DSG Transmission

[doc_777]

Abient temp
coolant temp
Throttle position
gear selector position
transmission mode
transmission temperature
vehicle speed
brake pressure
aircon compressor clutch status

those are just some of the conditions which the ecu uses to determine the idle speed

example - aircon clutch status changes - the idle speed changes because the ecu caters to the change of load. Likewise selecting neutral (you don’t actually select neutral, you change the position of a switch, and the transmission controller does its thing) - the trans controller tells the ecu about the change of transmission status and the ecu then determines the required idle speed based on every other condition that has input to determining idle speed.

computers don’t fail and cause catastrophic accidents as you claim. It’s either a software fault (which was coded by a human), or a hardware fault (with inadequate failover redundancy).

[doc_777]

Let’s not forget one more salient point - an idle speed of ~800 is preferable to ~1000 from a clutch wear perspective on takeoff. An Idle speed of ~1000 is preferable to an idle speed of ~800 from an engine efficiency perspective. So it’s no surprise to me that the idle speed increases when the tcu tells the ecu that a neutral gear position has been requested.

[Ozsko]

Read my reply above !!!

There is commonly-documented evidence throughout the internet, which indicates the plates do NOT disengage fully..... this is why some of us go into Neutral.

If this was the case any DSG car caught in a heavy traffic jam for any length of time would have the clutch on fire if it had any slipping as you describe at all. It can't do any harm to shift into neutral but I think what someone had done is noted that if a DSG car is not on auto hold and the foot brake is released it creeps and has extrapolated that because the engine speed did not rise the clutches must be partially engaged at all times. Slipping clutches as you describe simply are not tolerable.

[tigger73]

This is part of the reason the 7speed DQ200 dry clutches stuff up as they basically cook themselves in slow moving city traffic.


Sent from my iPhone using Tapatalk

[Spinifex]

........those are just some of the conditions which the ecu uses to determine the idle speed......

While they are all very good examples, they don't count for the experiences (backed up by documented evidence elsewhere) that I described in my original post. Aircon kicking in is NOT the reason why many people notice the change in engine-revs and "assume" the gearbox clutches are disengaging. Anyone who posts about this issue obviously has at-least a tiny idea of how car mechanisms work, and we wouldn't be so blindsided by an AC clutch engaging/disengaging at an identical moment we manually shift from D to N, to assume it's the gearbox and not the AC.

... computers don’t fail and cause catastrophic accidents as you claim. It’s either a software fault (which was coded by a human), or a hardware fault (with inadequate failover redundancy).

Exactly my point... regardless of it being either software or hardware-related, computer/electronic systems DO still fail, which can cause catastrophic accidents.
Your comment does nothing to invalidate my statement, and merely reinforces it, so thankyou for that one

......but I think what someone had done is noted that if a DSG car is not on auto hold and the foot brake is released it creeps and has extrapolated that because the engine speed did not rise the clutches must be partially engaged at all times.....

While that may be true of some of the reports that have been documented, it's not the convincing argument in all of them (or my particular case)

When stopped on a flat surface with no incline, foot mashed on the brake, shifting from D to N, there can occasionally be the following results:
A: revs change
B: audible change in engine tone
C: this is the kicker.... the car MOVES ever so slightly... you can physically feel the car releasing the "tension" or pre-loading, for want of a better term. It is an IDENTICAL feeling to shifting D to N in a traditional slush-box automatic.
It is akin (in reverse) to when a motorbike is sitting in Neutral, and clicks down into 1st gear.... even when holding the clutch in tightly, the gearbox kicks in with SOME engagement of the clutches... you can physically see, hear and feel the chain moving/tightening on the wheel.

[doc_777]

My experience is that there is almost certainly a different reason that you are claiming for the change in revs when neutral is selected. You seem to have made your mind up - all good. As I said - your story, tell it all you like. I KNOW what a grabbing clutch smells, sounds and feels like. Nothing in your description adds up to that in my experience.

[tigger73]

This is the problem as I see it. We're all looking at a black box and trying to explain what we're seeing without fully knowing the internal working of the black box.

Everyone has their own theory but unless you're the maker of the box and know how it works then it's all just theories and hypothesis.

No discussion in this thread is ever going to resolve this so we're best off agreeing to this and moving on.

