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E30 IX Spring Rates (Aggressive winter DD/rallycross)

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    E30 IX Spring Rates (Aggressive winter DD/rallycross)

    How have you guys set up the suspension on your IX's?

    I've used stock springs/shocks.
    Stock springs/Billy HD's
    & H&R springs/Billy HD's.

    The H&R/Billy combo wasn't bad, but it did lower the car and it is still a progressive rate spring.

    I'm from the world of road course race cars. We hate the unpredictability of progressive springs.

    My newest IX I just order a complete kit from Ground Control with 430F/600R linear Eibach springs and Billy HD's. My goal here is winter DD and occasional rallycross. I want stock height for the winter time with maybe a 1 inch drop for the summer.

    I know someone listed all of the factory and aftermarket spring rates for 80's-90's BMW's but they only posted the inch/pound rate for the first inch of travel. This is kind of useless information to me since they are progressive rate springs...

    Has anyone tested the amount of ramp-up on factory springs? How progressive are they? (cuz they feel like poo)
    The best one-stop shopping for German car parts and lifestyle: http://www.gutenparts.com/

    #2
    I'll be following this thread, because I almost could have written your post myself. (We're also practically neighbors -- I'm just over the mountain near Middlebury.) My previous iX had stock springs & shocks, followed by stock springs w/ Bilstein shocks. My current iX has H&R springs/Bilstein shocks. They're fine on the pavement, but lower and stiffer than I want. I do lots of driving in snow, with frequent diversions into ice racing (where softer is generally better), and winter rallies on rough, bumpy dirt roads. I want all the suspension travel I can get, with soft but predictable spring rates that can swallow up frost heaves at brisk speeds without banging the snot out of the suspension.

    There's all kinds of advice for lowering an E30, but not so much for raising and softening one.
    Dave
    '91 325iX

    Comment


      #3
      IMO, there's not much point in worrying about what the equivalent linear rate spring would be - I'd say the 430f/600r rates chosen are pretty much on the mark. you can always swap out different rates later, as they are cheap and readily available.

      if you want softer, ditch the Bilsteins. They are unnecessarily stiff. H&R springs aren't stiff at all - but coupled with the Bilsteins, they can feel that way (as will basically everything else).

      Fun fact: The "xi" H&R springs aren't really ix specific. They're the front OE sport spring from a standard E30 coupled with a Cabrio rear H&R spring, sold as a set. Not exactly a "race" spring. :)

      if you remove the stock spring perches for the GC there's no reason you couldn't raise the car higher than stock for winter and lower it in the summer - but beware you can have toe out problems in the rear when raised, especially if you've swapped out the ix subframe bushings for RWD aftermarket replacements.
      Build thread

      Bimmerlabs

      Comment


        #4
        Originally posted by Dave_G View Post
        I'll be following this thread, because I almost could have written your post myself. (We're also practically neighbors -- I'm just over the mountain near Middlebury.) My previous iX had stock springs & shocks, followed by stock springs w/ Bilstein shocks. My current iX has H&R springs/Bilstein shocks. They're fine on the pavement, but lower and stiffer than I want. I do lots of driving in snow, with frequent diversions into ice racing (where softer is generally better), and winter rallies on rough, bumpy dirt roads. I want all the suspension travel I can get, with soft but predictable spring rates that can swallow up frost heaves at brisk speeds without banging the snot out of the suspension.

        There's all kinds of advice for lowering an E30, but not so much for raising and softening one.
        HA! Good to e-meet you. I live in Hancock, VT and run the bike shop Alpine Bike Works at the bottom of the access road in Killington. I'm sure i'll meet you in person at an Ice race or a Rallycross at some point this winter.
        Last edited by berlow94; 11-08-2016, 06:51 PM.
        The best one-stop shopping for German car parts and lifestyle: http://www.gutenparts.com/

        Comment


          #5
          Originally posted by nando View Post
          IMO, there's not much point in worrying about what the equivalent linear rate spring would be - I'd say the 430f/600r rates chosen are pretty much on the mark. you can always swap out different rates later, as they are cheap and readily available.

          if you want softer, ditch the Bilsteins. They are unnecessarily stiff. H&R springs aren't stiff at all - but coupled with the Bilsteins, they can feel that way (as will basically everything else).

          Fun fact: The "xi" H&R springs aren't really ix specific. They're the front OE sport spring from a standard E30 coupled with a Cabrio rear H&R spring, sold as a set. Not exactly a "race" spring. :)

          if you remove the stock spring perches for the GC there's no reason you couldn't raise the car higher than stock for winter and lower it in the summer - but beware you can have toe out problems in the rear when raised, especially if you've swapped out the ix subframe bushings for RWD aftermarket replacements.
          I like that the Bilsteins are on the stiff side. After multiple phone calls to Ground Control, it seems that Bilsteins actually won't properly handle any spring rates higher than the 430/600 combo i'm going with.

