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Definitive Adjustable Trailing Arm Thread

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  • Definitive Adjustable Trailing Arm Thread

    While I have had my car on stands messing with the clutch/tranny, I was shocked to see the wear patterns on the rear tires....




    There is some tread on the tires left, yet the inner edges are worn to the belts. I had not really noticed because that portion is kind of hard to see when the car is on the ground....

    I am running the GC setup, with Kmac eccentric bushings, and the car is not lowered all that much. Maybe an inch max. The Kmacs are adjusted for minimum negative camber (at least they "were"...who knows where they have wandered to). When I installed the Kmacs, I knew they were a half assed POS solution, but they were easy.......:idea:

    So I need a way to remove some negative camber.....

    I am sure everyone with a lowered car has the same issue.

    I am aware of the IE kit, which would definitely be a relatively cheap solution. But they bring with them the issue of changing roll center, I assume difficult adjustment, and worst of all I would have to patronize IE.

    Muzzi Motorsport in Europe sells this setup:



    You can get it in completed form (shipping would kill those of us in the states), or as a weld in kit with just the critical bits. I like the rod end adustable toe, but the camber adjusts simply via a slotted bolt hole in the subframe, which is cheesy and introduces some of the same problems as the IE setup. Supposedly the Muzzi kit is a direct copy of the first generation DTM/Group A design..... The other problem is I imagine it uses a metric rod end, which would be a replacement problem in the USA.

    KK Motorsport also sells a "Hinterachsträger Gruppe A" which I think :lostme: is an adjustable rear suspension of some kind. I have emailed them but thus far no reply...

    "Ideally", I am looking for a dual rod end setup where all the adjustment is done on the trailing arms with the rod ends rather than messing with the pivot points on the subframe. I know all the later DTM versions worked like this, but I have not seen detailed enough photos to be able (with my limited skills) to copy something like that.

    Gustave, of course, built the "ultimate" trailing arms with all these features built in. But, the photos have vanished and Gustave is completely out of the E30M3 game (big loss to our little community:().

    So, does anyone have input? Good DTM car photographs? Suggestions? Available parts I am unaware of?

    Anyone?

  • #2
    I don't have any input really but I am also interested. It amazing what you can notice once the car is off the ground. I remember Magnus mentioning to watch for this when he ran into his last flat ( I think it was his last flat anyhow). I noticed a similiar thing with my front tires when removing them for sale. I couldn't believe the inside wear for such a LITTLE amount of driving. Showed me that it's important to get an alignment IMMEDIATELY after doing any suspension work up front.

    I will be interested to see if anybody has any input on something "good" for the rear end.

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    • #3
      Originally posted by ///Mflossin View Post
      Showed me that it's important to get an alignment IMMEDIATELY after doing any suspension work up front.
      what are you going to align? Toe is the only thing you can adjust, unless you have some aftermarket top shock mounts.
      That's why I made my quick adjustable top mounts. Go negative on track, set them back for the way home without any laser equipment. I ruined a set of front tyres in 2k miles with "sharp" toe and negative camber

      I looked at the Muzzi rear setup as well but disregarded it as to complicated to adjust. You will have to take the traling arm off to adjust toe! Don't think my garage will be amused if I block the aligment rig for a few hours.
      Last edited by UweM3; 03-09-2008, 10:59 AM.


      Goodbye M3, you served me well.

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      • #4
        Originally posted by UweM3 View Post
        That's why I made my quick adjustable top mounts.
        Very interest, any pics? I am about to put on a limited solution (KMAC kit). I don't to ruin a set of 18" as they are pricey
        Because anything worth doing is worth doing fanatically!
        Born date 01/88
        Ryan

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        • #5
          Uwe's camber plates is the most simple and cost effective solution for the road/track car. The ability to absorb impact is kept and adjusting them back and forth is literally a 5min job. You don't have to worry with the caster (like KMAC's) because it's a uni-directional adjustment. I have it on my car and couldn't recommend it more.

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          • #6
            Front camber/toe adjustment is really a no-brainer. Lots of good solutions there.

