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S13 Endurance Racing Alignment Suggestions?

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  • S13 Endurance Racing Alignment Suggestions?

    I have been stalking on this board for a while, stealing lots of good info for my Chumpcar S13 but have never posted. We have been racing for almost a year with the car now and are finally getting good enough to really try to tune the suspension. We are currently running stock caster. 2.5 deg neg camber on front and 1.5 neg on rear. Toe is 1/16" out in front and zero on rear. We are running 175 lb springs on front and just installed 150 lbs springs on rear(have not ran yet did have stock 112 lbs installed during last race). We are running BFG Rival tires in a 205/50 15 size on stock aluminum wheels.

    The main issue that we are having is the car is understeering horribly mid to late corner on both directions of corners. I can not get the car to rotate at all. I just keep on the gas and plow on thru the corner. The race that we noticed this the worst on was the last one at Charlotte Motor Speedway on their new road course. We attempted to change tire pressures to get it to turn in but no avail. We ended up with the best results around 36 psi front and 35 rear hot.

    Since that race we have installed a LSD from a Q45 and went from a stock 4.08 to a 4.6 gear. I have replaced the cut stock rear springs with 150 lb springs to try to stiffen the rear. We are running stock sway bars front and rear. I have made the rear camber and toe more adjust able but I don't know where to set it. Same with the front. I slotted the front upper strut mounts today and I am able to get up to 4 degrees neg on the front now and at least 3 on the rear.

    I would like to not use 4 sets of tires in a 14 hour race so keep that in mind. Currently I can run 14 hours on rears and about 10 on a new set of fronts.

    So what do ya'll think?
    91' S13 Endurance Racecar
    Sponsored by Pallets and Crates LLC Gainesville Ga
    04' Chevrolet 3500 Tow Vehicle, 02' Dodge Ram 1500 Truck, 87' Toyota 4 Runner "Top Less",
    15' Toyota 4Runner, 07' Honda Fit

  • #2
    You need LOTS more front roll stiffness. Not sure how you can really do that, but anything you can do to make the front bar work a bit harder will help - urethane bushings are the cheapest option here, but the improvement is small. Maybe a black painted eBay 30 mm front swaybar.......

    You also need more roll stiffness all around I'd say, and if you're lowered much, I'd try to shorten the traction rod a bit. There's a big post on here detailing measurements by Jason M that's pretty awesome.


    Personally, I'd aim for these numbers and get as close to them as you can:

    Front
    -3.5 to -4 deg camber
    0 to 1/16" toe out
    +7 to +8 deg caster

    Rear
    -1.5 to -1.8 deg camber
    0 toe if you feel it's still understeering, you can go up to 1/8" toe in to get some stability


    I'm surprised you're not destroying the outside of the fronts with that little camber and roll stiffness up there. I still wear the outsides a bit faster with -4 deg up front, granted my setup is a bit different than the average Chumpcar.


    You could also cut and weld the front spindles back together and drop the pickup about 40-50mm. Less ackerman seems to help inner tire wear as well.
    '18 Chevrolet Volt - Electric fun hatch for DD duty!


    DefSport Koni Sleeve and Spring Perch Buy!!!
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    • #3
      I have urethane bushings everywhere except the rear sub frame.

      The car is lowered quite a bit. I cut the front strut plates and raised them approx. 2" and installed a homemade coilover setup dropping it another 2" or so. Running Bilstein 3000gt inserts on front and koni sports on rear set on fully firm( painted flat black by the way).
      On rear lowered it proportionally by installing a "Coilover spring" on a homemade adapter on the rear strut.

      As far as destroying the outside of the front tires, I AM!!!! That is the only reason I am changing them after about 10 hours of track time. The outside edges are fried. The insides are barely worn.
      91' S13 Endurance Racecar
      Sponsored by Pallets and Crates LLC Gainesville Ga
      04' Chevrolet 3500 Tow Vehicle, 02' Dodge Ram 1500 Truck, 87' Toyota 4 Runner "Top Less",
      15' Toyota 4Runner, 07' Honda Fit

      Comment


      • #4
        More roll stiffness, more neg camber up front.

        You could easily run something like 400/300 spring rates on those dampers. Not sure if it's in the rules. It'd still be pretty compliant and easy to drive.
        '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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        • #5
          What first? More spring on all 4 corners or larger front sway bar?
          91' S13 Endurance Racecar
          Sponsored by Pallets and Crates LLC Gainesville Ga
          04' Chevrolet 3500 Tow Vehicle, 02' Dodge Ram 1500 Truck, 87' Toyota 4 Runner "Top Less",
          15' Toyota 4Runner, 07' Honda Fit

          Comment


          • #6
            more spring is your biggest need. 150 is WAAAAY too soft. 450/350 would be a good target. spring length is dependent on your modified shock setup so I can't help there. but get you some more spring on there.

            Than add more tire. a 205 is way too narrow to run a street tire and make it last. you're working them too hard on a 2700lb car to run a tire that narrow for a long time. they just get hot and greasy and wear faster. step up to an 8" or 9" wide wheel and run a 245 or 255. that will ad a lot more rubber to the equation so you'll turn better and the tires will run cooler and last longer.

            for sway bars, I run a modified sus tech sway bar. I cut the ends off and welded on an arm with multiple holes +- the original arm length so I can adjust it. I've since set it to the stiffest setting and left it there.
            No rear bar at all.

            Camber and caster of course changes based on tire type and width, as well as roll stiffness. with as soft a spring as you're running, no amount of static camber will make up for the amount of body roll you're seeing. Need to address the body roll first like Def said.
            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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            • #7
              More roll stiffness for sure (via springs). Then add a bit more up front with the biggest bar possible..

