[tylerhart_21]

Man, I am glad I waited to do the subframe bushing, then I wouldn't have known this. I just have two questions about the inserts, do I need to do an alinement after installing them or not, and compared to stock how do they feel?

[Jaronbwall]

tylerhart_21 Yep good call to come in here. There's some click-bait videos out there promoting full aluminum but it's not worth it. M3 or poly is the best. I'd get an alignment completed. It's smarter than ruining good tires.

[whyzee125]

Originally Posted by tylerhart_21

Man, I am glad I waited to do the subframe bushing, then I wouldn't have known this. I just have two questions about the inserts, do I need to do an alinement after installing them or not, and compared to stock how do they feel?

Just wanted to second the above opinion, you definitely need an alignment afterwards. I don't know how they feel but I gaurantee you that's a better move than solid aluminum.

[tylerhart_21]

Jaronbwall Well do, I will see if I can buy and install them before I get my new tires on. Just didn’t know cause you are unbolting and rebolting the subframe.

[tylerhart_21]

I know Phil325i did the inserts, just waiting on what he thought about them and were they worth it. Right now I am going to add the m3 front sway bar and the Dinan camber plates. Was on the edge with getting the subframe bushing since I am going with an Alpina style suspension set up.

[LivingLegend06]

I just came here to say that I also recently installed solid aluminum rear subframe bushings. I went with the 2 piece revshift bushings for the easy(er) install. My car is on completely stock suspension (msport 135i), I've been pretty happy with how the stock suspension rides and handles, I just didn't like how squirmy the rear gets under power or transitioning into hard harnering.

Not only did the aluminum bushings fix the squirmy rear end for me, but there was no change in ride quality or NVH. I'm not a "hardcore racer" type or someone who feels the need to justify my purchases to myself. I don't listen to loud music. I've purchased coilovers before and then swapped back to stock suspension after a few weeks because they were too harsh. I've done bushing in a handful of different BMWs in the past and always gone with oem rubber or "M" spec. I had read enough good things about the aluminum subframe bushings that I decided to try them, and I really don't think there is a downside to them. I think it's possible that there might be something else wrong with OPs car.

To be fair, I did change from summer to winter tires at the same time (exact same sizes on another set of stock wheels), and did a few other maintenance items so my car was down for about a month, so it wasn't exactly a back to back comparison, but I'm totally happy with how it rides and the NVH. I just rode in my father's E46 M the other day and was blown away by how much more road noise he has, on totally stock suspension and all season tires.

[whyzee125]

Originally Posted by LivingLegend06

I just came here to say that I also recently installed solid aluminum rear subframe bushings. I went with the 2 piece revshift bushings for the easy(er) install. My car is on completely stock suspension (msport 135i), I've been pretty happy with how the stock suspension rides and handles, I just didn't like how squirmy the rear gets under power or transitioning into hard harnering.

Not only did the aluminum bushings fix the squirmy rear end for me, but there was no change in ride quality or NVH. I'm not a "hardcore racer" type or someone who feels the need to justify my purchases to myself. I don't listen to loud music. I've purchased coilovers before and then swapped back to stock suspension after a few weeks because they were too harsh. I've done bushing in a handful of different BMWs in the past and always gone with oem rubber or "M" spec. I had read enough good things about the aluminum subframe bushings that I decided to try them, and I really don't think there is a downside to them. I think it's possible that there might be something else wrong with OPs car.

To be fair, I did change from summer to winter tires at the same time (exact same sizes on another set of stock wheels), and did a few other maintenance items so my car was down for about a month, so it wasn't exactly a back to back comparison, but I'm totally happy with how it rides and the NVH. I just rode in my father's E46 M the other day and was blown away by how much more road noise he has, on totally stock suspension and all season tires.

Thanks for sharing your experience! Glad your car doesn't sound like mine lol you'd be miserable. It could be a combo of mods in my case or my particular bushings (Bimmerworld vs revshift), but I don't think anything is wrong with my car. I have KW coilovers, Dinan RSM, etc. It's definitely not diff noise or bearing noise and the car was dead silent before. It's literally louder than a lifted Jeep with mud tires inside. Everything rattles and buzzes and the tone completely changed when I changed tires but it's still 100% obnoxious.

