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2 questions about s13 rear subframe and front wilwood calipers

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  • 2 questions about s13 rear subframe and front wilwood calipers

    Hey guys !

    I finally got some time this week end to work on my s13, again.

    First I still have a front brake problem. I can't figure it out. It looks like pad knockback, i get a spongy pedal after a hard turn. The rear brake works well, the front do not, resulting in unreliable and scary braking.

    It started when i installed wilwood superlite 4 pots calipers front. Thing is, i changed everything. At first i had crappy tyres, so no way this could have been too much grip. I changed master cylinder (for a known working one), lines, removed ABS, purged a thousand times. I changed both wheel bearings (for nissan ones), i even changed knuckles. I found recently the mastervac was pushing on the BMC all the time, so changed its settings and purged, again and again.

    The last change was fitting new calipers and light rotors from def. The new owner of the calipers does not have problem. I still do. I really don't understand. I found out that the caliper opens approx 1mm in the middle when braking at a standstill ... i don't really think it is normal, but i'd like your opinion on this.

    If anyone has an idea too, tell me ... My tuner suggested using a residual pressure valve on the front brake line, but he added he has no experience with them. Would that work ? Wouln't it always apply the pads on the rotors ? Any experience with these ? If it is ok, any idea of the pressure that should be used ?


    The second question is about the S13 rear subframe. I spent half of saturday adjusting my rear suspension links to dial out 1" toe out on max droop on each side. I now have 0 toe out on droop and some toe in on compression, and i am ok with that although i had to add more megative camber than i wanted to prevent binding.
    Thing is, now my right traction rod is approx 1" longer than the left one, and i think this is horribly wrong, like bent subframe wrong.

    So i need to check the subframe. The question is, how ? I could not find the s13 subframe measurement online. Does anyone have it ?

  • #2
    Originally posted by croustibat View Post
    I really don't understand. I found out that the caliper opens approx 1mm in the middle when braking at a standstill ... i don't really think it is normal, but i'd like your opinion on this.
    I don't understand what you're describing heh

    The FSM should list measurements for all the major mounting points on the car, if you can verify from the front to the mounting pin locations, you can rule out the chassis being the culprit

    Then move on to triangulating each pivot from the pins...
    http://responsetype.com/shop/

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    • #3
      The caliper is 2 parts. Press the brake pedal, and it will deflect from the center, approx 1mm. I was wondering if that really is how it is supposed to work. I don't think so, but then again i may be wrong.

      I already searched in the FSM, and on the internet, for measurements. I found a diagram with the unibody, unfortulately found no subframe.

      Comment


      • #4
        What size MC do you have? What rear brakes do you have?

        1 mm sounds like a lot. I couldn't visually detect any deflection in my Superlite 4 pots or Billet 6 pots.
        '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
          1mm is a bit much, but I've seen it before. what's the condition of your wheel bearings? everything torqued properly?
          It sounds to me like something isn't lining up properly- maybe a caliper mounting tab on your knuckle is bent, but you changed knuckles so that's probably not it.
          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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          • #6
            The MC is a 1" Z32, that we removed from my tuner car ( he went without mastervac, because his gtx3582r would not fit otherwise, so he needed a softer one. I trust him completely on the health of the MC)
            I used to have a 17/16 before, that i bough brand new and installed it as the same time as my previous brake kit (superlite 4pots 330x32 1 piece rotors). The only common name since my problems started is "wilwood superlite 4", and the OEM mastervac.

            Everything else has been changed for new parts at least once.

            Rear brakes are Z32 as well with endless "blue" pads. For the sake of testing i just changed them for rebuilt ones from centric. Same thing happens.

            It really is strange. Tuner says he just needs to move the front wheels hard with his hands when the car is on a lift to push pads back. That reeks of bad bearing, but wouldn't an air bubble somewhere do the same ? I think we purged it like 10 times now in 3 months.

            Def, did i need to torque the inner bolts on the superlite 4 before installing them ?

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            • #7
              If moving the wheels moves the pads, then you have something loose. Like matt said, wheel bearing would be top of a very short list.

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              • #8
                Guess i'll check bearings again then... how do i measure their play ? They are the stock bearing, pressed in.

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                • #9
                  Lift wheel off ground. Grab top and bottom and try to rock. Should be no play. If so, check the hub nut torque, first, but they do wear out.

                  I'd say probability is quite high that this is your problem. It would cause the rotor to deflect independent of the caliper.

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                  • #10
                    If you have really bad knockback a residual valve won't help. Residual pressure valves only hold a tiny bit of pressure (2psi on disc systems), mainly to keep the fluid from flowing back into a low-mounted master cylinder (like a floor-mounted setup). I'd certainly lean toward it being a problem either in the bearing or a crooked mount somewhere.

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                    • #11
                      If your guy says he can rock the wheels and push the pads back, then there's a problem with the wheel bearing or mounting surface the rotors are on..

                      S13 wheel bearings are notoriously weak, and the factory torque specs are way lower than an S14.. If it were me, I'd torque them to S14 specs and move on with life. (I pound them on my S14 for about 20 seconds with my impact wrench set to "obliterate")

                      http://www.motoiq.com/MagazineArticl...ike-I-Did.aspx
                      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
                        If your guy says he can rock the wheels and push the pads back, then there's a problem with the wheel bearing or mounting surface the rotors are on..

                        S13 wheel bearings are notoriously weak, and the factory torque specs are way lower than an S14.. If it were me, I'd torque them to S14 specs and move on with life. (I pound them on my S14 for about 20 seconds with my impact wrench set to "obliterate")

                        http://www.motoiq.com/MagazineArticl...ike-I-Did.aspx
                        I'll ask my tuner to retorque them, although i can't believe he forgot about that. The hubs are brand new S14 wheel hubs from nissan. The thing is, i could believe my 160.000+miles S14 knucke and bearings were shot, but changing them to brand new ones did not change anything .. still, worth a shot.

                        Thanks everyone. Everything is still pointing at faulty bearings...

                        Also, anyone has the measurements for S13 rear subframe ?

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                        • #13
                          Ok, tuner confirmed, he torqued it at 10mkg and was sure he was supposed to. Which is appox 72ft-lbs.
                          So the first time i had the problem, it really was because of a dead bearing, and the reason i did not see the faulty item was because the new one was not properly torqued...

                          Anyway, motoIQ says it needs 150 to 210 ft-lbs . Is this real ? That is 29mkg max !

                          Def, you are using an aluminium knuckle too, did you torque it that much ?
                          Last edited by croustibat; 09-29-2014, 10:44 AM.

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                          • #14
                            If you're using OEM wheel bearings, they need to be torqued to the maximum of factory specs. going to the minimum of factory specs will result in a short-lived bearing as there's too much play in there (as you're observing).

                            and yes. FSM specs say the same thing.
                            Attached Files
                            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


                            • #15
                              Yeah, def to the top of spec.

                              I haven't done wheel bearings for 2 years since I went to 200ish ft/lb. Used to be yearly.

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