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My S14 Track Toy

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  • #16
    A diff that biases under braking helps a lot with stability and a hair of toe out. S15 HLSD = rear moved around a bit. Cusco RS 1.5 = super stable under braking (and on power).
    '18 Chevrolet Volt - Electric fun hatch for DD duty!


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    • #17
      Looks like a nice setup and a fun car.
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      Suspension before power.

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      • #18
        Nice to see action in here again!

        On-off switch braking is notorious on these cars with race pads and Z32 setups. Hawks don't help the situation. HT-10's are better than DTC compounds with the initial bite, but too much bite isn't a good thing. It's a marketing gimmick. If your S14 was equipped with ABS and/or an automatic from the factory, the brake booster is the dual diaphragm unit which makes modulating aggressive brakes a PITA. It needs to be ripped out and burned with fire.

        Originally posted by olegyef View Post

        It feel stable under heavy breaking with the front toed out?
        I'm personally not a believer in it anymore and stopped running front toe out on my S14 endurance car for this reason. I found the instability under braking to outweigh the benefit of turn-in, especially when you're wheeling it with someone right beside you in the longest/heaviest braking zone on the track.

        You can tune for better turn-in via other methods and/or changing driving style while improving tire wear. I get as close as possible to zero on the front now. Although it's likely splitting hairs and my own thought experiment, there's also ackerman effect to take into account with toe angle settings. It's exaggerated more with toe-out. I always have some toe-in on the rear.



        Get your front camber to -3.5 or more. I don't have aero on my car and am at -3.8 to -4.0. Rear camber is -1.6 to -1.8. Caster is at 7.5-7.7. That much front camber is how I get tires to survive 9 hour races with good wear.

        As for understeer, you really shouldn't have much of it with your setup, especially with an aftermarket rear bar and a HLSD. Usually these cars with larger aftermarket rear bars make it too easy to slide the ass end around, especially when turning in. This causes the driver to be subconsciously cautious entering turns even though it might feel fast; like keeping partial throttle through a turn in an effort to stabilize the chassis (more on this below).

        Since you're new, focus on getting as much seat time as possible with proper driving instruction. Watching your video you seem smooth enough and it doesn't look like you're under-steering all that much. Being partial throttle through the turns (especially slow to medium speed turns) might seem like a good thing and this is a very common new driver trait. It actually causes more harm than good by keeping weight transfer off the front axle and causing un-intended understeer. Make an effort to stay off the throttle as long as you can approaching the apex of the turn.

        If you watch any in-car video of pros driving, they are basically never partial throttle after braking and before the apex of slow-medium speed turns. You want to be slowing up until the apex of a turn and then get on the gas as smoothly and quickly as possible. If the car feels unstable when you're completely off the throttle entering a turn smoothly it's because the setup needs work or you've completely over-cooked the entry.

        Here's an example of an amazing driver in a GT1 trans-am car. Watch his throttle and brake inputs before, during and after the turns. Obviously the car is way different, but the same techniques apply:

        https://youtu.be/p9N7z9gNZqc


        Another new track driver mistake; make sure your damper settings aren't too stiff. Feals are high pressure monotubes so they're inherently stiff to begin with. Start in the softest settings and gradually make them stiffer until you feel the car oscillations and transitions are controlled and predictable. Jacking up damper settings can wash grip away even though the car might feel like "it's on rails."

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        • #19
          The biggest S-chassis problem is that the rear is light, the rear suspension picks up a ton of grip relative to the front under roll, and you definitely want to let the rear suspension move.

          I think moderately stiffer rear bar (like no stiffer than a J30 ~19 mm hollow bar) is a good point to stop, and with pretty stiff rear springs it's likely not doing much. Toss on a stiff front bar, and stiff front springs to help control front axle roll. Then keep upping the rear springs until the steady state balance comes in with the alignment settings gills posted.

