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      03-12-2007, 02:16 PM   #1
M2002
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Second thought on DSG

This is what i could find on dsg in wikipedia. I was excited about DSG until i saw disadvantage number 1 below. Could BMW possible allow such a slow responsive throttle?
Someone please explain.

Advantages:
1-Extreme fast up shift and downshift time of 8 milliseconds
2-Practically no power loss whatsoever, because of the short shift time
3-Better fuel economy than the planetary geared automatic transmission and manual transmission
4-When the car is going downhill the clutch disengages, allowing the car to coast

Disadvantages:
1-Response time from letting off the throttle and then reapplying is lengthy, around 400ms, depending on the situation
2-Can be expensive to manufacture, this discourages many automakers
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      03-12-2007, 04:15 PM   #2
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Why is it an advantage to allow the car to coast?

That seems like a waste of gas to me.
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      03-12-2007, 04:16 PM   #3
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Quote:
Originally Posted by M2002 View Post
This is what i could find on dsg in wikipedia. I was excited about DSG until i saw disadvantage number 1 below. Could BMW possible allow such a slow responsive throttle?
Someone please explain.

Advantages:
1-Extreme fast up shift and downshift time of 8 milliseconds
2-Practically no power loss whatsoever, because of the short shift time
3-Better fuel economy than the planetary geared automatic transmission and manual transmission
4-When the car is going downhill the clutch disengages, allowing the car to coast

Disadvantages:
1-Response time from letting off the throttle and then reapplying is lengthy, around 400ms, depending on the situation
2-Can be expensive to manufacture, this discourages many automakers
2nd disadvantage shouldn't matter to most of people on this forum.
we got the dough right? LOL
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      03-12-2007, 09:43 PM   #4
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Quote:
Originally Posted by M2002 View Post
Advantages 4-When the car is going downhill the clutch disengages, allowing the car to coast
I highly doubt BMW would design the DSG tranny to disengage when coasting. They don't even do that in their automatic transmissions, conversly most GM auto transmissions do allow the engine to drop to idle when coasting (a feature I hate). I personnal want the transmission to stay engaged when coasting to take advantage of engine braking the same way it does in the current SMG tranny.
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      03-12-2007, 10:31 PM   #5
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DSG & coasting

Quote:
Originally Posted by skierman64 View Post
I highly doubt BMW would design the DSG tranny to disengage when coasting. They don't even do that in their automatic transmissions, conversly most GM auto transmissions do allow the engine to drop to idle when coasting (a feature I hate). I personnal want the transmission to stay engaged when coasting to take advantage of engine braking the same way it does in the current SMG tranny.
I agree--compression braking is a highly desireable feature that aids car control. Also, when coasting an engine is still using fuel, but when decellerating with no throttle the fuel is cut off. BMW will not use a coasting mode unless you shift into neutral.
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      03-13-2007, 05:00 AM   #6
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Does it bother anyone that DSG is more auto-like as it will kickdown to the lowest gear when you press on the gas, upshifts at redline and will creep forward when your foot is off the gas.
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      03-13-2007, 06:44 AM   #7
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Quote:
Originally Posted by heezyo2o View Post
Does it bother anyone that DSG is more auto-like as it will kickdown to the lowest gear when you press on the gas, upshifts at redline and will creep forward when your foot is off the gas.
That is exactly what bothers me as well!
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      03-13-2007, 07:35 AM   #8
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Quote:
Originally Posted by heezyo2o View Post
Does it bother anyone that DSG is more auto-like as it will kickdown to the lowest gear when you press on the gas, upshifts at redline and will creep forward when your foot is off the gas.
Nope I have tried the GTI one absolutely love it and believe that's the future!
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      03-13-2007, 10:25 AM   #9
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does it really downshift when you press the gas?

I thought you still had complete control over gear selection?
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      03-13-2007, 11:24 AM   #10
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Quote:
Originally Posted by heezyo2o View Post
Does it bother anyone that DSG is more auto-like as it will kickdown to the lowest gear when you press on the gas, upshifts at redline and will creep forward when your foot is off the gas.
It's posts like this which annoy me.

1) SMG kicks down to a lower gear when you press on the accelerator, so what difference does DSG make?

2) How do you know that IF BMW launch a DSG type gearbox it will automatically upshift? SMG doesn't.

3) How do you know that IF BMW launch a DSG type gearbox it will creep forward? SMG doesn't.
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      03-13-2007, 11:29 AM   #11
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Quote:
Originally Posted by mofomat View Post
It's posts like this which annoy me.

1) SMG kicks down to a lower gear when you press on the accelerator, so what difference does DSG make?

2) How do you know that IF BMW launch a DSG type gearbox it will automatically upshift? SMG doesn't.

3) How do you know that IF BMW launch a DSG type gearbox it will creep forward? SMG doesn't.
I smell DSGNV.
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      03-13-2007, 12:11 PM   #12
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never drove smg so i have no comment about this but some of you guys' posts are confusing the crap outta me haha
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      03-13-2007, 12:14 PM   #13
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Quote:
Originally Posted by mofomat View Post
It's posts like this which annoy me.

1) SMG kicks down to a lower gear when you press on the accelerator, so what difference does DSG make?

2) How do you know that IF BMW launch a DSG type gearbox it will automatically upshift? SMG doesn't.

3) How do you know that IF BMW launch a DSG type gearbox it will creep forward? SMG doesn't.
BMW can design a "DSG" type gearbox any way they like, but when we talk of DSG, we talk about it in it's current design as we know it.

