Engine/Transmission mount (or something different) inquiry

[NoVAphotog]

So after the morning group of runs at the autocross this past saturday, I noticed when I turned the car OFF, a loud rattling/metallic fluttering sound coming from underneath almost a bit in front of the gear shift lever.

Had several folks there listen to it and one who I spoke with earlier about E46's immediately said it sounded like the engine/transmission mounts. He said if it happened when you turned the car on, which it did not, it'd be more of an issue. That was the only time I noticed it to that extent, for the normal street driving I've done since I don't notice the sound to the same degree as after running the course.

My question is, could it be something else as I don't see why it would happen after aggressive driving but not after DD use if the parts are worn? :confused That said, I do get very slight shakes idling at red lights, etc. I'll be inspecting them as soon as the rain clears up and I get a chance to get under the car. Car is at ~60,800. Also, is it worth getting the UUC mounts since I do plan to autocross her again/in general they are better or just sticking with new OEM mounts?

(It's annoying I can't make it to the BBQ in VA as this would be an easy thing to check out there!) :(

[alexandre]

Try turning off the car in neutral without having the clutch engaged. Is it that noise ? If so it's normal, something about the lightweight flywheel.

[Hornung418]

Thats a no for engine mounts. If you put your car in 1st gear and accelerate with your hand around the shift knob you will feel it swing to the right from the torque load. Both cars I've owned needed the drivers side mount serviced. Honestly, it's a super easy job. But undoubtedly thts the sound you are hearing.

Six speed cars have a tendency to suffer from flywheel chatter. But we dont have a light weight flywheel...part numbers are the same as other non ZHP models.

Sent from my GS3.

[NoVAphotog]

I'll try both of these tests when I get home, also, Hornung did you mean that's a "yes" for engine mounts being the issue?

[LivesNearCostco]

I don't think fluttering metallic sound is engine mounts or transmission mounts, unless it's the right side heat shield (sits on top of passenger side engine mount) that's come loose and rattling. Could be some other head shield piece, or flywheel, or... ?

[Hornung418]

I'll try both of these tests when I get home, also, Hornung did you mean that's a "yes" for engine mounts being the issue?

Thats a no. I just described what the symptoms are for engine mount failure. Drivers side is often ripped in half.

I dont think it's anything to worry about. My car does it and I just accept it lol.

Sent from my GS3.

[Vas]

That noise is not from the engine/trans mounts.

As far as mounts go, M3 mounts are the way to go for an civil upgrade.

[Hornung418]

That noise is not from the engine/trans mounts.

As far as mounts go, M3 mounts are the way to go for an civil upgrade.

75D Poly if you like a raucous ride :biggrin

Sent from my GS3.

[LivesNearCostco]

BimmerWorld solid rubber motor mounts (Gruppe N replicas) for some extra vibration at idle but not really more noise and shouldn't notice any extra above 1000 RPM. BimmerWorld poly transmission mounts with cups however, add more NV (noise, vibration, but not harshness) on top of what the BW motor mounts add. I found the UUC black transmission mounts more civilized (barely any extra vibration and no extra noise compared to stock) but they haven't been very durable in my experience, possibly because I didn't use the enforcer cups?

Several people have given positive reviews of the Rogue Engineering solid rubber/poly transmission mounts. Supposed to be stiffer than stock but not more NVH than stock. The Vorshlag poly motor mounts are supposed to be strong but add even more VH than the BW solid rubber ones.

I've got other AKG bushings in the car but never tried their motor or transmission mounts.

[Hornung418]

The AKG mounts are friggin awesome! I had the 75D engine and trans combo in the 328i you can hear every whine of the gears. Such a rush to drive at slow speeds. However...the five speed gearbox had a resonant frequency at around 3000 rpm. And the whole cabin would shake as you fell through the rev band on deceleration. Quite annoying if you weren't flogging it. I was only able to transfer the engine mounts to my ZHP. But even they alone make the ride much more enjoyable!

Anyway, back to your issue, Dan.

Sent from my GS3.

[Johnmadd]

Try turning off the car in neutral without having the clutch engaged. Is it that noise ? If so it's normal, something about the lightweight flywheel.

Agreed, except for the lightweight flywheel because its a dual mass flywheel and is pretty heavy imo... I know because I've had mine changed thinking it was the infamous "death rattle" lol.long sentence short, clutch/flywheel/throw out bearing were all changed and still had the chatter.

If the sound when shutting off the car with with the clutch in is not there, then it is normal/common. Nothing to worry about if this is your issue.

[NoVAphotog]

If the sound when shutting off the car with with the clutch in is not there, then it is normal/common. Nothing to worry about if this is your issue.

I tried everything others mentioned earlier and didn't really feel/notice anything to the degree I felt before. When I'm under the car next I'll take a look at the mounts and take some pics, but based on what folks said they are probably fine. Thanks for the info everyone!