Announcement

Collapse
No announcement yet.

2013 Build Plan Discussion Thread

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

  • 2013 Build Plan Discussion Thread

    Since the 2013 season is rapidly approaching, I was hoping to get some discussion going on what you S-chassis guys have planned.

    I thought we could post our current setups, what we plan on changing and why. Then we can all discuss others' builds and hopefully improve upon each-other. Would be nice if we all kept the format as follows:

    Current Setup:
    Planned Changes:
    Expected Results:
    Questions for Other Members:

  • #2
    I'll start.

    Current Setup:
    Primarily autox but looking to get on the track. 89 240sx, SR20DET, GT2871 .64, 10.5:1 compression, LS2 coils, JW S3 cams, Greddy FMIC, Koyo rad, ID1000's, E85, Haltech PS1000, Wilwood Superlight front brakes, Altima rear brakes, Tanabe front sway bar and no rear bar, VLSD w/ 4.6 final, 245/45/17 Kumho XS's on all four, solid subframe bushings, adjustable ruca, traction/tension/toe rods, Z32 uprights, Koni 8611's with 450F/350R Hyperco coils, max camber/caster, slight front toe-out, zero rear toe.

    Planned Changes:
    THIS guy's front suspension setup along with Geomasters in the rear, clutch type (KAAZ?) LSD to replace my VLSD, shimming the subframe for less anti-squat (possibly swapping to S14 if I feel motivated), Whiteline rear bar on softest setting and a second gen mixed-flow EFR turbo (7163) if money permits.

    Expected Results:
    More traction from less anti-squat and clutch type LSD, more responsive power from EFR, Snappier handling from rear bar and better geometry. I had a stiff Tanabe bar on the rear but it was waaaay too tail happy so I took it off. Much better traction coming out of tight autox corners but it tends to push a bit on entry now so I'll see what a soft rear bar can do. Hopefully I'll be able to throw it into the corners with less roll and without pushing and still rocket out with more squat and a new LSD. Also on some of the slower turns I have a choice between staying in second and bogging down the 2871 or going into first and losing time shifting; hopefully the EFR will fair a little better down low.

    Questions for Other Members:
    What do you think of Kiesler's front suspension design? Personally I'm pretty excited for all it offers at only $600. 2" drop while maintaining a better than stock roll couple along with fully adjustable lca, toe and tie rods. Do 16" wheels fit over the Wilwood Superlights? I'm thinking of dropping down to 16's since I currently rub the wheel well on hard turns. Either that or just smashing the crap out of the metal. And any comments in general? Notice any flaws/holes in my setup?
    Last edited by LuckyX2; 02-23-2013, 01:32 PM.

    Comment


    • #3
      Using a rod end on the outer ball joint makes me question the design. Rod ends should not be used in shear.

      As for sway bar setup, I believe that the front of s13's & s14's are very under bar'd. The rule of thumb for a front engine rear wheel drive car is 50% of the roll rate should be from the bar & 50% from the springs. A 27mm whitleline (1-1/16") with a 11" lever arm (in single wheel bump) has a roll resistance of 402lbs/". S13 anitroll bar motion ratio .45" of bar endlink movement per 1" of wheel travel. Bar motion ratio =.45:1.Wheel rate=motion ratio^2 so.... .45^2=.20 .20*402lbs=80.4lbs/"

      Basically a 27mm bar has about 80lbs per inch roll resistance in single wheel bump. When you factor in the fact that the sway bar is connected to the chassis wheel on the right & left side, that number should be doubled to compensate for the fact that the right side ofthe chassis goes up & the other down durning roll. To sum all of that up, a 27mm bar has about 160lbs per inch, of roll resistance, (on paper) on an S13. Thats not much when compaired to the coil springs contribution.

      (1-3/8" to 1-1/2") front bar should be used because of the motion ratio of the front sway bar. A 7/8" or 22mm rear sway bar will not be ideal for a 27mm or 24mm front bar. A 22mm rear bar would be better suited for a 1-7/16 or 1-1/2" bar up front.