And sure SMG kicks down to a lower gear....if you're in auto mode. If you're in manual mode however, you can stomp on the gas and remain in the current gear. You've driven a SMG car, yes?
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      03-13-2007, 12:57 PM   #14
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Quote:
Originally Posted by heezyo2o View Post
BMW can design a "DSG" type gearbox any way they like, but when we talk of DSG, we talk about it in it's current design as we know it.

And sure SMG kicks down to a lower gear....if you're in auto mode. If you're in manual mode however, you can stomp on the gas and remain in the current gear. You've driven a SMG car, yes?
Firstly, yes I owned an E46 M3 with SMG II for three years. I'm afraid you are very much mistaken when it comes to how SMG works in manual mode. If you are in 3rd gear for example, in manual mode, and you stomp on the throttle and the software detects you should really be in 2nd, then it will change down for you.
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      03-13-2007, 12:58 PM   #15
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Quote:
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I smell DSGNV.
WTF does that mean?
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      03-13-2007, 05:19 PM   #16
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Quote:
Originally Posted by mofomat View Post
Firstly, yes I owned an E46 M3 with SMG II for three years. I'm afraid you are very much mistaken when it comes to how SMG works in manual mode. If you are in 3rd gear for example, in manual mode, and you stomp on the throttle and the software detects you should really be in 2nd, then it will change down for you.
What happens when starting up from say a stoplight?
if you let off the brake does it creep forward like an automatic?

sorry newbie here
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      03-13-2007, 05:39 PM   #17
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Quote:
Originally Posted by mofomat View Post
Firstly, yes I owned an E46 M3 with SMG II for three years. I'm afraid you are very much mistaken when it comes to how SMG works in manual mode. If you are in 3rd gear for example, in manual mode, and you stomp on the throttle and the software detects you should really be in 2nd, then it will change down for you.
Hmm, are you sure about that. I don't have three years of driving experience in a SMG II M3, but did drive one for about 10 months.

First off, let's define kickdown so there's no confusion. Kickdown in an automatic is when it shifts down to the lowest gear for best acceleration. SMG will only do this while in auto mode. With auto mode in the SMG, you can be driving in 6th gear, step on the gas and get third gear.

While in manual mode, you can be cruising in say 6th gear and fully depress the accelerator and still remain in 6th gear. Also, say you enter a turn in third gear while in manual mode. At the end of the turn, the car will remain in third gear even if it isn't in the best gear to accelerate. It will even allow the car to lug around, low in the RPMs in third gear a bit. While in manual mode, you have to downshift for yourself.

While in manual mode, SMG pretty much only downshifts for you to prevent a stall.

edit: At times, manual/sequential mode will put you in the right gear, but you cannot rely on it to do this. If you want to confidently be in the right gear, you need to downshift yourself, as you would in a traditional manual.

Last edited by heezyo2o; 03-13-2007 at 07:45 PM.
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      03-13-2007, 11:25 PM   #18
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Mofatmat, you may have 3 years of ownership but you seem to be confused about how the SMG works. If you are in manual mode it will not downshift to a lower gear when you go full throttle, The only time SMG will downshift (in manual mode) without the driver directing a downshift is when you're going too slow for the gear selected, like approaching a stop light or stop sign and still in to high a gear for that speed.

Put another way: In any gear with an SMG and the RPM above 1500 (maybe less) the SMG will not downshift on its own in manual mode even under full throttle.

Also, I don't expect DSG to be programmed to interface with the driver any differently than SMG, the main difference is it will shift faster.

Chitown - No the SMG does not creep forward like an automatic it acts exactly the same as a manual tranny if you have the clutch depressed. You will only get forward motion by giving it thottle.
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      03-14-2007, 08:54 AM   #19
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Yup if the E92 M3 comes with a SMG and not the DSG then I am getting my deposit back. I told my dealer absolutely no SMG for me!

SMG and Ferrari F1 box will be gone in a few years.
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      03-14-2007, 09:09 AM   #20
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Quote:
Originally Posted by skierman64 View Post
Mofatmat, you may have 3 years of ownership but you seem to be confused about how the SMG works. If you are in manual mode it will not downshift to a lower gear when you go full throttle, The only time SMG will downshift (in manual mode) without the driver directing a downshift is when you're going too slow for the gear selected, like approaching a stop light or stop sign and still in to high a gear for that speed.

Put another way: In any gear with an SMG and the RPM above 1500 (maybe less) the SMG will not downshift on its own in manual mode even under full throttle.

Also, I don't expect DSG to be programmed to interface with the driver any differently than SMG, the main difference is it will shift faster.

Chitown - No the SMG does not creep forward like an automatic it acts exactly the same as a manual tranny if you have the clutch depressed. You will only get forward motion by giving it thottle.
This is all correct. SMG in manual mode does not "kick down" to a lower gear when you get on the gas. The only circumstance in which it will downshift automatically in manual mode is if the downshift is necessary to prevent the car from stalling.

When you are stopped with your foot off the gas and no brake, the car will not creep forward with SMG, regardless of whether it is in auto or manual mode. If you are facing uphill, the car will roll backwards in this scenario (unless you use the hillholder function).
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      03-14-2007, 09:15 AM   #21
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OK. I may be at fault in my clarity. I agree, SMG in manual mode will NOT kick down in the traditional 'auto' sense. I was just trying to explain that it's a myth that SMG will never change down for you. It will change down to prevent you from stalling. Sorry if I've been unclear.
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      03-15-2007, 05:06 PM   #22
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Anyone who has a question on how the DSG works should really treat themselves and drive a VAG product with a DSG. They really are quite nice. The nay-sayers who complain about that little stuff either 1) never drove one and are just basing their hate on tech specs, or 2) are just really incredibly picky.

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