Review: 3DM Öhlins R&T kit + TMS camber plates + Syncro Design Works tension arms

[terra]

Yeah e60 is one of the ugliest BMWs but also one of the best engineered. Well the chassis is anyway, let’s ignore the engine .

Shame they couldn’t justify the costs to incorporate that grav-60 construction in the rest of the lineup or future models.

[Obioban]

Yeah e60 is one of the ugliest BMWs but also one of the best engineered. Well the chassis is anyway, let’s ignore the engine .

Shame they couldn’t justify the costs to incorporate that grav-60 construction in the rest of the lineup or future models.

The e60 is simultaneously great and terrible. Best steering feel M5, crazy light for its size, dynamically awesome engine... but worst interior, ugly exterior, worst back seat space despite being pretty large, SMG (mostly), not great at being water proof, and least reliable engine.

[hansbrix]

They have been cheap because of all that though and has a lot of the same issues the S65 has. The M6 is way uglier. I chose my M5 because was manual and it was cheaper than an M3 which was what I was always intending to buy. Maybe I will pick up a E92 M3 at some point too.

[IamFODI]

Update: This setup seems to be rather sensitive to tire pressure.

Several days ago, I noticed the car didn't feel as directionally stable as it used to. Sometimes, with no clear pattern, it felt like it was tramlining over every tiny undulation in the road. It was much worse in the rain, which was a terrifying combo with the car's subpar (IMO) hydroplaning resistance.

At some point it occurred to me that I hadn't checked tire pressures in a while, so I did that. All four tires were all a few PSI low. I pumped them all up to spec and the car feels MUCH better now.

No surprise that tire pressures count. What surprises me is how much they seem to count on my car. I don't remember tire pressure having this drastic an effect when the car was on its original suspension.

[hansbrix]

Interesting. Probably the overall wheel rate on the stock setup is dominated by the chassis spring rate, but your setup is now different, perhaps the spring rate of the tire now shines through more since you changed the chassis spring.

[IamFODI]

Interesting. Probably the overall wheel rate on the stock setup is dominated by the chassis spring rate, but your setup is now different, perhaps the spring rate of the tire now shines through more since you changed the chassis spring.

Of course. Great point. I guess the chassis springs are damped a hell of a lot more than the tires are, so if there's any undamped motion, the tires are a likely culprit.

Think it might also have to do with natural frequencies? I.e., the new suspension's natural frequencies happen to overlap more with those of underinflated stock-sized PS4Ss?

[maupineda]

In my honest opinion, I'd say you have too high of a spring rate (front and rear), also most aftermarket add a lot of stiffness to their damper setup... my car even with softer springs (with 17% flat ride) still rides very harshly, and until I do something with the dampers, I won't get what I want. I just wish FCM was a bit more affordable.

[IamFODI]

my car even with softer springs (with 17% flat ride) still rides very harshly, and until I do something with the dampers, I won't get what I want.

E9x?

[r4dr]

In my honest opinion, I'd say you have too high of a spring rate (front and rear), also most aftermarket add a lot of stiffness to their damper setup... my car even with softer springs (with 17% flat ride) still rides very harshly, and until I do something with the dampers, I won't get what I want. I just wish FCM was a bit more affordable.

That's interesting because Shaikh from FCM has commented that a lot of well-regarded, high-end dampers run high pressure with large shafts. Whatever that means.

[duracellttu]

Do you know what your corner weights are? What front and rear bounce frequencies did you target?

[IamFODI]

Do you know what your corner weights are?

With just me in the car and a full tank, sprung corner weights are something like:

880 865

855 830

But don't quote me because:

1. I only have rough estimates for the unsprung masses, and
2. I probably didn't set up the corner scales perfectly because I'm a noob.

What front and rear bounce frequencies did you target?

I didn't, really. See this post, after the italicized paragraph.

[derbo]

BRA-Fing-VO 👏

I love the systematic process approach to the review and requirements. I also appreciate the transparency you have.

[maupineda]

That's interesting because Shaikh from FCM has commented that a lot of well-regarded, high-end dampers run high pressure with large shafts. Whatever that means.

Yes, that is the same takeaway I took based on the testing FCM has shared on their youtube channel... basically, they add a lot of rebound force jacking the car down, plus the gas force, which makes the ride very harsh and fidgety.

[IamFODI]

Plan for the future: more bump travel.

Reasons:

1. Just hit the bump stops for the 3rd time since the install today. Horrible bumps -- far from the norm -- but if I can solve it, why not?
2. Calculations suggest I don't have much bump travel right now, and a ton of room to trade droop travel for it

I haven't taken any measurements; just calculated. Given:

- 343 lbs/in spring rate
- ~5 mm preload*
- 0.96 spring motion ratio
- 113 mm total damper stroke travel
- 25 mm bump stop length, of which 20 mm is usable*
- 880 lbs sprung corner weight

* = per Barry @ 3DM

Spring rate comes out to 343 / 25.4 = 13.5 lbs/mm.

880 [sprung corner weight] / 13.5 [spring rate] / .96 [motion ratio] - 5 [preload] = 62.9 mm suspension compression with car on the ground

113 - 25 = 88 mm damper stroke until bump stop engagement
113 - 5 = 108 mm total available damper stroke

So, roughly 25 mm damper stroke from rest until bump stop engagement, or 45 mm available damper stroke until things in the cabin get painful. Does that make sense?

[ultimatemj]

Curious what happened next...
I'm unhappy with my ride quality and my gut is the front is oversprung (8k(448lbin) which is mild by some but my understanding is stock ZCP is 3k(167lbin)...but my issue could just as easily be improper pre-load, so I've got some investigation to do.