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

[Obioban]

I made an interesting observation on my setup with ohlins w/ standard ohlins springs, 3DM strut spacers and GC Street Camber plates. Current ride height at the front is even lower than recommended at ~13.25" hub to fender and my bump:droop is still off, at about 40.5mm bump:52mm droop. Which is about 44:56 in terms of % of total travel. This means to reach the proper bump travel (approx 60% according to this thread) my ride height would have to be about 12.8" hub to fender. At what point is the trade off in height not worth it for achieving enough bump? Additionally, for those who have swapped out the standard ohlins springs for shorter/lower spring rate springs, how did you get anywhere close to proper bump travel without completely slamming the front? I would assume a shorter spring and a lower rate would put the ratio even further out than it already is unless I'm missing something.

My car is a euro spec M3 if that makes a difference. I have read the uprights are different?

The 3DM strut spacers are for US cars only-- they correct for the difference in the uprights with US cars. If you took them out, you should be able to be back in optimal bump/droop at a reasonable ride height. That said, for more bump travel (less droop), you'd want to raise your car.

[Thoglan]

I made an interesting observation on my setup with ohlins w/ standard ohlins springs, 3DM strut spacers and GC Street Camber plates. Current ride height at the front is even lower than recommended at ~13.25" hub to fender and my bump:droop is still off, at about 40.5mm bump:52mm droop. Which is about 44:56 in terms of % of total travel. This means to reach the proper bump travel (approx 60% according to this thread) my ride height would have to be about 12.8" hub to fender. At what point is the trade off in height not worth it for achieving enough bump? Additionally, for those who have swapped out the standard ohlins springs for shorter/lower spring rate springs, how did you get anywhere close to proper bump travel without completely slamming the front? I would assume a shorter spring and a lower rate would put the ratio even further out than it already is unless I'm missing something.

My car is a euro spec M3 if that makes a difference. I have read the uprights are different?

[tlow98]

I spoke with TC recently and he was adamant that the fronts would require camber plates. He seems unaware that there is a hack to run the E36 hats.

He really stressed the need to not go too stiff in the rear as it would inhibit putting the power down when exiting a corner. He said "you can do almost anything you want with the front, but you have to be very careful in the rear."

Jesse

Interesting stuff, thank you. I could have sworn TC used to sell their SA kit sans Camber plates for $1800-1900. Maybe I'm delusional.

[D-O]

Esp true if you have a bigger rear sway bar AND/OR if you've gutted the rear, which is much easier to do than the front.

Indeed. He did mention that they often go with no rear sway on their track cars.

Jesse

[Tbonem3]

Esp true if you have a bigger rear sway bar AND/OR if you've gutted the rear, which is much easier to do than the front.

[D-O]

I spoke with TC recently and he was adamant that the fronts would require camber plates. He seems unaware that there is a hack to run the E36 hats.

He really stressed the need to not go too stiff in the rear as it would inhibit putting the power down when exiting a corner. He said "you can do almost anything you want with the front, but you have to be very careful in the rear."

Jesse

[Obioban]

A lighter car would need a damper capable of GREATER rebound, not less fyi.

More vehicle weight effectively reduces spring rate.

I read his post as he can get away with a 600 lb spring instead of 700.

[Tbonem3]

A lighter car would need a damper capable of GREATER rebound, not less fyi.

More vehicle weight effectively reduces spring rate.

[tlow98]

i talked with TC a while back when I was considering 700 rear, and he told me his SA’s would not support 700#. Maybe he’s made some changes?

Thanks for the heads-up. That's probably ok in my situation, anyway. As Obioban pointed out my car is lighter anyway.

[Flat-Six]

Thanks for this, Obioban. After much research, I believe I'm headed in exactly this direction for my E46 sedan (TCK SAs 300/700, Turner endlinks). I'm not familiar with the E36 strut hats on the E46 platform. Is there a specific reason why you called that out here? Camber advantages?

The car will be a streetcar, on PS4S or similar traction levels, for now. I had a full GC set up in the past; coils 400/500 (IIRC), sways, and plates. It was ok, but it came with the car and had an unknown life. Everything would respond to adjustments but always struck me as a little harsh. Previous to that I had a Koni yellow + stock spring combo that was, well, lovely. This was all on my E46 m3. The sedan is much softer in its stock form. It's a 330i for reference. The balance is really good, but I need real bite and the stock stuff is all worn-out original items. This is meant to be a 'beater' with great dynamics. The springs available for the 330i are lacking and the M3 set up bolts right in. Plus I'm looking for more precision than 'just' Koni yellows.

