[Fundguy1]

Ok, so here's the basic setup.
Kw v2 coilovers, M3 front toe arms, rear diff lock(if I can find one)
Stock sport suspension
I see a lot of guys using M3 subframe bushings. Some guys using powerflex. I'm looking to get handling better than an M3, but not ride like a bucket. I drive this daily up to. 7 hours. I don't need too harsh. So what's the best bet. Go with M3, powerflex yellow? purple? What other suspension components, bushings should I replace and with what? I've got 202,000 miles so far. Need to order whatever this weekend.

[Stucks]

m3 subframe bushings are stronger rubber than oem e9x non m bushings, powerflex/whiteline/nolathane are polyurethane. if i had to estimate the durometer of oem e9x m3 subframe bushings, id say around 70a. oem 335i bushings are around 45a-50a i think. whiteline/nolathane/powerflex yellow are around 70a. powerflex purple are 80a and powerflex black are 95a. the akg blacks are 95a, and the akg delrins are 75d. if you daily drive the car on the street, i'd go with anything below 95a.



if you are unsure of all this, just go with the e9x m3 bushings or a 70a poly bushing for a daily driver.

[justpete]

Originally Posted by Fundguy1

Ok, so here's the basic setup.
Kw v2 coilovers, M3 front toe arms, rear diff lock(if I can find one)
Stock sport suspension
I see a lot of guys using M3 subframe bushings. Some guys using powerflex. I'm looking to get handling better than an M3, but not ride like a bucket. I drive this daily up to. 7 hours. I don't need too harsh. So what's the best bet. Go with M3, powerflex yellow? purple? What other suspension components, bushings should I replace and with what? I've got 202,000 miles so far. Need to order whatever this weekend.

Honestly, handling better than an M3 isn't going to happen with the stock sport suspension no matter what bushings, arms, and links are replaced. Talking from experience here since i started out with the stock sport suspension, went to the BMW Performance suspension, and then to a race tuned HVT suspension. There's no comparison. And it's still not enough, you'll need a full solid link suspension and solid delrin or equivalent hardness polyurethane driveline bushings and engine mounts. Oh, and it'll ride like a frickin go cart without any suspension. Mostly.

And this isn't nearly enough either, gotta be a better driver than an M3 driver since that's all that really counts. It's also the most difficult mod to make and takes the longest time to accomplish. More important than the hardware mods, too

[Fundguy1]

Originally Posted by justpete

Honestly, handling better than an M3 isn't going to happen with the stock sport suspension no matter what bushings, arms, and links are replaced. Talking from experience here since i started out with the stock sport suspension, went to the BMW Performance suspension, and then to a race tuned HVT suspension. There's no comparison. And it's still not enough, you'll need a full solid link suspension and solid delrin or equivalent hardness polyurethane driveline bushings and engine mounts. Oh, and it'll ride like a frickin go cart without any suspension. Mostly.

And this isn't nearly enough either, gotta be a better driver than an M3 driver since that's all that really counts. It's also the most difficult mod to make and takes the longest time to accomplish. More important than the hardware mods, too

I got the driver part covered. Lol. That aside I drove an M3 and was going to trade up but the deal was so outrageous it pissed me off. I decided to upgrade my current ride, which is in better shape than most with 20,000 miles, to acceleration, handling, and braking stats that were as good or better than an M3. At the same time it needs to be as streetable.

So M3 front toe arms, KW v2 coilovers, m3 subframe bushings, LSD, better tires, etc so far. No problems doing 4 wheel drifts in corners now prior to mods. I've got 500,000 miles driving in sports cars, schools, lessons, autocross, etc. track days are behind me but I still push my cars to their limits frequently. During the test drive with the saleswoman I had the m3 drifting in a corner. The sales woman went silent and eyes bugged out lol.

So thx for the bushing comparison. Looks like the yellow and the m3 are similar. Yellow are cheaper. Any benefit going to m3 more expensive? Durability? I'm getting new engine mounts, trans mounts, and a rear diff lockdown. Any recommendations on those vs stock? Any other company make a rear diff lockdown besides Defiv fab? They're moving their facilities and won't be shipping for a couple months. How about an improved shock tower mount, it other m3 bits, etc? Sway bars, swing arms, etc. additional bushings?

Thx.

[Fundguy1]

And thx about the subframe bushing data Sucks. Just trying to decide yellow or M3 now for rear subframe. I need to know asap on these because I'm doing them in 10 days probably.

[justpete]

Originally Posted by Fundguy1

I got the driver part covered. Lol. That aside I drove an M3 and was going to trade up but the deal was so outrageous it pissed me off. I decided to upgrade my current ride, which is in better shape than most with 20,000 miles, to acceleration, handling, and braking stats that were as good or better than an M3. At the same time it needs to be as streetable.