          My car was a little understeery at steady state, but it also made it super easy to attack and be aggressive even in the faster parts of the track. It was very neutral on power, and anytime I made it turn in better off throttle, I felt it made the car a tad squirrely on throttle and the times suffered by having to wait just a bit longer. Like I was gaining a bit of time on corner entry with a car that rotated a bit freer, but that meant I had to wait that split second later before really hammering on the throttle (no partial throttle once you pick it up right around the apex as gills mentioned). Looser on entry felt faster, and it was in that one section of track, but it was slower overall by making me wait that split second before getting on the throttle before every straight. Plus it made some of the bumpier sections of tracks way more drama than they needed to with the car really wanting to rotate freer.
          '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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          • #20
            Originally posted by gills View Post
            If your S14 was equipped with ABS and/or an automatic from the factory, the brake booster is the dual diaphragm unit which makes modulating aggressive brakes a PITA. It needs to be ripped out and burned with fire.
            Yeah.... I changed out to an auto brake booster, because I read some where its better with the Z32 brakes . Should I put back the skinny manual s14 booster back in or something else?
            I do gotta say I am alot happier with the W5 than I was with the HT10s.

            Originally posted by gills View Post
            As for understeer, you really shouldn't have much of it with your setup, especially with an aftermarket rear bar and a HLSD.
            I am thinking I might have overstated the amount of understeer I get. I will still try to get someone who knows what they are doing to drive my car and see what they think.

            Originally posted by gills View Post
            If you watch any in-car video of pros driving, they are basically never partial throttle after braking and before the apex of slow-medium speed turns.
            I noticed this as a problem of mine that I am trying to correct. I really worked at it at T2 at Laguna this last time.



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            • #21
              Like Def mentioned, having a setup with the tendency to understeer a small amount at the limit is always better for driver confidence. And, it can't be overstated how much driver confidence plays a part over all the other little things we debate about. Since you only have a KA, you don't really have a ton of on-throttle rotation capability so you can likely get away with a bit more looseness in your setup than something that can rotate easily when back on throttle.

              When I put on the S15 spec-R rear bar (21mm also) with already installed 500 lbs/in rear springs (600 lbs/in front), I didn't expect much either, but it added a significant amount of rotation to the car in mid corner. The caveat being that I went from no rear bar to a 19mm bar and a 1.5 way diff that was setup too tight with both setups for road course work.

              Also as Def mentioned with his blurb about diffs, it can't be overstated how much they affect setups. Most people just get a 1.5/2.0 diff and install them with the default settings. Problem is, the default settings are usually meant for drifting and too aggressive for road course work. It makes a car that is like a switch when on/off throttle (power dependent). The S15 hLSD is a perfect unit for where you're at.

              Originally posted by olegyef
              Yeah.... I changed out to an auto brake booster, because I read some where its better with the Z32 brakes . Should I put back the skinny manual s14 booster back in or something else?
              I do gotta say I am alot happier with the W5 than I was with the HT10s.
              You read that on Zilvia somewhere. If you have basic street pads that don't generate high torque, it's usually fine. People who don't track their cars think that crazy grab from barely touching the brakes is actually a good thing.

              Once you start going to aggressive pad compounds, even something like a dual street/track marketed pad like the Hawk HP+, it becomes a detriment. Adding more booster assist takes away from feel and modulation and contributes to the binary action of the brakes. I recommend throwing your manual S14 booster back in. It's single diaphragm and ~9" in diameter. The next best thing is a B13 Nissan Sentra E 1.6L non-ABS booster that is single diaphragm and ~8.6" diameter. This is what I recommend to anyone who runs big brakes, mine or otherwise. You just need to swap the threaded knub end that activates the master cylinder piston off the Sentra booster with the one from the 240.


              Definitely get someone with experience to drive your car. It will save you time and flatten the learning curve.


              Even though I've never driven Laguna in real life, T2 is a perfect turn to practice. There's a ton of run off and it's slow. Play as much as you can in that turn.
              Last edited by gills; 08-20-2020, 09:40 AM.
              Core4 Motorsports
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              • #22
                Yeah after my last track day I gotta take back the comments about understeer. The car rotates just fine, some times a bit too much lol:

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                • #23
                  Been a year since the last update. Car is still around and tracking. Biggest changes have been some solid rear bushings and a roll bar. I change the break booster to the skinny one, sooo much better.

                  Latest video from this weekend: https://youtu.be/y6Y5h6pRA0UIMG_20210813_092334.jpg

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