08-27-2016, 12:07 AM | #1 |
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Random 1st gear stutter/stumble with 6MT
I've owned my 2016 M235 6mt for a bit over 6 months and 6k miles. I've been driving manuals for decades and have always found the 6MT in this car difficult to drive smoothly under normal driving when in Sport+ or Sport with the aggressive throttle mapping. Lately I've been driving around in DSC Off and i much prefer the linear throttle and the lack of nanny intervention. WOT 1-2 and 2-3 shifts feel much better and shifting at part throttle is much smoother and easier to modulate.
Anyway, for the past two weeks or so since I've been driving in DSC Off, I've noticed a very random stumble/stutter as I'm leaving the light normally in 1st. The stumble seems to happen just as I'm releasing the clutch fully in 1st at a very slow speed. The feels like accelerator pedal goes dead for a split second and the acceleration pauses momentarily. It lasts not even a second but it's still felt and is rather annoying. Even more annoying is how random it is. It might happen once a day. I never feel in Sport+ or Sport with the aggressive throttle mapping. Perhaps it's somewhat masked by the overly quick throttle. The issue isn't even worth noting to the dealer because it's so random right now. All other driving situations are fine. The car has no modifications. Anyone else experience this? Is this possibly the CDV? |
08-27-2016, 06:46 AM | #2 |
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Maybe going to friction too quickly? I am not certain I'm understanding where you are feeling this from but I am still not perfect with this clutch on low speed acceleration leaving 1st, especially after 2 months in the shop. I typically get some bounce or stutter as the clutch engages and I attribute it to my timing being off and having no rev hang compared to the Civic.
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08-27-2016, 05:35 PM | #3 |
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I thought that at first too, but it doesn't feel quite like that. It really feels like the throttle dies for a split second rather than releasing the clutch too quickly and causing a momentary bog.
I do find the clutch take up to be quite wonky in this car, meaning the clutch has a ton of travel for initial engagement but the point it fully engages is quite narrow. I find this rather annoying around town, but during aggressive driving and on launches, it works really well. |
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08-27-2016, 06:26 PM | #4 |
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After getting familiar with the 235 over many months, I sometimes blip the throttle twice gently when releasing the clutch into first gear and taking off.
Then, as someone pointed out recently, you can almost take off on first gear (and reverse) with just the clutch and no throttle, so I apply gas near the end of when I let up off the clutch, but sometimes out of nowhere, when it feels like I'm doing everything right, I get clutch judder on a takeoff. |
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08-27-2016, 08:51 PM | #5 |
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Flaky clutch disc? This has happened to me in some of my previous manual transmission cars. One needed a new clutch disc every 10k miles to keep it smooth. And no, I did not abuse, ride or excessively slip the clutch.
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08-27-2016, 08:59 PM | #6 | |
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08-31-2016, 06:42 PM | #7 |
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Hey, this is normal, my car is the same, and i think we have a similar driving style.
My theory is this is how BMW limits torque at low RPMs so that clutch life is preserved. The expectation is that most drivers will slip the hell out of the clutch. (You'd be surprised how many europeans slip the clutch more than necessary).
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08-31-2016, 09:14 PM | #8 | |
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09-01-2016, 12:22 AM | #9 | |
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For the past few days I've been driving around solely in Sport+ and the car never had a low rpm hick up. I'm starting to think what I was experiencing in the non-aggressive throttle modes is a factor of a cold engine, the CDV delay, and/or some odd throttle tuning factor. The quicker throttle apparently gets around this issue simply because the throttle is quicker perhaps skates past this glitch. Like as noted before, these cars don't require much throttle to get going and starting out in 2nd on any sort of decline or even a 2mph roll is easy. With my WRX, i had to use 1st far more. |
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09-01-2016, 12:23 AM | #10 | |
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09-02-2016, 09:41 AM | #11 |
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10K on my new 2016 228i 6MT....never really noticed what the OP experiences getting into 1st....I feel the typical clutch shutter like I do with all MTs.
