Announcement

Collapse
No announcement yet.

Ice autoX, rallyX etc car build

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

  • #16
    Maybe his pal Alan gave him the tool!

    ~1992 240SX, SR20/Koni track day car
    ~2016 M3, daily driver

    Comment


    • #17
      allen wrenches are named after W.G. Allen so it's a person's name regardless

      and we all know spelling of names is irrelevant because IT DOESN'T MATTER WHAT YOUR NAME IS

      Comment


      • #18
        On the subject of spring rates - I think a dual spring setup would be pretty nice for this build. The hardest part would be determining where you want the "split point" between dual rate and single stiffer rate to be.

        Two springs in series give an equivalent spring rate of 1/Keq = 1/K1 + 1/K2. This holds true until you block the lowest block load spring, then you're running solely at the main spring rate. This makes it important to have a main spring that has enough travel and rate to keep the car off the bump stops, as large bumps will treat the series spring as just this one spring acting alone.

        Dual spring setups with equal rate end up with half the K1 and K2 spring rate. So 2x 300 lb/in springs = 150 lb/in rate. This seems a little low to me, closer to stock, then ramping up way over stock.

        You could do something like a 4" ERS 500 lb/in rate as K1 (tender) and a 8" 350 lb/in rate as your main K2 spring. That would give you an ultimate block capacity on the corner of 1708 lbs, and a total travel of 7.2" on the springs, so you'd have roughly 1" of usable preload for a 6" total stroke. You'd have a Keq of 206 lb/in until you get 1160 lbs of load on that spring stack, which is a decent bit over static (corner weighs are probably ~700-750 lbs on the high end up front, ~550-600 in the rear at the high end). The final ~450 lbs of rate would be at 350 lbs/in, then bumpstop for some of that. You can always up the main spring rate too if you want to do more to keep it off the bumpstop.

        A 4" 500 and 8" 400 setup would give you a Keq of 222 (you can see large spring rate jumps aren't causing Keq to go up much), and a total block load of 1968 lbs on the spring stack.

        I think the 8" 400 lb/in spring is probably the best, just a question of how much K1 spring length you can run.



        Eibach progressive tender springs would also work ok for this application. There's a 0200.250.250-650 p/n with a final rate of 650 lb/in and just over 2" of travel, block load of 924 lbs. The progressive nature would help ease into the higher K2 rate spring as the tender blocks. You'd start at 154 lb/in Keq, then end the tender travel at 248 lb/in. This would be over roughly 4.3-4.4" of travel, then a further 2.6" of available 400 lb/in spring travel.

        A less progressive Eibach tender, 0200.250.250-550, would give starting Keq of 154 lb/in, finish Keq of 232 lb/in, again, a little over 4" of total travel.

        The super progressive high rate Eibach tender 0175.250.600-1300 would be interesting. It has 1.7" of travel and starts at 600 lb/in and ends at 1300 lb/in. With a 400 lb/in K2 main spring that'd give you a starting Keq of 240 lb/in and a finishing rate of 306 lb/in at the 1513 lb/in block load. So you'd then have roughly an inch more of travel at 400 lb/in after that.

        So you can see that you can really tailor spring rates quite a bit. Giving you either two linear rates with a distinct transition, or a really linear rate over many inches of suspension travel, then a final stiffer linear rate to finish off the travel, then really stiff bump stops as the last bit of cushion. You can also preload any of these progressive springs to get rid of some of the initial soft rate.

        I would think on the dirt/ice, you might like a more progressive rate until you go off some sweet jumps or something like that, then it's all about keeping the suspension from beating itself to bits. That's why I'd probably lean towards a higher K2 main spring rate, just to have some ultimate load capacity in the spring stack so you're able to keep off the bumpstops on all but the biggest hits. A 400 lb/in rate is a lot less upsetting than a brief period of 300 lb/in rate then 1000 lb/in bumpstop.
        '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


        • #19
          Very interesting. I can see you're enjoying this thought experiment too. What do you think you would start with?
          ~1992 240SX, SR20/Koni track day car
          ~2016 M3, daily driver

          Comment


          • #20
            Do you think the surfaces you'd run on will be super rough, or lots of relatively small bumps like rocks/berms etc.? Any potential jumps, or all pretty flat?

