Weird drivetrain hum under load??

Bme30 · 07-02-2013, 08:01 AM

So I have only noticed this noise while making the extra power running e85.
To make a long story short I have a weird him under load....? The easiest way to hear the noise is when driving 45-60 (normal speed) cruising in 6th. The noise is ONLY present when in the speed range and I floor it to get around traffic...now remember this happens in all gears, but it is the easiest to hear while in 5th-6th. (Less engine noise).
The noise seems to come from the front to the middle of the car. Zero vibration!!! Just a hum noise. I do have a ungraded clutch with 5k miles. And a final note I don't hear the noise while running 93oct. I really think the added power helps exacerbate this noise.
Help!!!!! Any ideas!!!

Bme30 · 07-02-2013, 11:07 AM

Anyone???

Carl Morris · 07-02-2013, 03:27 PM

What's an "ungraded clutch"? Are you making a lot of power? Could be the DMFW toward the end of it's travel at the torque peak...

Jeff@TopGearSolutions · 07-02-2013, 04:35 PM

Quote:

Originally Posted by Carl Morris

What's an "ungraded clutch"? Are you making a lot of power? Could be the DMFW toward the end of it's travel at the torque peak...

Great question and one I feel is also related to the noises.

Bme30 · 07-02-2013, 10:33 PM

I have an ACT clutch, with the stock dmfw.
As for power i havnt had the car dynoed with the jb4 and e85. But people with similar mods people are seeing 400-430whp and 440-500trq. So I'm somewhere in that range.
Before when I was running meth on procede I dynoed 390whp and 440tq and this noise wasn't present.

David1 · 07-03-2013, 08:56 AM

It's the DMFW. Only fix is to swap to single mass or downshift more.

Bme30 · 07-03-2013, 09:20 AM

Quote:

Originally Posted by David1

It's the DMFW. Only fix is to swap to single mass or downshift more.

So I tried to recreate the issue this morning. On map 0,1 and 2 the noise isn't there, but on map 5 when autotune tunes for e85 it's back.
I'm starting to believe you are correct with the dmfw. I'm producing too much torque! Thanks for everyone input!!
And on a second note I went to my buddies transmission shop he suggested the same thing, but for shits and giggles we checked all the bushings and mounts and everything was fine.

07-02-2013, 08:01 AM	#1
Bme30 Major 88 Rep 1,039 Posts Drives: 335i coupe Join Date: May 2010 Location: 'Merika' iTrader: (2) Garage List 2007 335i [0.00]	Weird drivetrain hum under load?? So I have only noticed this noise while making the extra power running e85. To make a long story short I have a weird him under load....? The easiest way to hear the noise is when driving 45-60 (normal speed) cruising in 6th. The noise is ONLY present when in the speed range and I floor it to get around traffic...now remember this happens in all gears, but it is the easiest to hear while in 5th-6th. (Less engine noise). The noise seems to come from the front to the middle of the car. Zero vibration!!! Just a hum noise. I do have a ungraded clutch with 5k miles. And a final note I don't hear the noise while running 93oct. I really think the added power helps exacerbate this noise. Help!!!!! Any ideas!!!
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07-02-2013, 11:07 AM	#2
Bme30 Major 88 Rep 1,039 Posts Drives: 335i coupe Join Date: May 2010 Location: 'Merika' iTrader: (2) Garage List 2007 335i [0.00]	Anyone???
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07-02-2013, 03:27 PM	#3
Carl Morris Captain 19 Rep 650 Posts Drives: 2008 335xi 6MT Join Date: Feb 2012 Location: San Jose, CA iTrader: (0)	What's an "ungraded clutch"? Are you making a lot of power? Could be the DMFW toward the end of it's travel at the torque peak...
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07-02-2013, 10:33 PM	#5
Bme30 Major 88 Rep 1,039 Posts Drives: 335i coupe Join Date: May 2010 Location: 'Merika' iTrader: (2) Garage List 2007 335i [0.00]	I have an ACT clutch, with the stock dmfw. As for power i havnt had the car dynoed with the jb4 and e85. But people with similar mods people are seeing 400-430whp and 440-500trq. So I'm somewhere in that range. Before when I was running meth on procede I dynoed 390whp and 440tq and this noise wasn't present.
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07-03-2013, 08:56 AM	#6
David1 Brigadier General 814 Rep 3,953 Posts Drives: 09 E92 09 X5 Join Date: Mar 2007 Location: Columbus, OH iTrader: (1)	It's the DMFW. Only fix is to swap to single mass or downshift more. __________________ 2021 M2 Comp Sunset Orange \|Black with orange Stitching Dakota Leather\|Executive Pkg\|DCT
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