[marcel b]

VAG (Audi and VW) had DSG / DCT already since 2003, I know, I had an Audi with DSG myself. Porsche introduced it much later, even one year later then BMW did. I drove a SMG II myself and it really cannot be compared to the DCT. SMG II is not as smooth and much more violent. I feel bad driving in one of the faster programs and feeling the gears being slammed in. DCT doesn't have this, just keeps pulling

To be precise about the DCT, the whole layout can be seen as 2 automated manual gearboxes, both with their own clutch, in one housing.

[Dougie335]

Sheps,
Getting used to the different way the M3 drives. Only done 400 miles as I've been on holiday so still an age to go to the 1200 miles service. Its really hard to keep the revs down.

Dougie.

[G82Dude]

Originally Posted by marcel b

To be precise about the DCT, the whole layout can be seen as 2 automated manual gearboxes, both with their own clutch, in one housing.

I would tend to agree with that. Two robotised manual gearboxes, each with their own clutch that is!

[M3-FAST]

Originally Posted by a1reader

Mine doesn't blip when going into gear either. It only blips on downshifts

+1 - mine has never blipped from standstill or indeed going up the box.

It blips when dropping back down the cogs and automatically blips when it comes down the cogs by itself to prevent stalling/labouring of the engine.

I just pop mine into drive and the revs don't change. Neither does it creep forward unless a tiny push is given on the throttle pedal. Then it will start to crawl. Once the brake is applied and the car halted, it won't crawl again until the throttle touched again.

The OP can look forward to an awesome experience as I love this gearbox. 100x better than an auto slushbox as the car behaves like a manual (no torque convertor?) when required and an auto when lazy

[a1reader]

Originally Posted by M3-FAST

+1 - mine has never blipped from standstill or indeed going up the box.

It blips when dropping back down the cogs and automatically blips when it comes down the cogs by itself to prevent stalling/labouring of the engine.

I just pop mine into drive and the revs don't change. Neither does it creep forward unless a tiny push is given on the throttle pedal. Then it will start to crawl. Once the brake is applied and the car halted, it won't crawl again until the throttle touched again.

The OP can look forward to an awesome experience as I love this gearbox. 100x better than an auto slushbox as the car behaves like a manual (no torque convertor?) when required and an auto when lazy

+1

Exactly my experience. DCT is an awesome bit of kit. Enjoy

[scottc]

VW were the first to bring it to production cars (MK4 R32) but it was actually Porsche that developed it first.

The first actual DCTs arrived from Porsche. Developed for Porsche racing cars in the 1980s,[1] when computers to control the transmission became compact enough: the Porsche Doppelkupplungsgetriebe (English: dual clutch gearbox) (PDK)[1] used in the Porsche 956[1] and 962[1] Le Mans race cars from 1983,[1] and the Audi Sport Quattro S1 rally car.[4][5]

http://en.wikipedia.org/wiki/Dual_clutch_transmission

[marklim]

i think what douggie meant was that, in a normal steptronic 335i, the moment we engage "D" or "R", it instantly moves forward. whereas in the DCT, it takes about half a second due to the reduce in clutch engagement speed.

[Dougie335]

Look I'm telling you guys the DCT 335i blips the throttle when R is engaged when engine is cold. Even the wife was complaining today that the DCT M3 does not. It just sits there. Someone buy my old 335i from Sytner's and you'll see.

Dougie.

[creepy coupe]

Originally Posted by Dougie335

Look I'm telling you guys the DCT 335i blips the throttle when R is engaged when engine is cold. Even the wife was complaining today that the DCT M3 does not. It just sits there. Someone buy my old 335i from Sytner's and you'll see.

Dougie.

This should read--

"My old 335i with DCT blips the throttle when R is engaged when engine is cold"

Coz no one elses does

[toxicnerve]

The only reason for blipping the throttle is to match engine speed to the gearbox speed.

If the car is at a stand-still there is no need to blip the throttle, in fact, if you did blip the throttle the engine speed would be higher and it would make shifting into gear more difficult.

Again, on upshift, there is no need to blip the throttle, when you going up through the gears the result of changing from say 2nd to 3rd is to reduce the engine speed. Blipping the throttle on an upshift would be counter productive!!

Blipping the throttle is helpful for downshifting through the gears only. As said before, it helps to match the engine's speed (RPM) to the speed of the gearbox (and therefore rest of the drivetrain/wheels) and makes gear changes much smoother with less strain on various components of the drivetrain.

If you dont blip the throttle through the downshift you will experience jerky changes as the engine is forced to increase it's speed by the wheels/gearbox. Another effect is that it produces bucket loads of engine braking!

