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04-05-2009, 01:03 PM | #1 |
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M-DCT Lag - What's the reason?
So it appears we have someone on version 33.0 (new software fix) and still the lag is present in all it's glory.
At what point will the optimists (swamp included) conceed that I was indeed correct and it's basic design has the flaw and no amount of upgrades will cure or eliminate it completely. |
04-05-2009, 05:29 PM | #2 | |
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04-06-2009, 09:35 AM | #3 | |
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1. It was not there before (at least not to the extent it is now) 2. This issue does not appear in downshifting to 1st gear (which is a much more "difficult" gear to handle). 3. Common sence. I am not a DCT specialist knowing how the DCT was designed (far from that) but knowing the very basics, in my logic I cannot convince myself why the lag cannot be fixed. Anyway, let's see if and when the lag will be fixed... I will chase BMW with another follow up letter to see what the official position is. |
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04-06-2009, 09:49 AM | #4 | |
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Also, we have no proof yet that PROGMAN 33.0 even included an official fix for the lag. I realize that nitramsen has an "in" of some sort, but I'd like verification. Plus he mentioned something about a "custom version". If this update was indeed meant for the masses and meant to correct something of significance, then we should get much more information (though nothing of substance from official sources) as the update is propigates and more is discovered about it. Personally I am skeptical any of that will happen, because. |
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04-06-2009, 10:17 AM | #5 | ||
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Now in my opinion that would mean that it DOES have an underlining flaw in it's design for this to not have been fixed, whether the flaw is lag or something else but with each cure there's something else that seems to get worse. Quote:
I have driven a few DCT gearboxes now and the only one with these issues is the M-DCT, in fact compared to Porsche's PDK the M-DCT isn't half the polished package which to me is proof positive that BMW released their version far to soon and with not enough development work. Here's a question for you. Does the Ferrari DCT suffer the same issues? |
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04-06-2009, 10:29 AM | #6 | ||||
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No one is arguing that other DCT products are able to operate without the low speed lag. No one is arguing whether the BMW software has bugs. So citing comparable examples, again, isn't adding anything new right now. We've discussed all of this before, and we agree that the lag is an issue (a serious one) that other comparable transmissions do not exhibit. I just don't personally think it is unsolveable via software at this point. And frankly if it is, then BMW is in for a long road because this will eventually get the attention of the NHTSA (it could be years, who knows) and they will eventually force BMW and their supplier to fix all the cars (at least in the US) even if it means redeveloping the entire transmission from scratch. Unfortunately, it may take death or serious injury for that to happen. |
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04-06-2009, 12:49 PM | #7 |
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Hmmm, it doesn't seem that you, mkoesel and I are saying the same thing at all. You are purporting there are essentially unfixable design flaws causing the lag. Most others, based primarily on the behavior of the tranny with the first software revision from the factory, claim it is primarily a software only issue that was altered significantly and for the worse with the first software revision. It seems painfully obvious that it can be fixed. However, there is the remote possibility that this lag is intricately linked to the previous delay between paddle actuation and the beginning of clutching. Others have suggested this but I find the two only very, very loosely related.
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04-06-2009, 01:37 PM | #8 |
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I am basically saying that the lag may be the resulting best solution of curing the other issues that where present in the transmission. Maybe I am the sole person here that finds it amazing that M-DCT was launched with so many problems and is still having problems after (if memory serves me) at least two upgrades.
There is many things that BMW have got right with the transmission, D4 is one setting that is very well judged for spirited driving while still proving useful around town, S1-2 is also a great balance between speed of shift and smoothness and finally D1 is very good in snow. Another great thing is the gear stick and how it's used, other should follow their example in my opinion. But for a car that is so well developed and judged else where it highlights the gearbox's failings all the more. |
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04-06-2009, 03:09 PM | #9 | ||
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What would hold some weight to sway my opinion is if they released an update that very clearly addresses the low speed lag (fixes it or makes it much better), but then recreates old bugs fixed in previous releases. I would then begin to wonder if the transmission just cannot be "balanced" for lack of better word to where all systems operate harmoniously together and "all holes are plugged" (for lack of better idiom). But that hasn't happened yet. So again, really there is nothing new to glean from this latest update. Quote:
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04-06-2009, 05:32 PM | #10 |
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This might be worth checking but you now get the DCT in the 335, admittedly with a different software with less setting, is it known whether the lag is present on it also.
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04-07-2009, 08:48 AM | #11 | |
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Best regards, south
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04-07-2009, 09:56 AM | #12 |
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If that is true then sure that strengthens my case that the M-DCT is flawed, why else would they use another gearbox supplier when a perfectly good one has already been developed, the only requirement would be scaling down the options on the software.
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04-07-2009, 10:06 AM | #13 |
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Everything that was said was just a hunch. What we know for sure that the normal 3 series DCT will have less programs compared to the M-DCT (based from BMW announcement).
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04-07-2009, 10:24 AM | #14 | |
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P.S. South is usually right on these things, so if he reckons it's different then chances are it is. |
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04-07-2009, 10:49 AM | #15 | |
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Best regards, south
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04-07-2009, 10:52 AM | #16 | |
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- Complexity - Availability And probably a half dozen other possibilities I didn't think of. Footie, your witch hunt against the M-DCT transmission is causing you all sorts of irrational conclusions. The 335i DCT does not use the same paddle arrangement as the M3 M-DCT either. So then, we must conclude the M3 paddles are flawed also, yes? I mean, why else would they use a different setup on the 335i? |
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04-07-2009, 10:54 AM | #17 |
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South, seems to me then, it is very similar to the manual transmissions in these two cars. Same part, although the M gets an additional cooling unit as I recall it.
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04-07-2009, 10:58 AM | #18 | |
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Getting back to the gearbox, if it does prove to be lag free then it may mean the complexity of the software is the M-DCT's downfall and I was wrong to consider that the gearbox design was flawed. Though this is yet to be proven either way. |
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04-07-2009, 11:06 AM | #19 | |
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It's not a witch hunt, I am a little upset as many are that after so long the gearbox is still causing problems. Given BMW's M-division's engineering credentials I expected more, and given that it's the dearest of all the DCTs from rival competitors I think it should have be properly developed. As for the paddle differences, I don't understand why BMW don't offer the M3 style paddles as the other ones are no better than the shit Porsche put with their PDK. Who here would have been happier with only 3 manual and 2 auto modes if it worked 100%, I know I would if that happened to be the cure. Complexity leads to problems no matter what it is. |
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04-07-2009, 12:03 PM | #20 | |||
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However, again here, even if we find that the 335i implementation is lag free, it still can not be concluded 100% that the additional modes in the M3 are the cause for the M3 issues. The M3 has a completely different drivetrain including the engine and differential, not to mention all the electronics that control it. The complex interaction between the transmission and these things means that the two will likely be programmed very differently regardless of how many Drivelogic programs are involved. |
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04-07-2009, 11:43 PM | #21 | |
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South - can you ask around on some forums in Europe about this? An extra big thanks in advance if you can (especially given your club membership ). |
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04-08-2009, 02:30 AM | #22 | |
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My argument is that IF (big if) but if the DCT in the 335 is indeed lag free then the software setup in the M3 is seriously flawed for one reason or another. But none of this matters, the problem I have is the supposed years of development done by BMW plus the extra year of production and still we have these issues with the gearbox. I personally expected more from M-Division and to be honest with you, I thought you would have felt the same way. Yeah it's frustrating but it can be a serious problem, especially as we in Europe have lots of roundabouts (rotors) where you merge with moving traffic on a regular basis. |
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