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Dialing out under steer?

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  • Dialing out under steer?

    I've got a problem with my car under steering. I'd like it to be more neutral or have a slight tendency to over steer.

    Right now the car is on 8k/6k springs with tender springs in the rear with a welded diff and the stock sway bar. I do have some 9k and 7k springs I could try out. I wanted to have an adjustable rear sway bar on by the next event to help dial in the balance of the car, but its back ordered until the week of the event at the very earliest.

    I'm thinking of looking for more / easier rotation by testing out the car in a couple different configs:
    1. Without the tender springs,
    2. Without the rear sway bar, and
    3. Possibly with stiffer rear springs.

    Any idea which of those might get the desired effect with minimal other sacrifices to my overall handling?

    Also, do we gain toe in under compression in the rear? If so, how many are running a bit of toe out in the rear to help rotation?
    '95 240sx

  • #2
    1. The tender springs should not make a difference.
    2. Removing the rear sway will add more understeer.
    3. Stiffer rear springs will help with rotation.

    Not on the list but recommended. More camber up front, less in the rear will help with understeer. I am running -3.2 up front and -1.5 out back.

    If you have a huge front sway bar, that will add understeer. However, I've found stiff springs up front and a large bar are necessary on our cars with sticky tires.

    My front splitter really gave me the front bite I have been searching for. Don't know if that is a possibility for you.
    Chicago Region SCCA SM # 688
    TSSCC SM # 688


    • #3
      1. good to know
      2. I figured as much
      3. Sweet, something feasible.

      I'm already running -3.2 or so up front and -1.5 or -2 in the rear (can't remember exactly, probably needs to be checked given how long its been since it was last aligned)

      Front sway is kinda big (sikky set to full soft), I could add a front splitter, I'm not restricted by any class at the moment.
      '95 240sx


      • #4
        The welded diff is your main culprit for understeer, you're technically always understeering or oversteering. What tires are you running?

        The rear gets toe out under compression.


        • #5
          Yeah, the diff is not helping my case. I'm putting off a 1.5 way till after this season because I'd rather use my budget to run more events than mod the car for the time being.

          I'm running old yokohama AD048 r-comps when I do a track weekend, azenis for street stuff. Both sets are 225/50-16's. Power wise, I estimate I'm making somewhere in the 150whp range.
          '95 240sx


          • #6
            GET RID OF THAT DRIFTER DIFF !! Lockers or welded diffs create so much corner entry understeer that you are better off to have an open diff.

            Seriously, I ran a Kaaz 2 way for one event and then immediately took it out and sold it. While it powers both wheels which is great for drifting, it creates so much foward motion that corner entry will always suffer with a push until you are able to rotate the back end around and slide the car through the corner. Not the fast way around any corner, especially for auto-x.

            Now for road racing, you can kind of get away with it.... but you will ALWAYS still have to hesitate before you can put throttle down. (I had a welded solid rear diff in my 200SX (RWD) race car...but it really sucked on tighter corners with that diff)

            If you're on a budget, just shim a VLSD up.


            • #7
              I'll second Don's opinion on welded diff's and on the KAAZ. I had a KAAX as well and it made so much noise that people in the parking area and in the grid were always asking what was broken! I made the mistake of trying to drive it to the gas station with mis-matched rear tires...., It would snatch the wheel to the right when accelerating and to the left when deccelerating. It was so violent it would almost pull my hands from the wheel. Oh yeah, it also made the car understeer badly. I run a helical now and no rear bar. It's very neutral but I can still steer it with the throttle when I want too. ;-)
              Don Johnson (really!)
              Just so you know.


              • #8
                Helical with a 4.3 ratio would be nice; possibly even ideal... For now my best option may be to shim my old J30 diff. Not really sure how to figure out the appropriate amount of shimming required.

                The process is clear enough from googleing about it, just don't know how to set it for the correct amount of brake-away TQ, or if its just a crap shoot considering the use and mileage on the unit.
                '95 240sx


                • #9
                  Ugh, J30 diff WILL NOT come apart. The left hand stub axle is like 1.5" out but wont pop loose. The other stub axle comes out just fine.

                  I suppose I'm dealing with adding more rear spring for VIR on the 13th.
                  '95 240sx


                  • #10
                    I'm just gonna order the biggest Shim and take out the old one. Should be enough, better then those p that order the big ones and still put the stock one lol. That just sounds bad.
                    Can't wait to get another S-Chassis to throw it in. Especially with my 4.375 sitting right next to it


                    • #11
                      Random question on the VLSD... Can I hit on the stub axle from the inside through the center of the diff? Its the only thing I can think of that might give me better luck.
                      '95 240sx


                      • #12
                        Some nissan vlsds have a 1/4" pin through the middle- not sure about an r200 tho.
                        I just used a big rubber mallet and kept tapping on the flanges, turning, and tapping more. Eventually they come apart. Some I was ready to take a 5lb sledge to, but eventually the rubber mallet did the job.
                        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


                        • #13
                          Originally posted by Matt93SE View Post
                          I just used a big rubber mallet and kept tapping on the flanges, turning, and tapping more. Eventually they come apart. Some I was ready to take a 5lb sledge to, but eventually the rubber mallet did the job.
                          Exactly what I had to do with two R200 diffs. But oddly, it was only one of the stubs; the other just came out with no problem


                          • #14
                            After over an hour wailing on the left output shaft with my 4# sledge and only getting it out an inch or so... I think something's wrong. The other side needs just a couple of taps and its free.
                            '95 240sx


                            • #15
                              If you've got a slide hammer that usually gets them right out. Hitting them with a mini-sledge helps, but it's such an off center blow that it tends to bind things up a lot when the c-clip is being a POS.

                              Alternatively, hold the diff by the output shaft, then hit the diff housing to get a direct pulling force on it.
                              '18 Chevrolet Volt - Electric fun hatch for DD duty!

                              DefSport Koni Sleeve and Spring Perch Buy!!!