[dxb335d]

Originally Posted by toxicnerve

The only reason for blipping the throttle is to match engine speed to the gearbox speed.

If the car is at a stand-still there is no need to blip the throttle, in fact, if you did blip the throttle the engine speed would be higher and it would make shifting into gear more difficult.

Again, on upshift, there is no need to blip the throttle, when you going up through the gears the result of changing from say 2nd to 3rd is to reduce the engine speed. Blipping the throttle on an upshift would be counter productive!!

Blipping the throttle is helpful for downshifting through the gears only. As said before, it helps to match the engine's speed (RPM) to the speed of the gearbox (and therefore rest of the drivetrain/wheels) and makes gear changes much smoother with less strain on various components of the drivetrain.

If you dont blip the throttle through the downshift you will experience jerky changes as the engine is forced to increase it's speed by the wheels/gearbox. Another effect is that it produces bucket loads of engine braking!

I drove home once without touching my brakes. Over 100 miles of engine braking (In work car) and only touched them for complete standstill which was couple of times at some lights.

Was fun.

Another time had to drive 70 miles home stuck in third gear.

[marklim]

is the DCT's 1st gear's engine break naturally "jerky" ?

[creepy coupe]

Originally Posted by marklim

is the DCT's 1st gear's engine break naturally "jerky" ?

The DCT hardly ever gets to 1st gear, you have to doing around 5 mph or less before it selects 1st.

[marklim]

i normally downshift to first gear to slow down (and to show off) and realise that during the engine brake, the car is really jerky. feels like another car has kissed the back of your car. anyone experiencing that as well ?

i drove one of my friend's DCT 335i as well and his has the same behaviour upon downshifting.

[marcel b]

when shifting down the car first accelerates a bit, which is caused by the blipping of the throttle to match the gearbox speed. This is something to get used to. But when the gear is in it is smooth. I prefer this compared to no blipping and a locking backaxle when downshifting
I often shift back to first, more or less every time I slow down as the plopping sound of the (performance) exhaust just makes me smile. I think first gear goes to 70km/h (40mph) so when putting it in first at lower speeds is no problem.

[marcel b]

Originally Posted by scottc

VW were the first to bring it to production cars (MK4 R32) but it was actually Porsche that developed it first.

The first actual DCTs arrived from Porsche. Developed for Porsche racing cars in the 1980s,[1] when computers to control the transmission became compact enough: the Porsche Doppelkupplungsgetriebe (English: dual clutch gearbox) (PDK)[1] used in the Porsche 956[1] and 962[1] Le Mans race cars from 1983,[1] and the Audi Sport Quattro S1 rally car.[4][5]

http://en.wikipedia.org/wiki/Dual_clutch_transmission

correct, but this was only in race cars, not in production cars. It is strange that Porsche introduced this technology so late in production cars and kept using the old tiptronic automatic gearbox for so long...

[toxicnerve]

Originally Posted by marklim

i normally downshift to first gear to slow down (and to show off) and realise that during the engine brake, the car is really jerky. feels like another car has kissed the back of your car. anyone experiencing that as well ?

i drove one of my friend's DCT 335i as well and his has the same behaviour upon downshifting.

That probably is someone kissing the back of your car, remember engine braking does not light up your brake lights!!

j/k

The feeling is probably due to the violence/strength of the braking forces created in first gear.

Originally Posted by marcel b

when shifting down the car first accelerates a bit, which is caused by the blipping of the throttle to match the gearbox speed...

Are you sure? The throttle blip should come fractionally after the clutch that was just in use has been disengaged. You will hear the revs blip but the speed of the car during the blip should barely change and if anything it will decrease.

In a DCT it should go something like this:

1. Driving normally
2. Initiate a downshift
3. Clutch disengages - You're effectively in neutral now
4. Throttle blips - See above, as you're in N, there should be no power transfer to the driving wheels when the blip happens.
5. Gear change occurs
6. Clutch re-engages (in a DCT it will be the "other" clutch, as opposed to the one that disengaged in stage 3.
7. You're driving normally again.

All that happens in the blink of an eye...

[marcel b]

Originally Posted by toxicnerve

Are you sure? The throttle blip should come fractionally after the clutch that was just in use has been disengaged. You will hear the revs blip but the speed of the car during the blip should barely change and if anything it will decrease.

In a DCT it should go something like this:

1. Driving normally
2. Initiate a downshift
3. Clutch disengages - You're effectively in neutral now
4. Throttle blips - See above, as you're in N, there should be no power transfer to the driving wheels when the blip happens.
5. Gear change occurs
6. Clutch re-engages (in a DCT it will be the "other" clutch, as opposed to the one that disengaged in stage 3.
7. You're driving normally again.