So M3 front toe arms, KW v2 coilovers, m3 subframe bushings, LSD, better tires, etc so far. No problems doing 4 wheel drifts in corners now prior to mods. I've got 500,000 miles driving in sports cars, schools, lessons, autocross, etc. track days are behind me but I still push my cars to their limits frequently. During the test drive with the saleswoman I had the m3 drifting in a corner. The sales woman went silent and eyes bugged out lol.

So thx for the bushing comparison. Looks like the yellow and the m3 are similar. Yellow are cheaper. Any benefit going to m3 more expensive? Durability? I'm getting new engine mounts, trans mounts, and a rear diff lockdown. Any recommendations on those vs stock? Any other company make a rear diff lockdown besides Defiv fab? They're moving their facilities and won't be shipping for a couple months. How about an improved shock tower mount, it other m3 bits, etc? Sway bars, swing arms, etc. additional bushings?

Thx.

The M3 bushings are likely more durable than the yellow urethane bushings but they still flex. Delrin or rigid urethane parts would be better if you're putting a lot of torque to the wheels. If you're upgrading engine and trans mounts then more rigid diff mounts would help too, the M3 diff bushings/mount are essentially the same as non-M3 so you might look into Delrin or AKG urethane versions, might avoid the need for a diff lock-down, dunno for sure.

Shock mounts other than bolt-in clevis/eye types which reduce travel won't be nearly as rigid but without the M3 swingarm with its better lower mount wouldn't help much really. More solid lower shock mounts would help but are limited by the swingarm's rigidity limitations. Changing the swingarms changes the lower shock mount so the shocks have to change to a different body design, the toe arms won't be long enough so they have to change, and depending on the fender clearance, wheel ET, and tire diameter the upper links may have to change to Heim joint rigid arms to allow camber to be fully adjustable. Welded-in spherical bearings at the subframe for the swingarm are critical items to help keep the suspension from twisting under torque loading, definitely a must if you think you need a lock-down.

If you end up with Heim joint arms you'll want to replace the ends with Aurora Performance Race parts along with Seals-It seals. Really expensive but worth it although you might not like the endless creaking and cracking noises.

Trailing arm bushings will need to be changed to spherical bearings to keep the entire assembly more solid under load but don't really need to be replaced with race versions unless you don't mind the potential for body damage in the event of a collision that would otherwise allow them to fold up like the stock parts are designed to do.

No need to increase rear sway bar torsional stiffness at this point since it'll reduce traction, spring rate and shock rebound are more important considerations. Installing adjustable sway bar end links so the preload can be zeroed out is more important, front and rear. If anything the rear sway bar should be as minimal as possible if the rest of the suspension is reworked to be as rigid as possible.

Replacing the bushing in the lower front control arm with a spherical bearing makes a marked improvement in steering precision and response but it's really only worth it if running camber plates that entirely eliminate upper strut mounting compliance. And there are some chassis stiffening bars from Ultra Racing that can help keep the front and rear subframes from flexing although that's kinda secondary really.

All of this really doesn't help all that much without a good set of dampers and springs, JRZ or HVT and Swift or the like. It's a lot of work but it will make handling better than a stock M3/M4. With a completely rigid link setup you'll also have to routinely check nut and bolt torque due to the increased vibe and shock but it just comes with the territory. Oh yeah, and with more rigid engine mounts you'll need an ATI Super Damper to keep from killing the engine. That or have the engine blueprinted and balanced from top to bottom. The ATI is a lot cheaper although you'll probably have to have it custom made. Worth it though to be able to run solid driveline mounts, imho.

[Fundguy1]

Thanks for the awesome response. Makes me know I need more research. For the moment I think I'll go with oem non subframe stuff, m3 or purple powerflex subframe, and the rear lockdown, give it a few months, then come back to it to replace what's needed. The main concern I have is that the ride might get too stiff and the extra maintenance. I drive 50,000 a year in this for work. 8 hour drives are common. Getting to stiff would suck too lol. It's a hard balance.

[justpete]

Originally Posted by Fundguy1

Thanks for the awesome response. Makes me know I need more research. For the moment I think I'll go with oem non subframe stuff, m3 or purple powerflex subframe, and the rear lockdown, give it a few months, then come back to it to replace what's needed. The main concern I have is that the ride might get too stiff and the extra maintenance. I drive 50,000 a year in this for work. 8 hour drives are common. Getting to stiff would suck too lol. It's a hard balance.

No worries. Eight hour drives with a full rigid suspension would kinda suck. And 50Kmi/yr would make ongoing maintenance a real pita, no argument there. I only drive maybe 15Kmi/yr for work but need to carry customers out to lunch on occasion so it all works as a conversation starter...