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Picking spring rates for street coilovers (Öhlins R&T)

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    Picking spring rates for street coilovers (Öhlins R&T)

    Interested to get some opinions on a suspension upgrade. My E90 is my DD & family car, so 100% street use. Main thing I'm looking for is better feel and agility (I miss my old sub-3100 lb car) without big NVH compromises. Not going to lower the car more than 10mm if at all.

    Current favorite candidate is an Öhlins R&T kit with Swift springs and some kind of street camber plate (likely TMS Hybrid, maybe GC Street), all from Barry @ 3DM Motorsport. Also doing front tension arm monoballs. The thing I’m stuck on is spring rates.

    I feel like I’d love to go for flat ride. That, plus stiffer springs all around and Öhlins’s DFV to control secondary ride, seems like a great match for my use. It'd also be cool to try this out and offer feedback that might be useful for the community. Looking at spring rates in Swift’s catalog, I could get flat ride with 228 lbs/in front and 800 rear springs (42-45% stiffer than stock). That’d nudge handling balance toward oversteer, but I wouldn't mind throwing in a front sway bar anyway.

    AFAICT, the main downside is that 228 lbs/in is below the rule-of-thumb minimum for the front dampers’ out-of-the-box valving (and 800 is not far from the max in the rear). It'd be no issue to have the dampers revalved before the kit ships, but it’s not like Barry has tried-and-tested damper curves for this particular use case sitting around waiting to be used
    , and I don’t like the idea of spending a lot of time and money sending dampers back and forth until we find the perfect curve. We’d have to guess, and I don't know how to estimate the likelihood that we’d end up with a better result (for my use) than Öhlins’s out-of-the-box spring rates and damper valving.

    Thoughts?
    Last edited by IamFODI; 08-08-2020, 11:23 AM.
    2008 M3 Sedan 6MT
    Slicktop, no iDrive | Öhlins by 3DM Motorsport | Autosolutions | SPL

    2012 Mazda5 6MT
    Koni Special Active, Volvo parts

    #2
    I don't believe I've seen anyone try to run those rates before.

    I'd say go for it.
    I've installed a few sets of Ohlins and they do feel great and slightly stiffer than stock but every well damped.

    So far I've run:
    10k (560#) / 16k (892#) on BCs which were stiff but really not that bad as I thought it would be. It felt great on the track, but the dampers were the weakest link.

    Changed the fronts to 400# and the car felt better on the street, haven't taken the car to the track on this setup. .

    My new setup which I haven't installed as yet is AST 5300, a 3way setup with remote reservoirs.
    They came with 504# / 784#, but I think I will run 400# / 892# springs I have.

    Comment


      #3
      After a lot of discussion, reading, spreadsheeting, and general hand-wringing, I get the impression that this situation is much more complicated than I had thought and will likely require more experimentation than I'm comfortable with right now. I opted for the out-of-the-box R&T spring rates (342 lbs/in front, 685 lbs/in rear), though still with Swift springs, and the stock sways. Fingers crossed...
      Last edited by IamFODI; 08-18-2020, 05:19 PM.
      2008 M3 Sedan 6MT
      Slicktop, no iDrive | Öhlins by 3DM Motorsport | Autosolutions | SPL

      2012 Mazda5 6MT
      Koni Special Active, Volvo parts

      Comment


        #4
        Hey IamFODI, so you bought Ohlins. Those frequencies definitely give you pitch. The beautiful aspect about Flat Ride is provided the dampers don't have a terrible amount of rebound bias, you can run them at the softer end and still get good control. Did you get dyno curves?

        tdott - If you have yet to install the AST 3 ways, I would be interested in dyno testing them, especially to determine gas force and very-high speed compression and rebound levels. I have been uniformly UNIMPRESSED and even DISMAYED at how over-pressurized, and over-damped, AST / MCS / JRZ and their brethren are. I have plenty of data to prove it. One recent E36 M3 customer took off a set of AST singles that he said 'were trying to kill him.' After seeing the wonky behavior I can see why!
        Shaikh Jalal Ahmad
        Suspension Decoder @ Fat Cat Motorsports, Inc.
        Youtube: Suspension Truth
        FCM E46 M3 Ride Harmonizer spreadsheet

        Comment


          #5
          Didn't get dyno curves. It's just the default valving though so it shouldn't be hard to find. Let me see if I can request it.

