSG should behave like a slush automatic that people end up inching in traffic or slipping the clutch excessively unknowingly. Some people are more sensitive to the car and will "feel" the slipping, some, or rather, MOST people aren't. That's the problem.

 

BTW, I was under the impression that LuK built the entire transmission. So from what you are saying I am gathering that LuK only made the clutch, and the mechatronics is built by VW with parts sourced from various vendors. So it is in effect a "VW mechatronics".

Edited December 30, 2016 by Detach8

[No_worries]

The dry 7 speed doesn't need fluid changes. At least that is the official response from VW. There are 2 separate oil circuits in the bone dry 7dsg. One for the gear box set and the other for the mechatronics module.

[Detach8]

  On 12/30/2016 at 5:43 AM, No_worries said:

The dry 7 speed doesn't need fluid changes. At least that is the official response from VW. There are 2 separate oil circuits in the bone dry 7dsg. One for the gear box set and the other for the mechatronics module.

 

I will never believe that... for all transmissions that claim no fluid change is required... all oils break down over time.

[No_worries]

  On 12/30/2016 at 5:45 AM, Detach8 said:

I will never believe that... for all transmissions that claim no fluid change is required... all oils break down over time.

Which oil change do you really recommend to bone dry dsg owners? The gearbox set or the mechatronics module? I read somewhere (sorry need to find that document) the oil in the mechatronics module is contained under pressure so when you drain it off, it is as good as having to replace the whole unit. Perhaps you can share the symposium course materials with as I am interested in VW inner circle view on this.

[Fels]

  On 12/30/2016 at 5:33 AM, Detach8 said:

You can reduce how much it slips, because the transmission tends to shift quickly to gear 2 while the engine RPM would be still low and it has to slip the clutch to prevent stalling. By not inching forward in traffic or holding on to gear 1 for longer periods, e.g. up an incline in many shopping center carparks, you prevent the transmission from slipping the clutch excessively. When people drive manual cars, they don't tend inch forward in traffic or slip the clutch while going up slope -- or at least I don't do that. It's not only bad for the gearbox but generally tiring to be holding the half-clutch all the time. The problem is the general expectation that a DSG should behave like a slush automatic that people end up inching in traffic or slipping the clutch excessively unknowingly. Some people are more sensitive to the car and will "feel" the slipping, some, or rather, MOST people aren't. That's the problem.

 

BTW, I was under the impression that LuK built the entire transmission. So from what you are saying I am gathering that LuK only made the clutch, and the mechatronics is built by VW with parts sourced from various vendors. So it is in effect a "VW mechatronics".

Har? Ok... happy New year.

[Johnny86]

So the MU from VW any different from Audi?

 

Clutch pack wise?

 

Self admit noob here wanna understand

[merc280v6]

  On 12/30/2016 at 6:04 AM, Johnny86 said:

So the MU from VW any different from Audi?

 

Clutch pack wise?

 

Self admit noob here wanna understand

All from the same VAG parts bin lah ...

Economies of scale, parts warehousing and inventory planning, scheduling & cost control.

 

Edited December 30, 2016 by merc280v6

[Beregond]

  On 12/30/2016 at 5:43 AM, No_worries said:

The dry 7 speed doesn't need fluid changes. At least that is the official response from VW. There are 2 separate oil circuits in the bone dry 7dsg. One for the gear box set and the other for the mechatronics module.

just some info,

i did bring my friend to replace before. as u say they call VW , VW say dun need replace , can last lifetime.

drain out from btm of gear box and pump back. 

the oil less then 3L only. (7 speed)

 

not sure if its ATF or simply gear oil.

(but even gear oil need replace over time)

 

my other 2 friends with GTI i notice got 6L of oil, 

(6 speed)

Edited December 30, 2016 by Beregond

[merc280v6]

  On 12/30/2016 at 6:04 AM, Johnny86 said:

So the MU from VW any different from Audi?

 

Clutch pack wise?

