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  • Hit the track, now need your advice

    Hey Guys, i'm new to posting but not new to the site so this is my semi intro post.

    So after countless "need more mods before i track" purchases.
    I've finally slapped my s13 on a full course HPDE at Atlanta Motorsport Park here in GA. Car held up better than i expected but is now time to start getting it to drive like i expect and looking for the advice from the guys that have been there done that.Other needed upgrades aside lets get to whats installed.

    Suspension mods
    Koni 8211/8210 setup on 600/425 springs
    Stock front/rear sway
    All bushings and knuckles replaced
    Solid Subframe bushings
    Replaced inner/outer rods

    Drivetrain
    Sr20 275-300rwhp
    1.5 cusco LSD rear

    Tires/wheels
    RPF1 17x9
    255/45/17 Nitto NT05's
    Z32 front brakes / stock rears
    HP+ Up front / DTC 60 rear
    Z32 15/16 master cylinder

    The Driver
    Couple years track experience with my fair share of instructing with at least a good hand full of cars and car types. Still lots to learn but far from beginner.

    Car Has no downforce mods and is running shortly lower the stock height.

    Now to how it drives
    Rebound/Dampening set full stoft the rear would get happy at almost any speed at 1/3 throttle and mild corners. While it made for exciting laps, lap times started to suffer from having to partial throttle way before exit on almost every corner.
    Adjusting just front dampening alone almost felt like a understeer/overstreer nob. While i expected a change in cornering, slight increase in front dampening pushed me farily far into the understeer area almost to the point that half way caused me to modulate just to stay on the track and found myself smashing the gas to get the rear around the tight stuff.
    Some have told me having your setup so close that slight changes is all thats needed to fine tune leans on a perfect setup. But i found increasing dampening helped in some of the corners where i needed it but hindered me in others, granted i didn't adjust rebound. 1 point of adjustment to fine tune a car just didn't feel right.

    What i've been thinking
    I've decided to grab a progressive front sway bar for adjustments and going to get 550 springs vs 600 to help offset the stiffness (not sure if its enough tho). I know the lsd is going to lean me more towards understeer so i've contemplated front splitter and rear wing but want to get suspension closer to what i want before i do it.

    I know suspension tuning depends on track but curious what you guys would do with these symptoms on a fairly low speed track big on the low speed technical stuff.So what do you guys think?

    Stay stock rear sway on 425 springs?
    Get the 550 with the sway bar but install a splitter?
    Put a good wing on and bring the dampening softer upfront?


    Some pics of the event to get a idea of the body lean (granted i don't know if these where my hot laps or not).







  • #2
    What is your alignment first of all.



    Next, I'd say get an S14 rear subframe or mod your LCA pickups for less anti-squat. Its geometry is much better for track driving.

    Aero stuff is nice, but definitely get it handling well before that.

    What Cusco LSD do you have btw? I've been contemplating a 1.5 way RS.
    '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


    • #3
      Originally posted by Def View Post
      What is your alignment first of all.
      Front
      Camber - 2.0
      Caster - 7.0
      Toe - 0.0
      Cross camber - 0.1
      Cross Caster - 0.5

      Rear
      Camber - 1.5
      Toe - 0.07
      Cross camber - 0.0
      thrust Angle - 0.0

      Originally posted by Def View Post
      Next, I'd say get an S14 rear subframe or mod your LCA pickups for less anti-squat. Its geometry is much better for track driving.
      Aero stuff is nice, but definitely get it handling well before that.
      I've thought about the s14 when i was doing the bushings, but being i had zero baseline on how the car handled as is, didn't want to toss more Frankenstein mods into the mix.

      Originally posted by Def View Post
      What Cusco LSD do you have btw? I've been contemplating a 1.5 way RS.
      Exactly the one i'm running. I'm super happy with it, but then again i'm not searching for hundredths yet so the annoying nuances some complain about like late throttle input mid corner i'm yet to feel. Figure though that if that becomes an issue i'll just get the preload adjusted if i understand it correctly.

      Comment


      • #4
        IMO, add some more shock to the rear. I as having issues like that a while back, and everyone was saying "stiffen the front, soften the rear". problem only got worse!

        eventually, I went back to the original settings I had on the shocks 5 years ago and the car magically started handling like I wanted again. I run 450/350 springs, big front bar, no rear bar, and damper settings on both ends are "about half" on my KTS coils. yeah it's not a direct comparison to your car, but I was having the exact same mid-corner + exit oversteer, and stiffening the rear shocks w/ no rear sway helped a ton.

        with the cusco LSD, you may be able to run some rear bar, but you might just try those settings and see where it gets you. one sway bar link is easy enough to yank out between sessions while chasing a setup issue.

        hope that helps.
        Originally posted by SoSideways
        I don't care what color they are as long as they are LONG AND HARD.
        '04 G35 Sedan 6MT- The DD
        '96 240SX- The Track Toy

        Comment


        • #5
          You need more front camber for sure. Those tires want about -3 to -3.5.

