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03-12-2007, 02:16 PM | #1 |
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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 |
03-12-2007, 04:16 PM | #3 | |
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we got the dough right? LOL |
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03-12-2007, 09:43 PM | #4 |
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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
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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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03-13-2007, 07:35 AM | #8 |
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Nope I have tried the GTI one absolutely love it and believe that's the future!
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03-13-2007, 11:24 AM | #10 | |
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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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03-13-2007, 12:14 PM | #13 | |
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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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03-13-2007, 05:19 PM | #16 | |
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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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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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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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