            If it's going to be super rough but no real jumps, I'd probably tend towards one of the softer setups, and you can even get a dual linear spring setup to almost entirely run in its lower combined Keq spring rate by giving each spring a ton of travel (if you've got room). If you disconnected the front sway bar and ran those 250>550 progressive tenders plus a 400 lb/in main spring, you'd have a very compliant setup on the inner wheel for any bumps, and the outer wheel rate would go up to keep your roll somewhat under control. You could also get a lot of tunability with the softer progressive spring by dropping your main spring down to a 300 lb/in setup that's maybe a hair longer like 9-10" if you've got room. You'd get a Keq of 137 to 194 lb/in over the dual spring travel range, which should be buttery smooth over bumps etc.

            If you have any sort of jumps, that's going to drive you to a much stiffer main spring to try to keep the suspension working on landing, and you'll just have to deal with the stiffer rate in other driving when you bottom out your secondary spring. Probably the stiffer 650>1300 lb/in progressive tender and a 400 or even 450 lb/in main spring.

            A lot of it depends on your available spring space, but I assume you can toss a perch just over the spindle mounting ears to give you a lot of potential space to fit a spring, then just raise up/preload to where you want to be.

            It's a cool thought experiment, because it's a lot different than track driving constraints and objectives for sure.


            You thought about some 16" or even 15" wheels and snows? I think they might fit over the Wilwoods, or you could just source some Z32 fronts for 16"/15" fitment when building the whole corner up. Or you going to run the 17's that are currently on it?
            '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


            • #21
              Here's my thread on GRM. There are some pretty serious rallycross dudes there. Sounds like summer tires might be the ticket for this type of stuff. The main place I'm planning to go is a mixed kart track and dirt track. No jumps, but probably ruts. The ice racing is on frozen lakes, and can get pretty rutted too I think. But again, no big rocks or jumps... Not like stage rally.


              https://grassrootsmotorsports.com/fo.../141033/page1/
              ~1992 240SX, SR20/Koni track day car
              ~2016 M3, daily driver

              Comment


              • #22
                Your current rates are 560/425 from memory. 10k swift springs, I think 7.5 kg/mm Eibach/GC rear barrel springs. I'd be worried about it bottoming out on the downpipe as it sits, much less if you dropped the rates in half roughly.

                You really might need stock front spindles to get enough ride height... but maybe not depending on the dampers. It wouldn't be that horrible/costly to build up a full corner of damper + spindle + brake components, then just swap it on via 3 bolts up top, 2 ball joints (FLCA + tie rod) on the bottom. It'll give you ~2" of ride height you'll likely need just to get clearance.


                I agree with the GRM/Miata guys saying you need something in the 200-300 lb/in range. Anything less than that and you'll be bottoming out the suspension everywhere.
                '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


                • #23
                  Yea i definitely can't run it as is or with lower rates at current height.

                  If I piece together full corners with spindles and brakes, I'll also have to get another set of hubs and studs, and bleed the brakes when I swap over. Starting to really be a lot of parts and work, no? The Evo front struts look to be around 3" longer than stock so I'd imagine I have room to weld on brackets for them to get the car a bit higher than current. I should just buy a set of the Bilstein HDs for the Evo so I have something to work with and start playing with this. In all my free time.
                  ~1992 240SX, SR20/Koni track day car
                  ~2016 M3, daily driver

                  Comment


                  • #24
                    You might be able to weld the ears low enough on the housing to get enough travel, but keep in mind the 8611s have about 5.6" of travel, and the housings on there have the ears pretty low. Might be room for another 2-2.5" there, then whatever the longer strut gets. It might be enough, but keep in mind that setup basically has the 8611 topped out with minor preload with the mounting ears down pretty far on the strut.

                    I wouldn't think swapping the corner would be too bad. Bleeding the brakes with speedbleeders doesn't take very long at all, and you've got to do it once or twice a year anyway.

