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  • Roll Centre Correction

    Hi all,

    I need your interest and support (not money, just putting your hand up to back up what I'm going to say in the next handful of paragraphs).

    Now I'm sure most (if not all) of you gentlemen are aware of the roll centre correction ball joints or uprights out there available for S chassis vehicles (S13,14 and 15). If not, I'll give a fast run down now.

    What my major gripe is that the roll centre adjusting ball joints don't actually correct it by very much. Around 15mm - 20mm at the max. And also they cannot be applied for rear suspension.
    For example:


    Hard Race Roll Centre correcting ball joint


    KTS Roll Centre correcting tie rod end

    Now, on the other end of the spectrum is the more expensive option that is roll centre correcting suspension uprights/knuckles/hubs whatever you want to call them.
    This is an example.

    Gp sports Hyper Knuckle


    Powered by Max Knuckle

    These correct the roll centre by a larger amount (30-40mm) however they all incorporate a shorter steering arm which creates a faster steering ratio. Great for drifting, but will cause nervousness/instability at high speed circuit driving. They are also sketchy looking cut and shuts of the OEM knuckle, again not something I'd trust for high speed circuit racing.
    Now this is where a company called DRIFTWORKS comes in.

    Latest release Geomaster 2 hubs

    More information on Geomaster 2 in this video:
    http://www.youtube.com/watch?v=FD9RvhUx9vI

    Now these are great, they will correct both front and rear bump steer and also correct excessive negative camber change in the rear of the S chassis - a big issue on the S chassis that is one effect that causes lack of corner exit traction. However, the issue is that these still have the shortened steering arm - creating a faster steering ratio, and also the geometry eliminates Ackerman angles.

    What I want to know is whether any of you S chassis racers out there will put your name down for a set of knuckles if Driftworks released a new line of Geomaster 2 hubs where all the roll centre correction is there but the OEM steering arm length is maintained and perhaps with a little but less roll centre correction (30mm instead of 50mm). If Driftworks see enough demand for this then they may extend their production line and develop our dream knuckle.
    Let me know!

    Peace
    Last edited by tez; 03-10-2012, 06:47 PM.

  • #2
    Thats old info on this forum. Use the search button.

    A new front knuckle with RC-correction, bumpsteer correction, stockish ackerman, faster steering, abs compability and S13 hub compability would be nice.

    There is a bit of debate if a rear upright realy is worth the money for our cars.

    Comment


    • #3
      Originally posted by BeerBringer View Post
      Thats old info on this forum. Use the search button.
      The point of my post was not to inform or educate. You didn't need to read between the lines to figure that one out.

      Originally posted by BeerBringer View Post
      A new front knuckle with RC-correction, bumpsteer correction, stockish ackerman, faster steering, abs compability and S13 hub compability would be nice.
      Why would you want S13 hub compatibility? Is retaining wheel stud PCD a standard in any American Motorsport regulation? And ABS? :S

      Originally posted by BeerBringer View Post
      There is a bit of debate if a rear upright realy is worth the money for our cars.
      Once the S-chassis is lowered the negative camber development under suspension compression is huge. As if the camber change at standard height is not bad enough with the length difference of the rear LCA and CA. There is no debate, it needs it. Either raising the subframe, or roll centre correction. Balanced with pro squat geo depending on power levels/diff ratio if you are that way inclined.
      The driftworks rear knuckles have been proven to significantly improve traction of lowered S-chassis vehicles.
      Last edited by tez; 03-10-2012, 06:14 AM.

      Comment


      • #4
        Stock steering ratio is too slow. There are other options for RC correction though.
        '18 Chevrolet Volt - Electric fun hatch for DD duty!


        DefSport Koni Sleeve and Spring Perch Buy!!!
        http://www.nissanroadracing.com/showthread.php?t=5902

        Comment


        • #5
          Originally posted by tez View Post
          The point of my post was not to inform or educate. You didn't need to read between the lines to figure that one out.


