[vladmury]

Hi fellas, after the rear subframe was removed to mount the M3 subframe bushings (rear flex disc between differential and driveshaft removed) I get a strange drivetrain vibration just before car stops rolling when in D or R. After applying the brakes and stop the car rolling, the vibration dissapears. I tried putting the car in N at 20 mph and stopping, no vibration.

I had the car in the shop to check if everything was mounted properly, they have not found anything wrong apparently so the rumbling noise is still there.

When I approach a traffic light for example and I come to a stop , the rumbling noise starts. I think its due to extra vibration from the engine being transmitted in the cabin.

It might be due to M3 bits mounted I am wondering if the torque converter , gearbox mounts can do this? Its funny because the issue appeared after mounting the M3 bits, now wondering if that is nornal or not. I got installed M3 control arms as well.

The vibraation is noticeable only when engine is warm and appers only car is rolling at low speed and stops. As soon I start accelerating there is no noise or vibration.

Any ideas are welcomed.

Thanks
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[Yozh]

What flex disc between the diff and shaft. There is none on the 335d

[vladmury]

I know, but my car is a 325d that has a flex disc between diff and shaft. anyway that was checked and it doesnt seem to be the cause since its doing only when engine is warm.

[Thecastle]

I have the same issue with my D.

I installed powerflex yellow rear subframe inserts on my 335d. I instantly noticed a significant increase in idle vibration and noise. My car vibrates so much at idle now it causes things in the dash to start buzzing. Anyway for me the problem is worse when the engine is cold and becomes better as it warms up.

I also developed diff whine under hard acceleration in 4,5,6th gears at around 2000rpm after the install.

Like you I went down the route of could it be the guibo, diff mounts, transmission mounts, etc.... Even changed the diff fluid and added liqui MoS2.

What I suspect is the following. The engine mounts maybe bad and not vacuum adjusting their stiffness correctly as they should transmitting too much vibration to the drive-line. Or the rear sub-frame is out of alignment. Apparently subframe alignment/torque can cause the symptoms as well.

The cause is when re-installing a lot of people support the rear sub-frame by putting a jack under the diff. Then tightening the bolts with the jack holding up the sub frame. This according to my suspension expert could cause the sub-frame to be misaligned. So he recommended lifting the car, loosening all the sub-frame mounts equally and letting the sub-frame hang there to relax the bushings. Then tighten the sub-frame back up according to the manual without the sub-frame being supported by the diff. I'm going to try this in the next week or two to see if it eliminates my problem.

[BB_cuda]

Castle, clarification please. For some reason I thought you had bushings inserts. You mention full blown yellows above. I did same as you and had jack under diff. The front bushes enter into downward protruding dowels (from the chassis). I suppose I can try this as I'm still dealing with a clunk noise I'm searching to stop. I had frame down again this last weekend. I'm not getting diff whine though nor the vibration. I have harder powerflex than you so I'm wondering if I either did something different or got lucky. Of course, you're not getting clunk noises though. Maybe we need to meetup and listen to each other's noises.... group therapy, haha.

[vladmury]

I also have the differential whine after the M3 bits, its noticeable when accelerating from 2000 rpm. Before installing the bushings and M3 arms I had no vibration or noise at all.

The most annoying is the rumble, if the engine mounts were broken before why there was no noise? The M3 bits were installed by the workshop so they had the right tools to do it...I might change the engine mounts but I have no other ideas since I am afraid the extra vibration is due to stiffer bushings.

[BB_cuda]

Both the M3 rear guide and upper arms have inboard ball joints instead of rubber bushings. These will transmit more noise through them into the sub frame. Did you install diff bushings too? This is a stronger transmission of whine than anything else. I used powerflex purple instead of black hoping for a good compromise between stiffness and lack of noise.

[BB_cuda]

OP, take a look at your rear transmission mounts. I recall a guy finding those partially broken. May not be the case for you but good to look. People are upgrading those with rogue engineering ones. I can't speak to their attributes though.

[335dsleeper]

Op- I know you mentioned you tested in neutral and the vibration wasn’t there but, I encourage you to look at your tires and wheels. These can cause issues similar to what you’re describing and can change with temperature etc.

[vladmury]

I will check the mounts in the weeekend and I have a though that it might be the exhaust which was removed by the workshop hitting the body.

When I start the car there is thump noise for less than a second right when engine starts. It comes from the rear.

I have access to a lift and will put car in gear and check nothing is loose.

[Thecastle]

Originally Posted by BB_cuda

Castle, clarification please. For some reason I thought you had bushings inserts. .

yes as I mentioned in my other post, I have the poweflex yellow rear subframe inserts for the 335d installed on my car. I also have Koni FSD's and monroe upper strut mounts as additional mods, and of course the u-haul hitch which ties the subframe to the rear bumper for reinfocement.

But only the install of he poweflex yellow inserts made an immediate change in idle quality, rumble, and diff noise.

[BB_cuda]

I re read your 1st post in this thread. I agree that it's likely your motor mounts. If your car is in park, that would take the yellows out of the equation. I will also try the retightening of the sub frame bolts without jack. Those front dowels would align the frame though unless there is some slop between the dowels and front bushings. Going to advantage CL on 11/20 for airbag recall (finally).

[vladmury]

I have changed the motor mounts and the vibration is still there.
I suspect the torque converter might be the one causing it.

Drive shaft is fine , gearbox mounts are fine , also the guibo disc.
It appears only in D or R when sitting on the brakes or when about to come to a stop.

It goes away when I accelerate or put in P or N.

[aaddam2]

my GF's ford fusion (SPORT, aka nascar) has this same issue. still looking into what it is but from reading around on their forums but could be vacuum related, or some other type of mount. if it it only appeared only after you did the inserts there has to be some play somewhere when the subframe was dropped. and from what ive read that even solid aluminum bushings do not cause that amount of vibration.

[Yozh]

I’m on solid subframe bushings and I do not have strange noises. Op, have you checked the transmission mounts and differential mounts?

[vladmury]

Update : its the torque converter I will have it replaced in the near future.

[Yozh]

How do you know it’s the torque converter?

[BB_cuda]

Originally Posted by Yozh

How do you know it’s the torque converter?

+1???

[vladmury]

I had the car on a lift and someone in the car while we looked under , the vibration comes from the gearbox when steping on the brakes while the car is in D or R. The rumble seems to be caused by the torque converter.

[335dsleeper]

What?

[jomiri]

Vlad, are you still running xHP stage 2? It sounds like your issue is RPM dependent. I'm wondering if it has to do with the TCU tune. After I updated to xHP stage 3 v2.0 and I noticed somewhat similar symptoms.

The downshift threshold seems to be much lower, meaning RPM's are much lower when braking. I get some minor vibrating around 700 RPM when decelerating.

[vladmury]

Yes but I have flashed the stock map now and the rumble has reduced a bit, maybe its placebo.

When the rumble starts the rpm is at idle so not sure how that can make a difference. I will run on stock map for a while and see if its xhp tune related