Bushings

[spazzyfry123]

Car background:
2011 E90 M3 6MT base with OEM suspension (non EDC/ZCP) with about 60k miles on it.
After keeping it in the garage, I've realized that it's much more fun to grab these keys instead of the DD. So I sold the other car and made this my DD, and going into maintenance/upgrade mode to make the car a bit more reliable and solid. Rod bearings will hopefully be done by year's end, new spherical bearing shifter is being made...But a gripe of mine as I drive it more is the car feels a little...loose.

I have another thread that I think I should consolidate with this one and is better suited for this forum regarding a clunk I am experiencing if my shifts are not perfectly aligned (6MT) http://www.m3post.com/forums/showthread.php?t=1442238

I'm a bit sensitive to mechanical feeling in the car in the sense that I seem to always throw small "issues" out of proportion, but also sensitive in that I love the mechanical feedback from the car. The clunk I mention above may just be normal, but I'm not convinced. I am also noticing that when I let off the gas while driving that the car's behavior does not appear very solid. I won't say the car darts, but it seems to have a higher reaction to on/off throttle than I would expect. It certainly shifts around - drivetrain movements alter the car's balance. Again, I'm pretty sensitive to it and it's making me paranoid.

Now I'm sure that a lot of this could just be usual stuff, but what's a good recipe and things to generally go after to tighten the car up? It is a daily driver, but one with decently loud exhaust that will mask drivetrain whine and the lot. I want a solid car with plenty of feedback but not a go-kart on cinder-blocks when I go over a bump.

From what I've been finding, solid rear subframe mounts with upgraded Delrin-type differential bushings seem to be the go-to. I'd like to get your input on my specific scenario. Should motor mounts be addressed? What about control arms? Etc...

I should also mention that I am considering lowering the car, but I think a full KW V3 coilover setup or similar would be overkill on a car that sees road miles mainly with the occasional trip to the mountains and an AutoX weekend. I'd like to be planning ahead with what is done to the car so that I don't go back and change things around again when I come back to lowering the car. A system I was considering is KW's kit here since I'm pretty impressed with the OEM suspension https://www.kwsuspensions.net/produc..._/-/-/25320057

Long-winded, I know. What's everyone's take?

Thanks!
Tyler

[pbonsalb]

Definitely do stiffer rear subframe bushings. Makes an immediately noticeable difference. Beware solid or Delfina or 75D poly diff bushings — they will whine. My 95A poly diff bushings whine about as much as I would tolerate in a comfortable daily driver.

[spazzyfry123]

Originally Posted by pbonsalb

Definitely do stiffer rear subframe bushings. Makes an immediately noticeable difference. Beware solid or Delfina or 75D poly diff bushings — they will whine. My 95A poly diff bushings whine about as much as I would tolerate in a comfortable daily driver.

Thanks. Rear (and differential) seems to be the only one that I ever see mentioned. Are there other things that are generally changed/upgraded while this is happening? Would you recommend solid subframe bushings for the every day ride?

I really think I'll be focusing my "mods" on suspension and chassis bits over power. Car is pretty balanced, but I just wish it was a little tighter.

[pbonsalb]

I don’t think solid subframe bushings add much nvh. I used 75D poly mostly because they are a piece of cake to install. 75D is close to delrin. It’s the diff bushings that will whine if too hard.

I would check your suspension and replace any arms with worn bushings. The only ones I might upgrade for a street car are the front tension or strut rod bushings. Some people run slightly stiffer motor mounts — I tried Rogue but they added too much nvh at idle so I sold them. I would at least replace them with new Corteco mounts since they seem to be worn on most cars when changed - sometimes cracked and usually a little bit collapsed.

[spazzyfry123]

So talking with my shop today they will change out the motor and transmission bushings/mounts at cost with no added labor when they dig in to change out my rod bearings. I think this is a good start since I've read that our motor mounts tend to fail prematurely. Seeing that I'm just buying parts and no added labor, let's do it. What recommendations do you folks have for a street car that will see some fun time now and again? While I've never used it, AKG has been recommended to me in the past.

Motor: (75d too hard? I was only able to find these in this hardness)
https://www.akgmotorsport.com/produc...yurethane-75d/
Transmission: (I'd imagine the transmission and motor mounts should match; but I only see 95a on their site)
https://www.akgmotorsport.com/produc...ly-95a-e9x-m3/

As a separate question, seeing that quite a bit (labor) is involved to change the rear subframe bushings over to solid, what other items are generally good to get done while you're in there? Would now be a good time for a different sway bar for example?
I'm going to replace the differential bushings as well as change its fluid/seals. Other (very helpful) threads on a similar subject recommend aluminum subframe and Delrin differential - agree?

Subframe: (Solid aluminum)
https://www.turnermotorsport.com/p-4...e82-1m-e9x-m3/
Differential: (95a a good choice? Or will I need to replace these "frequently"?)
https://www.akgmotorsport.com/produc...yurethane-95a/

I'm a big believer in making the most of time while you're in there. I'd like for whatever approach I take for it to be as much of a "do it and forget it" type deal so that I'm not replacing bushings every 30k miles. This is why my '71 Honda CB is 100% completely disassembled in the garage when all I wanted to do was change out the ignition system...