          Why would you want S13 hub compatibility? Is retaining wheel stud PCD a standard in any American Motorsport regulation? And ABS? :S


          Once the S-chassis is lowered the negative camber development under suspension compression is huge. As if the camber change at standard height is not bad enough with the length difference of the rear LCA and CA. There is no debate, it needs it. Either raising the subframe, or roll centre correction. Balanced with pro squat geo depending on power levels/diff ratio if you are that way inclined.
          The driftworks rear knuckles have been proven to significantly improve traction of lowered S-chassis vehicles.
          I did not mean to be rude and be one of those "Search!!!!" guys.
          Apologize for that.

          Alot of people already have 5-lug S13 hubs. So it would be nice and save some money. Going S14 hubs is no big deal but it would be nice if both were avalible. This is just a part of my 'wish' list.

          ABS is nice to have when it starts to rain. And there is even a thread on here about retrofiting S2000 abs! If someone is going to make a grip oriented knuckle why not add the posibility to run ABS?

          Is the camber gain realy that bad in the rear?
          I have been runing 2.5 degrees of camber in the rear with even wear on my tires. That is 0.5 to 1 degrees more than most people on here but it seams to work fine for me. Guess i have to pull my rear fenders and try less rear camber.
          The driftworks spindels has been proved. But on what kind of setup? If your super low drift stance then yes there is a huge gain. But if your running NRR 'normal' low than the gain is probably not that big.

          I would totaly love faster steering. But I don't think the 0 ackerman of the DW spindels are good for us.

          Raising the subframe is a very cost effective mod. Most of us have or will replace our subframe bushings anyway.

          Correcting front RC and bumpsteer in one cost effective and easy way is my priority at the moment.

          /Marcus

          Comment


          • #6
            The DW knuckles are borderline prohibitively expensive, but are a good option in my opinion.

            Comment


            • #7
              Originally posted by Def View Post
              Stock steering ratio is too slow. There are other options for RC correction though.
              Care to share your wisdom. I would very much be interested to learn of other methods of Roll Centre correction.

              Originally posted by BeerBringer View Post
              Is the camber gain realy that bad in the rear?
              I have been runing 2.5 degrees of camber in the rear with even wear on my tires. That is 0.5 to 1 degrees more than most people on here but it seams to work fine for me. Guess i have to pull my rear fenders and try less rear camber.
              The driftworks spindels has been proved. But on what kind of setup? If your super low drift stance then yes there is a huge gain. But if your running NRR 'normal' low than the gain is probably not that big.
              If I get a chance on a quiet day at work I'll try and put my car on the wheel aligner to get some camber figures with and without load in the back.
              If you ever drive next to a lowered S13 (lowered from standard by approx 30-40mm [maybe about 8mm of clearance between top of the tyre to guard on 235/45R17's]) and you observe the rear end as the suspension compresses and decompresses over road irregularities its quite disturbing how bad the camber gain is in the rear. Your point is well made regarding the gains depending on height set up.

              Originally posted by BeerBringer View Post
              I would totaly love faster steering. But I don't think the 0 ackerman of the DW spindels are good for us.
              Correcting front RC and bumpsteer in one cost effective and easy way is my priority at the moment.

              /Marcus
              This is what I would like to achieve here. The DW knuckles are very much drift oriented where they want the 0 Ackerman. But we circuit folk are after different specs. The DW knuckles themselves are very cost effective considering that you don't need expensive Ikeya formula arms or custom CNC'ing your own knuckles. The Ebay copies of the Ikeya's are rubbish, I have tried a set and they're of terrible quality. Not to mention Roll Centre Correcting rear LCA's don't actually have any positive effect on the operation/geometry of the rear suspension.

              Originally posted by Beejis60 View Post
              The DW knuckles are borderline prohibitively expensive, but are a good option in my opinion.
              Well the powered by max "super angle" knuckle mod parts themselves are $200. Then you consider that you are modifying you own knuckles as well.
              Once you get the DW knuckles then thats it, no further parts required, no need for any other roll centre correction component. And at $500 a pair, I think its money well spent. Ikeya formula LCA's are way over that. On S13 you just run S14 front LCA to increase track.

