Announcement

Collapse
No announcement yet.

Adjustable Control Arms options

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • Adjustable Control Arms options

    Hello everyone!

    I will be in the US shortly and I was intending of buying AKG adjustable control arms. They cost 1200USD.

    I was wondering what other options I have before spending those money on the AKG product. I 've seen some time ago Gustave's control arms selling.

    Please share with me your thoughts
    Motornuts, what did you do with your car today?

    My projects:
    http://beta.motornuts.com/scaraveos/MR2-Spyder
    http://beta.motornuts.com/scaraveos/BMW-E30
    http://beta.motornuts.com/scaraveos/EP82

  • #2
    For that kind of money that's the only option really.

    Comment


    • #3
      The main question is: what do you want to achieve?


      [email protected]

      1969 2002 racecar
      1989 M3 racecar
      e39 Touring

      Comment


      • #4
        Lee,

        1) I 've happened to bend 2 sets of standard controls arms. I want something stronger. (10)
        2) I need control arms with standard geometry. The stock ones always change the camber/toe because they are not precisely made. (10)
        3) I want to fix the roll couple as much as possible (20)
        4) I am thinking of widening the wheel base (20)
        5) Adjustability (7)

        I've set the importance of what I want to achieve with 20 the most important.

        e30rida,
        lets not think of the value
        Motornuts, what did you do with your car today?

        My projects:
        http://beta.motornuts.com/scaraveos/MR2-Spyder
        http://beta.motornuts.com/scaraveos/BMW-E30
        http://beta.motornuts.com/scaraveos/EP82

        Comment


        • #5
          Thanks for clarifying your needs. Here's my take, but others can have a different point of view.

          1- I want stronger - The "DTM" CAs are NOT stronger than stock. They are lighter, more precise and will require very regular inspection. As any race parts.

          2- Precisely made What brand of CA do you use?

          3- Roll center.. The DTM CA will do that. If you have an e30 M3, you can adjust roll center with a spacer in between the botom of the strut and the Ackerman arm

          4- Widening the track. Get e46 CAs, or if you have an e30 M3, you get offset roll center spacers increasing the front track by 40mm

          5- Adjustability. Yup. You can adjust caster. But do you really need to adjust caster? You can use 96+ e36 M3 CAs and eccentric CA bushings for even more caster.


          [email protected]

          1969 2002 racecar
          1989 M3 racecar
          e39 Touring

          Comment


          • #6
            interessting topic!

            4) I am thinking of widening the wheel base (20)
            4- Widening the track. Get e46 CAs, or if you have an e30 M3, you get offset roll center spacers increasing the front track by 40mm
            I am also thinking of widening the wheelbase by 15mm per side...

            e46 CA will increase 30mm per side, which is too wide for stock fenders IMHO (sad because it would be easy otherwise...)

            I don't like wheel spacers because they mess up the steering geometry (stock scrub radius is 14.4mm, so a wheel spacer of 15mm will increase the scrub radius by 100%).
            I haven't figured fully yet, but I assume the offset roll center spacer does the same to scrub radius.

            I am thinking of changing the location of the CA in the crossmember, i.e. moving the sleeves (where the CA bolt goe through) towards the outside. That should give me increased trackwidth with otherwise unchanged geometry. Spare crossmember is at a workshop to be prepared, so more to come soon...


            1) I 've happened to bend 2 sets of standard controls arms. I want something stronger. (10)
            +1 for the question on the brand, do you use OE BMW E30 ones? Alloy or steel? Where do they get bend? "Normal" hard track driving or rallying or shunts?

            1- I want stronger - The "DTM" CAs are NOT stronger than stock.
            Interessting to hear that. Is that statement based on some mechanical integrity calculations? I mean, I can see the intension in the changed design (reducing the bending forces etc.), but I always assumed the M-engineers may have designed them stronger than stock. I maybe wrong, though.


            Thomas
            sigpic

            Comment


            • #7
              Hi Thomas

              In regard of the strength of those DTM copies, and who ever the supplier is, remember that despite being engineered by Motorsport, the goal of the original part was not to necessarely offer stronger parts, but lighter and adjustable, while parts on street driven cars are intended to be bulletproof even i the ost adverse situation. Install and forget. Also, remember that the forces on the DTM part are not applied the same way as on the OEM control arms.

              On stock comtrol arms, the force on the rear pick-up point (CA bushing) is sideways, while on the DTM control arms, the force is longitudinal. Therefore the two bolts engineered for a sideways force, now have to work in a different way than originally engineered. And while the initial sideways force was on a ratio of about 1:1, with the DTM arm, as the front pick-up point is about halfway on the arm, then the rear pick-up point must sustain about double the force.

