Motor, Transmission, and Differential Mounts

[135]

Further update:

I finally had the solid diff mounts installed. No noticeable increase in NVH but I already had a solid diff brace installed, which at the time did make diff whine noticeable, which is something I've learned to live with and ignore.

Summary of installed solid mounts:

• Sold rear subframe bushes (RSB) - no increase in NVH.
• Solid diff mounts - no noticeable increase in NVH with an already installed sold diff brace. There would likely be some increased diff whine without a sold diff brace but would be bearable.
• Solid engine mounts - very minor (easily bearable) increase to NVH. Becomes unnoticeable.
• Solid trans mounts - introduces considerable NVH but just bearable.

YMMV depending on your tolerance level for NVH.

[Redd]

135 is yours DCT or 6MT?

[135]

Originally Posted by Redd

135 is yours DCT or 6MT?

6AT

[///Mobbin]

Originally Posted by ///Mobbin

I'm already considering going back to stock for the street

Still quite a bit of noticeable NVH, waiting on my raised idle tune to come in and will have some more thoughts to share after I try that out.

Truly brilliant on the track but perhaps a bit much for the street, current thinking at least.

Originally Posted by SQ13

I might be interested if you decide to sell.

So I ended up pulling the Turner 90A mounts out awhile back and am about to post them for sale, let me know if you are still interested, <1k miles on them and they still look new.

Back on OE engine mounts again, we'll see how long that lasts!

[SYT_Shadow]

Originally Posted by ///Mobbin

So I ended up pulling the Turner 90A mounts out awhile back and am about to post them for sale, let me know if you are still interested, <1k miles on them and they still look new.

Back on OE engine mounts again, we'll see how long that lasts!

Have you tried the BW solid rubber mounts? Other than idle they don't bother me at all, and idle you sort out increasing the rpm of your tune

[///Mobbin]

Originally Posted by SYT_Shadow

Have you tried the BW solid rubber mounts? Other than idle they don't bother me at all, and idle you sort out increasing the rpm of your tune

Originally Posted by ///Mobbin

I just installed the AKG 95A transmission mounts on my DCT M3, they are totally hilarious, I can actually hear the clutches engaging now. Totally concur with the track-car-only descriptor on the website. Love them for my purposes but I definitely wouldn't install these on a street car. The AKG 75D engine mounts are going in next week (OE engine mounts currently installed).

Originally Posted by ///Mobbin

Okay, so that was short lived. Even for a car I drive on the street ~4 times per month and to/from the track the AKG 95A transmission mounts were too much NVH for me. I reinstalled some new OE rubber mounts last night and I feel like I am in a brand new car now, world of difference, and this is with the AKG 75D engine mounts still in. I would seriously only recommend the poly transmission mounts for cars that are trailered to/from the track.

Interesting additional observation, my exhaust sounds way better w/ the OE transmission mounts. I detected a change when I installed the polys but didn't realize how drastic it was. Engine mounts only FTW, leave those transmission mounts stock folks!

So I guess I'm a glutton for punishment, have a track weekend coming up at MSRH with Chin and decided to temporarily re-install these poly transmission mounts, work has been slow and it only took an hour or so, figured why not. Brake feel w/o the poly engine mounts has not been as aggressive so hoping just the trans mounts will approximate them and they are much easier to install and remove depending on my mood. I also have a super comfy daily now, m340i, leaves room for more NVH in the m3 now. Need to order some poly AKG engine mounts next haha. :

[//steve\\]

I really need to get a sit in a totally stock M3 just to compare to mine.

My car has the Vibratechnic engine mounts, Group-N trans mounts, solid Diff and Subframe bushings. It makes noise but I can't say there is any kind of crazy NVH. Vibration is really the only part of NVH that tends to bother me as stuff just feels broken when it's excessive. The drivetrain feels super direct though which is really nice.

[///Mobbin]

Uhm yeah, so I've yet again determined the 95a transmission mounts are too much for the street. Leaving them in for the upcoming track weekend then fresh OE mounts going back in. Still searching for the ultimate street/track config though and just contacted AKG to see if their 80a engine mounts will work on our cars.

AKG 80a Engine Mounts

Will report back with what I hear!

Originally Posted by ///Mobbin

Or not! Unfortunately the bottom bolt broke off from one of the mounts during install and was rusty at the break-point. Bimmerworld would have sent me a new mount out right away but since they are backordered right now I'm getting a refund instead. The old mounts are now being reinstalled. Bummer but better that it broke now than later. Will revisit this purchase at a later date.

^The reason I haven't gone back to the Bimmerworld mounts yet btw.

[///Mobbin]

Pro tip on easy method for swapping transmission mounts. Jack and adaptor sold on Amazon, rubber pads borrowed from another tool. Fwiw the mounts felt great on track but not quite as nice as firmer engine mounts. Still of the opinion that the NVH is not worth it. Also, check out that clean DCT pan at 90k miles!!

[Kelse92]

Originally Posted by ///Mobbin

Pro tip on easy method for swapping transmission mounts. Jack and adaptor sold on Amazon, rubber pads borrowed from another tool. Fwiw the mounts felt great on track but not quite as nice as firmer engine mounts. Still of the opinion that the NVH is not worth it. Also, check out that clean DCT pan at 90k miles!!

I'm jealous of that clean DCT pan! Mine got a new pan and gasket and full service this time last year and I inspected it last week while doing some maintenance and it's already leaking
Also, thanks for the pics of the trans mounts swap. Something I'm tempted to try out at some point.... hmmmm

[kyippee]

Originally Posted by ///Mobbin

Uhm yeah, so I've yet again determined the 95a transmission mounts are too much for the street. Leaving them in for the upcoming track weekend then fresh OE mounts going back in. Still searching for the ultimate street/track config though and just contacted AKG to see if their 80a engine mounts will work on our cars.