              Comment


              • #8
                Originally posted by tez View Post
                ...Well the powered by max "super angle" knuckle mod parts themselves are $200. Then you consider that you are modifying you own knuckles as well.
                Once you get the DW knuckles then thats it, no further parts required, no need for any other roll centre correction component.
                I think you need to go check out all the new Part Shop Max products. The DIY components you reference here are just for angle modification and bump steer correction and nothing to do with roll center.

                They make fully modified knuckles with roll center, bump steer, and two options for angle one that is drift oriented with low ackerman and another with less angle and stock askerman for grip. Because these knuckles have bump steer correction built in you can run stock tie rod ends, no need for expensive bump steer correction outers like the SPLs.
                S12 || N13 || S13 || B16

                Comment


                • #9
                  Originally posted by NismoPlsr View Post
                  I think you need to go check out all the new Part Shop Max products. The DIY components you reference here are just for angle modification and bump steer correction and nothing to do with roll center.

                  They make fully modified knuckles with roll center, bump steer, and two options for angle one that is drift oriented with low ackerman and another with less angle and stock askerman for grip. Because these knuckles have bump steer correction built in you can run stock tie rod ends, no need for expensive bump steer correction outers like the SPLs.
                  You're sharp. The photo i pulled off google was just for illustration purposes.
                  Last edited by tez; 03-11-2012, 05:16 PM.

                  Comment


                  • #10
                    Originally posted by tez View Post
                    Once you get the DW knuckles then thats it, no further parts required, no need for any other roll centre correction component. And at $500 a pair, I think its money well spent. Ikeya formula LCA's are way over that. On S13 you just run S14 front LCA to increase track.
                    Wat? They must have lowered their price because last time I checked, I thought they were like $800ish.


                    Or perhaps that was both front and rear? Or fronts plus their steering extender things? Can't recall but I remember something about them being in the $800 range.

                    Comment


                    • #11
                      If you follow the zilvia thread on suspension (which is surprisingly awesome) you will find that the PBM offering is currently the most 'customizable' as to what you ask for and get and most competitively priced vs the others (such as that jdm company or the driftworks setup).

                      Their LCAs and front caster rod conversion of sorts are pretty sweet and work in conjunction with the spindles. It's the best we have at the moment.

                      Until someone comes up with something new and even more awesome hopefully

                      I asked the swedish company or whatever that made the super over-engineered drift knuckles... if they could do all the math for a super grip setup instead :P They said they dont see as much interst and wouldnt venture unelss there was certain interest.

                      In other words we'd have to all be willing to ask. He told me they would spend 10k on research and development as they did on the drift knuckle setup
                      "hexa-dodecahedron-triple-threaded-super-eleventy-way-adjustment-spec" dampers. -Def

                      Comment


                      • #12


                        My dream knuckle has finally arrived

                        http://www.gktech.com/index.php/s-ch...ory-price.html

                        Comment


                        • #13
                          http://www.speedhunters.com/2011/09/...s_chassis_pt1/

                          ^^this car and other grip cars are running the driftworks knuckles and seem to be doing quite well.

                          When I asked PBM about making me a grip setup, and what the kpi/ackerman would be like, the best response they could give me was 'somewhere between stock and zero' which is one reason I modded godspeed arms for RC and used SPL outers for bumpsteer. I now wish I had just bought modified knuckles, either PBM or Driftworks.

                          By the way, PBM now has cast knuckles on the way:

                          Comment


                          • #14
                            Originally posted by tez View Post
                            My dream knuckle has finally arrived

                            http://www.gktech.com/index.php/s-ch...ory-price.html
                            There's also a sort of group buy on here for us to get some. IDK if you were in that thread, but search it out.

                            Comment


                            • #15
                              Originally posted by kewilso3 View Post

                              By the way, PBM now has cast knuckles on the way:
                              [img]http://www.gtfactory.jp/cms/e107_files/public/1351547346_2_FT10622_dsc04359.jpg[img]
                              Those are actually forged just like the Nissan OEM, they should be superior to the cast versions ERA-1 is making.
                              S12 || N13 || S13 || B16

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