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  • Ice autoX, rallyX etc car build

    I'm trying to convince a buddy to build an S13 for the fun low friction stuff you can do around here. My wife seems not totally opposed to me being involved in this despite having hit the hard limit for number of cars I can own where we're currently living.

    My thoughts are try to grab a car with an SR swapped or pick one up since I have a few nice clutches, a flywheel, various other parts, experience etc. Not wanting to turbo a KA but a stock KA would be okay. Just think some boost would make this a lot more interesting.

    So otherwise, clutch diff, reinforce some suspension parts, snow tires on stock or other narrow wheels. I could arrange for some bucket seats easily.

    And then dampers and springs. There's the Bilstein motorsport strut custom fab option which would be sweet overkill. Alternatively, 3000GT front and something else rear Bilstein HDs, perhaps Evo. Would the typical Bilstein setup be able to run at stock height or a little higher and still have some droop travel? I've only played with Konis and JDM coilovers.



    Last edited by turtl631; 11-22-2017, 10:29 PM.
    ~1992 240SX, SR20/Koni track day car
    ~2016 M3, daily driver

  • #2
    You could do stock replacement Koni yellows and have tons of travel with a reasonable spring rate like 350/300 with the height jacked way up, like stock or 1" higher than stock.
    '18 Chevrolet Volt - Electric fun hatch for DD duty!


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    • #3
      ...and I vote for a fairly stock drop-in SR with maybe a T28, injectors, Z32 MAF and tune. It'd be PLENTY of power and really fast response. Turbo KA could work too, but good condition original year KAs are so rare now it's probably easier to get a barely used SR from Japan at this point.
      '18 Chevrolet Volt - Electric fun hatch for DD duty!


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

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      • #4
        Thanks for the input. I’m interested in the Bilsteins just to do something different and play with mono tubes. How spendy are the 36mm motorsport struts? Trying to avoid cost creep. I have a set of spherical shod Z32 rear uprights but I see a path that involves 46mm bilstein Motorsport struts, 5 lug, Z brakes, beefy control arms, Braid etc wheels...and this is the path to building a stage rally car which is not the current objective. Although maybe someday?

        The T28 suggestion is a good one. Z32 MAF, 550cc injectors, flash tune, bolt on fmic and exhaust bits. Easy. Again, the $$$ path of small EFR, Infinity ECU is the wrong one.

        I have to read more about differentials for loose surfaces. Seems like the one place to splurge. I do wonder if my Cusco RS 1.5 way and 4.6 R&P would work well. Can’t sell the damn thing NIB for a fair amount...
        ~1992 240SX, SR20/Koni track day car
        ~2016 M3, daily driver

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        • #5
          The Bilstein motorsport struts are pricey...I want to say they're in the $650/ea range, then you need to get spindle mounting ears fabbed, then you need to machine the top of the strut shaft for a thread, then you need to valve it, then you need to build and pressurize the strut... It's a lot of work, and IMO, not much benefit over just a reasonable OTS Koni/Bilstein.

          Maybe you could find a Bilstein insert that's a hair longer than the 3000GT stuff? Just not sure those would give enough travel at a reasonable spring rate, since you probably want like 4" of bump travel and a couple inches of rebound. Pretty sure stock Konis can do that, they're pretty long.

          The Cusco RS + 4.6 would be sweet for rally/ice stuff. I'd go down to at least 80% lockup, maybe 60% (but then you might overheat it on track?). You can also bump the preload down from 6 to 4 springs to loosen it up a bit at neutral throttle.

          I wouldn't worry too much about really swank dampers, I think it's more important to get something that offers reasonable damping (adjustable is probably good too to tune things IMO, at least until you know what rally really likes - I'd think softer would be better in general as long as it's not pogoing?), and LOTS of travel. Any bottoming out will make the car difficult to drive, so first order of business is lots of bump travel, and you'll be at a high enough ride height to use all that travel without smashing the tire into the body.

          I think the usual front tension rod + fabbed FLCA (you can copy the ones I did on my car, it took an afternoon to do it for both) + cheap rear arms with replaced rod ends would be fine for this. Maybe some rear subframe limiter cups and call it good. Easy enough prep, then get a reliable powertrain and go to town.
          '18 Chevrolet Volt - Electric fun hatch for DD duty!


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

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          • #6
            The 3000gt bilsteins are pretty tall. That'd probably be my pick, plus every bilstein seems pretty damned resilient to abuse.

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            • #7
              I had a set before, they seemed quite a bit shorter than I remember OEM Koni fitment being. But it's been many years.

              Honestly, if I were going to spend some $$$ on the build, I'd spend it on an EFR setup rather than lots of $$$ for dampers. I think you'd notice that a lot more since it almost changes the character of the car (faster spool/transient response and more power 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

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              • #8
                Bump!