      If you look into baseline suspension settings the front motion ratio is about .94:1 & the rear is about .99:1 as measured by me, on my S13. My ideal spring rates are going to be 650-700lbs front, 350-400 rear. I'm starting out with a 1-7/16" bar front & a .750" bar rear.

      Thats one of the many things I'm working on this year. I tend to do my own thing regardless of what others do. (Or at the very least, I attempt to do my own thing... .) Everyone tends to copy eachother. Do the math & the research for yourself. My research shows me that we are using really small bars up front, with generally too large of a rear spring/bar combo.
      Last edited by Jason M; 02-23-2013, 03:30 PM.

      Comment


      • #4
        I'll ask him about that and see what he says. Things are early enough in production that it could be changed.

        And I agree about the spring rates and sway bars. I think that might be from the fact that the S-chassis is so popular in drifting. People see that drifters have stiff rears (good for drifting but not much else) and then they think that's what they should do. I've been trying to stay away from that as you can see with my setup. While not as extreme as yours, I'm running stiffer front springs compared to the rear and the thickest off the shelf front bar I know of. The Tanabe bar is 30.4mm or almost 1-1/4" so my 22mm Whiteline in the rear is probably a little too much but I have one on hand so I figured I'd try it on the softest setting. I saw a lot more grip coming out of corners when I removed the rear bar entirely and I'm trying to keep that but while getting rid of the understeer on entry that came with it. It's a tricky balance.

        So yeah, let us know how those 650+lbs springs work out in the front. Maybe I'll kick up my front rate a bit if that works out well.

        And one more question. Would the Geomaster uprights that I'm planning be Street Mod legal? Part E of the SM rules states: "Suspension components are unrestricted as long as they use the original attachment points. For the purposes of this rule, “suspension” is defined as any item that is designed to move when a wheel is deflected vertically. This includes shocks/struts, control arms, steering knuckles, uprights, etc., but not tie rods, steering racks, and subframes." Would the Geomaster items be considered to have altered attachment points? Also I'm thinking that S14 subframes would not be allowed since it requires bushings with offset bolt holes and part H states: "Subframe bushings may be replaced with bushings of any material as long as they fit the original location. Offset bushings may not be used." Would that fall into that category?
        Last edited by LuckyX2; 02-23-2013, 05:04 PM.

        Comment


        • #5
          Uprights and spindles are unrestricted. Do not relocate or modify any of the inner pickup points and you are withing the rules. Shimming the rear subframe would be illegal in SM.

          BTW I forgot to mention that I'm running a Nascar Sway bar setup in the rear. It's a 7/8" end splined bar, 43" in length. I just picked up 10 bars off of Ebay for $150. I have .5", .55", .6", .65, .70",.75".8",&.85" bars to play around with. They also make a 7/8" (.875") bar that I would like to have. You could buy the 7/8" bar and slide it right into the 22mm whiteline or tanabe poly mount, but any other size would require custom sway bar mounts. They all require splined 6-8" aluminum arms & spherical endlinks. I built my setup for under $200 using circle track parts.



          I'm still in the planning phase of the front Nascar Bar setup. I'm going to use a 1-1/2" 49 spline ended bar, 37.5" wide.
          Last edited by Jason M; 02-23-2013, 05:25 PM.

          Comment


          • #6
            Originally posted by Jason M View Post
            Using a rod end on the outer ball joint makes me question the design. Rod ends should not be used in shear.

            As for sway bar setup, I believe that the front of s13's & s14's are very under bar'd. The rule of thumb for a front engine rear wheel drive car is 50% of the roll rate should be from the bar & 50% from the springs. A 27mm whitleline (1-1/16") with a 11" lever arm (in single wheel bump) has a roll resistance of 402lbs/". S13 anitroll bar motion ratio .45" of bar endlink movement per 1" of wheel travel. Bar motion ratio =.45:1.Wheel rate=motion ratio^2 so.... .45^2=.20 .20*402lbs=80.4lbs/"

            Basically a 27mm bar has about 80lbs per inch roll resistance in single wheel bump. When you factor in the fact that the sway bar is connected to the chassis wheel on the right & left side, that number should be doubled to compensate for the fact that the right side ofthe chassis goes up & the other down durning roll. To sum all of that up, a 27mm bar has about 160lbs per inch, of roll resistance, (on paper) on an S13. Thats not much when compaired to the coil springs contribution.

