Electronic suspension for the E46 M3

[cobra]

Apologies if this is too off topic, I can create a separate thread if need be. But, how do you dial in something like that without being subjective?

I understand that you want a system that's critically dampened, but I can't think of an objective way to get to that point. I'm imagining that it's just a bunch of trial and error.

Edit: I think what I wrote above sounded a bit too passive aggressive/skeptical and didn't mean it that way. I'm genuinely curious to hear the method you (and others) use to dial in suspension. So far, I've just been blindly turning knobs based on what I think will make it feel "better".

I've also struggled with this. As far as I can tell, there is no "correct", as everything is subjective in the end. There are, however, a lot of "wrong" setups. Even at the highest level of racing, no two cars are the same due to the preferences of the drivers.

This is a really interesting document I found, and worth a read: http://www.kaztechnologies.com/wp-co...m-Kasprzak.pdf

A good 'starting point' is about 0.5-0.7 of critical damping. Of course that also depends on a lot of other variables.

[Obioban]

Apologies if this is too off topic, I can create a separate thread if need be. But, how do you dial in something like that without being subjective?

I understand that you want a system that's critically dampened, but I can't think of an objective way to get to that point. I'm imagining that it's just a bunch of trial and error.

Edit: I think what I wrote above sounded a bit too passive aggressive/skeptical and didn't mean it that way. I'm genuinely curious to hear the method you (and others) use to dial in suspension. So far, I've just been blindly turning knobs based on what I think will make it feel "better".

That's a large part of why I ended up going with the FCM shocks on the coupe. Objectively valved, on a shock dyno, for my specific spring rates and corner weights. Because it's valve specifically for my car, I used a non adjustable stock as my starting point. Less moving parts is less places to leak and fail, and less room to screw it up.

My general strategy for the other cars (M5 and M3 wagon are on Koni yellows) is as soft as possible without feeling any secondary oscillations.

[Obioban]

I've also struggled with this. As far as I can tell, there is no "correct", as everything is subjective in the end. There are, however, a lot of "wrong" setups. Even at the highest level of racing, no two cars are the same due to the preferences of the drivers.

This is a really interesting document I found, and worth a read: http://www.kaztechnologies.com/wp-co...m-Kasprzak.pdf

A good 'starting point' is about 0.5-0.7 of critical damping. Of course that also depends on a lot of other variables.

That's a pretty good write up. It even includes flat ride!

Extracting a quote...

So how much damping do you want? Just enough! Any more reduces grip, increases tire force variation and tire wear, and makes the ride worse. What we want is the correct amount of damping. Overdamping or underdamping increases the variation of tire force to the track, reducing tire adhesion or grip.

Exactly why I think the optimal shock setting for the street is the same as for the track.

[Sharocks]

Just gonna say, an SS 1LE blew my mind suspension and handling wise.

I would love to swap in Mag Ride but it's not worth it lol

[r4dr]

Just gonna say, an SS 1LE blew my mind suspension and handling wise.

I would love to swap in Mag Ride but it's not worth it lol

Same thing with the GT350. It dances like a much lighter, smaller car on the track. It's pretty astounding.

[Obioban]

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

[Sharocks]

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

My friend is a ME for Multimatic in Toronto, they bank off of supercars but it's awesome that GM offers it on a $35k car.

[elbert]

I know this goes against conventional wisdom, but I’d argue the optimal damping is the same on the street and track…

I completely agree with this. My car also sees both track and street, and once I got it dialed in, I haven't touched the knobs.
The key is picking the right spring rate.

[jet_dogg]

Just gonna say, an SS 1LE blew my mind suspension and handling wise.

I would love to swap in Mag Ride but it's not worth it lol

All bout dat spool valve tech son.

[Sharocks]

All bout dat spool valve tech son.

That and V8 noises lol

[heinzboehmer]

I've also struggled with this. As far as I can tell, there is no "correct", as everything is subjective in the end. There are, however, a lot of "wrong" setups. Even at the highest level of racing, no two cars are the same due to the preferences of the drivers.

This is a really interesting document I found, and worth a read: http://www.kaztechnologies.com/wp-co...m-Kasprzak.pdf

A good 'starting point' is about 0.5-0.7 of critical damping. Of course that also depends on a lot of other variables.

Thank you for that link, looks to be filled with useful information. I'll have to sit down and give it a thorough read soon.

That's a large part of why I ended up going with the FCM shocks on the coupe. Objectively valved, on a shock dyno, for my specific spring rates and corner weights. Because it's valve specifically for my car, I used a non adjustable stock as my starting point. Less moving parts is less places to leak and fail, and less room to screw it up.

My general strategy for the other cars (M5 and M3 wagon are on Koni yellows) is as soft as possible without feeling any secondary oscillations.

Man, I really need to pay FCM a visit. My car is nowhere near ready for a fully custom valved suspension setup (I have way too many components to change still for it to make sense), but they're local and I think it would be very valuable to learn how suspension is set up objectively.

[cobra]

That's a large part of why I ended up going with the FCM shocks on the coupe. Objectively valved, on a shock dyno, for my specific spring rates and corner weights. Because it's valve specifically for my car, I used a non adjustable stock as my starting point. Less moving parts is less places to leak and fail, and less room to screw it up.

My general strategy for the other cars (M5 and M3 wagon are on Koni yellows) is as soft as possible without feeling any secondary oscillations.

What shock architecture are you running for the FCM setup? I came across one of his videos where he craps on twin tubes in favor of monotubes, but I know a lot of people (including myself) who are pretty happy with Koni's overall.