          Maybe a touch more rear toe in but its probably not a big issue.


          Did you deactivate any plates in the RS diff? They come shipped at 100% lock which is too much. Id recommend 80% or maybe even 60%.
          '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


          • #6
            Originally posted by Matt93SE View Post
            IMO, add some more shock to the rear. I as having issues like that a while back, and everyone was saying "stiffen the front, soften the rear". problem only got worse!
            eventually, I went back to the original settings I had on the shocks 5 years ago and the car magically started handling like I wanted again. I run 450/350 springs, big front bar, no rear bar, and damper settings on both ends are "about half" on my KTS coils. yeah it's not a direct comparison to your car, but I was having the exact same mid-corner + exit oversteer, and stiffening the rear shocks w/ no rear sway helped a ton.
            hope that helps.
            450/350 seems so soft,specially with no rear bar, what tires are you running?I've thought about adding more rear shock, but the rear honestly felt pretty good on the track i was on, was the front i was not happy with. More front shock reduced my oversteer but also made the car more unstable on the rough stuff.

            Originally posted by Def View Post
            You need more front camber for sure. Those tires want about -3 to -3.5.
            Maybe a touch more rear toe in but its probably not a big issue.

            Did you deactivate any plates in the RS diff? They come shipped at 100% lock which is too much. Id recommend 80% or maybe even 60%.
            I notied the front camber after i ran, i figured around 2 would be a good baseline until i searched the forum and noticed you guys running 3+. Changing out some more suspension parts and getting a realignment and will take the camber into consideration. Also when you say more rear toe, you referring to + or -?

            As for the lsd, it was a "installed then sold" style used lsd. Fairly new but no idea what was done to it. Honestly it feels like 100%. I can forsee needing to play with it or even going helical as i get to know the car better, but as is it does make the rear feel alot more predictable, specially if i run a curb hard under throttle.


            How do you guys feel about going from 600/425 stock bars, to 550/425 big front bar with the alignment changes?

            Comment


            • #7
              for a track-only car, go for -3 to -3.5 camber front, -2 to -2.5 rear.
              for a street-driven car, I'd say stay where you are on camber to help with tire life.

              I run zero toe front and rear... but that's just my prefs. lots of people prefer a touch of toe-in..
              Originally posted by SoSideways
              I don't care what color they are as long as they are LONG AND HARD.
              '04 G35 Sedan 6MT- The DD
              '96 240SX- The Track Toy

              Comment


              • #8
                Originally posted by Matt93SE View Post
                for a track-only car, go for -3 to -3.5 camber front, -2 to -2.5 rear.
                for a street-driven car, I'd say stay where you are on camber to help with tire life.

                I run zero toe front and rear... but that's just my prefs. lots of people prefer a touch of toe-in..
                Good 2 know, i'll be looking at making those changes once i get the suspension back in order.

                Comment


                • #9
                  I have a helical, and I hate it. bad move IMO.. I'm faster on track with the stock worn out VLSD than I am with a helical.

                  the S13 tends to use a bit more rear spring than the S14, but generally I see a 450/350 (or 8/6 kg/mm) used for a street/track setup. That's what mine are and I just never changed them out. for a race car, you can up them quite a bit. some guys run 800/600 springs and like them, but I'd rather run a bit softer spring so the car doesn't bounce as much. (the tracks around here are all pretty bumpy..)
                  Originally posted by SoSideways
                  I don't care what color they are as long as they are LONG AND HARD.
                  '04 G35 Sedan 6MT- The DD
                  '96 240SX- The Track Toy

                  Comment


                  • #10
                    I don't have a problem with my HLSD. It really has no bad manners when the car is setup right IMO.

                    When I say more toe in, I think that's negative... but I honestly haven't aligned based on degrees in many years. The diagram on the alignment screen should show which is toe-in. I don't think you need a ton, but I like to run between 3/16 and 1/8" TOTAL toe-in for the rear.

                    IMO, anything over -2 deg camber in the rear is too much. If you look at how much camber the rear gains, it gets ridiculous with that much static camber when you add in a few degrees of roll with mildly corrected rear geometry.


                    The S14 rear subframe really does feel much better than the S13. But you can mod the stock subframe without too much difficulty to reduce anti-squat if you don't want to do the whole subframe swap.


                    I run 500/380 with slightly stiffer than stock bars front and rear. It feels good IMO, but could use some more roll stiffness. I don't think going to a softer front spring is the way to go for you. I've been thinking about 550/400 or 600/450 and tweaking bars, but the car handles pretty well as is. I already feel like some of the rougher tracks around here it's on the edge of what sort of ride frequency it can run, and any higher might make it a slower more than anything.
                    '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
                      It's funny because I have decent front grip at Road Atlanta but terrible front grip at AMP. I'll be back out there soon to try to figure it out.

