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

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  • IamFODI
    replied
    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
    3. There's room at the top of the of the damper piston to space it down even further

    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?

    Could easily pick up another 10+ mm with an additional spacer on the damper piston. Not inclined to do that right away, but something to think about if the camber plates ever have to come apart. More likely I'll just tweak the front next time I go in for an alignment.

    Leave a comment:


  • maupineda
    replied
    Originally posted by r4dr View Post

    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.

    Leave a comment:


  • derbo
    replied
    BRA-Fing-VO 👏

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

    Leave a comment:


  • IamFODI
    replied
    Originally posted by duracellttu View Post
    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.


    Originally posted by duracellttu View Post
    What front and rear bounce frequencies did you target?
    I didn't, really. See this post, after the italicized paragraph.
    Last edited by IamFODI; 11-04-2020, 08:15 PM.

    Leave a comment:


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

    Leave a comment:


  • r4dr
    replied
    Originally posted by maupineda View Post
    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.

    Leave a comment:


  • IamFODI
    replied
    Originally posted by maupineda View Post
    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?
    Last edited by IamFODI; 11-04-2020, 10:33 AM.

    Leave a comment:


  • maupineda
    replied
    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.

    Leave a comment:


  • IamFODI
    replied
    Originally posted by hansbrix View Post
    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?

    Leave a comment:


  • hansbrix
    replied
    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.

    Leave a comment:


  • IamFODI
    replied
    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.

    Leave a comment:


  • hansbrix
    replied
    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.

    Leave a comment:


  • Obioban
    replied
    Originally posted by terra View Post
    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.

    Leave a comment:


  • terra
    replied
    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.

    Leave a comment:


  • Obioban
    replied
    Originally posted by r4dr View Post

    Wow, TIL. The E93 is hefty hefty.
    The e60 is also just a much lighter/volume chassis (because it alu, likely) than the e90.

    If you take the non M versions, and compare same engine, same trans, same drivetrain, body (so, say, rwd 528i 6mt sedan vs rwd 328i 6mt sedan), the e60 is only ~70 lbs heavier than the e90. BMW had to do a ton of work to get the e9X M3 to be lighter (plastic fenders, CF rood, etc), and they still only ended up ~300 lbs lighter for similarly speced cars (e90 M3 vs e60 M5).

    On top of that, the hardtop vert adds a ton of weight to the e9X.

    Leave a comment:

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