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

[DropTopKingM3]

Fellow NY'er selling these. Not mine but I just saw them.
https://www.facebook.com/marketplace...3-f32fe771d58a

I picked these up earlier tonight from Frankie Onefastsicilian 👍

[Fresh1179]

For those wishing to access the link regarding "how to use" contained within the spreadsheet:

https://www.youtube.com/watch?v=m2ci...orsports%2CInc.

Thank you for posting this, extremely helpful.

[DropTopKingM3]

Fellow NY'er selling these. Not mine but I just saw them.
https://www.facebook.com/marketplace...3-f32fe771d58a

Yep I’m meeting up with him tomorrow. That’s why I asked in here. Appreciate it bro.

[lvm3sm46]

I’m about to have a set of ohlins road and track installed on my car. I won’t be using camber plates. I will be running 19x9.5 BBS LM in front. Would I still need the spacer ?

Fellow NY'er selling these. Not mine but I just saw them.

https://www.facebook.com/marketplace/item/489687292501519/?ref=search&referral_code=marketplace_search&referral_story_type=post&tracking=browse_serp%3A9cfcbcf5-8fc7-40e6-9c23-f32fe771d58a

[Obioban]

I’m about to have a set of ohlins road and track installed on my car. I won’t be using camber plates. I will be running 19x9.5 BBS LM in front. Would I still need the spacer ?

Yes— you can only get it from 3DM, AFAIK.

[DropTopKingM3]

I'm running 350 front left, 325 front right, 700 rear left, 628 rear right (which results in the same frequencies left/right with just me in the car).

The Ohlins don't have much travel up front-- you should set your ride height solely by bump/droop ratio, to make the most of it. They have 92mm of total travel, so I like to set the ride height at 32mm of droop (giving 60mm of bump travel). If you have US spec kingpins, combined with pretty much any camber plate on the market, that's going to put you low (too low for optimal handling). When I had US kingpins, I was running spacers on the shock mount to get the car sufficiently high. Now that I'm on CSL kingpins, they're no longer necessary. (side note: 3DM now sells spacers for this purpose).

My guess is that Ohlins developed their setup with Euro kingpins, which have the same shock mounting location as the Euro ones... but the US ones are different. Or designed without consideration for camber plates. Either way, non US Kingpins or the spacers above or the spacers I designed all address the issue.

Because I'm still running spacers of my own design (just now milled down further, since I got the CSL kingpins), I tweaked them so my 32mm of drop travel happens and exactly 13.5" up front. Rear is 13", and the the Ohlins have plenty of rear travel and let you set the bump/droop travel independently of ride height-- so I'm at 60% bump, 40% droop (143.5mm of total rear shock travel).

I’m about to have a set of ohlins road and track installed on my car. I won’t be using camber plates. I will be running 19x9.5 BBS LM in front. Would I still need the spacer ?

[Obioban]

What is the total metal to metal travel of the ohlins in the back?
I know the front is 92.5mm and have set bump/droop at 60/40 accordingly. Puts me at about 13.25" hub to fender which I'm happy with. Just wondering if the rears have the same travel as the front?

143.5mm

[Thoglan]

What is the total metal to metal travel of the ohlins in the back?
I know the front is 92.5mm and have set bump/droop at 60/40 accordingly. Puts me at about 13.25" hub to fender which I'm happy with. Just wondering if the rears have the same travel as the front?

[repoman89]

repoman89 Oh, yes it's possible I have it backwards lol. Embarrassing. I'll have to play around with ride height and see what happens to the droop.

You don’t even have to play around with it. Just put the front in the air — no matter what preload you set the shock will be at full extension == full droop. For me that was about 15” hub to fender distance IIRC with the 3DM kit and my Turner camber plates. Then you have 92mm or almost four inches to full compression (really 92mm divided by the ~0.94 or whatever it is motion ratio making it pretty much four inches). Split four inches into 60:40 desired bump:droop means you want the ride height to be somewhere around 13.5” in my example.

[cobra]

The 60:40 is a ballpark range, but that 60 is partially bump stop. Ideally, you want a good amount of travel before the bump stop engages, as the bump stop functions as another (and progressive) spring-- so when you're in the bump stop, spring rate increases, grip decreases.

