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12-04-2012, 07:34 PM | #1 |
Rocky
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Jet or turbine sound as you decel/downshift towards a stop light
What is that jet or turbine sound as you decel/downshift towards a stop light or full stop? I had the same sound on my 09 M3 DCT.
That sound was non existent on the crappy 11 550i. So we know its not the turbos. I am thinking its the DCT tranny. Thoughts? Love that sound BTW.
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12-05-2012, 01:54 AM | #6 |
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12-05-2012, 08:48 AM | #7 |
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Thanks for dumb reply.
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12-05-2012, 08:49 AM | #8 |
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So why are you commenting on a car you dont have? Contribute or go away.
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12-05-2012, 09:35 AM | #9 |
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12-05-2012, 05:15 PM | #10 | |
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12-23-2012, 09:29 PM | #13 |
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Any sound clip so we know what it is?
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12-24-2012, 06:34 AM | #14 |
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12-25-2012, 12:52 AM | #15 |
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It's normal drivetrain noise
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12-25-2012, 07:56 AM | #16 |
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12-25-2012, 11:08 AM | #17 |
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I believe it is normal drivetrain noise too. I hear it on my car and it reminds me of the gear "whine" you would hear on a sequential race transmission (like a Hewland or Xtrac). Gearboxes with straight-gears typically have this sound although its usually louder and more pronouced. I am not familiar with the gear design in the F10 M5 but I'm assuming its something similar. I know what you're talking about - most pronouced on a decel to a red-light at certain RPMs - and it's definitely not the active sound.
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12-25-2012, 03:09 PM | #18 |
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Sounds like drivetrain noise. It's probably from the tooths on the gears as they are transferring force/torque on the "wrong" side of the gear teeth. They are designed to transfer torque under acceleration and might make more noise when decelerating as the teeth are engaging on the opposite side of the tooth. Race transmissions or transmissions that are for heavy duty use have more straight cut gears. Straight cut gears make more noise but don't generate the longitudinal force that wants to push the driving and driven gears apart from each other (one gear wants to go forward and the other rearwards, creating a lot of frictional losses and stress on bearings).
An automatic transmission uses planetary gears and don't operate in the same way as a manual transmission. My guess is gear noise. |
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12-25-2012, 03:45 PM | #19 |
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12-26-2012, 04:40 AM | #20 |
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12-27-2012, 03:44 PM | #21 |
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I've test driven two M5's, they all have the same sound. The one I ended up with has this sound as well. I actually like it, makes me feel like I'm in a jet
My only complaint is that during very cold weather (below freezing), it seems to 'screech' but goes away quickly once it's warmed up. |
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12-27-2012, 04:02 PM | #22 | |
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If you haven't driven a GTR, then you don't know how good you got it. Performance and (quiet) luxury in the M5 is so much better. At the end of the day, it is still a hi perf machine with moving parts. |
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