              Basically, the situation is the same as, say, with a Formula One suspension triangulation. How long will it last on your daily driver? Sure it was designed to sustain high forces. But was it designed to last as long as waht's required for a daily driver. Basically, a race part is enginered for a race environement.

              A bit like the solid DTM shifters with the console bolted on the shell. Sure it feels way more precise, but drivers with rubber engine/tranny mounts soon realized it was a bad combination. Upon braking, the motor was pulling on the shifter rod and sometimes pulling out of gear. It required solid mounts.

              BTW. I have never seen an OEM steel control arm bend, unless the car is involved in an accident. And as far as changing the roll center on an e30 (non-M) car, I think that Bimmerworld's e36 kit can easily be adapted to the e30. Non-M e36 control arms have the same geometry as e30. In fact, I have often put e30 control arms on e36s to make them last longer...

              BTW guys, be assured I am not talking down on any of the DTM CA suppliers. They all make great parts. Simply highlighting it was designed for track duty.
              Last edited by LeeVuong; 03-26-2010, 07:01 AM.


              [email protected]

              1969 2002 racecar
              1989 M3 racecar
              e39 Touring

              Comment


              • #8
                Hi Lee

                I get the point of your argumentation on the raceparts. Very frequent inspection / replacement intervalls allow the use of fast-wearing bearings etc.
                And I fully agree on the description of the changed loads on the rear CA bearing, which should have a longitudinal support for compensation (as had in the DTM design).

                I missed the point before that Scaraveos has an E30, so he may be missing the M3E30's oportunity for rollcenter-correction. So one could indeed adapt something like the Bimmerworld E36 race-design (needs spacers on the steering as well) or maybe better change to M3E30 hardware?

                Thomas
                sigpic

                Comment


                • #9
                  Thanks for sharing your thoughts

                  The CA I am using are steel ones from ebay and cheap. I use the car on track but there are sometimes that I will over do it and I will go off track. It happened 2-3 times resulting in bent CA (we don't have good traps). The design I see on the AKG CA seems solid and I noticed that the bolt that connects the 2 parts of the CA is thin so it will brobably break before the CA bends.

                  I don't have an M E30 so I can't use spacers to fix the roll center. I have thought multiple times to change to M E30 hardware but then I will have to make new brake adapters/hats and buy new wheels which added to the expensive M3 hardware makes a big sum.

                  Also, buying E36 Race CA (bimmerworld) is not an option as they are expensive and it will be sad if they bent.

                  Those are the reasons that make me think AKG CA is a good option. And I also was wondering if I have any other options.
                  Last edited by scaraveos; 03-27-2010, 11:51 AM.
                  Motornuts, what did you do with your car today?

                  My projects:
                  http://beta.motornuts.com/scaraveos/MR2-Spyder
                  http://beta.motornuts.com/scaraveos/BMW-E30
                  http://beta.motornuts.com/scaraveos/EP82

                  Comment


                  • #10
                    You are regularly bending steel control arms engineered for toughness and durability. Do you expect smaller aluminun parts to fair better. It looks like the real problem is not the control arms anyway ;-)


                    [email protected]

                    1969 2002 racecar
                    1989 M3 racecar
                    e39 Touring

                    Comment


                    • #11
                      If you will be driving on the roads in Greece (especially Athens, which are crappy), I'd go with some stock steel control arms from the 96+ E36 M3.

                      YMMV....Just my 0.02 drachmas/euros/dollars


                      Nick

                      Comment


                      • #12
                        I think we have now ruled out 1,2,5 as non being important(or not true). So keeping in mind 3,4 I should either choose a "DTM" CA design or some short of aftermarket stock style control arms like BimmerWorld E36 Race design. I was hoping Gustave's had a DTM crossmember style mounting but they dont. So that leaves me with those options I guess. I am not sure if the E36 Race arms would fit though.

                        Nikos you are right about the Greek roads in general, but I just drive the car from track and back mostly.
                        Motornuts, what did you do with your car today?

                        My projects:
                        http://beta.motornuts.com/scaraveos/MR2-Spyder
                        http://beta.motornuts.com/scaraveos/BMW-E30
                        http://beta.motornuts.com/scaraveos/EP82

                        Comment


                        • #13
                          Just for the history,

                          I ordered muzzimotorsport control arms. They are normal E30 arms with adjustable outer joints and with a spacer on the outer bolt and with half the price of the AKG arms.

                          Thanks for sharing your thoughts
                          Motornuts, what did you do with your car today?

                          My projects:
                          http://beta.motornuts.com/scaraveos/MR2-Spyder
                          http://beta.motornuts.com/scaraveos/BMW-E30
                          http://beta.motornuts.com/scaraveos/EP82

                          Comment

                          Working...
                          X