All that happens in the blink of an eye...

I am sure, as when going downhill in eg 4 with 40mph, and shifting back to 3 and 2, the car in the end is driving faster. I noticed this difference as I normally only use engine braking when going downhill (there are a lot of hills around where I live). When driving behind an other car I have to be careful not to come too close. With a manual I never had this issue. The braking force of a manual when releasing the clutch with high revs is much greater then with the DCT. IMO the DCT wants to avoid this, which is good by the way. I had my rear axle locking up when downshifting once going downhill in my Z4M. NOT FUNNY at all. Lesson learned there that I really had to use the throttle (with the right side of my left foot) while braking and downshifting.

[toxicnerve]

Originally Posted by marcel b

I am sure, as when going downhill in eg 4 with 40mph, and shifting back to 3 and 2, the car in the end is driving faster. I noticed this difference as I normally only use engine braking when going downhill (there are a lot of hills around where I live). When driving behind an other car I have to be careful not to come too close. With a manual I never had this issue. The braking force of a manual when releasing the clutch with high revs is much greater then with the DCT. IMO the DCT wants to avoid this, which is good by the way....

That's really weird and not what I would expect at all!! Of course, going downhill the increase in speed might just be the effect of gravity? Also I assume the DCT avoids harsh engine braking simply by feathering the clutch or modulating the throttle appropriately? I will have to take your word for it to be honest as I've only test driven cars with DCT and never had one for an extended period of time.

Does anyone else with experience of a DCT car have anything to add to this discussion?

Originally Posted by marcel b

I had my rear axle locking up when downshifting once going downhill in my Z4M. NOT FUNNY at all. Lesson learned there that I really had to use the throttle (with the right side of my left foot) while braking and downshifting.

You should try it on a bike!

Engine braking on bikes is insane, my instructor taught us about it but we were learning on 400cc bikes. On a 600cc and 1000cc bike the effect is MUCH more pronounced and I've seen even experienced riders locking wheels if they don't get their throttle blip just right or if they're a bit aggressive letting the clutch out on a downshift.

The first time I did it....well, let's just say I needed a change of pants. Picture it, I'm out on a country back-road coming up to a tight turn, I brake late but in a straight line, drop a gear and let the clutch out just as I lean the bike over to make the turn. The back wheel locks up and steps out by what felt like a frickin' mile! In reality I imagine the "step-out" was barely a couple of inches, but when there's nothing but air between you and the asphalt believe me it feels like a lot more!

Luckily my leathers contained anything that fell out of my butt!!

[creepy coupe]

I've noticed the "slight surg" during blipping, but only when you're not on the brakes and at anything over 15-20 mph it's not noticable.

[zltm089]

Originally Posted by toxicnerve

The only reason for blipping the throttle is to match engine speed to the gearbox speed.

If the car is at a stand-still there is no need to blip the throttle, in fact, if you did blip the throttle the engine speed would be higher and it would make shifting into gear more difficult.

Again, on upshift, there is no need to blip the throttle, when you going up through the gears the result of changing from say 2nd to 3rd is to reduce the engine speed. Blipping the throttle on an upshift would be counter productive!!

Blipping the throttle is helpful for downshifting through the gears only. As said before, it helps to match the engine's speed (RPM) to the speed of the gearbox (and therefore rest of the drivetrain/wheels) and makes gear changes much smoother with less strain on various components of the drivetrain.

If you dont blip the throttle through the downshift you will experience jerky changes as the engine is forced to increase it's speed by the wheels/gearbox. Another effect is that it produces bucket loads of engine braking!

plus one!!! ...Correct!!!

[zltm089]

Originally Posted by toxicnerve

In a DCT it should go something like this:

1. Driving normally
2. Initiate a downshift
3. Clutch disengages - You're effectively in neutral now
4. Throttle blips - See above, as you're in N, there should be no power transfer to the driving wheels when the blip happens.
5. Gear change occurs
6. Clutch re-engages (in a DCT it will be the "other" clutch, as opposed to the one that disengaged in stage 3.
7. You're driving normally again.

All that happens in the blink of an eye...

Stage 4, will get the revs higher, so when stage 5 happens, i.e gear change, the revs will be already in the "high" range, making it a bit smoother...

I've noticed this on the TTS aswell...although its a proper manual six speed gearbox, when I put the car in neutral when driving around, if I press the accelerator just to "rev" the engine, its as if the accelerator is a bit "sticky" and keeps reving even after I've released the pedal....so I'm assuming that this helps, when doing manoeuvres like the heel n toe...