            (1-3/8" to 1-1/2") front bar should be used because of the motion ratio of the front sway bar. A 7/8" or 22mm rear sway bar will not be ideal for a 27mm or 24mm front bar. A 22mm rear bar would be better suited for a 1-7/16 or 1-1/2" bar up front.

            If you look into baseline suspension settings the front motion ratio is about .94:1 & the rear is about .99:1 as measured by me, on my S13. My ideal spring rates are going to be 650-700lbs front, 350-400 rear. I'm starting out with a 1-7/16" bar front & a .750" bar rear.

            Thats one of the many things I'm working on this year. I tend to do my own thing regardless of what others do. (Or at the very least, I attempt to do my own thing... .) Everyone tends to copy eachother. Do the math & the research for yourself. My research shows me that we are using really small bars up front, with generally too large of a rear spring/bar combo.
            I agree with this. My own back of the napkin calcs show a larger bar is needed. I'm going to be tossing a 30mm bar on the front, stiffen it up, and try to relocate the mounting point on the FLCA as far out as possible and see how it responds.

            I've got a 19mm hollow J30 bar on the rear now with the stiffness up about 10-15% off the stock bar... been thinking about a hollow 22mm rear bar and welding on some adjustment arms to see how it fares with a little more stiffness adjustability.
            '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


            • #7
              Here was Keisler's response when asked about shear loads on the outer heim:

              "Shear load in a vertical manner is next to nothing because the bump load will be transferred though the spindle into the strut and spring. If we were dealing with a double A arm suspension, this could possibly be a area of concern because bump load would be traveling though the heim joint. Now lets discuss shear load from a front impact... the stud on a factory lower ball joint will be seeing almost identical shear loads as the heim joint in my suspension design. The factory stud is a bit smaller then a 3/4 heim joint. The ultimate and yeild strengths of the stud are also not as high as the chrome moly heim joint."

              Maybe I'm missing something but that's not what you were talking about when you mentioned shear loads, were you? Shear would be side to side as in hard braking, not up and down as with suspension compression, right?

              Here's a close up of the end being used:


              And here's what he said when I tried to clarify the question was more about horizontal loads:

              "Yes, hard breaking would be in the same direction as a front wheel impact like I discribed. The smaller, weaker factory balljoint stud has shown it's test over time. I don't foresee any problems with a 3/4 chrome moly joint. Once again, I appreciate the questions"
              Last edited by LuckyX2; 02-23-2013, 06:59 PM.

              Comment


              • #8
                This is why people get nervous when you get random guys designing suspension parts.

                It's not shear you guys are concerned with, it's BENDING. As in, during braking, the wheel is pushed back with the most force it will ever see. Say the rod end is threaded all the way out for super phat drifter track increase. That long ~2" shank is now acting like a breaker bar that the braking force is transferring through.

                This bending force puts the shank in severe tension and compression. It basically magnifies the original force by the ratio of half the diameter and the length of lever arm. So say 2" like we earlier said for lever arm, then for a .75" diameter rod end you're talking about a minor thread diameter of roughly .67", which means the braking force gets multiplied by roughly 2/.33=6.

                So if you're braking at 1.5 G, and for simplicity sake say all your braking is done up front (probably not far from it at 1.5 G), your S13 has a passenger so you're at 3000 lbs. That's 2250 lbs at each tire. And the max tensile force the rod end experiences is about 13.5 ksi. Not enough to make it immediately fail, but I'd be a little nervous over the long term for fatigue considerations. Especially since this max stress is right at the minor diameter of a thread root, which again effectively magnifies its actual stress amount.