          EDIT: Apparently I'll get dyno curves on my exact dampers after all. Will share when I get them.
          Last edited by IamFODI; 08-19-2020, 12:08 PM.
          2008 M3 Sedan 6MT
          Slicktop, no iDrive | Öhlins by 3DM Motorsport | Autosolutions | SPL

          2012 Mazda5 6MT
          Koni Special Active, Volvo parts

          Comment


            #6
            Originally posted by Suspension Decoder View Post
            tdott - If you have yet to install the AST 3 ways, I would be interested in dyno testing them, especially to determine gas force and very-high speed compression and rebound levels.
            I am about to send them to TX to get resealed/rebuilt. They did say they will Dyno match L&R, I'll confirm that they will provide the data before sending them in.

            Thanks.

            MCS 2WNR and MCS 3WR are a popular setup. Also many owners rave about them, some of whom are driving instructors with experience with several of the major brands on this platform.
            Last edited by tdott; 08-19-2020, 04:12 PM.

            Comment


              #7
              Ahh.. the old reseal and rebuilt. I wonder how many miles you have on that setup before you get to pay for the privilege of needing additional service work?!

              Its funny - the kind of dyno testing most shops do is NOT as thorough as what I look at. Especially with the 19mm or 22mm shafts that many mcs or ast have, the gas force is often VERY high and that is a hidden downside with those 'popular setups.' I'm informing people, slowly but surely, that better-optimized options exist.

              Again, let me know if you want me to test them fully - I can reimburse for your shipping cost and will make a video to show what's going on, no funny editing just useful info for the BMW community.
              Last edited by Suspension Decoder; 08-25-2020, 01:14 PM.
              Shaikh Jalal Ahmad
              Suspension Decoder @ Fat Cat Motorsports, Inc.
              Youtube: Suspension Truth
              FCM E46 M3 Ride Harmonizer spreadsheet

              Comment


                #8
                Just adding a data point...

                The previous owner of my car (E92 ZCP) had installed Fortune Auto 510 w/ 10K(560) front 14K (784lb) rear.
                2 of the dampers needed rebuilt, I didn't want to have the car down for a couple weeks, and it felt too stiff.
                So I swapped them for new FA500 w/ 8k(448) front 12k(672) rear.

                My car is a daily driver, and I have the dampers set fairly "wide open" (4clicks from full soft). The change to 8k/12k is still notably "stiff" on Chicago roads, but feels OEM+ and "works".

                Cheers

                Comment


                  #9
                  Thanks, everyone, for your input.

                  My kit has been delayed, apparently due to supply issues. Hopefully not for too much longer. Looking forward to weighing in myself. :]
                  2008 M3 Sedan 6MT
                  Slicktop, no iDrive | Öhlins by 3DM Motorsport | Autosolutions | SPL

                  2012 Mazda5 6MT
                  Koni Special Active, Volvo parts

                  Comment


                    #10
                    Originally posted by ultimatemj View Post
                    Just adding a data point...

                    The previous owner of my car (E92 ZCP) had installed Fortune Auto 510 w/ 10K(560) front 14K (784lb) rear.
                    2 of the dampers needed rebuilt, I didn't want to have the car down for a couple weeks, and it felt too stiff.
                    So I swapped them for new FA500 w/ 8k(448) front 12k(672) rear.

                    My car is a daily driver, and I have the dampers set fairly "wide open" (4clicks from full soft). The change to 8k/12k is still notably "stiff" on Chicago roads, but feels OEM+ and "works".

                    Cheers
                    Thanks for your comments and notes. That setup clearly has pitch, so it'll feel smoother if you drive backwards

                    Running damping closer to full soft is usually a better idea as there is NO benefit (beyond perceived 'sportiness') when cranking up the adjuster.

                    Got shock dyno curves?
                    Shaikh Jalal Ahmad
                    Suspension Decoder @ Fat Cat Motorsports, Inc.
                    Youtube: Suspension Truth
                    FCM E46 M3 Ride Harmonizer spreadsheet

                    Comment


                      #11
                      Originally posted by Suspension Decoder View Post
                      Running damping closer to full soft is usually a better idea as there is NO benefit (beyond perceived 'sportiness') when cranking up the adjuster.
                      I'm curious about this because I helped set a car up recently and my experience doesn't necessarily match this statement. For background, it's an F82 ZCP with Ohlins R&T (the earlier version with a stiffer rear spring) on NT01 tires.

