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Discussion Starter · #1 ·
OK, folks... like many of us, my MDX has a slightly whiny torque converter (most prominent at 60-65mph, in D5 - shift to D4 and it goes away). I'm not worried about a failure, but it would be nice to quiet it down.

Yes, I thought (for a millisecond) about dropping the engine and transmission subframe, splitting the tranny off and replacing the TC. But there is no way that's worth eliminating what's really a very slight (though annoying to an anal shadetree mechanic like me) problem.

I'm thinking about how the noise gets from the transmission to the cockpit, and am pretty much convinced the noise isn't just traveling through the air, or it would be a lot more evident with the windows down (and it isn't). It's got to be coupled to the chassis, and it seems like that's going to happen via the two bottom transmission mounts.

So... has anyone ever noticed a reduction in transmission noise (whine or otherwise) by replacing the two (small, cheap) transmission mounts? If the rubber in these mounts is like any other similar rubber, it goes from soft and pliable (and sound-deadening) to hard (and not so much sound-deadening).

Any input would be appreciated. I really don't mind swapping them out just to test the theory, but if someone's done that without an improvement, it will save me the time.
 

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Haven't tried anything specifically.

At first I was thinking rubber isolation mounts or sheets that you could buy at an industrial hardware store.

I was also thinking some noise was transferring through the engine since it's connected to the trans.

Then I recalled two things when my power steering gear went out in my 08 TL. First, the gear leaked from the steering input shaft into the cabin and made a big mess. I recall having to pull the drivers side carpet to replace it and some insulation. The insulation on the firewall was about an inch thick, high density foam material. Reminded me of the temperpedic stuff. There was also jute and something that looked like fiberglass house insulation but was plastic and non shedding. Second, when the input shaft cover and insulator was removed, I had to drive the car and it was amazing how much noise came into the car through that hole.

Saying this because sound absorbing and/or insulating might be the way to go. Speaker sound deadening mat or that temper material seems like it would help a lot. (I got the carpet and all the insulation for that gear leak at a local pick your part for $20! Maybe that's a low cost way to experiment.)

Here's a link to an EPA text on quieting that covers a range of noise issues and abatement. There's a section on blocking high pitched and low pitched noise. You might find something helpful.

Have fun!

https://nepis.epa.gov/Exe/ZyNET.exe...ge&MaximumPages=1&ZyEntry=1&SeekPage=x&ZyPURL
 

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Discussion Starter · #4 ·
Interesting articles. I'll dig into that EPA article a little to see what I can learn. I did put a couple layers of flooring underlayment (basically 3mm thick neoprene) under the carpet in the cockpit area of my classic GMC motorhome (it's a front wheel drive using the Olds Toronado drivetrain). Made a HUGE difference in sound coming up from the engine and tranny (which you're essentially sitting on top of). I was listening carefully to the whine this afternoon, and it's really impossible to determine where it's coming from - it's kind of "all around", which would make sense if it's being coupled into the cockpit through the chassis (or unibody, more accurately). You're right - the tranny is coupled so tightly to the engine that it really increases the possibility of acoustic paths... I'm thinking that if I had a few thousand dollars worth of high tech microphones and scopes, and a dyno, I could really figure this thing out! ;-)

The transmission article is interesting, too - happily, it seems to apply to only '01-02 models, and seems to be a very different type of failure than our typical 60-65mph whine. I'm confident that no one would be able to hear my tranny complaining as I drive by.
 

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Discussion Starter · #5 ·
Just ordered a set of Beck Arnley transmission mounts. Now it's just a matter of popping them in (should be easy... famous last words), and hopefully will reduce the whine.
 

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Hey Habby, I'm curious to hear how this goes for you. I have the same issue. It seems the noise may be getting worse, or hopefully, I just may be noticing it more.

Is this a sign the TC is going to have to be replaced eventually?


Sent from my iPad using Tapatalk
 

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Discussion Starter · #7 ·
Sadly, the swap didn't help. The old mounts were a little weatherchecked, but still pretty pliable (I was hoping they were hard and brittle, contributing to the transmitting the noise to the chassis).

The TC whine (the kind that starts around 60mph in D5, and goes away when you shift to D4) isn't likely to indicate a future failure - seems to be just a common niggle with our trannies.

FWIW, I just bought a contact piezo microphone and installed a spectrum analyzer app on my 'droid phone. With any luck, I'll be able to see the "spike" at the whine frequency so I can establish a baseline for the noise and see if anything I plan to do actually helps. I might also be able to kinda/sorta trace the noise to the cockpit... it's just tough since you have to do the troubleshooting while driving 60mph. I'm planning to try a couple additives to see if it quiets the whine down, and with any luck will be able to actually measure the results (instead of relying on subjective guesstimates, which can be subject to perception bias).
 

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@habbyguy ... just following up to see if you had any luck with the whine since your last post from a few years back. Mine does the same at around 60, and goes away when shifting from D5 to D4. Still shifts fine but a little annoying when on the highway.
 

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Discussion Starter · #10 ·
I never did really eliminate it. I DID notice a significant reduction after each transmission fluid drain-and-fill. My next step was going to be putting some sound-deadening material under the front carpets, but I sold the vehicle before that happened.
 
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