[feuer]

Originally Posted by Torgus

Weird I have zero NVH from my subframe bushings...

Originally Posted by Tambohamilton

I got a noticeable amount just from M3 ones

With various parts changed vehicles end up with different frequencies so some get NVH and some don’t.

[feuer]

Originally Posted by whyzee125

Here's a video at normal highway speed: https://www.youtube.com/shorts/m0L3NVsXTG8

That’s really bad. What else you have done from suspension work in the rear?

[Tambohamilton]

Originally Posted by whyzee125

I genuinely appreciate that! It seems to be really amplified road noise/resonance through the cabin. It changed in pitch quite a bit when I switched from Michelin to Continental tires so I think the majority of it's just tire noise that's now being transmitted to the car somehow. Really not sure why it's so much louder in my case than others.

You have the Turner bushings right? The shop (Kadunza in Knoxville, TN) installed Bimmerworld aluminum bushings in my car. They look similar in design but could have different amounts of surface area or something that's causing the difference.

Here's a video at normal highway speed: https://www.youtube.com/shorts/m0L3NVsXTG8

Only watched the video now. You've got a bad wheel bearing or something. Does the noise change when cornering?

[whyzee125]

Originally Posted by Tambohamilton

Only watched the video now. You've got a bad wheel bearing or something. Does the noise change when cornering?

Nope. Zero change in corners, zero change on/off throttle. No noise while spinning in the air on jacks. Everything is definitely installed correctly too, I've been under there many times. Also changed in frequency significantly when I switched tire brands.

[whyzee125]

Originally Posted by feuer

That’s really bad. What else you have done from suspension work in the rear?

KW street comfort, Dinan rear shock mounts, M factory LSD with new stock bushings. Everything else suspension wise is stock.

[feuer]

Originally Posted by whyzee125

KW street comfort, Dinan rear shock mounts, M factory LSD with new stock bushings. Everything else suspension wise is stock.

Have you checked that LSD ? M Factory had issues with bolts coming loose. That noise you got there is very bad and loud.

[GnomeChild]

Originally Posted by feuer

Have you checked that LSD ? M Factory had issues with bolts coming loose. That noise you got there is very bad and loud.

Wonder if he would have had this problem going M3 LSD......... (only teasing! )



Anyway, I digress. Sorry to break up the party but I got a PM with some questions on this retrofit and just thought it'd be good to share just in case, who knows, 5 years down the line when we all have our e93 braces installed and have abandoned this thread, people can find thorough answers quickly without having to ask the same questions

It should just be plug and play. E93s already have a similar brace in place from the factory that can possibly just be swapped out for the beefier M3 version

The Thrust brace (circled in blue) from what I know, requires spacers on an e90. If the e93 has a similar or same gas tank, it will probably also require the spacers but since the e93 is based of the e92 and e92s have a smaller thrust brace from factory there is a good possibility the M3 version may be bolt-on, no spacers required. I am going to try and install it without, but am fully expecting to order spacers if need be

Cheers fellas

[Torgus]

I watched the video. Something is fucked up. I did solid diff bushings at the same time as the subframe and I do get diff whine but that is it. Literally no NVH, holy hell that is loud as fuck in that video I wouldn't drive a car that had NVH like that. The only suspension mod I had at the time was lowering springs. I don't see how subframe bushings can make that much noise.

BMW has moved to solid mounts on the F10 M5 and F8X M3/M4 and even more models.

You changed tires you said, did they have any issues balancing the wheels? Did they road force balance them? Can you get them road force balanced? It almost sounds like a bent rim or suspension component, granted internet troubleshooting from a 2 second video clip is basically impossible. Does the sound change based on RPM or speed? Do you get the same NVH going slow at say 25 mph? Any chance you can throw on someone else's rims and go for a quick drive? If the rims fix it then someone from the shop took your car on a joy ride and hit a big pothole or did something else equally stupid and fucked up.

The subframe bushings have no effect on up and down, just left and right movement of the subframe, if that makes sense. The bolts that attached the subframe have the same clamping force regardless of bushing material. You should not be able to tell the difference going straight on a flat road at a constant rpm between stock and solid subframe bushings. There is zero deflection on a flat road. When the rubber bushings would normal deflect, that is when you will 'feel' the difference. Taking a corner, going WOT(assuming you are making decent WHP), etc. Times when the rubber bushing would 'give' and deflect. Straight flat road, zero deflection.