                      I had tracked it a couple times and was never impressed with the car -- it felt kind of lazy and numb, but since I was just hopping in the driver's seat for fun I didn't think much about it. Then I kind of thought about the car's setup and this most recent DE I cranked up the dials to 5 clicks from full hard. They had been either at full soft or very close to full soft. It transformed the damping both on track and off track. On the track, I could finally execute weight transfer, especially in rapid, quick sections in a way that matched the car's speed through the section, and on the street it felt like the damping was actually keeping up with the relatively high spring rates. It rides better on the street, noticeably so. On track, it felt as if I finally tied my shoelaces i[ and my same movements and inputs resulted in the car responding with agility and no delay.

                      With that in mind, is this because this is where the Ohlins dampers should have been set to match these spring rates in the first place? I'm struggling to reconcile that experience and transformation with your statement that either full or close to full soft is where you want dampers.
                      '03.5 M3 SMG Coupe - Jet Black / Black

                      Comment


                        #12
                        Originally posted by Suspension Decoder View Post
                        Thanks for your comments and notes. That setup clearly has pitch, so it'll feel smoother if you drive backwards Got shock dyno curves?
                        I think I do have dyno curves for the FA510s, but not sure about the FA500s...I'll look.

                        Which springs (front or rear) would you suggest changing would improve the ride? And to what spring rate?

                        Thanks.
                        Last edited by ultimatemj; 08-25-2020, 03:44 PM.

                        Comment


                          #13
                          Originally posted by Suspension Decoder View Post
                          Ahh.. the old reseal and rebuilt. I wonder how many miles you have on that setup before you get to pay for the privilege of needing additional service work?!

                          Its funny - the kind of dyno testing most shops do is NOT as thorough as what I look at. Especially with the 19mm or 22mm shafts that many mcs or ast have, the gas force is often VERY high and that is a hidden downside with those 'popular setups.' I'm informing people, slowly but surely, that better-optimized options exist.

                          Again, let me know if you want me to test them fully - I can reimburse for your shipping cost and will make a video to show what's going on, no funny editing just useful info for the BMW community.
                          Dyno of the front AST5300 is attached. It looks like it was done with all adjusters fully open and then again fully closed.
                          Attached Files

                          Comment


                            #14
                            Originally posted by r4dr View Post
                            I'm curious about this because I helped set a car up recently and my experience doesn't necessarily match this statement. For background, it's an F82 ZCP with Ohlins R&T (the earlier version with a stiffer rear spring) on NT01 tires.

                            I had tracked it a couple times and was never impressed with the car -- it felt kind of lazy and numb, but since I was just hopping in the driver's seat for fun I didn't think much about it. Then I kind of thought about the car's setup and this most recent DE I cranked up the dials to 5 clicks from full hard. They had been either at full soft or very close to full soft. It transformed the damping both on track and off track. On the track, I could finally execute weight transfer, especially in rapid, quick sections in a way that matched the car's speed through the section, and on the street it felt like the damping was actually keeping up with the relatively high spring rates. It rides better on the street, noticeably so. On track, it felt as if I finally tied my shoelaces i[ and my same movements and inputs resulted in the car responding with agility and no delay.
                            Interesting -- I just had a comparable experience on the street with my own Öhlins R&T kit. Started at full soft and ended up 5 clicks from full hard all around, though it was for ride purposes rather than handling. I didn't like the excess motion on full soft. Higher settings kept things more controlled and helped the car settle faster after a bump.

                            Full review forthcoming.
                            2008 M3 Sedan 6MT
                            Slicktop, no iDrive | Öhlins by 3DM Motorsport | Autosolutions | SPL

                            2012 Mazda5 6MT
                            Koni Special Active, Volvo parts

                            Comment


                              #15
                              Originally posted by IamFODI View Post
                              Full review forthcoming.
                              Finally done and posted! https://nam3forum.com/forums/forum/e...-arm-monoballs
                              2008 M3 Sedan 6MT
                              Slicktop, no iDrive | Öhlins by 3DM Motorsport | Autosolutions | SPL

                              2012 Mazda5 6MT
                              Koni Special Active, Volvo parts

                              Comment

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