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Definitive Adjustable Trailing Arm Thread

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  • #61
    Looks good...

    One thing - Have you checked the Bumpsteer yet?
    I had to raise the inner steering tierod mount inorder
    to bring the bumpsteer inline. You can only lower the
    outer point so far before it interferes with other components.

    Mike
    sigpic

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    • #62
      I have made a inner mount that's adjustable. As the car is now, it's completly wrong

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      • #63
        Originally posted by Turbo ///M3 View Post
        Guess they would be approx $2000
        for front and rear??? sign me up:heart:

        Karl Kraus --Education is a crutch with which the foolish attack the wise to prove that
        they are not idiots.

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        • #64
          $2000 is an estimate for rear only, front $1000-1200

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          • #65
            Turbo, if you have say a rh thread on the outer diameter of the "bolt" that is threaded into the trunnion and a left hand thread on the inner diameter of the same bolt and rod end/lock nut then you have a very compact "turnbuckle" and can make a considerable adjustment without having to remove the assembly. This is the same as the post 1990 DTM cars. If you can find photos of a DTM or Group A Bigazzi car, they seemed to use this style of adjustment on quite a few of their suspension joints, ie front camber and castor adjustment as well as the rear suspension.

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            • #66
              There is RH -LH treads, Rod end is LH and sits in a Rh bolt that's bolted to the arm.

              BTW, mine are 100% replicas from DTM trailingarms.

              Photobucket

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              • #67
                I'd be interested in a set of the rear adjusters if you decide to sell only that part.

                Pete

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                • #68
                  Pete, You need to modify the inner bushing mount aswell to use a spherical bearing, and the hole needs to be treaded.
                  I have a pretty complex jig with a mill mounted to it to modify this hole, and to mill off the outer mount, so the new part can be placed exactly where it's supposed to be, it can't be off by more than a few millimeters, than it will hit the "framerail".
                  The angle of the new part also needs to be right, if not you will get forces in the wrong places and you might snap the rodend or bolt.

                  But if you are willing to give it a try i can probably sell you a kit.

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                  • #69
                    Originally posted by Turbo ///M3 View Post
                    The angle of the new part also needs to be right, if not you will get forces in the wrong places and you might snap the rodend or bolt.
                    I imagine, like all fabrication jobs, actually doing this is a lot more complicated than it looks to us casual observers.....

                    I don't understand what you mean about maybe snapping the bolt or rodend. If the new adjustment part was not welded on at perfectly the correct angle, it seems like you would wind up getting unwanted toe changes when adjusting camber, or you might use up some of the angularity play in the rod end. But, wouldn't you have to be so far off that you exceeded the rod end "play" before you would have to worry about breaking something?

                    Excuse my ignorance if I am missing something. I am just trying to visualize what you are talking about.....

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                    • #70
                      Made a little drawing, This may not be a big issue, but should be concidered on a high horsepower cars.
                      Photobucket

                      What I'm trying to say, is that I have used a lot of time building a jig to make them right, and you would probably use just as long, and it seemes like waste of time to make one set for yourself.
                      You can't just cut here, weld here, and everything comes out right. And there's really limited space under there with the adjuster in place, so it needs to be right.

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                      • #71
                        I definately argee with you Turbo M3 that there the force needs to be directed axialy through the turnbuckle. Doing a quick free body diagram (I am an engineer and this is what we do) I am noticing that this configuration wouldn't be very good at handling the moment (turning force) that is induced by the brake system. Obviously this isn't a very big issue as the touring cars had quite large braking systems and still ran this type of trailing arm adjustment system.

                        Sorry, I am kind of thinking out loud.

                        -Kelly

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                        • #72
                          Have you got your inner pivot free so it can slide transversely as the arm raises and lowers. On my first car the inner rod end was I think 20 mm bore and was free to slide on a hardened and polished sleeve that the 12 mm locating bolt went through.

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                          • #73
                            Originally posted by Turbo ///M3 View Post
                            Pete, You need to modify the inner bushing mount aswell to use a spherical bearing, and the hole needs to be treaded.
                            I have a pretty complex jig with a mill mounted to it to modify this hole, and to mill off the outer mount, so the new part can be placed exactly where it's supposed to be, it can't be off by more than a few millimeters, than it will hit the "framerail".
                            The angle of the new part also needs to be right, if not you will get forces in the wrong places and you might snap the rodend or bolt.

                            But if you are willing to give it a try i can probably sell you a kit.
                            Well I would be using this on a 73 2002 so my bet is that it would not fit your jig anyway. Pm on the way.

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                            • #74
                              wow thats beautiful... ive just finished my front coilover setup and wanted something more heavy duty for the rears and look what i find! i love it!
                              I am definately interested in this!

                              subscribed

                              Aussie dollar really sucks at the moment!

                              sash

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                              • #75
                                Without spending big $$$ in such sn elaborate suspension, I suggest raising the subrame by 12mm, simply by using subframe mounts with 12mm shorter upper part. 12mm shims between the subframe mount and the lower retaining cup, 12mm shim between the subframe and the diff, and you ust have removed a lot of unneeded camber, caused by lowering the car. I have done this very simple mod on a DM racecar and we gain so much rear traction, especially with stiff 1200# rear springs. It takes about 2 hours to make the simple mod. But as far as I know it requires solid rear subframe mounts.


                                [email protected]

                                1969 2002 racecar
                                1989 M3 racecar
                                e39 Touring

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