Per the bimmerworld website: "Most of the NVH is absorbed through other rubber bushings in the suspension. Customers who use these on the street have not reported any additional ride harshness with solid subframe mounts. What you will notice is that the rear suspension feels planted and more stable - which is exactly what you want!"

[whyzee125]

Originally Posted by feuer

Have you checked that LSD ? M Factory had issues with bolts coming loose. That noise you got there is very bad and loud.

Yup, happened to mine and was replaced with the new bolts. It was dead silent before the bushings. I'm obviously not infallible so there very well could be something up, but it's not noisy running on jack stands. It also completely changed when I switched tires, the michelins make more of a "tatatata" sound whereas the Contis make more of a "GrrRrrRrr" sound lol.

I thought I was crazy until I saw a few people like Harold @ HPA and AKG say these add a ton of NVH. I'd been investigating everything I could think of under the car at that point and all seemed good so once I found out that some others have had the same experience I chalked it up to just being the combination of these bushings on my particular car.

Oddly, I also got an increase in vibration and harshness which most others seem to say they did not, but those aren't significant. Just the noise.

[whyzee125]

Originally Posted by Torgus

I watched the video. Something is fucked up. I did solid diff bushings at the same time as the subframe and I do get diff whine but that is it. Literally no NVH, holy hell that is loud as fuck in that video I wouldn't drive a car that had NVH like that. The only suspension mod I had at the time was lowering springs. I don't see how subframe bushings can make that much noise.

BMW has moved to solid mounts on the F10 M5 and F8X M3/M4 and even more models.

You changed tires you said, did they have any issues balancing the wheels? Did they road force balance them? Can you get them road force balanced? It almost sounds like a bent rim or suspension component, granted internet troubleshooting from a 2 second video clip is basically impossible. Does the sound change based on RPM or speed? Do you get the same NVH going slow at say 25 mph? Any chance you can throw on someone else's rims and go for a quick drive? If the rims fix it then someone from the shop took your car on a joy ride and hit a big pothole or did something else equally stupid and fucked up.

The subframe bushings have no effect on up and down, just left and right movement of the subframe, if that makes sense. The bolts that attached the subframe have the same clamping force regardless of bushing material. You should not be able to tell the difference going straight on a flat road at a constant rpm between stock and solid subframe bushings. There is zero deflection on a flat road.


Per the bimmerworld website: "Most of the NVH is absorbed through other rubber bushings in the suspension. Customers who use these on the street have not reported any additional ride harshness with solid subframe mounts. What you will notice is that the rear suspension feels planted and more stable - which is exactly what you want!"

Thanks for the reply! I had both sets road force balanced--the Michelins were installed before the bushings and balanced great--one didn't even need weights! The noise started when I did the bushings but it sounded like amplified tire noise so I went back to the Continentals which were a little quieter. It did reduce the noise some but mainly just changed the pitch of the noise.

I agree, the subframe doesn't move under normal straight driving but I think the OEM design does have the subframe sort of 'suspended' in the rubber where some noise and shock could be absorbed. Yes, mine's noisy even at 25mph. It's pretty bad at every speed.

To be clear I'm not arguing, I'm just at a loss as to why mine is so loud and I'm jealous yours is so quiet haha. I've since found a few posts like the one below that make me think my car is fine but I could be overlooking something. Everything was 100% quiet before the bushings though.

https://www.m3post.com/forums/showpo...8&postcount=29

[Torgus]

HPAutosport knows their shit. This is so weird. If you were local I would force you to take my car for a spin. If my car sounded like yours I would never drive it.

There is a right and wrong way to install the bushings fwiw:



There is a flanged face on them.

From the turner install instructions:

C. Each mount needs to be pressed in from the bottom of the sub-frame (the flange on the mount faces
the ground) NOTE: The factory BMW bushings where installed the opposite way (from the top of
the sub-frame).


Bimmerworld: "Both front and rear aluminum subframe mounts install with the flange on the bottom. This may be different
than the stock mount orientation that may have the flange on the top. The “stopper” washer originally used
on the bottom is not re-used."


It is interesting bimmerworld says their bushings are for all E9X where as turner has separate ones for the m3 and non M e9x.

[whyzee125]

Originally Posted by Torgus

HPAutosport knows their shit. This is so weird. If you were local I would force you to take my car for a spin. If my car sounded like yours I would never drive it.

There is a right and wrong way to install the bushings fwiw:



There is a flanged face on them.

