The lifespan of a DCT?

[stu]

Just a quick question for a boring Monday afternoon!

The current breed of DCTs in the B8 RS4s and so on... how long do you think they last before replacement, and how would you know if they needed doing? Are they pricey?

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I've seen £8,500 supplied and fitted for a B8 S4 DCT box...

[stu]

I've seen £8,500 supplied and fitted for a B8 S4 DCT box...

Think I'll stick to my manuals.

[stu]

Another quick hunt online mentions that some DCTs are 'non serviceable items', supposedly covered by the car makers up to 150,000 miles.

[bam_bam]

A few things have gone wrong but there are ways to better the clutches and hold more power. No doubt a lot of the solenoids and electrics will be upgradable soon too. They're going to be one of the most ubiquitous gearboxes around in 2-3 years, solutions will be popping up very quick.

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A few things have gone wrong but there are ways to better the clutches and hold more power. No doubt a lot of the solenoids and electrics will be upgradable soon too. They're going to be one of the most ubiquitous gearboxes around in 2-3 years, solutions will be popping up very quick.

I'm not so sure... The recent jump in tech for conventional automatics makes them a compelling alternative. The new zero-shift 8 speed units are stunning and damn hard to tell from a DCT manual.
I'm not sure what advantage a DCT box has over a new tech slushmatic box (and I hate slush-matic boxes).

I know there are some big power DCT boxes but they are quite specialised and hardly "run of the mill".
If you find yourself with a car with a dry clutch DCT then you are limited from the word go unless you are prepared to throw some expense that way.

The big things against DCT are build cost, repair cost and weight. Most of the ones I've looked at have a weight gain of between 20-40kgs over a manual.
The MAIN benefit of DCT to manufacturers and the fundamental reason why they are all clambering over the technology is simple politics... DCT gearboxes perform better in economy and CO2 tests than manuals and automatics. It's why most performance cars in Europe won't get a manual option as it completely stuffs the CO2 levels.

My view is that DCT is nothing really that new or on principle that clever. Porsche had DCT systems for their race cars in the 80's (and I'm more impressed getting that working with 80's tech than what we have 30 years later!). The refinement and engineering however is very special and getting it to work for the mainstream is an achievement.
However there is still plenty of other options in the pipeline... Zeroshift have some stunning (and elegantly simple) mechanisms that allow 0ms gear-changes with one clutch and conventional gearboxes. They are not alone either - XTrac have a similar performing system that uses a complicated (and tricky to get you head round) ratchet gear mounting system that allows two gears to be engaged at ones for a seamless shift.
I do think that if these systems had been production ready then DCT would never have got a look in given the extra complexity.

[Nickyboy]

I've seen £8,500 supplied and fitted for a B8 S4 DCT box...

That's one reason why I am nervous about an ECU remap.

[535dboy]

I've seen £8,500 supplied and fitted for a B8 S4 DCT box...

That's one reason why I am nervous about an ECU remap.

Probably plenty of room in the safe limits for it to not be a problem but understand your concerns.

DMS used to warranty any faults that were deemed to be as a result of their map

[adsgreen]

I've seen £8,500 supplied and fitted for a B8 S4 DCT box...

That's one reason why I am nervous about an ECU remap.

Interestingly that was on a mapped car and was covered by warranty...

[bam_bam]

A few things have gone wrong but there are ways to better the clutches and hold more power. No doubt a lot of the solenoids and electrics will be upgradable soon too. They're going to be one of the most ubiquitous gearboxes around in 2-3 years, solutions will be popping up very quick.

I'm not so sure... The recent jump in tech for conventional automatics makes them a compelling alternative. The new zero-shift 8 speed units are stunning and damn hard to tell from a DCT manual.
I'm not sure what advantage a DCT box has over a new tech slushmatic box (and I hate slush-matic boxes).

I know there are some big power DCT boxes but they are quite specialised and hardly "run of the mill".
If you find yourself with a car with a dry clutch DCT then you are limited from the word go unless you are prepared to throw some expense that way.

The big things against DCT are build cost, repair cost and weight. Most of the ones I've looked at have a weight gain of between 20-40kgs over a manual.
The MAIN benefit of DCT to manufacturers and the fundamental reason why they are all clambering over the technology is simple politics... DCT gearboxes perform better in economy and CO2 tests than manuals and automatics. It's why most performance cars in Europe won't get a manual option as it completely stuffs the CO2 levels.

My view is that DCT is nothing really that new or on principle that clever. Porsche had DCT systems for their race cars in the 80's (and I'm more impressed getting that working with 80's tech than what we have 30 years later!). The refinement and engineering however is very special and getting it to work for the mainstream is an achievement.
However there is still plenty of other options in the pipeline... Zeroshift have some stunning (and elegantly simple) mechanisms that allow 0ms gear-changes with one clutch and conventional gearboxes. They are not alone either - XTrac have a similar performing system that uses a complicated (and tricky to get you head round) ratchet gear mounting system that allows two gears to be engaged at ones for a seamless shift.
I do think that if these systems had been production ready then DCT would never have got a look in given the extra complexity.

Can anyone say CVT?

[adsgreen]

Can anyone say CVT?

I tried but it came out "cervut".

It's kinda like saying "look-ada-tuv" in dixons.

[doodlebug]

My particular favourite was the request for a number for bosom.

[bam_bam]

Can anyone say CVT?

I tried but it came out "cervut".

It's kinda like saying "look-ada-tuv" in dixons.

Good. Let it be the word that's never spoken.

[stu]

Ads, about the Zeroshift and the XTrac... they sound very very clever. Great info. I think one or both of them featured in a gearbox-heavy edition of Evo last year.

Just a thought: how would an engine<>gearbox<>wheels system deal with the shock of instant ratio changes? Maybe 'shock' isn't the right word... stress? Or, in other incorrect terms, the synchronising of the rotational forces/inertia/whateveritscalled of the engine to the rest of the transmission. The phase that clutches smooth out when gradually disengaging/engaging.

[adsgreen]

Ads, about the Zeroshift and the XTrac... they sound very very clever. Great info. I think one or both of them featured in a gearbox-heavy edition of Evo last year.

Just a thought: how would an engine<>gearbox<>wheels system deal with the shock of instant ratio changes? Maybe 'shock' isn't the right word... stress? Or, in other incorrect terms, the synchronising of the rotational forces/inertia/whateveritscalled of the engine to the rest of the transmission. The phase that clutches smooth out when gradually disengaging/engaging.

Not really much different to how it's done now.
All clutches have springs in help absorb the engagement process. Couple this with advanced engine ECU's that can precisely adjust load to match very very quickly then no reason why you can't do it.
Take current DCT's - no way they could shift in 10ms without actively dealing with engagement shock forces.

With the seamless changes you could use the same it would just have to be better

You could always use a leaf out of a race drivers handbook too - opinion is divided and it's a matter of personal preference and specific vehicle requirements but many used to dab the clutch or just add a little pressure to it to "help things along" during a gear change.


What I'd like to see on a DCT box is the return of a clutch pedal... (bear with...)
the clutches in the dct box are completely computer controlled (and very finely controlled). What you could do with a clutch pedal is feed this input into the computer and if you added some force feedback you could replicate a manual setup without sacrificing the advantages of the DCT.
For example, when you want to have fun, you put the box into "fully manual" and you use the clutch to change gear. The box simply takes the clutch pedal input and controls the appropriate "live" clutch.
Then you have got the basic modes for semi auto (no clutch pedal, auto change on paddle shift) and full auto (fully auto gearchanges).