I've since also found out that Harold @ HPA, one of the most trusted suspension gurus for this platform strongly recommends against solid bushings due to the "massive increase in NVH" in his own words. AKG also says the same.

I think I'm going to the AKG 95A poly bushings or M3 ones.

[Wolf 335]

Originally Posted by whyzee125

Thanks for sharing your experience! Glad your car doesn't sound like mine lol you'd be miserable. It could be a combo of mods in my case or my particular bushings (Bimmerworld vs revshift), but I don't think anything is wrong with my car. I have KW coilovers, Dinan RSM, etc. It's definitely not diff noise or bearing noise and the car was dead silent before. It's literally louder than a lifted Jeep with mud tires inside. Everything rattles and buzzes and the tone completely changed when I changed tires but it's still 100% obnoxious.

I've since also found out that Harold @ HPA, one of the most trusted suspension gurus for this platform strongly recommends against solid bushings due to the "massive increase in NVH" in his own words. AKG also says the same.

I think I'm going to the AKG 95A poly bushings or M3 ones.

Guy's first post is a praise to revshift aluminum bushings. Seems legit.

[Tambohamilton]

Originally Posted by Wolf 335

Guy's first post is a praise to revshift aluminum bushings. Seems legit.

Guys 3519th post is trashing another seemingly legit post. Seems legit.

[Wolf 335]

Originally Posted by Tambohamilton

Guys 3519th post is trashing another seemingly legit post. Seems legit.

I appreciate your post.

[LivingLegend06]

Originally Posted by Wolf 335

Guy's first post is a praise to revshift aluminum bushings. Seems legit.

I honestly didn't realize this was my first post here. But yeah you caught me, I made this account 10 years ago just waiting for this day.

[whyzee125]

Originally Posted by LivingLegend06

I honestly didn't realize this was my first post here. But yeah you caught me, I made this account 10 years ago just waiting for this day.

Welcome! haha

[TyroneShoelaces]

Originally Posted by LivingLegend06

I honestly didn't realize this was my first post here. But yeah you caught me, I made this account 10 years ago just waiting for this day.

Playing the long con. Nice try spammer

[StradaRedlands]

I picked up some M3 subframe bushings, and hope to install them along with a full rear end rebuild. Aspirational goal, as it's going to take a lot of motivation on my part! Maybe a summer project. But they seem like the best route for a DD that is driven spiritedly.

[whyzee125]

Originally Posted by StradaRedlands

I picked up some M3 subframe bushings, and hope to install them along with a full rear end rebuild. Aspirational goal, as it's going to take a lot of motivation on my part! Maybe a summer project. But they seem like the best route for a DD that is driven spiritedly.

Nice dude, let me know how you like them! I haven't decided between M3 and AKG 95A, but I have some other maintenance I need to do in the meantime so I'll get there eventually lol

[Tambohamilton]

Originally Posted by whyzee125

Nice dude, let me know how you like them! I haven't decided between M3 and AKG 95A, but I have some other maintenance I need to do in the meantime so I'll get there eventually lol

Just go OE M3 and have done with it. They're plenty stiff enough for spirited driving, and probably transmit less NVH than all comparable competitors.

[M-technik-3]

Street car, no thanks, track oriented car that sees some street duty sure.

[StradaRedlands]

Originally Posted by whyzee125

Nice dude, let me know how you like them! I haven't decided between M3 and AKG 95A, but I have some other maintenance I need to do in the meantime so I'll get there eventually lol

I hear you on that... I need to pull the intake and do the full PCV/Starter/Sensor replacement sooner rather than later. Not really looking forward to that or the back end for that matter.

[carguy138]

OP I'd suggest having the rear end checked out, something doesn't add up. Might be a wheel bearing or differential bearing on the way out.

Was the driveshaft dropped during the install? If the center support bearing isn't properly loaded, it will sound exactly like what you are describing. Also if the rear differential was dropped and the driveshaft nut wasn't fully re-tightened, it could be binding.

FYI I have delrin subframe bushings and experienced no change in NVH. I did notice gear whine after I installed delrin differential bushings which became worse when I installed a rear differential brace.

When I installed the Wavetrac, I ended up removing the differential brace and am very happy with it now.