From the turner install instructions:

C. Each mount needs to be pressed in from the bottom of the sub-frame (the flange on the mount faces
the ground) NOTE: The factory BMW bushings where installed the opposite way (from the top of
the sub-frame).


Bimmerworld: "Both front and rear aluminum subframe mounts install with the flange on the bottom. This may be different
than the stock mount orientation that may have the flange on the top. The “stopper” washer originally used
on the bottom is not re-used."


It is interesting bimmerworld says their bushings are for all E9X where as turner has separate ones for the m3 and non M e9x.

Haha I wish I could so I could see what I'm missing! It's super weird indeed. Just checked and mine are all pressed in from the bottom.

[Simbl]

The e91 has a similar brace that may be more likely to fit. Either way looking forward to hearing if it makes any difference to drive. Keep us updated!

[GnomeChild]

The bolts have arrived from ECS but I have been shuffling my feet getting around getting to "installing" them

Pressing personal circumstances and different mods/maintenance have taken precedence over this one. It's very low on the priority list but hopefully sometime next week I can confirm "fitment" of it at least off the car

[Simbl]

Any news of the fitting of the rear e93 brace. Thinking of doing it myself.

Trying to find as many braces as possible to stiffen the chassis up. You look the f and g series cars and the have so much bracing.

[GnomeChild]

No, unfortunately this is super low priority, I probably won't get around to it at least until I do the M3 rear end LSD/subframe swap and even then it will probably be after. Frankly I have also been slacking on the bolt confirmation aspect. I got those in months ago but never fitted the bolts/crossbars together to confirm. Oops

Will get around to it one of these days (hopefully)
Too many projects I'm juggling all at once. Just taking things one mod at a time

It has been done before, so there is no issues on if it can be done, it's just an issue of no documentation on the work involved

[Raimund]

Originally Posted by GnomeChild

I still like these a lot. Maybe the best part about it is how it will tuck away behind the trunk liner and be completely invisible. A dedicated aftermarket cross brace would probably be more effective but would probably signal to everyone that my priorities may not be in order and that I spend too much on my car. Plus it would surely interfere with the use of my fold-down rear seats I spent nearly $1000 installing a few years ago

I definitely spend too much money on my car but I surely don't want anyone being able to tell just from looking at it

I am about to install these braces in my E90. The holes line up perfectly, the fabric liner just needs to be trimmed and rivnuts added into the holes.

E92 showing where the fabric is trimmed


E92 brace held up to an E90

[The Nightman]

Originally Posted by Raimund

I am about to install these braces in my E90. The holes line up perfectly, the fabric liner just needs to be trimmed and rivnuts added into the holes.

E92 showing where the fabric is trimmed


E92 brace held up to an E90

Let us know if you find rivnuts that fit. I think it was attempted and the best solution was to weld in retaining nuts.

It was also found that these were unnecessary on the E90 as only coupes had them. Even the E90 M3 does not have these while the E92 M3 does.

[neilvan]

I've done it on 2 cars; still 1 more to go.

You want wide flange riv nuts. The hole isn't perfect for anything so just keep it centered. I reused the factory bolts for it

[Raimund]

Originally Posted by neilvan

I've done it on 2 cars; still 1 more to go.

You want wide flange riv nuts. The hole isn't perfect for anything so just keep it centered. I reused the factory bolts for it

Thanks for the feedback. Where did you buy your rivnuts and which size did you use?

[Raimund]

Originally Posted by The Nightman

Let us know if you find rivnuts that fit. I think it was attempted and the best solution was to weld in retaining nuts.

It was also found that these were unnecessary on the E90 as only coupes had them. Even the E90 M3 does not have these while the E92 M3 does.

Yeah true. I got them for free so no loss to install besides a few bucks and 1 pound gain. I mainly wanted to test fit them to see if the rear k braces available for the e92 would bolt it to secure my rear seat delete to

[Simbl]

Originally Posted by GnomeChild

No, unfortunately this is super low priority, I probably won't get around to it at least until I do the M3 rear end LSD/subframe swap and even then it will probably be after. Frankly I have also been slacking on the bolt confirmation aspect. I got those in months ago but never fitted the bolts/crossbars together to confirm. Oops

Will get around to it one of these days (hopefully)
Too many projects I'm juggling all at once. Just taking things one mod at a time

It has been done before, so there is no issues on if it can be done, it's just an issue of no documentation on the work involved

I was actually talking about the e93 and e91 underbody rear brace that is pictured at the start of the thread.

Nobody has fitted them as far as I can see.