                And that is why people need to have some basic engineering background before they go designing parts and not even understanding why things are a problem.
                '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


                • #9
                  Is it not shear forces that induce a bending though? Braking would place a shear force on the bolt and bend it. Kinda saying the same thing, right? Either way, I tried to make it clear to him exactly what I (we) are concerned about. I sent him THIS link about rod ends in bending and showed him this picture of exactly what we're concerned will happen:


                  Apparently he said he's familiar with rod ends being a no-no but feels that using rod ends is beneficial enough for adjustability and ease of use that he made a design decision to go in that direction. He then compensates for the rod end's weakness to bending by going with oversized chrome moly units. He just got his shipment of rod ends in a few days ago and he says he plans on stress testing them himself and publishing the numbers translated into G force and MPH impact. If he's not satisfied with the performance he said he's still early enough in production that he'll change the design, probably to a spherical I'm guessing.

                  HERE'S his facebook page if you feel like keeping up to take with his progress.

                  Also what about threading on an extra nut if you plan on running it long so that the nut is flush with the LCA and covering up some exposed threads? Using your 2" example, if we tossed a 1" thick nut on there and threaded it down flush with the lock nut on the LCA wouldn't that be like just having 1" of the thread exposed and thus halving the bending force? The bending motion of the threads would translate into a compression resisting the bending off of the nut which is compressing on the LCA. Or am I completely wrong about that?
                  Last edited by LuckyX2; 02-24-2013, 12:36 PM.

                  Comment


                  • #10
                    No, a shear force is different than the tensile and compressive loading that happens due to the rod end being loaded in bending. Although the shear force at the jam nut doesn't help things.

                    Shear is perpendicular to the axis we are talking about, the bending generates forces in that plane.
                    '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


                    • #11
                      His pictures make it look like the wheel hub boss will be bolted on with a small button head bolt from the back.... That sketches me out a bit.

                      Comment


                      • #12
                        Here's his reply regarding the spindle:

                        "The 7075 spindle hub recesses into the spindle body over .25 inches and a .625 bolt is used. The FOS of the spindle design is around 2.5 that of the factory."

                        We're starting to focus a little to much on this though. I love the discussion but let's see some build plans/ideas too!

                        Edit: He just tested the rod end too. At "full" extension (only 3/4" threaded in) it gave way at 6000lbs applied to the eye of the rod end which would be 4G of braking force in a 3000lb car assuming 100% of the braking is at the front and about 6G with 65% done by the front. He'll be posting results from 1000 tests at 1/2 the ultimate strength later also.
                        Last edited by LuckyX2; 02-25-2013, 10:19 PM.

                        Comment


                        • #13
                          My only build plan is to put extended studs in this weekend, do an autocross Sunday, and then replace the rod ends and COM bearings in the back. Then it's up for another year of abuse

                          Comment


                          • #14
                            Originally posted by LuckyX2 View Post
                            Here's his reply regarding the spindle:

                            "The 7075 spindle hub recesses into the spindle body over .25 inches and a .625 bolt is used. The FOS of the spindle design is around 2.5 that of the factory."

                            We're starting to focus a little to much on this though. I love the discussion but let's see some build plans/ideas too!

                            Edit: He just tested the rod end too. At "full" extension (only 3/4" threaded in) it gave way at 6000lbs applied to the eye of the rod end which would be 4G of braking force in a 3000lb car assuming 100% of the braking is at the front and about 6G with 65% done by the front. He'll be posting results from 1000 tests at 1/2 the ultimate strength later also.
                            I posted a more detailed response on Zilvia where I saw this "testing info." This guy is in over his head.
                            '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


                            • #15
                              Originally posted by e1_griego View Post
                              My only build plan is to put extended studs in this weekend, do an autocross Sunday, and then replace the rod ends and COM bearings in the back. Then it's up for another year of abuse
                              It must be nice to have a car that's done being tweaked and just ready to drive hard... I'm hoping I'll be at that point after this year.

                              Originally posted by Def View Post
                              I posted a more detailed response on Zilvia where I saw this "testing info." This guy is in over his head.
                              Thanks, I sent him a link to your post to see what he says. I'm not a mechanical engineer (computer engineer actually) so I know about basic topics but not the finer points like what you had posted. I'm glad I can just say "Here, test it this way" now, rather than trying to interpret and pass along to him what I felt others were saying. I'll update on Zilvia what his response is.
                              Last edited by LuckyX2; 02-26-2013, 08:32 AM.

                              Comment

                              Working...
                              X