            It is the rears where it gets tricky and difficult......
            Last edited by Ironhead; 03-09-2008, 11:55 AM.

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            • #7
              Originally posted by Ironhead View Post
              Front camber/toe adjustment is really a no-brainer. Lots of good solutions there.

              It is the rears where it gets tricky and difficult......
              What camber are you running? Do you have a recent alignment sheet? How was the toe? Your car doesn't look too low so if you have around -2.5º camber you're alright unless your toe in is not right or you do too much highway driving.

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              • #8
                Originally posted by Ironhead View Post
                The other problem is I imagine it uses a metric rod end, which would be a replacement problem in the USA.

                Perhaps try www.mcmastercarr.com ...

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                • #9
                  Ironhead,

                  My tires used to look like yours. I then welded in the IE adjusters (which use BMW eccentric bolts), making sure to offset them for maximum camber removal. Static camber is now -0.75 degree. The car launches better, is noticably more neutral, and has never slipped on me. It is a little difficult to get the wrenches on, but I would still say that it's moderately easy to set toe and camber.

                  I hate dealing with IE, but I highly recommend this kit...
                  Anders

                  "Objects in mirror are losing..."

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                  • #10
                    Originally posted by Anders View Post
                    Ironhead,

                    My tires used to look like yours. I then welded in the IE adjusters (which use BMW eccentric bolts), making sure to offset them for maximum camber removal. Static camber is now -0.75 degree. The car launches better, is noticably more neutral, and has never slipped on me. It is a little difficult to get the wrenches on, but I would still say that it's moderately easy to set toe and camber.

                    I hate dealing with IE, but I highly recommend this kit...
                    Thanks dude...

                    I am sort of leaning that way. It is not the "ideal" solution, but I waste too much time pursing ideal solutions. Did you have to "clearance" the sheet metal on the bottom of the car to get things to work?

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                    • #11
                      To offset the brackets "up" for max camber removal (on the inner arms), I merely had to slightly push up the sheetmetal with the handle of my softblow. Very easy, and very little needed.
                      Anders

                      "Objects in mirror are losing..."

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                      • #12
                        how many miles did you put on those tires? My tires are wearing great and I'm about 3/4" lower then your car. that looks like a toe problem not a camber problem, but I can't figure out how you got extra toe in the rear
                        ApexRaceParts.com - Facebook Fan Page - Twitter

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                        • #13
                          I agree it might be a toe problem. Last I adjusted the Kmacs I had zero toe, but who knows how they might have shifted? Those things are absolutely miserable to try to adjust, and I am not even going to mess with it until I get some sort of proper adjustment setup installed.

                          Not sure of tire mileage....not much though.

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                          • #14
                            If it's toe-related, wouldn't you need toe-OUT to get that sort of wear (inside edges)??? That would make it feel pretty damn tail-happy though....

                            From what I remember, when I installed my IE brackets on my rear subframe, I didn't have to clearance any sheetmetal.

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                            • #15
                              The Muzzi soulution is not really early Grp A, its a sorta copy, but what its missing is the really neat threaded part that adjusts camber.
                              Adjusting either is a giant pain in the ass in the early Grp A configuration.
                              You have to take the bolt completely out of the rod end ad then spin to adjust. It takes a long time.
                              there is no easy fast way (ask me how I know).

                              But its good, solid, proven and doesn't move. The trailing arm moves like a machine part, no pre-load, no play, it just swings like a hinge.

                              Dont sweat the metric rod ends, getting tthem is no problem.
                              They are more expensive than comparable sized SAE threaded ones, but getting them is a no brainer, many outlets.

                              HTH
                              Jimmy p.
                              jimmy p.
                              87 E30 M3 Prodrive British Touring Car
                              88 E30 M3 Zinnoberot - Street
                              88 E30 M3 Lachsilber - Race (#98 SCCA SPU)
                              92 E30 M Technic Cabrio - S14 POWERED!
                              98 318Ti M44, Base - Morea Green
                              04 Ford F350 - V10

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