As to whether it is required to move the transmission into Neutral I'd be referring to the owners manual and there is no mention of moving the selector to neutral in the manual. If you are going to be stationary for an extended time I'd personally put the car in P with the handbrake on as then the car is being held rather in N it still requires application of the foot brakes.

[Sydneykid]

Based on discussions with a friend of mine who works at VW, moving the selector to neutral when stationary has the same effect as a firm foot on the brake pedal ie; the DSG clutches are fully disengaged. In Drive with no foot on the brake pedal or on the accelerator pedal then the ECU assumes that you want to crawl forward at a very slow rate, obviously after the hill start brake hold disengages. The gear indicator will show D1 or D2.

I don't get the "mystical magic" stuff that floats around about DSG's. They are just a manual gearbox with electro hydraulic clutch actuation, that's it.

This differs to an automatic gearbox with a torque converter (TC) which always transmits some power. TC's are a fluid coupling between the engine and the transmission and as such heat up the fluid whenever there is a differential between the engine rpm and the gearbox rpm. Which is why they need a transmission cooler. Moving an automatic gearbox to neutral disengages the gears (bands) which is why the loading changes, but the TC is still engaged.


Cheers
Gary

[Spinifex]

Sigh...... and if my posts were actually read in their entirety, I've made it clear several times that I'm not talking just about the change in engine revs, when shifting D to N while stopped. I pretty clearly described other effects that I (and others) have noticed - but whatever.

What my original post was asking, is can anyone in the know actually confirm or deny if the story about the DSG oil-pump (if there even is such a thing) actually stops pumping, while in Neutral - and therefore it's recommended NOT to sit in Neutral for prolonged periods of time... or is this just a myth?

[INASNT]

My MK6 R which I had for 7 years and did 120,000km never had a transmission issue.. I never put the car in neutral when stopped, drove to the city in peak hour traffic 3-4 days a week in those 7 years..

[tigger73]

Sigh...... and if my posts were actually read in their entirety, I've made it clear several times that I'm not talking just about the change in engine revs, when shifting D to N while stopped. I pretty clearly described other effects that I (and others) have noticed - but whatever.

What my original post was asking, is can anyone in the know actually confirm or deny if the story about the DSG oil-pump (if there even is such a thing) actually stops pumping, while in Neutral - and therefore it's recommended NOT to sit in Neutral for prolonged periods of time... or is this just a myth?

If you read the manual it says not to tow the car in neutral because when the engine is not running there is also no lubrication of the gearbox and this can lead to a failure.

It doesn't mention anything about lack of lubrication when the car is running but suggests not putting the car into neutral when going downhill as then you'll be relying solely on the brakes to slow you down and not using the engine to keep the speed in check.

So only issue is when moving the car when the engine is off. You want to put your car onto a flatbed truck rather than your traditional tow truck that just lifts 1 set of wheels off the ground.

[BinChook]

Would this be an issue if the rears were lifted and front wheels were rolling on the ground? Can we assume if front is lifted,the rear Hadlex clutch pack is depressurised and disengaged, it’s apples?

[Wazza 162]

I'm almost sorry I asked the question, didn't think it would cause so much controversy but thanks to all that have given lots of varied and informative views. I suppose that's what these forums are good for.

[anonymousmoose]

Just drive it normally like any other auto.
The ride can be jerky in stop/start traffic or when starting off from standstill, but once on the move the shifts are super swift

I put it into sports mode in snails pace traffic. Holds gears longer and no jerk

[Ozsko]

Sigh...... and if my posts were actually read in their entirety, I've made it clear several times that I'm not talking just about the change in engine revs, when shifting D to N while stopped. I pretty clearly described other effects that I (and others) have noticed - but whatever.

What my original post was asking, is can anyone in the know actually confirm or deny if the story about the DSG oil-pump (if there even is such a thing) actually stops pumping, while in Neutral - and therefore it's recommended NOT to sit in Neutral for prolonged periods of time... or is this just a myth?

Ask the question the other way, why would there be a neutral if VW knew it would damage the box? In reality the car selects neutral when it comes to a halt when the first motion shaft between the motor and box stops spinning, all manual cars do this as it is the drive splines on the clutch plate that causes the gearbox to engage with the motor. When this happens and the first motion shaft stops nothing in the gearbox rotates or pumps anything unless the oil pump is electric.