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DCT vs 6MT

Discussion in 'E90/E92/E93 M3 (2008-2013)' started by bharatmd, Apr 30, 2009.

    • Member

    thedge9

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    missing the point of manual

    For some its not just about time, some find joy in the precise technique in making a great downshift. Comparing it to F1 seems excessive

    srobmw guest

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    +1

    Love the perfect downshift

    bharatmd guest

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    6mt vs dct

    i am going for 6MT. Never could get that feeling with dct/smg/or whateva the heck they call it!!!!!!
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    bimmer5

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    tes drive both

    You need to drive both - and twice. I had intended to go m-dct but had such fun w/ the 6mt that I went old-school.

    Both are great. If I lived in the city I may have gone m-dct.

    bigbranddan guest

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    7 spd DCT in my 2009 M3

    I went for the DCT because of LA traffic stop and go. I like it most of the time. There are a few quirks that BMW does need to work out of this transmission.

    1) When coming up to a light there is a delay when in 2nd and wanting to go to 1st gear. There have been a few times I want to make a left turn and the hesitation is un-nerving, in the middle of the intersection and no throttle.

    2) It doesn't downshift/upshift frequently enough. The M3 engine doesn't have lots of bottom end torque so gear selection is critical. If I am on the FWY and the car is in 7th and I put my foot on the gas it stay in 7th, no acceleration so I step harder, then it finally jumps down three or four gears. How about jumping down one gear for every 10% of throttle push?

    In the canyons the 7 speed is amazing, easy to have the correct gear all of the time. Puts a big smile on my face on any twisty road. But that hesitation at the light, it feels like the trans needs revs to make it work quickly and idling toward a stoplight doesn't give it the energy required to work properly.

    MAYBE BMW WITH COME OUT WITH AN UPDATED SHIFT PROGRAM THAT CAN BE DOWNLOADED INTO MY CAR, PLEASE???
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    az3579

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    The problem is that you're using it as an automatic transmission. DCT is not an automatic transmission. It is meant to be shifted manually using paddles. The "automatic" function of it is there to be used as a convenience, not as a primary. So, if you find that it's never in the right gear, then put it there and you'll have allllll the power you'll need!

    Remember, this ain't no stankin' Steptronic. :D
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    wanesso

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    This wife is the one with the new M3, 6 speed MT---drove the SMG DCT at the driving school and they are definitely smooth, fast, and fun BUT they don't beat the feel of the car with the stick in your hand---either way it's a fabulous car (and it keeps the non-stick shift drivers safely away, in this case....the husband):D

    fiberoptic guest

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    Shift hesitation from 2nd to 1st

    I experience downshift delay from 2nd to 1st even when rev matching engine and transmission. Does anyone else have this and is there a way to fix this other then double clutching?
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    az3579

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    You mention double-clutching - do you have DCT or 6-speed?

    fiberoptic guest

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    It's a 6 speed and it takes more time than my old 330Ci and E36 M3. Upshifts no problem and 6->5->4 good when engine is revved 4000+, but it seems when going 2->1 requires 7000+ and still has mechanical hesitation in the shift box. It's not gear grinding it feels like the shifter is being held and I don't want jam it into gear.
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    epbrown01

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    Hm - CDV (clutch delay valve)?

    fiberoptic guest

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    Shifting sluggish.

    I've heard of this before from Turner Motorsport. One of the guys said they have modified clutch cylinders and valving on their race cars. Any body aware of this and whether there are aftermarket mods. available?

    fiberoptic guest

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    Looking at many Bimmerfest posts like:
    Clutch Delay Valve (CDV) delete rocks!

    After years of reading about the CDV delete, I finally got around to doing this mod to my M3. I accomplished the task by utlizing the UUC stainless steel clutch line, and man, what a difference it makes to the shifting! Before the mod my clutch often felt as if it was slipping, and no matter how hard I tried, getting a 2nd gear scratch was pretty much impossible. Now, whenever I launch, or speed-shift, my rear tires are screeching, and my clutch pedal feels 100% positive. I recommend this mod for anyone who wants to enhance the experience of driving their BMW...

    It appears everyone suggests to get rid of the CDV.
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    CSBM5

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    Check with Dave Zeckhausen, www.zeckhausen.com, since he has long provided gutted CDVs for BMWs that have them (some don't, like the E39 M5), so you can replace the valve and still look factory stock.
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    az3579

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    It was my understanding, as good manual-driving practice, to never shift into 1st from 2nd while the car is still moving, unless you perfectly rev-match. The latter is incredibly hard to do right, so why would you need to shift into 1st while the car is moving?


    Anyway, the CDV delete is a very popular mod, and I don't believe there is anyone who has done it and isn't satisfied with the result! :)
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    CSBM5

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    I do it all the time -- we run most of our autocrosses on airports and almost always have a turn-around cone element. :)
    • Member

    az3579

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    I was referring to regular every-day driving. Of course it's almost inevitable to shift into 1st on an autocross course sometimes, but on the street you're most likely not going to bother rev-matching, while on the course it would be in your best interest to do so.

    I reread the past few posts and failed to see the part "even when rev-matching..." posted by fiberoptic. My bad! That's probably the CDV playing with you though.
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    330indy1

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    +1

    it's a no-brainer

    SchnuckiE30 guest

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    Dct ...

    I've kept up on these trans designs, mainly through Roundel, and it seems that the manuals would certainly be lighter and definately less complicated. The one main advantage I see for the DCT is the avoidance of the "money shift", missing the next gear down for 3 gears down by accident, letting the clutch out and you know the rest. This isn't possible with the DCT, thus saving big bucks on the low-probability incident. Do you concur?

    Else, just keeping updated on all things BMW. I hope they get through this continuing economic crash. This country is in no way recovering and there's more downside coming. I'll keep the E30 humming along for now >>>>>

    convertibleguy guest

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    I have the same low speed issue on my 08 and you are right, it can be unnerving. For the freeway downshifts, you might try using one of the faster drive program settings to see if it improves things. The system defaults to 3, try 4 or 5.

    In general, you can't beat DCT because it at least gives you to option of automatic-like mode and blazing-fast manual mode.

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