The 50mm I meant as the bare minimum. Some shocks have WAY less then the 228mm of your Konis. E.g. my old Ohlins had 92.5mm of front metal to metal travel. The less you have, the more critical it is optimize the use of it. The Konis have so much that the 60:40 really isn't that critical to focus on-- unless you do something extreme, you're unlikely to be outside of it.

What shocks are you thinking about moving to?

Ok gotcha. Seems to me like relying too much on the bump stop is bad for performance. Maybe it's good for making a car that feels comfortable traveling in a straight line, and still hold it up when cornering, allowing OEM's can use soft spring rates while keeping a sporty feeling?

Wow, 92.5mm up front is short! My front Konis have 143mm metal-to-metal up front. I haven't taken any measurements about how far in it sits statically yet, but will post it up here when I do.

I know for the rears, when I lift the rear of the car in the air, the wheels droop a LOT. I can't imagine them ever getting that far down while cornering. Any more, and the spring starts to gets loose. So it's very possible I can reduce that droop travel and still never reach it because the shock has so much travel. I will try to do my best to maintain the same amount of bump travel so it's not bottoming out on rough roads.

The shocks will be custom with triple-adjustable piggyback monotubes - I will share more as I get closer. Right now I'm just in the measuring stage.

[Obioban]

Can anyone comment a little more on bump/droop travel? I am looking at fitting some shocks and it might change the ratio in the rear. As a reference, my Koni shocks have 228mm of metal-to-metal travel and measure 600mm from the lower mounting bolt to the shoulder on the shaft. Some quick measurements shows that with Dinan springs, it is sitting about 40% into its travel statically, which is exactly what the OP suggests as a target. It also has 137mm of travel beyond that point, not counting the bump stop, which is significantly more than the 50mm in the OP.

Obioban, was the 50mm bump travel until it hits the bump stop or actual shock stroke?

If I fit the shorter shocks I'm looking at, it will affect the ratio. If I want the total compressed length to be the same (knowing this doesn't cause any rubbing/interference issues), I might end up with a 35/65% split instead. Thanks!

The 60:40 is a ballpark range, but that 60 is partially bump stop. Ideally, you want a good amount of travel before the bump stop engages, as the bump stop functions as another (and progressive) spring-- so when you're in the bump stop, spring rate increases, grip decreases.

The 50mm I meant as the bare minimum. Some shocks have WAY less then the 228mm of your Konis. E.g. my old Ohlins had 92.5mm of front metal to metal travel. The less you have, the more critical it is optimize the use of it. The Konis have so much that the 60:40 really isn't that critical to focus on-- unless you do something extreme, you're unlikely to be outside of it.

What shocks are you thinking about moving to?

[cobra]

Can anyone comment a little more on bump/droop travel? I am looking at fitting some shocks and it might change the ratio in the rear. As a reference, my Koni shocks have 228mm of metal-to-metal travel and measure 600mm from the lower mounting bolt to the shoulder on the shaft. Some quick measurements shows that with Dinan springs, it is sitting about 40% into its travel statically, which is exactly what the OP suggests as a target. It also has 137mm of travel beyond that point, not counting the bump stop, which is significantly more than the 50mm in the OP.

Obioban, was the 50mm bump travel until it hits the bump stop or actual shock stroke?

If I fit the shorter shocks I'm looking at, it will affect the ratio. If I want the total compressed length to be the same (knowing this doesn't cause any rubbing/interference issues), I might end up with a 35/65% split instead. Thanks!

[Thoglan]

repoman89 Oh, yes it's possible I have it backwards lol. Embarrassing. I'll have to play around with ride height and see what happens to the droop.

[repoman89]

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?

Maybe it’s too early to be thinking about this, but don’t you want to raise your ride height to gain bump travel and decrease droop travel? For example if you went to 13.75” hub to fender you’d gain about 13mm of bump travel at the expense of 13mm in droop travel. And the lower you go the less bump travel you have, up to the limit of riding on the bump stops all the time at like 11.5” (not that it’s necessarily possible to achieve that)

[Obioban]

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.

They did.

You can still piece it together, since they sell all the components individually, as well.