Also, mega appreciate all that went into this thread. The decades of trial/error and the spreadsheets from FCM. It's really eye-opening and I'm incredibly happy to return to the E46 platform. I moved my E91 on to my sister as she loved it and I fell out of love with it. Sounds like you know that story!

i talked with TC a while back when I was considering 700 rear, and he told me his SA’s would not support 700#. Maybe he’s made some changes?

[tlow98]

Ok, I was about to make a thread about strut mounts/top hats/camber plates. One of the things I was going to ask about is E36 "hats". Are hats and strut mounts the same thing? Why can't E46 M3 hats be used with TCK coilovers? Which E36 hats are we talking about?

Hats = Strut mounts, Yes. The E46 M3 hats are rather unique from memory - they are offset and different than regular E46 hats. And E36 for that matter.

[K-Dawg]

Good to know about the E36 hats. I'll ask TC Kline what they recommend with respect to the spring rates.

I don't know what TCK will recommend, but I bet 300/700 will ride and handle better. I went from 550/600 to 300/600 on my TCK DAs and the difference was huge.

[K-Dawg]

The stock e46 M3 hats can't be used with the TCK coilovers. The e36's can. If you aren't doing something that benefits from having camber plates (tracking, autox), factory BMW hats tend to be quieter/more reliable/longer lasting.

Ok, I was about to make a thread about strut mounts/top hats/camber plates. One of the things I was going to ask about is E36 "hats". Are hats and strut mounts the same thing? Why can't E46 M3 hats be used with TCK coilovers? Which E36 hats are we talking about?

[tlow98]

... are you the guy that bought my e91 a couple of years ago?

The stock e46 M3 hats can't be used with the TCK coilovers. The e36's can. If you aren't doing something that benefits from having camber plates (tracking, autox), factory BMW hats tend to be quieter/more reliable/longer lasting.

The non-M cars are lighter than the M3, so the above setup might be a tad stiff on the sedan.

No, I did not buy yours, but I considered buying yours and selling mine when you had yours up for sale. But being on the other side of the country is a pain. On M3F my old username was "DodgeStratus" and went down the fun road of E46 + Evolve Carbon box + HP Ecu, etc etc

Good to know about the E36 hats. I'll ask TC Kline what they recommend with respect to the spring rates. I haven't had this car on the scales but it is about 100 ~ 150 lbs lighter than my old M3 stripper according to common knowledge. On the M3 the only option was H/K, but no sunroof, power seats, etc. Whereas this sedan is loaded with a terrible, heavy hole in the roof. For now...

[Obioban]

Thanks for this, Obioban. After much research, I believe I'm headed in exactly this direction for my E46 sedan (TCK SAs 300/700, Turner endlinks). I'm not familiar with the E36 strut hats on the E46 platform. Is there a specific reason why you called that out here? Camber advantages?

The car will be a streetcar, on PS4S or similar traction levels, for now. I had a full GC set up in the past; coils 400/500 (IIRC), sways, and plates. It was ok, but it came with the car and had an unknown life. Everything would respond to adjustments but always struck me as a little harsh. Previous to that I had a Koni yellow + stock spring combo that was, well, lovely. This was all on my E46 m3. The sedan is much softer in its stock form. It's a 330i for reference. The balance is really good, but I need real bite and the stock stuff is all worn-out original items. This is meant to be a 'beater' with great dynamics. The springs available for the 330i are lacking and the M3 set up bolts right in. Plus I'm looking for more precision than 'just' Koni yellows.

Also, mega appreciate all that went into this thread. The decades of trial/error and the spreadsheets from FCM. It's really eye-opening and I'm incredibly happy to return to the E46 platform. I moved my E91 on to my sister as she loved it and I fell out of love with it. Sounds like you know that story!

... are you the guy that bought my e91 a couple of years ago?

The stock e46 M3 hats can't be used with the TCK coilovers. The e36's can. If you aren't doing something that benefits from having camber plates (tracking, autox), factory BMW hats tend to be quieter/more reliable/longer lasting.

The non M cars are lighter than the M3, so the above setup might be a tad stiff on the sedan.