I'm not totally sold on the flat ride concept. I would argue that many stock vehicles come with higher rear frequencies to account for added passenger and luggage weight. Perhaps in the end it's better to have a slight increase in the rear from a driving comfort perception, but it's secondary to other goals.

I do think that having too many adjustments, for the average person, is confusing. Especially those with a lot of adjustment range - it is easier for someone to really screw up the ride if they don't know what they're doing. I think that's one of the great things about electronic shocks with "soft" and "firm" that do adjustments on their own. Of course it's not necessary, and a properly tuned setup will work decently well in all conditions, but might end up being compromised?

[Obioban]

What shock architecture are you running for the FCM setup? I came across one of his videos where he craps on twin tubes in favor of monotubes, but I know a lot of people (including myself) who are pretty happy with Koni's overall.

I'm not totally sold on the flat ride concept. I would argue that many stock vehicles come with higher rear frequencies to account for added passenger and luggage weight. Perhaps in the end it's better to have a slight increase in the rear from a driving comfort perception, but it's secondary to other goals.

I do think that having too many adjustments, for the average person, is confusing. Especially those with a lot of adjustment range - it is easier for someone to really screw up the ride if they don't know what they're doing. I think that's one of the great things about electronic shocks with "soft" and "firm" that do adjustments on their own. Of course it's not necessary, and a properly tuned setup will work decently well in all conditions, but might end up being compromised?

H&R coilovers are my base— which allows me ride height adjustment with non adjustable bilsteins.

Rear cargo capacity may be a perk to flat ride, but I don't think it's the main reason,. EVERYTHING stock comes with flat ride-- porsche GT cars, Corvettes, Miatas, the FSAE car in the guide above, etc.

I was skeptical of it at first as well, because it's so contrary to how pretty much every turner sets up spring rates on these cars (exception: Dinan). But, springs are cheap and every single OE on every car I've seen doing it stock intrigued me, so I tried it. It was the most transformative thing I've ever done to the car-- it settles faster, drives more predictably at the limit, rides better, and goes faster. I'd very much encourage you to try it-- probably $100 to swap out your front springs, and short term you can disconnect your rear sway to get a reasonable FRC.

That's basically how my experimentation went... first I tried the Ohlins with lower front spring rate and no rear sway. That was significantly better than the stock ohlins setup, so then I beefed up the front sway and put on a stock rear sway. Even better.

At that point I was impressed enough with flat ride that I coughed up $5000 for custom valving from them (... and every option they offer...), to get the shocks to match. So far, on the street, they're crazy impressive. I'm withholding final judgement till I get them on the track (may not be soon... tires are sold out, I'm out of tires, and I'm in the process of moving and building a house), but on the street they're easily the grippiest and most composed suspension setup I've ever driven on any car. Certainly better than I was ever able to tune my old quad adjustable, remote reservoir Motons/JRZs to be.

So I'd say, pick up some softer front springs (or stiffer rears-- idk what your current setup is), disconnect your rear sway, see how she do. It was very much of a eureka moment for me.

I've also moved the M3 wagon to flat ride since the start of this experiment-- and it was similarly improved. I was uncomfortable driving it above ~100mph before, but now she's steady as stock at speed.

[cobra]

H&R coilovers are my base— which allows me ride height adjustment with non adjustable bilsteins.

Rear cargo capacity may be a perk to flat ride, but I don't think it's the main reason,. EVERYTHING stock comes with flat ride-- porsche GT cars, Corvettes, Miatas, the FSAE car in the guide above, etc.

I was skeptical of it at first as well, because it's so contrary to how pretty much every turner sets up spring rates on these cars (exception: Dinan). But, springs are cheap and every single OE on every car I've seen doing it stock intrigued me, so I tried it. It was the most transformative thing I've ever done to the car-- it settles faster, drives more predictably at the limit, rides better, and goes faster. I'd very much encourage you to try it-- probably $100 to swap out your front springs, and short term you can disconnect your rear sway to get a reasonable FRC.

That's basically how my experimentation went... first I tried the Ohlins with lower front spring rate and no rear sway. That was significantly better than the stock ohlins setup, so then I beefed up the front sway and put on a stock rear sway. Even better.

At that point I was impressed enough with flat ride that I coughed up $5000 for custom valving from them (... and every option they offer...), to get the shocks to match. So far, on the street, they're crazy impressive. I'm withholding final judgement till I get them on the track (may not be soon... tires are sold out, I'm out of tires, and I'm in the process of moving and building a house), but on the street they're easily the grippiest and most composed suspension setup I've ever driven on any car. Certainly better than I was ever able to tune my old quad adjustable, remote reservoir Motons/JRZs to be.

So I'd say, pick up some softer front springs (or stiffer rears-- idk what your current setup is), disconnect your rear sway, see how she do. It was very much of a eureka moment for me.

I've also moved the M3 wagon to flat ride since the start of this experiment-- and it was similarly improved. I was uncomfortable driving it above ~100mph before, but now she's steady as stock at speed.

Thanks for the feedback and background

I currently have Koni sport and Dinan springs... stock bumps, sways, etc. I measured the springs to be quite a bit stiffer in the rear (28%) and a little stiffer in the front (12%) than stock.

Were you running Road & Tracks or TTX's? I've heard good things about both, but the R&T's are much more common.

I have some reading to do but would like to come up with a nice solution. Have you shared your spring rates, damper curves, and swaybar settings anywhere?

[timmo]

I'm not totally sold on the flat ride concept. I would argue that many stock vehicles come with higher rear frequencies to account for added passenger and luggage weight. Perhaps in the end it's better to have a slight increase in the rear from a driving comfort perception, but it's secondary to other goals.

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