              More tire is good too.


              450/350 is getting more in the ballpark of what you need (I run 512/370, about to bump the rears up to 400). But I'd worry a bit about those dampers controlling really stiff springs in an endurance setting and the heat going in. But I suppose limiting body roll is key to making consumables last, and probably better overall than giving the dampers an easier time.

              So yea, somewhere in the 400-475 range up front, 300-350 rear range is good on springs.
              '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
                Thanks for the info. Looks like I have some research to do.
                91' S13 Endurance Racecar
                Sponsored by Pallets and Crates LLC Gainesville Ga
                04' Chevrolet 3500 Tow Vehicle, 02' Dodge Ram 1500 Truck, 87' Toyota 4 Runner "Top Less",
                15' Toyota 4Runner, 07' Honda Fit

                Comment


                • #9
                  Are those Alignment specs y'all are giving me with Driver or without?

                  I plan on trying to set this thing up this afternoon and wanted to check as I know the camber changes greatly when my big ass gets in the car!
                  91' S13 Endurance Racecar
                  Sponsored by Pallets and Crates LLC Gainesville Ga
                  04' Chevrolet 3500 Tow Vehicle, 02' Dodge Ram 1500 Truck, 87' Toyota 4 Runner "Top Less",
                  15' Toyota 4Runner, 07' Honda Fit

                  Comment


                  • #10
                    I always get my ass in the car when aligning. Won't hurt. Camber usually changes ~0.2* with my softy springs

                    Also, you might want to consider dumping the PU bushings in the suspension pivots with running this soft suspension. Next time you have your front struts out, articulate the LCA and watch the tension rod pivot and how much it rotates off axis. It'll be way more than you think. General consensus is to either keep the OEM rubber, get stiffer rubber (Megan racing the only company that I know of), then go straight to spherical/rod end bearings. PU in static points is fine.
                    Last edited by gills; 08-13-2015, 09:21 AM.
                    Core4 Motorsports
                    CLICK HERE for Wilwood FSL6R Radial Bracket & Rear Wilwood BBK GROUP BUY
                    S14 VQ AER Endurance Racing Team

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                    • #11
                      ...And it's nice to have another budget endurance racer here.

                      Def's alignment recommendation is pretty much what any front engine modern car with a macpherson strut suspension needs to run when racing. You need to run at the very least -3.0* camber if you don't want your tires destroyed prematurely.

                      If it makes you feel any better, the springs in my car are 140lbs/in F 190 lbs/in R (stock rates are ~100lbs/in F&R) on KYB GR-2 OE replacement struts/shocks. We run a godspeed 30mm front ARB and stock rear ARB, 15x8 wheels with 225/45 tires (Rivals at the moment). Last race we had our alignment almost identical to Def's specs; we were at -3.5* in front, closer to -2.0* in rear, 1/16" toe out F, 0" toe R (stockish caster since we don't have adjustable tension rods and/or camber plates. Slotted strut top holes for camber adjustment). Tire wear was very tolerable. 2 full practice days and a weekend race on the same set of Rivals. That was Lemons though, which tends to have some more traffic than Chump. Doing my first chump event next weekend at Limerock so I'm curious to see the difference in tire wear.

                      The car handles fairly neutral in this configuration and, most importantly to me, is very predictable. Good turn-in on corner entry, moderate push mid corner and corner exit. Dependent on driving style too, of course. Definitely get that front camber above -3.0* and increase spring and/or get a large front ARB.
                      Core4 Motorsports
                      CLICK HERE for Wilwood FSL6R Radial Bracket & Rear Wilwood BBK GROUP BUY
                      S14 VQ AER Endurance Racing Team

                      Comment


                      • #12
                        Originally posted by beasleysteven View Post
                        Are those Alignment specs y'all are giving me with Driver or without?

                        I plan on trying to set this thing up this afternoon and wanted to check as I know the camber changes greatly when my big ass gets in the car!
                        For as soft as your springs are I'd at least throw in an average weight based on the drivers on your team.

                        Comment


                        • #13
                          Picked up 400 lbs Front and 300 rear springs from Summit Racing Last night. Nothing like major changes the weekend before 14 hours of racing action!!! Time to get to work!!
                          91' S13 Endurance Racecar
                          Sponsored by Pallets and Crates LLC Gainesville Ga
                          04' Chevrolet 3500 Tow Vehicle, 02' Dodge Ram 1500 Truck, 87' Toyota 4 Runner "Top Less",
                          15' Toyota 4Runner, 07' Honda Fit

                          Comment


                          • #14
                            After a long weekend of work I go the 400/300 springs installed and my alignment set. The springs were quick and painless to install but a major problem when trying to get me ride height back down to earth while getting that 4 deg of camber.
                            I finally got my ride height back to 24 3/8" front and 25" on the Rear Measured from the ground to the top of the wheel arches on the body.

                            My alignment Settings I finished with are
                            Front -4 Deg
                            0 Toe
                            Not sure of the Caster, Assuming it is fairly close to stock

                            Rear -1.75 Deg
                            0 toe

                            How are you all measuring caster? I have a Longacre Caster/Camber gauge but I have been told they are not very reliable in the Castor dept as that is actually a dynamic measurement instead of a static one. Any advice?
                            91' S13 Endurance Racecar
                            Sponsored by Pallets and Crates LLC Gainesville Ga
                            04' Chevrolet 3500 Tow Vehicle, 02' Dodge Ram 1500 Truck, 87' Toyota 4 Runner "Top Less",
                            15' Toyota 4Runner, 07' Honda Fit

                            Comment


                            • #15
                              Turn front wheels +20 deg, measure camber, turn front wheels -20 deg, measure camber. Calculate caster.
                              '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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