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Rear grip issues on track-S13

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  • Rear grip issues on track-S13

    I need some input from other S13 owners who track their cars. Just a quick background on my set up.

    S13, gutted with rolllbar ~2725 lbs. w/driver, 350 whp
    FEAL race coilovers Front-9k rear 6k
    S13 rear subframe, solid mounts, NO rear sway bar, Whiteline front, spherical endlinks.
    all tubular arms/sphericals front and rear with the exception of the RLCA,(E.S. bushings).
    Tomei/KAAZ 1.5 way LSD (broken in correctly, fresh fluid)
    17x9 5Zigen wheels, Nitto NT01 255/40/17
    alignment F -3.5, +6.5, 1/4 toe out R -1.5 1/4 toe in

    I have issues with rear grip/getting back on the throttle. The front has great bite, they get a little greasy late in a session but nothing unusual. The rears however are going off early in the session and a general lack of rear grip, 3rd gear wheel spin (both wheels).

    I'm contemplating raising the spring rates, switching to 4 Hoosier R7's (245/40/17) possibly switching to the S14 rear subframe.....or maybe adding helper springs to the rear (more droop).

    Any set-up input is appreciated. Spare me the keyboard warrior/driver coaching.

  • #2
    S14 rear subframe for sure. S13 has way too much anti squat.

    Cheap dampers aren't helping you either on finding traction at corner exit.
    '18 Chevrolet Volt - Electric fun hatch for DD duty!


    DefSport Koni Sleeve and Spring Perch Buy!!!
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    • #3
      What Def said. That's a LOT of toe on both ends too. I run zero toe both ends. maybe 1/8" on each end on a twisty track.

      helper springs wouldn't hurt, but if you're spinning both wheels on exit, then you have other issues. do you feel it break loose midway through the corner- like the ass end just squats and falls away, or does it come loose when you're on the gas?

      Mine used to "fall away" about mid turn and I cranked up the rear damping, which helped a lot. Since they're only single adjustables, I just turned the knob a few clicks stiffer. boom.

      I'm running 8k/6k on the 240, so your front/rear ratio is a bit high for balance. upping the rear rate to 6.5 or 7k might not hurt.

      on my RX7 w/ solid rear axle, I stiffened compression and that's what made the difference getting drive off the corner in it. same symptoms, same results, stiffening compression helped.
      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

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      • #4
        Def,

        Are you familiar with FEAL coilovers?

        http://www.rallyracingsuspension.com/page9.php

        I do rallycross as well as road racing, I was more than impressed with Odi's products on my WRX. I've had Koni inserts, 8610's, KTS coilovers, etc. FEAL is NOT a Megan racing/BC garbage product.

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        • #5
          Anyways, thanks for the input. I will agree that the lack of pro-squat with the S13 subframe is probably the major contributing issue. The car just didn't want to take a set in the rear, mid corner. I played with the rebound dampening (sorry, single adjustable, can't afford Motion Control's like all the baller TT guys) and it helped but the underlying issue was still present.

          I'll reduce the toe on both ends, see if that helps. I wanted the toe-in in the rear for the straight line stability. At Summit Point main I hit 140+ in the front straight, I'd prefer the car to not be nervous, esp under braking.

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          • #6
            You do Time trial at Summit point?? Never seen another S13 out there!

            PM me some details. I am shooting to do a Trackdaze event in the dead heat of July (5th)

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            • #7
              RalliartRsX,

              I just did an HPDE 3 event at Summit this past weekend with NASA. I was trying to get a 'check drive' to get into TT but I was 8th in queue and missed out. I've never done a Trackdaze event, how is it? Would an instructor be required? I've completed 7 HPDE 3 events, does that have any weight with the SCCA? I'm not opposed to re-installing a passenger seat and harnesses and getting more track time.

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              • #8
                Originally posted by Trofeo View Post
                Def,

                Are you familiar with FEAL coilovers?

                http://www.rallyracingsuspension.com/page9.php

                I do rallycross as well as road racing, I was more than impressed with Odi's products on my WRX. I've had Koni inserts, 8610's, KTS coilovers, etc. FEAL is NOT a Megan racing/BC garbage product.
                I'm familiar enough with them. They look like all the other Taiwanese offerings on the market, and so far I haven't ridden in a car setup with them that performed well.

                An S14 rear subframe helps, but if you really feel like the rear is all over the place, I'd say your dampers are probably the biggest issue.



