Solid Subframe Mounts - Any Differences?

[wyatth]

I keep thinking about solid subframe bushings/mounts based on the rave reviews on the forums. The worst reviews seem to be “not that noticeable,” which, for the cost of parts/labor, would be a shame. But on the other hand, it seems like one of the few no-lose/win-win changes one can do to the car. I am happy with my ZCP suspension with Dinan camber plates and sway bar, and think this could round it out (just a weekend fun car). At 52K there’s not a lot of justification for it from the maintenance side of things, but that could also keep the total bill in check (unless I go down the path of “Oh, carbon driveshaft while you’re in there...”).

Im curious if there’s any difference in the bushings/mounts offered by the various reputable manufacturers. They all look slightly different, but presumably work the exact same. So what gives? Probably few have any experience handling or installing different examples but worth a shot asking if any of them are better (wider footprint/chassis support? easier install?) than others.


Bimmerworld




AKG




Turner



... and of course there’s MRF, MS, etc ...

[Redd]

Do it. It's one of the best mods I've ever done, with no downsides and it makes your chassis feel 1 generation younger. I swapped cars with my friend during a hill drive this past weekend. The first thing he noticed was how much more planted my car was. The first thing I noticed about his car on stock rubber subframe bushings was how unsettled it was in the middle of a turn. If I ever get another M3, solid subframes will be the first thing I do.

All solid subframe bushings should be the same. I've not heard of any of them giving issues. Fwiw, I went with Turner and have no complaints.

[Atomicteal_M3]

I have a brand new set of Bimmerworld solid subframe bushings if anyone is interested.

[Helmsman]

Still after Victors report?

https://www.m3post.com/forums/showthread.php?t=1633323

[Not Sure]

definitely worth it. i went with Turner. car feels amazing and should have come this way from the factory.

[roastbeef]

They make a big difference.

[amrazM]

You may want to consider doing a rear sway bar while youre in there, I ended up getting AKG because I couldn't get a response from MRF. AKG bushings are good, they aren't too hard to slip into the subframe.

I did SF, diff, carbon driveshaft and RSB at the same time plus all the bushings in the rear subframe. The car has become noticeably tighter at the rear. Stock form when the car oversteered it would feel like the car would snap out at the back, its much more controlled and neutral feeling now.

[tom @ eas]

Makes a fantastic difference upgrading to solid.

[wyatth]

Originally Posted by Helmsman

Still after Victors report?

https://www.m3post.com/forums/showthread.php?t=1633323

Victor and SYT Shadow are the 2 people who said it wasn’t really noticeable. And I trust their impressions. But then 100 other people say it’s their favorite mod. Soooo..... maybe everybody else was on a bad alignment before? No idea, lol.

[Vybz]

I don't know about my favorite mod, but the difference is 100% noticeable. The amount of wheel hop on stock bushings is horrifically unacceptable, and if you take your car to the track or have ever hard launched your car there is NO WAY you could not notice.
If your car is a weekend fun car/ daily driver with no intention of ever really being pushed; I don't see a reason to do this mod. Differential whine is a reality, it's not crazy loud, but it's definitely noticeable and the average joe doesn't like hearing mechanical whining from the back of his/her car.

BUT... being someone who snapped a differential bolt at the drag strip (due to the excessively violent wheel hop of the stock rubber bushings) , if you do track/push your car, this mod is not only peace of mind but a VERY significant upgrade/reinforcement of the subframe. Ever since that day, I installed solid aluminum bushings and have never looked back. Wheel hop COMPLETELY eliminated, power goes straight to the ground. Not my favorite mod, but definitely one I couldn't live without. Difference is night and day.

[VictorH]

Good discussion. Yes, I'm one of the doubters as to the overall benefit of this modification. I also happen to be a logical, sequential guy and try to modify my vehicles to enhance performance ( I figured my bushings would be worn out at the mileage and use I had which is why I replaced the stock ones). My questions
1) If your car feels more planted, stable etc, what was the effect on lap times when all other factors have been held stable?
2) Are there any other objective, measurable improvements you can attribute to the solid sub-frame bushings?

I suspect we are perhaps in a bit of a "I like the sound of this muffler, better than that muffler." Each of us has a preference, and maybe solid bushings "feel better" but I challenge anyone to show me objective data that these are in fact a measurable performance enhancing modification.

It's okay we all like to feel good about changes we make to our cars. I've done the subframe bushings and I drive my car almost every day except weekends (those are the track days), I'm happy with the change, but it's a big investment in labor for something that might not have effect on anything other than "feel."