[whyzee125]

Originally Posted by carguy138

OP I'd suggest having the rear end checked out, something doesn't add up. Might be a wheel bearing or differential bearing on the way out.

Was the driveshaft dropped during the install? If the center support bearing isn't properly loaded, it will sound exactly like what you are describing. Also if the rear differential was dropped and the driveshaft nut wasn't fully re-tightened, it could be binding.

FYI I have delrin subframe bushings and experienced no change in NVH. I did notice gear whine after I installed delrin differential bushings which became worse when I installed a rear differential brace.

When I installed the Wavetrac, I ended up removing the differential brace and am very happy with it now.

They replaced the CSB at the same time and I did think of this, but this shop is pretty top notch so I really don't think they F'ed that up. It sounds like road/tire noise and not a bearing noise though anything is possible for sure. The fact that HPA and AKG (and the shop I used) recommend against it due to NVH makes me think I may not be crazy but of course I can't definitively say nothing's wrong with my car's rear end.

The thing is, everyone who says they like the solid bushings also say there's no added harshness and that's just simply not true either. I have a fairly soft suspension setup and absolutely no doubt about it, it's way harsher with the solid bushings. My gripe is the noise, but it's very noticeably harsher as well which a bearing wouldn't cause.

[jzx_andy]

OP, I'm sorry that this has resulted in a fail in your case.

What other mods do you have? While NVH is subjective, I find the question of how "noticeable" NVH from mods is highly dependent what you've done (or what you haven't done) to the rest of the car.

If your car is completely stock, oem exhaust, mounts, factory clutch etc, I would think some people would find certain mods almost intolerable in terms of NVH, due to how quiet a factory specification e9x is overall. Just imagine a bone stock e9x with upgraded engine mounts, it'd probably feel like something's out of place since the vehicle will really only resonate a lot of NVH while idling, and completely goes away the moment you accelerate/cruise. On the other hand, that sort of NVH would feel more "natural" on a car that's gone the whole 9 yards with a louder exhaust, rear end, tyres, etc. In the latter case, the vehicle would be louder than a stock e9x under all conditions - idle, load, cruising at speed, etc, but the noise wouldn't be coming from one area.

I would presume you perceive subtle changes in NVH quite well and/or have a very tame example of an E9x, given that you refer to all season street tyres as being "a little noisy". There is nothing wrong with this perception, though it is a useful reference point for when NVH becomes noticeable in your specific case.

That said, a lot of people who go for solid subframe bushings would have already done various other modifications that each increase NVH in their own way, such as an aftermarket exhaust, single mass flywheel, engine mounts, trans mounts rear shock mounts, coilovers, larger wheels, dual use road+track tyres, etc. These other modifications coupled together help to balance and, in effect, drown out NVH that's coming from one specific source.

I opted for PLM solid subframe bushings on a car that sees street use 99% of the time. I fitted them shortly after having done a bunch of other upgrades, inclusive of poly engine mounts (which I found add a noticeable amount of NVH and would recommend against from a cost vs benefit vs comfort analysis). The only item I've left alone at this point is the factory catback. All that said, I found the NVH increase from solid subframe bushings to be minimal and I'm ok with the upgrade.

Do let us know how you fare once you've replaced them for something else. All the best.

[carguy138]

Heat shield rubbing top of the driveshaft in front of the rear diff? Also take a look at the mounts and make sure the subframe is fully seated on the bushings.

For perspective, I had a BMW PE exhaust and sold it. Found it too loud (even with stock DP). I'm also running the stock dual mass flywheel (manual) and 335is engine mounts. I also found the stock runflats to be way too harsh and ditched those early on for michelin PSS tires.

all mods to give context (car feels like a stock E90 M3 in terms of NVH).
-koni yellows
-dinan springs
-poly front control arm bushings
-UUC front sway bar
-e90 m3 rear swaybar
-e90 m3 front strut tower brace
-e93 m3 rear chassis brace
-turner delrin subframe bushings
-turner delrin rear differential mount bushings (DID ADD NOISE but similar to a stock subaru STI)
-wavetrac LSD
-335is engine mounts
-PSS tires in summer/ blizzaks in winter.
-stock exhaust and stock downpipe.
-335is/550i clutch with DMF
-dinan front camber plates

everything else is stock.