 

Self admit noob here wanna understand

You do appear to be worried (based on this and your previous questions posed in MCF around the same topic).

 

If you had bought an Audi A1, or A3 with the DQ200 dry DSG ... well, you'd need to live with the uncertainty of your car stalling one day and the need to call for help, from wherever you are.

[Fuelsaver]

  On 12/30/2016 at 5:33 AM, Detach8 said:

You can reduce how much it slips, because the transmission tends to shift quickly to gear 2 while the engine RPM would be still low and it has to slip the clutch to prevent stalling. By not inching forward in traffic or holding on to gear 1 for longer periods, e.g. up an incline in many shopping center carparks, you prevent the transmission from slipping the clutch excessively. When people drive manual cars, they don't tend inch forward in traffic or slip the clutch while going up slope -- or at least I don't do that. It's not only bad for the gearbox but generally tiring to be holding the half-clutch all the time. The problem is the general expectation that a DSG should behave like a slush automatic that people end up inching in traffic or slipping the clutch excessively unknowingly. Some people are more sensitive to the car and will "feel" the slipping, some, or rather, MOST people aren't. That's the problem.

 

BTW, I was under the impression that LuK built the entire transmission. So from what you are saying I am gathering that LuK only made the clutch, and the mechatronics is built by VW with parts sourced from various vendors. So it is in effect a "VW mechatronics".

the concept similar to every complicated product, building also built by a builder (main contractor) but also sub out to different subcontractors of different trades / specialties.. so consumers will take it that it's vw gb / mu in layman understanding.

 

so now it's fault "analysis" to gb / mu defect to wc subcon fault..

[Johnny86]

  On 12/30/2016 at 7:54 AM, merc280v6 said:

You do appear to be worried (based on this and your previous questions posed in MCF around the same topic).

 

If you had bought an Audi A1, or A3 with the DQ200 dry DSG ... well, you'd need to live with the uncertainty of your car stalling one day and the need to call for help, from wherever you are. ðð¼

 

And next time, do more research before buying anything ... cars notwithstanding ð

 

However, if you are contemplating to get an entry-model Audi, suggest you do a rethink.

Just got an "entry level ah Beng wannabe 1.4T conti" with conventional 6AT but am exploring options to "upgrade" to an A3 1.4T sportback as space and cabin quality wise it ranks out top in this segment.

 

Hence my queries on Audi but it's really just the A3.

 

If not, just remain with my ah Beng wannabe car , go on the road, windows down, system and finger up.

Edited December 30, 2016 by Johnny86

[merc280v6]

  On 12/30/2016 at 9:51 AM, Johnny86 said:

Just got an "entry level ah Beng wannabe 1.4T conti" with conventional 6AT but am exploring options to "upgrade" to an A3 1.4T sportback as space and cabin quality wise it ranks out top in this segment.

 

Hence my queries on Audi but it's really just the A3.

 

If not, just remain with my ah Beng wannabe car , go on the road, windows down, system and finger up.

Well done man!

[Gasguzzler]

  On 12/30/2016 at 7:30 AM, Beregond said:

just some info,

i did bring my friend to replace before. as u say they call VW , VW say dun need replace , can last lifetime.

drain out from btm of gear box and pump back. 

the oil less then 3L only. (7 speed)

 

not sure if its ATF or simply gear oil.

(but even gear oil need replace over time)

 

my other 2 friends with GTI i notice got 6L of oil, 

(6 speed)

 

In spite of what VCS claims, I change my DSG oil every 20k km.

 

Gearbox ran creamy smooth up to the day I sold the car. Mileage close to 80k km.

 

BTW, it's the 7 DSG.

Edited January 18, 2017 by Gasguzzler

[Wt_know]

wah every 20k must change transmission oil

Edited January 18, 2017 by Wt_know

[Kangadrool]

confirm no need to change... until it breaks down.

  On 12/30/2016 at 5:45 AM, Detach8 said:

I will never believe that... for all transmissions that claim no fluid change is required... all oils break down over time.