e46 M3 suspension setup, or how to not downgrade your car with suspension mods

[liam821]

Yeah, great info, thanks for posting.

[Cubieman]

Nice read, always learning!

[ViN]

This is very helpful. Thank you, Ian.

[T.J.]

Preface

So, generally...
-the stickier your tires are, the more roll stiffness you need
-the less suspension travel you have, the more stiffness you need
-the higher (stiffer) the frequency is, the less grip you have
-the stiffer the sways, the less grip

I know what you’re getting at here but I think bullet point 1 and 4 contradict each other. There is a trade off between stiffness and camber of the outer tire. Another consideration, car with unbalanced front to rear roll stiffness and soft stock sways will have less maximum grip than a car with stiffer aftermarket sways if the car has better matched F&R roll stiffness.
Also, stiffness is not as much of a factor on a smooth road.
I think a good takeaway for everyone is that this is very complicated and easy to get the system out of wack when you start changing things.

[Obioban]

I know what you’re getting at here but I think bullet point 1 and 4 contradict each other. There is a trade off between stiffness and camber of the outer tire. Another consideration, car with unbalanced front to rear roll stiffness and soft stock sways will have less maximum grip than a car with stiffer aftermarket sways if the car has better matched F&R roll stiffness.
Also, stiffness is not as much of a factor on a smooth road.
I think a good takeaway for everyone is that this is very complicated and easy to get the system out of wack when you start changing things.

Hmm, I worded that poorly. I way trying to convey that the stiffer the springs and/or sways are, the less grip you'll get from a given tire. Completely agreed that a stickier tires on a stiffer setup often results in more grip than a less sticky tire on a softer setup. Let me work on rewording that to be clearer...

[Obioban]

Other thread was weirdly glitchy (nobody could see changes I was making to the first post), so I made a new thread, moved all the replies over, and deleted the original. That said, you're all unsubscribed as a result :P

[mcfreid]

Fantastic thread! I know setups can vary wildly depending on other suspension/weight modifications. However, for those of us running a mostly stock setup, it would be great to know some general recommendations (spring rates, dampers, ride height, sway bars, etc) to cut through the complexity.

[Obioban]

Fantastic thread! I know setups can vary wildly depending on other suspension/weight modifications. However, for those of us running a mostly stock setup, it would be great to know some general recommendations (spring rates, dampers, ride height, sway bars, etc) to cut through the complexity.

Couple disclaimers:
1) you should really run the numbers! It doesn't take that long and it's amazing how quickly small changes DO make your car different. There's a reason BMW used so many different spring combinations, depending on how your car was optioned.
2) I'm going to suggest a flat ride setup, which some people are on board with and some are not. I very intentionally avoided flat ride in the original post, to keep everything uncontroversial. I've been running flat ride for while on all my cars, and am hugely on board with it at this point.

That said, for a very close to stock car, this would likely be pretty stellar:
TCK SAs
300 lbs front springs, 700 lb rear springs
Turner front sway (with turner sealed adjustable end links)
stock rear sway

If street only: e36 strut hats

If also track: Camber plates (I like the turner hybrids) and adjustable rear control arms
-possibly also swap out front sway for GC Race sway (unsealed end links will get noisy over time on GC's) and swap stock rear sway for CSL rear sway

[wahsm]

Great write up, to add to this there is a good book called “high-performance handling for street or track”

[Grke46m3]

Hey Ian,
you have extensive knowledge with turner hybrid camber plates with ohlins dfv. I currently have ohlins with a csl rear bar and a hotchkis front on medium stiff. Car feels great but I want to experiment with flatride. If I got the turner hybrid camberplates 3ddm front strut spacer and 8inch 350 front 60mm springs would that be a good start? With the front strut spacer and the tuner plates I shouldn’t have any droop issues correct?

[Obioban]

Hey Ian,
you have extensive knowledge with turner hybrid camber plates with ohlins dfv. I currently have ohlins with a csl rear bar and a hotchkis front on medium stiff. Car feels great but I want to experiment with flatride. If I got the turner hybrid camberplates 3ddm front strut spacer and 8inch 350 front 60mm springs would that be a good start? With the front strut spacer and the tuner plates I shouldn’t have any droop issues correct?

Which kingpins do you have installed?

[T.J.]

Hey Ian,
you have extensive knowledge with turner hybrid camber plates with ohlins dfv. I currently have ohlins with a csl rear bar and a hotchkis front on medium stiff. Car feels great but I want to experiment with flatride. If I got the turner hybrid camberplates 3ddm front strut spacer and 8inch 350 front 60mm springs would that be a good start? With the front strut spacer and the tuner plates I shouldn’t have any droop issues correct?

If it feels great why mess with it? Does it have an uncomfortable pitching motion?

[Obioban]

If it feels great why mess with it? Does it have an uncomfortable pitching motion?

More comfortable, faster, easier to drive at the limit...

[Grke46m3]

Which kingpins do you have installed?

Stock kingpins.

[Obioban]

Hey Ian,
you have extensive knowledge with turner hybrid camber plates with ohlins dfv. I currently have ohlins with a csl rear bar and a hotchkis front on medium stiff. Car feels great but I want to experiment with flatride. If I got the turner hybrid camberplates 3ddm front strut spacer and 8inch 350 front 60mm springs would that be a good start? With the front strut spacer and the tuner plates I shouldn’t have any droop issues correct?

I've been running the Vogtland 7.5" springs. That lets me get the ride height adjuster higher, for the same ride height, so I can fit the tire under the adjuster instead of next to it. They have just enough travel to cover the Ohlins travel.

The turner hybrids will work nicely with the 3DM front strut spacers-- should address the bump issue entirely.

What's the flat ride ratio with the 350 fronts? going off intuition, it feels like that might not be enough to get you into the flat ride range (assuming you're keeping the stock 628 rears).
Vogtland also sells 325s, which is what I'm running on the passenger front side of my car (and the passenger rear is a stock Ohlins 628).

... I suspect you're going to want to go back to the M3 stock rear sway (instead of the CSL sway). But, again, I haven't run the numbers for your car, so just guesstimating.