                BTW, I'd also run zero toe up front, or close to it. No reason to chew up tires with that much toe. And that much toe-in for the rear is going to make the car sluggish to change direction when it's all setup well.
                '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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                • #9
                  Def, in your opinion what makes the FEAL coilovers inferior to a common Koni insert set-up? On a bumpy ass track like Summit the dampening was great over all the bumps until I cranked the rebound dampening up to 11 and it got hairy under braking. In my mind I assumed the S14 subframe (pro squat), stickier tires and stiffer spring rates or delta front to rear was the solution. I'm a cheap ****er and would rather use your guys empirical knowledge to save me a few bucks. I'll digest your suggestions and make my independent conclusions.

                  Also, I ran 1/4" toe out in the front of my old Sentra SE-R and currently on my 02 WRX (basically an 04 STi at this point) and the front end bite (initial turn in) was great.

                  Why should I reduce toe on both end? What do the fast 240SX guys run in TX? Koni's and double zero toe?
                  Last edited by Trofeo; 06-08-2015, 03:52 PM.

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                  • #10
                    Originally posted by Trofeo View Post
                    Def, in your opinion what makes the FEAL coilovers inferior to a common Koni insert set-up? On a bumpy ass track like Summit the dampening was great over all the bumps until I cranked the rebound dampening up to 11 and it got hairy under braking. In my mind I assumed the S14 subframe (pro squat), stickier tires and stiffer spring rates or delta front to rear was the solution. I'm a cheap ****er and would rather use your guys empirical knowledge to save me a few bucks. I'll digest your suggestions and make my independent conclusions.

                    Also, I ran 1/4" toe out in the front of my old Sentra SE-R and currently on my 02 WRX (basically an 04 STi at this point) and the front end bite (initial turn in) was great.

                    Why should I reduce toe on both end? What do the fast 240SX guys run in TX? Koni's and double zero toe?
                    I'm not saying they're the worst damper in the world, but the dyno screams cheap generic Taiwanese piston design with a needle valve adjuster. There's only so much you can do with that...

                    Plus they tend to be really short/small to allow kids to "slam" them, which leads them to get really hot, and thus performance changes greatly when working them hard.

                    Konis aren't the end all be all damper by any stretch, but at least they have good valving, and a good adjuster that doesn't move the damper force knee by a ridiculous amount as you're tweaking the rebound.


                    I feel like excessive amounts of toe-out are a bandaid for something else being setup wrong on a FR car. A hair of it is fine if you really like it that way, but 1/4" is a huge amount.

                    I personally like zero toe up front, either 1/8-3/16" toe in rear depending on how stable the car is. I'd run a touch more caster up front as well, maybe a touch more front camber as well (our cars really need tons of camber).
                    '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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                    • #11
                      I agree w Def on all points, which doesn't happen that often.

                      I run zero toe both ends for road racing. That alignment may work well for FWD and AWD, but RWD is a different animal. AWD cars still have enough of the FWD understeery tendencies to use that much toe. Just not the same case in a RWD car.

                      For a tight track, you might run 1/8" out to help turn in, but on a faster course toe out makes the front end nervous at speed and under braking.
                      Also depending on your bumpsteer curves, you could have a fair amount of dynamic toe to deal with. (Custom arms and everything do more harm than good if they're not set up properly.)


                      Oh.. and no double motion control crap here. . My RX7 has JRZ triples on it. :P
                      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

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                      • #12
                        Originally posted by Matt93SE View Post
                        I agree w Def on all points, which doesn't happen that often.
                        How does it feel to be right for a change?
                        '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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                        • #13
                          This might sound stupid, what about tire pressures? A lower rear tire pressure might aleveate some of the traction issues.

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                          • #14
                            I have the SPL bumpsteer kit up front, I have 1/8 toe out under full compression. The rear toes in less under compression.
                            I played with tires pressures all weekend, pressures and temps were good. I contacted Nitto regarding temps and pressures for the NT01 right after I bought the tires, I tried their recommended hot pressures and even went below them in an attempt to cure the issue.

                            My first step will be to buy an S14 rear subframe, then dial out the front and rear toe and probably buy some Hoosier R7's.

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                            • #15
                              Out of curiosity, how old / how many heat cycles do you have on the NT01's?

                              It's a tough call, sticky tires will make bad stuff work. By the same token, you'd hate to chase your tail, and have to reevaluate if you plan on stepping up to a better tire regardless.

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