          The trailing arm bushings look pretty fresh, as do the subframe bushings. (All stock components) I have a set of AKG poly trailing arm bushings ill probably get around to installing after the winter and i'm thinking about coupling those with the Condor IX-specific subframe bushings. When that happens i will definitely be welding in adjustment tabs.

          For now I'm just going to fill the subframe bushings in with 3M window weld to stiffen them up. (This stuff dries to approximately the hardness of poly) Also going with Condor solid motor mounts and t-case mount.
          I also have a lightened M20 flywheel and Sachs HD clutch ill be putting in as well as a brand new VC from BMW. :)
          Did i mention Garagistic IX-specific DSSR and AKG solid mounted race shifter?

          Might as well go full retard while the transmission and t-case are out.
          The best one-stop shopping for German car parts and lifestyle: http://www.gutenparts.com/

          Comment


            #6
            I realize this thread is almost four years old, but I’m curious how this setup is working out for you? I am looking for a similar setup. I probably won’t do any rallycross but I would still like a fairly stiff setup at or near stock height as I drive on dirt roads every day.

            I was originally going to put the stock springs in with the bilsteins that came with the car but figured if I was going to take everything apart why not upgrade things.

            Comment


              #7
              Originally posted by VTiX View Post
              I realize this thread is almost four years old, but I’m curious how this setup is working out for you? I am looking for a similar setup. I probably won’t do any rallycross but I would still like a fairly stiff setup at or near stock height as I drive on dirt roads every day.

              I was originally going to put the stock springs in with the bilsteins that came with the car but figured if I was going to take everything apart why not upgrade things.
              I ditched the setup because of how unreliable the E30 AWD system wound up being. ESPECIALLY now that BMW doesn't have any more T-case viscous couplers left.
              When it is working, it works phenomenally well! But it doesn't take much break something.
              I sold the car all together.

              I would be interested in doing an E46 330XI with this setup though! LSD in the rear would be a must, but their T-cases's seem much more durable. They make great power too if you put ZHP cams and software in them.
              The best one-stop shopping for German car parts and lifestyle: http://www.gutenparts.com/

              Comment


                #8
                Meh. The E46 tcase has no locking ability at all - it's utter shit in comparison. Mechanically simpler without because it's an open differential. Slip is regulated by brakes instead, not great for performance. Also they eat CV shafts for breakfast.

                I haven't found ithe E30 to be unreliable at all, and daresay I've had mine longer than almost anyone. Jeeze, I'm at around 300k miles now, a lot of those being hard driven and track miles.

                200kish now on a franken manual t-case built from the original automatic one and the 280k mile one from my parts car (the VC on that one finally died after several years of track use and abuse).

                I do have a brand new in box t-case though if I need it in the future, but I'm not putting thousands of miles on the car anymore, so I probably never will. Also, the VC can be rebuilt anyway.
                Build thread

                Bimmerlabs

                Comment


                  #9
                  The T-case didn’t seam to mind track use, it was loose surfaces that cook the VC.
                  I too have put well over 100k hard asphalt miles on a high mileage t-case without issue.
                  ive also taken a brand new VC from BMW and rendered it useless after less then 25k of driving on loose surfaces where the VC has to work hard to maintain front/rear lockup.

                  Its my understanding that the E46 t-case is a permanent front/rear torque split of 38%/62%. The brake bias “LSD” affect is only for left/right torque distribution per axle. Hence my comment where a rear LSD should be installed.
                  The best one-stop shopping for German car parts and lifestyle: http://www.gutenparts.com/

                  Comment


                    #10
                    Originally posted by berlow94 View Post

                    I ditched the setup because of how unreliable the E30 AWD system wound up being. ESPECIALLY now that BMW doesn't have any more T-case viscous couplers left.
                    When it is working, it works phenomenally well! But it doesn't take much break something.
                    I sold the car all together.

                    I would be interested in doing an E46 330XI with this setup though! LSD in the rear would be a must, but their T-cases's seem much more durable. They make great power too if you put ZHP cams and software in them.
                    Hey Andrew....just curious, is the T-case on the ix I bought from you the new case you mention or is it a used one? Seems to be working fine but just wondering. I bought a nice rust free 88 ix from Idaho with high miles (260k), and plan on using the 89 ix I bought from you for parts, so would be good to know about the transfer case.

                    Thanks!
                    89 325ix coupe Diamondschwartz
                    1994 Mazda Miata

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