[DRLane]

Originally Posted by VictorH

Good discussion. Yes, I'm one of the doubters as to the overall benefit of this modification. I also happen to be a logical, sequential guy and try to modify my vehicles to enhance performance ( I figured my bushings would be worn out at the mileage and use I had which is why I replaced the stock ones). My questions
1) If your car feels more planted, stable etc, what was the effect on lap times when all other factors have been held stable?
2) Are there any other objective, measurable improvements you can attribute to the solid sub-frame bushings?

I suspect we are perhaps in a bit of a "I like the sound of this muffler, better than that muffler." Each of us has a preference, and maybe solid bushings "feel better" but I challenge anyone to show me objective data that these are in fact a measurable performance enhancing modification.

It's okay we all like to feel good about changes we make to our cars. I've done the subframe bushings and I drive my car almost every day except weekends (those are the track days), I'm happy with the change, but it's a big investment in labor for something that might not have effect on anything other than "feel."

Wouldn't the strongest indicator be that all the M vehicles post the E generation come stock with directly bolted subframes? It's an investment, but very DIY'able if you have access to a lift.

[Redd]

Are solid subframes faster? I don't know. If you're a good driver and able to sense tire grip thru the hands and butt, then maybe you don't need solid subframes.

But for me, the solid subframes removed the rear end shimmy over rough surfaces and that helped inspire a lot more confidence in pushing the car. So for me it was a great mod.

[Bartledoo]

I did solid subframe bushings and poly diff bushings because I snapped a diff bolt and didn't want another. Wasn't expecting a big change but it was a huge difference in feel and wobble reduction. I've only tracked with the solid bushings so I can't compare, but I'm confident the added feel and stability enhances one's ability to go faster. Shit, fast people can go faster with something as simple as a better seat.

[Vybz]

I want to add on that when I say a completely solid rear end, I'm including the differential. Which is the source of differential whine, not the sub frame bushings.

Victor, I don't think it gets any more objective than going from a vehicle prone to wheel hop, with excessive movement of the rear subframe and diff, to modifying the bushings and completely eliminating both symptoms. If I had access to a stock e9x I'd literally attach a gopro to the rear and make videos of both so you could compare the two while being hard launched.

Who knows maybe I'll find someone willing to contribute their stock e9x for science.

[wyatth]

I don’t launch nor track so wheel hop isn’t a concern, nor are faster lap times. I just appreciate a solid chassis, and the comments addressing lateral shimmy over imperfect roads are of particular interest.
I installed AKG 95A subframe and differential bushings in my 6MT E46. The subframe did feel nicer, but modest, so I’m hoping solid makes it more worthwhile. The 95A whine was minimal but I plan on stock differential bushings for this car (DCT).
I do like the ZCP setup and don’t have interest in adding other monoballs or doing much else. Conceptually I can see the solid subframe “getting the most out of” the current setup, but I’ve also read “it highlights the shortcomings of the stock suspension” and along the lines of “stock subframe isn’t holding you back if you’re on less than the best coilovers.”

[Not Sure]

you are overthinking this. i paid a lot to get them installed and would do it again in a heartbeat. 100% worth it. stock ZCP suspension, stock differential bushings, DCT. street use only.

[Redd]

You will notice solid subframes on street driving more than track driving cos track surfaces are perfect. There's not much to unsettle a car mid corner at the track. On the street however, every little rut, dip, manhole cover and expansion joint makes the back end wiggle if you have some steering angle. Solid subframes get rid of this wiggle.

[aus]

Most people will like what they put a lot of money into buying.
I always take that into consideration when gathering advice.
I'm interested in this as well, but no willing to spend the money on it yet. I'm a decent drive at the track but there are guys who are considerably faster. I do feel the rear hop around a little over bumps and shimmy under hard braking, but it's only at track speeds. Not worth it for me yet.
.

[romero1990]

also interested to know more. as mine approaching 130K, I suspect there is a whole bunch things to keep an eye on and replace altogether. For me it's gonna be one of those do it all while down there, and the choice of components becomes important.

[wyatth]

Originally Posted by Not Sure

you are overthinking this.

I tend to do that! But your setup speaks to me, thanks!


At 130K I’d probably go in with a full refresh list and justify it as a maintenance/mod combo.


Now to figure out how/why all of these offerings do the exact same thing while looking so different.

[Redd]

Originally Posted by aus

Most people will like what they put a lot of money into buying.
I always take that into consideration when gathering advice.
I'm interested in this as well, but no willing to spend the money on it yet. I'm a decent drive at the track but there are guys who are considerably faster. I do feel the rear hop around a little over bumps and shimmy under hard braking, but it's only at track speeds. Not worth it for me yet.
.

Go drive a car with solid subframes. It's immediately noticeable.