                Def was in town and we got to talking about this...my friend isn't going to be buying anything in the near future. There's expanding local rallycross action, some of which is mixed tarmac and dirt (kart track with dirt section). I can't run the S13 as is, but we were thinking I could put together a set of dampers with much softer springs and just swap out for the loose surface action. Springs in the 300/250 range, maybe less? So my use case is S13 with GKTech drop spindles in front and Z32 spindles rear. Can I just grab some Evo 8/9 Bilsteins and go to town? Seems like rear length is okay and they'll work fine, just need a spacer for the lower fork mount. Stock Evo spring rates are around 200 lbs/in so should work well with the approximate spring rates I want to run. What about the front? I know I'll have to fab up and weld on new mounting ears for the Evo struts. How does the length work out on these cars? Z28ricer??
                ~1992 240SX, SR20/Koni track day car
                ~2016 M3, daily driver

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                • #9
                  I have pics somewhere on here of evo 8 bilstein. I think they're about an inch taller than stock s13 rear shocks.

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                  • #10
                    Should work out okay for what I'd be doing. Any thoughts on fronts? You can now freely buy 240SX fitment Bilstein B6 in the US, but since I have no stock front housings to work with and Z32 rear uprights, this won't work for me. I could just grab a set of used Evo MR Bilsteins and do custom front brackets.
                    ~1992 240SX, SR20/Koni track day car
                    ~2016 M3, daily driver

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                    • #11
                      It's probably still doable to find some OEM S14 front struts (the GKTech spindles are S14 fitment on bolt size, otherwise drill out the S13 housings). That plus a Koni yellow would be pretty easy. You can't weld on a completed strut(it'll blow up in your face), so not sure the Evo route up front makes sense.


                      If the car is too low with the GKTech front spindles, you could always get a set of stock spindles up front that go with your rally setup. Get some extra 5 lug hubs for them, and instead of taking off the strut to spindle bolts, you undo the FLCA ball joint and tie rod and move the brakes over. It's more work, but not a crazy amount more since you'll be doing this like once or twice a year? Or maybe even build up fronts with everything you'd need and like 4 pot Wilwoods to make swapping even easier and then you just bleed brakes, which with speedbleeders takes around 10 mins. You could have the strut bolted to the upright, brakes already bolted up, then just do the balljoint and tie rod. If you got good at breaking those balljoints free with the HF popper, you could finish a corner in like 20 mins minus bleeding.

                      I think a really long 300/250 would work well if things aren't super bumpy, or if the courses are really rough, maybe a 200/175 with some preload to keep the height up?

                      I'd lean towards stock strut housings and a stock length Koni. Decent rate with long travel, probably higher than stock ride height and about 50-70% more rate should be able to take all sorts of abuse out there.



                      It sounds like a fun project. Get some cheap but effective parts tossed together and some sweet skinny snows to go rip it up.
                      '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


                      • #12
                        BTW - aren't Z32 rear Konis available? Stock length struts are pretty long, and you can always preload your low rate springs to get the ride height. You'll probably want some preload anyway to able to get the suspension using all the droop with sways attached. Speaking of that, you might need to check that the front sway will work through such a huge range of motion. It starts to get friendly with the GReddy oil pan at I think more bump travel on both, so maybe you'll be fine, but you'll definitely have to make sure everything "works" when going between the two setups. Shouldn't be super difficult.

                        The 30 mm front bar might be too much for the soft springs too.
                        '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


                        • #13
                          I read a scattering of postings on different forums that Koni twintubes don't hold up well on bumpy loose surfaces. The rallycross crew seems to really like Bilsteins and they hold up well. So I figured I'd go with the safer option.

                          If I were welding up Evo housings I'd remove the insert first...

                          Yes, this would be a few times a year probably. There are ice autocross events on frozen lakes in winter, and tarmac/dirt rallycross in warm weather. A few venues for this in the area.

                          I could just disconnect the sways for this stuff, probably would work better over the bumps.

                          Seems fun! It would be nice to find an additional place to run the car too, and winter events could help keep me sane here.



                          Evo 8 Bilstein B6 specs (B6 is what is readily available, and close to OEM):

                          FRONT
                          Free Length: 19.35
                          Compressed Length: 13.35
                          Compression Valving: 58
                          Rebound Valving: 150

                          Rear
                          Free Length: 21.73
                          Compressed Length: 15.96
                          Compression Valving: 96
                          Rebound Valving: 147
                          Last edited by turtl631; 06-27-2018, 07:59 PM.
                          ~1992 240SX, SR20/Koni track day car
                          ~2016 M3, daily driver

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                          • #14
                            http://dafastone.blogspot.com/2012/0...amond.html?m=1

                            This is a walkthrough of taking apart the stock Evo bilsteins. Seems easy enough, just add the step of cutting off the mounting ears and welding on a new pair that I would have to fab up. There is a set for sale locally with pretty low miles that look nice for $400.
                            ~1992 240SX, SR20/Koni track day car
                            ~2016 M3, daily driver

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                            • #15
                              Originally posted by turtl631 View Post
                              http://dafastone.blogspot.com/2012/0...amond.html?m=1

                              This is a walkthrough of taking apart the stock Evo bilsteins. Seems easy enough, just add the step of cutting off the mounting ears and welding on a new pair that I would have to fab up. There is a set for sale locally with pretty low miles that look nice for $400.
                              You do realize you're taking mechanical disassembly and reassembly instructions from someone that spelled "allen key" as "alan key."

                              I'm sure you are aware of this, I just wanted to reiterate the point, which may or may not be pertinent in the future depending on the outcome of this side project.
                              '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

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