[pbonsalb]

If it’s a street car, I think if you put in 75D motor mounts and 95 trans mounts you will be paying for labor to take them out pretty soon and parts and labor to install softer mounts in those locations.

[spazzyfry123]

Originally Posted by pbonsalb

If it’s a street car, I think if you put in 75D motor mounts and 95 trans mounts you will be paying for labor to take them out pretty soon and parts and labor to install softer mounts in those locations.

As you can tell, this is new for me. Is the best solution to change out to OEM? I've seen the "Group N" style as well, but don't really understand why one way or another.

[pbonsalb]

For street motor mounts, I would do OEM, which is made by Corteco, or maybe Bimmerworld Group N replica or maybe Vibra Technic Street mounts. I would want to ask someone about the Bimmerworld mounts before buying them. People say the Vibra Technic Street mounts are fine. I went with Corteco after trying Rogue and finding they added too much NVH.

Trans mounts don’t seem to wear like motor mounts. I changed my motor mounts at 60k and they were slightly collapsed — a little shorter than new ones. My trans mounts at 90k felt just like new ones. And new ones are very soft. I am about to try 80A trans mounts — I’ll install them this weekend. I think they may be too stiff but I decided to give them a try. I’ll know more in a few days.

[Dan Bilzerian]

Strongflex Poly Bushings!!!!!

[spazzyfry123]

Originally Posted by pbonsalb

For street motor mounts, I would do OEM, which is made by Corteco, or maybe Bimmerworld Group N replica or maybe Vibra Technic Street mounts. I would want to ask someone about the Bimmerworld mounts before buying them. People say the Vibra Technic Street mounts are fine. I went with Corteco after trying Rogue and finding they added too much NVH.

Trans mounts don’t seem to wear like motor mounts. I changed my motor mounts at 60k and they were slightly collapsed — a little shorter than new ones. My trans mounts at 90k felt just like new ones. And new ones are very soft. I am about to try 80A trans mounts — I’ll install them this weekend. I think they may be too stiff but I decided to give them a try. I’ll know more in a few days.

Just ordered Bimmerworld Group N mounts to replace while I'm swapping over to BE bearings. Of course the mounts are also on backorder like the bearings......

Can't wait!

[pbonsalb]

Originally Posted by pbonsalb

Trans mounts don’t seem to wear like motor mounts. I changed my motor mounts at 60k and they were slightly collapsed — a little shorter than new ones. My trans mounts at 90k felt just like new ones. And new ones are very soft. I am about to try 80A trans mounts — I’ll install them this weekend. I think they may be too stiff but I decided to give them a try. I’ll know more in a few days.

I am not liking the 80A poly trans mounts. Noticeable vibration above 2000 rpm and particularly in the 2000-3000 rpm range that is hard to avoid in daily driving. I will be removing them. They would be fine for a track car or a car that gets driven to the track but I personally would not want to drive with these every day. It’s a nice comfortable car - why make it do yo don’t want to drive it as much?

[spazzyfry123]

Originally Posted by spazzyfry123

Just ordered Bimmerworld Group N mounts to replace while I'm swapping over to BE bearings. Of course the mounts are also on backorder like the bearings......

Can't wait!

ETA on Group N motor mounts... Late January delivery.

Anyone have a good alternative? I liked what Group N (Bimmerworld's, not the actual $800 mounts) had to offer for the price. An upgrade over OEM, but not teeth rattling.

[pbonsalb]

From everything I have read, the only other mounts to consider for a street car would be the vibra technics fast road.

[e46e92love]

First, you can check your motor mounts for wear easily. If she has been in the garage most of her life and not driven that hard, even at 60k miles motor mounts may be fine, so changing will make no difference. Everyone will pretend to be experts and tell you they must be gone, but mine and others are fine after more miles than you and more track time. YMMV.

Regarding bushings and suspension?-no reason to go with a three way coil-over like some have suggested. If nothing else most of the forum loves to spend $$$ thinking more is better, it's not. If you plan to set and forget, three ways are a waste, if you plan to track more you better be a suspension tuning guru or going from street to Limerock to Pocono (for example) is gonna be frustrating. Everyone will say I'm an idiot, then you will get lapped (in your times) by guys with supposedly "inferior" two ways who are WORSE drivers. No bueno.

Also remember, which it sounds like you already got figured out, suspension is built from the ground up. Using stock bushings and then cranking your coil overs to the hardest setting to get that taught feeling doesn't actually do what you want other than lead to early wear on your expensive after market shocks. You need a good base which is where control arms, bushings, etc come in as others have said.

Despite what companies will try to sell you there is still trade off between street performance and track performance. With your car being mostly street driven and it sounds like you are trying to avoid nvh I would highly recommend thinking twice before going to solid rear bushings or harder bushings on your diff / subframe.

I did a full suspension overhaul replacing everything worn including ALL bushings. No one here would probably care about my setup but if interested PM me. I track 7-10 Days a year and daily drive her ass to keep that S65 working. 75k on the odo and she still purrs better than ever, from Limerock to black rock (a street near me?).

Good luck, and again, PM with any questions, be happy to discuss details, my setup and trade offs.

Cheers,
e46e92

[atopa2002]

Do sway bars , at least the front sways, swift lowering springs , shortened one top camber plates or whatever they call them and e36 bump stops transformed my car .
There is a tread for this transformation , look for it .