Electronic suspension for the E46 M3

[jet_dogg]

My buddy had sent me the fcm link several months ago and I immediately closed the window after it started getting into cringey marketing copy territory.

Don't know if it's still like that but du needs to hire an editor or some such.

[Obioban]

I'll play devil's advocate here:



Source

Granted, unless you're super-hardcore, most of us don't run aero on track. I'm currently running 440/550 lb F/R with my GC DAs and tbh, it's not that bad. I do have 900 lb springs ready to go in the rear to get me to flat ride but gonna be honest sometimes I get spooked by that number... though I have to keep reminding myself that's more like ~450 lb wheel rate given MR^2

Aero suspension setups are a completely different ballgame… and likely completely unnecessary for the standard wing/splitter (or any car not developed without extensive use of a wind tunnel). Less ride height variation becomes a negative, after a point, for non aero cars.

Transient response... I think it's easy to lose perspective. My front spring are "soft" (compared to many people's coilover setups) at 375/350 lb/in (driver/passenger).... but stock is 142. That means I'm 155% stiffer than stock! That is actually a HUGE increase, despite being "soft".

Rear wheel traction coming out of corners, less roll stiffness is what allows for this. You can get this through softer springs and/or softer sways. It's pretty much impossible to have a flat ride setup with anywhere near neutral FRC without having a soft (or no) rear sway.

[Obioban]

I'll play devil's advocate here:



Source

Granted, unless you're super-hardcore, most of us don't run aero on track. I'm currently running 440/550 lb F/R with my GC DAs and tbh, it's not that bad. I do have 900 lb springs ready to go in the rear to get me to flat ride but gonna be honest sometimes I get spooked by that number... though I have to keep reminding myself that's more like ~450 lb wheel rate given MR^2

One more thought, on the topic of transient response.

Transient response is limited by the lower frequency end of the car, as that's the end that takes longer to settle. Assuming we were both at stock weights, with your 440/550 setup you're at 2.14hz front, 1.84 hz rear. With my 362.5/675 front (averaging my left/rights) setup, I'm at 1.95hz front, 2.03hz rear-- meaning my flat ride setup has better transient response, before the improved settling speed resulting from flat ride is factored in.
(and in reality my transient response is a little better still, as my car is ~10% lighter than stock).

[cobra]

Something worth mentioning is bump stops. Are you running factory bumps or shortened ones? I'm pretty sure a stock M3 quickly runs into the bumps. Perhaps aftermarket setups use shorter ones so the effective spring rate is not as high as it seems?

[Obioban]

Something worth mentioning is bump stops. Are you running factory bumps or shortened ones? I'm pretty sure a stock M3 quickly runs into the bumps. Perhaps aftermarket setups use shorter ones so the effective spring rate is not as high as it seems?

Me? Mine are cut down. I want to avoid using them if at all possible— bump stops ramp the effective spring rate up QUICKLY, and higher spring rate = less grip. I hope to only contact them if I jump the car or something similarly atypical.

One of the things I found most appealing about FCM’s shock builds is that they put a huge emphasis on preventing jacking down, which hopefully will mean a lot less use of bump stops than traditional setups.

That said, I think the overwhelming majority of aftermarket setups spend way more time in the bump stops than stock.

[old///MFanatic]

I think Bilstein makes / made one for the non-M. Perhaps that could be made to work with the M3. Nothing M-specific as far as I'm aware.

Correct Bilstein marketed one for the non-M E46 but not the M3. I had Bilstein PSS9 coil-over kits for both my E46s once side by side and only thing I recall was the spring numbers on them being different. Leading me to believe only the spring rates were different.
I looked into Bilstein electronic kit figuring I could just swap the springs for the M3. But considering it only had two settings on the electronic button (Sport or Normal) it seemed more of a downgrade from 9-10 available manual settings. Although I never touch them after dialing in to my preference.
My brother has electronic button adjustment factory in his Porsche and I did like it first time I drove it. His new VW Golf R has it too and it’s rather nice going in LA canyons and then city streets with touch of button. I personally like the different “on the fly” settings for different feels.

[timmo]

Yeah, bump stops are a big one. I can't say for sure but I would think that given how soft the stock suspension is, that under ride or regular driving you aren't hitting them, but you are during hard cornering. I suppose the ideal case would be a stiffer suspension where you are ever so slightly above the bumpstops even in the most extreme cornering cases

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[cobra]

Me? Mine are cut down. I want to avoid using them if at all possible— bump stops ramp the effective spring rate up QUICKLY, and higher spring rate = less grip. I hope to only contact them if I jump the car or something similarly atypical.

One of the things I found most appealing about FCM’s shock builds is that they put a huge emphasis on preventing jacking down, which hopefully will mean a lot less use of bump stops than traditional setups.

That said, I think the overwhelming majority of aftermarket setups spend way more time in the bump stops than stock.

Yeah... if this car gets lowered very much (as people do) you start running out of travel and depend on them to not bottom out super hard haha.


Interesting discussion guys thanks for the feedback I think I will try out an electronic setup and see how it works, out of curiosity.

[liam821]

Mag ride really is in a class alone. There's a reason Ferrari licenses it from GM 🤣

I really enjoyed the magride on my old Audi, it was a fantastic system that worked really well.

[ac427]

Yeah... if this car gets lowered very much (as people do) you start running out of travel and depend on them to not bottom out super hard haha.


Interesting discussion guys thanks for the feedback I think I will try out an electronic setup and see how it works, out of curiosity.

Did you try an electronic suspension kit?

I was looking at Tractive and they make a kit for the E46 but not the M3.

[cobra]

Did you try an electronic suspension kit?

I was looking at Tractive and they make a kit for the E46 but not the M3.

No, though I did try it out on another vehicle. Not really my thing unless it's a fully active system with sensor inputs to adjust on the fly. Even then, my personal preference is a well tuned, passive system as it's predictable and consistent, and overall less complicated.

[e90076]

Not electronic but I will say I recently had the RaceWerks MCS coilovers installed and I’m very happy with them.