AKG 80a Engine Mounts

Will report back with what I hear!

^The reason I haven't gone back to the Bimmerworld mounts yet btw.

How about revshift? I have their 80A transmission mount on my car (DCT)

[Redd]

Anyone had their Vibra-technics engine mount die on them. Mine are 2+ yrs 9k kms old and the right side one rubber is shredded.

Are they repairable?

[Rochen_00]

Originally Posted by Kelse92

I'm jealous of that clean DCT pan! Mine got a new pan and gasket and full service this time last year and I inspected it last week while doing some maintenance and it's already leaking
Also, thanks for the pics of the trans mounts swap. Something I'm tempted to try out at some point.... hmmmm

Check that it is not the O-ring located just above the side pan

Here you have more info:
https://www.m3post.com/forums/showthread.php?t=1697657

[///Mobbin]

Originally Posted by Redd

Anyone had their Vibra-technics engine mount die on them. Mine are 2+ yrs 9k kms old and the right side one rubber is shredded.

Are they repairable?

So Vibratechnics were the second engine mounts that I tried (long ago) and one mount failed on me after only one track day, I believe it was the passenger side mount. The top visible rubber melted and flattened down, it looks like that may be what happened to yours as well. The vendor I purchased them from made me send them in for inspection and ultimately gave me a refund. I had thought it was just a quality control issue and I got a bad mount but maybe others have had this issue as well.

[Redd]

Originally Posted by ///Mobbin

So Vibratechnics were the second engine mounts that I tried (long ago) and one mount failed on me after only one track day, I believe it was the passenger side mount. The top visible rubber melted and flattened down, it looks like that may be what happened to yours as well. The vendor I purchased them from made me send them in for inspection and ultimately gave me a refund. I had thought it was just a quality control issue and I got a bad mount but maybe others have had this issue as well.

Damn. I've written in to VT US and UK and no reply yet. What mounts are you on now Mobbin?

[///Mobbin]

Originally Posted by Redd

Damn. I've written in to VT US and UK and no reply yet. What mounts are you on now Mobbin?

I'm back on OE engine mounts for now and think I will try the Powerflex "Street" mounts next. I think they have two different urethane components, one piece that is 65a and one that's 80a, intrigued by the design point. Man I don't want to do this job again but the car just feels so much better with upgraded engine mounts on track, think I may need to try these.

[//steve\\]

I have them in my car but no complaints or issues that make me feel like I need to check them. That said, I intend to have the car on stands soon to do some maintenance (and likely test pipes) so I'll try to take a look.

[Redd]

Originally Posted by ///Mobbin

I'm back on OE engine mounts for now and think I will try the Powerflex "Street" mounts next. I think they have two different urethane components, one piece that is 65a and one that's 80a, intrigued by the design point. Man I don't want to do this job again but the car just feels so much better with upgraded engine mounts on track, think I may need to try these.

Yeah I've got the Powerflex Street mounts in my shopping cart right now cos I think the VT mounts are a material/design problem and even if VT replace them for me I don't think I want to continue using them. I'll try to get a refund but mine are over 2 years old, so...

The Powerflex mounts look interesting especially with the lifetime warranty.

[Mr_Reeves]

You guys should look into the BW Group N mounts. I have them on mine and so far very impressed. They are about 30% stiffer than the OE mounts and follow the same design ethic but improved so that the metal thread does not shear from the rubber bushing so will outlast even OE mounts.

NVH increase was marginal but turn-in was sharper and the feeling of the power delivery was more direct.

I agree with Mobbin about NVH of stiffer gearbox mounts however. I have the Revshift 80A 'OEM+' mounts in my 6MT and I'd say they are just about on the very edge of what is acceptable for the street. I have an RTD shifter though so wanted precision over anything else. I'd be interested to see what the car is like back in the OE gearbox mounts again though...

[rhyary]

Originally Posted by Mr_Reeves

You guys should look into the BW Group N mounts. I have them on mine and so far very impressed. They are about 30% stiffer than the OE mounts and follow the same design ethic but improved so that the metal thread does not shear from the rubber bushing so will outlast even OE mounts.

NVH increase was marginal but turn-in was sharper and the feeling of the power delivery was more direct.

I agree with Mobbin about NVH of stiffer gearbox mounts however. I have the Revshift 80A 'OEM+' mounts in my 6MT and I'd say they are just about on the very edge of what is acceptable for the street. I have an RTD shifter though so wanted precision over anything else. I'd be interested to see what the car is like back in the OE gearbox mounts again though...

Is there any benefit to a DCT going with that 80A stiffer trans mount?

If I understand correctly the stiffer mount for a manual allows you for a more precision lining up the gears for quick shifting under load.

But what about for DCT?

I am bringing this up because my motor mount are Turner 90A and while I feel the vibration, I like it and my car is not daily.

If I install the 80A on the DCT mount and the added vibration kind of add to the harmony of vibration, that would feel more sporty to me.

Short version:
Is stiffer trans mount 80A beneficial to DCT if I don't mind the vibration?

[rhyary]

@///Mobbin,
If I like the 90A motor mount, do you think I would like the 95A trans mount?

[Mr_Reeves]

Originally Posted by rhyary

Is there any benefit to a DCT going with that 80A stiffer trans mount?

If I understand correctly the stiffer mount for a manual allows you for a more precision lining up the gears for quick shifting under load.

But what about for DCT?

Good question. I'm not sure about DCT. My reason for choosing stiffer transmission mounts were, as you suggest, to give more precision to the shift action and ensure secure location of the shifter when in gear.

If that benefit is not there with a DCT then I would not imagine it being necessary or desirable.

Maybe one of the DCT guys can chime in on this one.