                    Hubs and studs aren't that pricey IMO, but if you don't need them, I can see avoiding changing it all over.
                    '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


                    • #25
                      Well, if I go to smaller brakes then I can run 15s and the wheel and tire options explode. Would be nice for snows for winter events, or trying rally tires. 15x6-7 with 195-205 tires are very standard sizing. The GRM guys have me talked into summer tires for the dirt/tarmac hybrid rallycross events, and I have that covered, at least. Enkei!! This is their gravel rally wheel, RC-G4.

                      RCG4-White.jpg
                      Attached Files
                      Last edited by turtl631; 07-04-2018, 07:53 AM.
                      ~1992 240SX, SR20/Koni track day car
                      ~2016 M3, daily driver

                      Comment


                      • #26
                        That RC-G4 is pretty sweet. I can't get them unfortunately, special order min qty 40 only!

                        It's kind of surprising how few 15" 5x114.3 wheels there are. I seem to recall there were quite a few back 10 yrs ago or so, now it's completely dried up.

                        The 26 mm Z32 front calipers (probably some Stoptech 309 pads would do great, maybe do them in the rear given the DTC-30s are annoying).

                        Maybe these up front? https://www.ebay.com/itm/JDM-Nissan-...EAAOSw5QlbNmXH

                        You could even move the ABS sensor to the GKTech uprights with an ABS S14 hub up there for accurate front wheel speed. Just wire it into the teflon shielded wire right there and set the pulses per rev.


                        It sounds like a fun setup, and you'd also have spares for a ton of stuff.
                        '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


                        • #27
                          I ordered the CT9A Evo VIII/IX Bilstein HDs from Summit. I received one rear, was able to cobble together hardware to toss on my Fortune Auto spherical beating hats and Tein upper mounts. I may swap the upper mounts on the car with the new ones I have though and subject them to the abuse of dirt and snow. These new T3 camber plates and Tein rear mounts are so shiny and nice .

                          Length seems about right, a few inches longer than the 8610 eyeballing it. Just need to decide on a spring setup. With the circlip in the stock Bilstein groove, I'd have about 10" of spring space. Overall, I will be dealing with some smaller bumps and probably some ruts in the dirt, but no big jumps or huge obstacles. I like the Eibach 250-550 progressive tender with 400 lb/in main spring idea. Maybe move the spring perch down to fit more spring? If I had more like 12"+ I could do the 3.5" tender with a 7-8" main spring.
                          ~1992 240SX, SR20/Koni track day car
                          ~2016 M3, daily driver

                          Comment


                          • #28
                            Keep in mind you almost surely want a bit of preload, and probably longer than a 7” and maybe 8” main spring so you don’t bind it.

                            I do have those old eBay camber plates I need to ship you.
                            '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


                            • #29
                              I picked up a set of 8 inch 400lb Springs along with the 250 - 550 progressive helpers. I also got some 5" threaded sleeves and pretty stout small bump stops from 5x racing. I figure if I'm hitting the bump stops with this setup I really want some serious spring rate at that point. The front Evo struts are somewhat delayed, hopefully I get those in about a week. That's where the real question lies with this whole thing, determining if I need a new front spindle set up. The rears were easy, I put together a fixture and used my bandsaw to cut another circlip groove about 2 in below the stock one. The sleeves I got do a nice job of capturing the circlips so they don't go flying off.
                              ~1992 240SX, SR20/Koni track day car
                              ~2016 M3, daily driver

                              Comment


                              • #30
                                Bilstein is on mega backorder, now Summit says October. Soooo...probably no rallycross S13 action this year. Its okay as I'm focused on getting the tune "good enough" and just driving the thing. I think I'm burning through some goodwill with my wife with as much time as I've spent wrenching and driving this year so not the worst thing as the events are 2+ hours away and I'd rather spend my time on the track. That said, the opportunity to drive this thing on some loose surfaces still sounds awesome and I'll press on.
                                ~1992 240SX, SR20/Koni track day car
                                ~2016 M3, daily driver

                                Comment

                                Working...
                                X