                      Comment


                      • #12
                        Originally posted by Def View Post
                        I run 500/380 with slightly stiffer than stock bars front and rear. It feels good IMO, but could use some more roll stiffness. I don't think going to a softer front spring is the way to go for you. I've been thinking about 550/400 or 600/450 and tweaking bars, but the car handles pretty well as is. I already feel like some of the rougher tracks around here it's on the edge of what sort of ride frequency it can run, and any higher might make it a slower more than anything.
                        The subframe bushings came with spacers to adjust squat.Might need to do more research on that. And from both your post, its sounding like i'm running stiffer than needed spring rates in general with my shock setup, another reason why going stiffer on dampening hurt my times. My original fear was that going large front sway was just going to create perm understeer. if you where thinking about 600/450 and tweaking bars, perhaps i should stay 600/425 and just get a rear bar to match the front so i can back down on the dampening

                        While i know its easy to get a car to under or oversteer to your liking, my issue is i don't want to reduce overall grip to much trying to do so. Got some guys saying 380 rear with no bar , then others doing 450+ with a large bar.

                        Originally posted by icantdrift View Post
                        It's funny because I have decent front grip at Road Atlanta but terrible front grip at AMP. I'll be back out there soon to try to figure it out.
                        Thinking this is because most the hard corners in RA are uphill or flat, AMP has a lot of off camber descending corners. Always felt like my front tires where dam near off the ground.

                        Comment


                        • #13
                          Tire size and compound play a huge role in the optimal spring rates. As does aero vs not aero. When I ran RA1's and no aero, my springs rates were 500 front 350 rear. With Hoosier A6's and aero, 650 fronts aren't enough. Next yr I'll be testing 750 and 800. Rezlo runs true slicks and has 840 front and 700 rear.

                          You basically need to set up the car for a specific tire. Track surface and grip level should factor in also but I would just set it up for the track you go to most and then make shock and sway bar changes at other tracks.

                          If possible take some different springs rates to the track. Springs are easy to change and as long as you get the ride height the same, the alignment will be unaffected.
                          NASA Time Trials TT3


                          BTW I work for Garrett

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                          • #14
                            RA is a super smooth track, so you can likely run high rates there and be faster than lower rates. Never had the pleasure to run at AMP (is that fairly new? I moved away from Atlanta in early '05).

                            Honestly, I don't think 25 lb/in of spring in the rear is going to be a very noticeable change. That's almost within the range where the tolerance of the two springs could make them almost the same rate.

                            One of the neat things of this forum is that people DO try different setups to see what works for them. I always laugh at guys on a BMW forum running a setup that they don't like, but it was suggested to them by some guy 2000 miles away and that means it's got to be "the best." It is a bit daunting because there are so many opinions out there though.


                            If you want a cheap upgrade for a rear bar, a hollow 19 mm J30 bar fits on our cars, and it's a little bit stiffer than the stock 15 mm rear solid S13 bar (and lighter too). I run it on my car with the lever arm changed about 10% stiffer and it feels pretty reasonable, but I'll probably got a little stiffer in the rear. A stiffer front bar is a must for our cars IMO.



                            I honestly think most your mid corner oversteer issues are due to your diff. You've got to have a really stable car to run an aggressive clutch type diff. As when it ramps up the lock, it is going to make a neutral car tail happy as hell. That's why factory cars with clutch type diffs (E36 M3 is one example), they are setup super mild. The E36 M3 has a 2 way 25% lock diff with just a few clutch plates. It's just enough to bias some traction between the wheels. A really rowdy diff just makes the car behave very differently.

                            I guess that's one benefit of the helical, as it only biases a multiple of the torque going into it from one wheel to the other via friction. So it's easier to setup in that respect.
                            '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 240sxTTC View Post
                              Tire size and compound play a huge role in the optimal spring rates. As does aero vs not aero. When I ran RA1's and no aero, my springs rates were 500 front 350 rear. With Hoosier A6's and aero, 650 fronts aren't enough. Next yr I'll be testing 750 and 800. Rezlo runs true slicks and has 840 front and 700 rear.

                              You basically need to set up the car for a specific tire. Track surface and grip level should factor in also but I would just set it up for the track you go to most and then make shock and sway bar changes at other tracks.

                              If possible take some different springs rates to the track. Springs are easy to change and as long as you get the ride height the same, the alignment will be unaffected.
                              /bow
                              Exactly the info i needed to see. Next set of tires i think i'll be moving from nt05's to RS3's. Sounding like the more aggressive the tire the more aggressive the needed spring rate. But over all spread seems to stay relatively close. Looks like i might stay 600/425 grab a rear bar and try different set of tires and feel things out again. Really don't want to do a 500/380 style setup and stiffen the sways to max trying to reduce roll. would only cause other issues on the more uneven tracks.

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