06-19-2017, 05:17 AM | #1 |
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'clonk' on downshifting in manual M2?
Has anyone experienced this? it's only when downshifting and seems to come from behind when you release the clutch in the new gear.
It's more apparent when carrying a bit more speed and even more so when block changing from say 5th to 3rd. It's not all the time (and of course I can't replicate it when I try!) it may be that this is quite normal, not sure.. Thanks |
06-19-2017, 08:33 AM | #2 |
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Does the speed at which you let the clutch out make a difference? Ie, if you slowly release the pedal you don't get the noise?
A couple other things to try to aid in diagnosis: 1) In any gear, accelerate at about 1/2 throttle, then abruptly take your foot off the gas. wait 1 second then back on the gas for a second, then back off the gas for a second. Basically you want to set up a bucking/lurching motion in the car. Pick a nice side road where you wont get reported for drunk driving! Try in a couple different gears and see if you can isolate to a gear or set of gears. 2) Find a nice smooth strip of road where you can just cruise along at like 30 Mph. Doesn't matter which gear. Take your foot off the gas, leave the car in whatever gear you are in, and pump the clutch in, clutch out, clutch in, clutch out. I'm thinking you might have something loose in the driveline or rear end. The above will help confirm. |
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06-19-2017, 08:38 AM | #3 |
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I notice this only when I am downshifting way too slow. The rev-match seems to like clutch shift release clutch really quick and it works well. If the engine does the rev-match and you let the clutch out after the RPMs drop, you get the clunk.
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06-19-2017, 09:24 AM | #6 |
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It all depends on the settings your in. On sport+, it will occur more. You just have to understand the cars behavior and try to be smoother when releasing the clutch at slow speeds.
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06-19-2017, 09:51 AM | #7 | |
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Many thanks for this, I'll give it a try.. |
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06-19-2017, 09:54 AM | #9 |
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06-19-2017, 09:55 AM | #10 |
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06-19-2017, 10:43 AM | #12 |
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I had the same thing thought my clutch stop was messing me up so I removed it. Still had the issue sometimes. The solution: release the clutch quickly/make sure you know exactly where the catch point is.
If I released the clutch "normal" like I would in any other car I got the clunk. So I release it much quicker now. Initially I thought the catch point was towards the middle/up top, but for me it's in the beginning, so I just make sure to briefly pause at that point then release and my downshifts no longer have the clunk. As before I was just releasing past the catch point I suppose which shocks something. Just wondering, what exactly is making that sound though? The diff? |
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06-19-2017, 01:14 PM | #13 |
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I think it might be the dual mass flywheel at it's limit, making the clunk feeling. It helps with springs to absorb the shock, but at max, it would make sense to me it would feel like a clunk as the clutch wont really slip after it is engaged enough to load the flywheel. I could be talking out my ass though, but I don't know what else in the drive line would have slack to clunk.
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06-19-2017, 01:33 PM | #14 |
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Yes, the quicker the clutch release the better it seems. From 3rd to 2nd it is most noticeable if you are too slow releasing at the top. The pedal has to be all the way at the end of it's up stroke. Trying to be slow and smooth at the top doesn't work. Guess the release point is that high although it doesn't seem like that when feathering out from 1st gear let's say. To me the sound seems/feels to be coming from the rear differential. Maybe some inertia from the drive shaft after the rev match or something?
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06-20-2017, 01:55 AM | #15 | |
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Love these forums for getting top feedback like this, thanks very much |
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06-20-2017, 01:57 AM | #16 | |
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06-20-2017, 09:44 AM | #17 |
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Awesome! Forums are great.
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06-21-2017, 09:21 AM | #18 |
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I experienced this only in the break-in period but haven't since.
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