I drive mostly in Comfort mode...I'll switch on to Sport+ and "feel" what he's stating about |
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09-03-2016, 11:51 PM | #12 |
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When I'm starting off in first, I always tap the throttle just a little bit to where you can feel the engine "shake" and then I slowly release the clutch at that point. Works fairly well for me.
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10-26-2016, 03:26 PM | #13 |
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I thought I'd update this thread after nearly two months. This issue is clearly caused by the internal clutch delay valve (CDV). By being a bit slower and careful with my clutch foot, I don't experience the issue.
Another thing, running a clutch stop seems to negatively impact around town drivability as well. I ran a homemade 3/16" thick clutch stop for quite a while to reduce the clutch throw and engagement point. Apparently the CDV and self-adjusting clutch mechanism do not like you running a clutch stop. I had become annoyed with how much I had to "think" when trying to get a smooth start with the Sport throttle mapping. It was often a very slight bog or a bit to rapid. The 1-2 shift could be a little jerky too. I've been driving manuals for decades and found this car to be by far the hardest to leave the line smoothly when trying to leave at a moderate pace. Turns out the clutch stop was the problem. I removed that last week and all the modulation issues disappeared. I guess I ran the clutch stop for so long that I forgot how the car drove prior. |
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10-26-2016, 06:58 PM | #14 |
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Don't know if it's related but with a cold engine and ASS on, the car would sometimes almost stall itself getting off the line. No problem after it warms up.
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10-26-2016, 10:12 PM | #15 | |
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But I don't see the clutch stop as being a negative. I thought the factory clutch travel was excessive, so I took BentZero's tip and bought the $10 Burger Tuning clutch stop - best cheap mod ever! I removed one of the washers because there was no free play before engagement with all of them. With the removed washer it grabs maybe 1 to 1-1/2 inches from the floor. About the same engagement point as my Mini with no clutch stop.
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10-27-2016, 09:53 AM | #16 |
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Maybe my car or foot are different. I'm far smoother leaving the line and on shifts without any sort of clutch stop in place. I can more easily gauge the friction point and range. I do agree that the clutch throw is excessive.
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10-27-2016, 11:24 AM | #17 |
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I share your pain too...I've only ever driven stick, and after 30000 kms...I'm still stuttering this car off the line...
Doesnt help that the Throttle mapping differs between the modes, and I change my shoes often between work dress shoes, runners, boots all contributing to me occasionally looking like a rookie at stoplights... |
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10-27-2016, 12:08 PM | #18 |
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Mine does as well. Only when the car is warm. It chatters as i release the clutch. If i do my normal rpm when getting going in 1st gear (~1k rpm), it'll go thud-thud-thud as im releasing the clutch. If i give it a little more rpms (~1.5k rpms) it'll thud usually just once before it fully engages. Everyone says dual mass flywheel is the cause. Considering im hearing a lot of people with similar issues, i think im inclined to believe it and just live with it.
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10-27-2016, 04:34 PM | #19 | |
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I will say that launching this car hard is very easy. I can really feel that line between a fractional amount of spin and avoiding bogging. |
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10-28-2016, 12:14 AM | #20 | |
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(By the way, I'm not just letting the clutch out and allowing the engine to shake...This happens even when I rev to about 1200 and slowly let the clutch out while maintaining revs) |
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10-28-2016, 11:55 AM | #21 |
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My 230i is at the dealer now. I was having rough shifts and the car was shaking at start up and idle. Made the car feel cheap. I have a BMS clutch stop on the way and I plan to change to motul oils when I hit 1500 miles. Hopefully that will help the shifting. The foreman and I went for a ride and he said that is how the BMW shits, i.e. CVD mechanism. I guess I was expecting a bolt action precision shift. I'll keep you guys posted on what they say.
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10-29-2016, 09:46 AM | #22 |
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I have the same thing OP describes in 135i , at first I thought it was a missfire or sparkplug related, changing the plugs improved it but it's never fully gone away. I just blip the throttle a bit taking off and it's my work around. Annoying but several techs have test drove my car and not noticed anything out of the ordinary so I assumed it was just my driving habits.
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