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  • Some rear wheel speed sensor testing. I've got my hands on an E46 M3 rear sensor and Z33 rear sensors. The clearance between the sensor housings on the Z32 diff cover and the stock 240 3x2 bolt pattern output shaft diameters where an ABS tone ring would sit is about 3/8". My plan is to use extra front S14 tone rings I have laying around installed on machined output flanges. The OD on those ABS tone rings is 97mm. That leaves about 1mm clearance between the tone ring and the sensor housing, which is a perfect air gap.


    The E46 M3 rear wheel speed sensors work surprisingly well. Their depth seems just about perfect with the end of the sensor flush with the housing, which would leave that 1mm air gap. They don't have the 90 degree wire output, more like 45 degree, but it still will clear the subframe. Of course the mounting hole doesn't line up. It's pretty close, but this would be the "hardest" thing to deal with (besides turning down the diameter of the output shaft to accept the ABS tone ring):

    E46 M3 sensor inside diff cover sensor housing:



    Mounting hole alignment:




    The Z33 sensor is basically the opposite. The mounting hole lines up perfectly, but the depth is a bit too much. These have 90 degree wire outputs like Z32 sensors and the two rear sensors are tied into one harness plug. Definitely clears the subframe as well.

    Z33 sensor inside housing:


    Alignment with mounting hole is exact:




    As for the front sensors, it seems that active sensors (have an IC built inside that generates a square wave vs analog sine wave of older style sensors) that have their pickup 90 degrees from normal, or read from the side (which is what will mimic S-chassis uprights/spindles wheel sensor mounting provisions) are uncommon. Most seem to read dead on/at the tip.

    The E46 M3 front wheel speed sensor may actually be the right solution. My modified OEM uprights are non-ABS so I still need to drill them to test this. But,nonetheless, here's a E46 M3 front wheel speed sensor:

    Reads from side here:


    Most sensors I've come across read from tip like this, which would require custom bracketry on the upright (using E46 M3 sensor just as an example):
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    • I recommend NiCopp 3/16" line for brake lines. Super easy to bend by hand and flare to 37 deg.
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      • So because these 4-channel systems use EBD - Electronic Brake Distribution cycles solenoids pertaining to the rear circuit in the ABS modulator in closed loop control to proportion the rear circuit, you don't want mechanical proportioning devices in your system at all.

        All Nissan BMC's of the S-chassis era that are worth using have built in proportioning valves. Hoping that I could get away with using my Z32 BMC, I removed the internal prop valve and tested to see if rear proportioning would be removed. Surprisingly, nothing changed. I checked this by measuring caliper clamping force, not pressure, with these nifty scales:

        Front:


        Rear:




        Someone in that NRR thread I shared in my previous post ended up using a 2001 Pathfinder BMC that doesn't have internal proportioning. It also has oddball output locations on the top of the MC and the other on the driver side/left side, which is nice for people wanting to keep their lines away from turbo/exhaust heat. The inclination of the reservoir is also greater than the Z32.


        2001 pathfinder BMC (pictures from "Scores240" on NRR):





        Here's a Z32 BMC for reference to show you the difference in the reservoir inclination:





        Because I don't care for the specialized outputs of the pathfinder and want to keep the same sizing as what's in the car now (17/16"), I'm eyeing the Z33 BMC. The inclination on the Z33 looks the same as the pathfinder. BTW, it seems that Nissan has been using 80mm as their standard for BMC hole mounting through at least Z33:





        Just eyeing the pictures, the center-center spacing of the reservoir inlet ports looks the same as the Z32. The height offset between the ports also looks the same. I wouldn't be surprised if the Z32 reservoir could just pop right in the Z33/pathfinder. I do like the reservoir and cap better that's on the Z33/pathfinder though. The Z32 always leaks some during races. I just don't like that inclination when mounted in an S.




        Here's some more info and pictures on the output shaft and front ABS tone ring:







        Output shaft just needs a couple mm's removed. Should work perfectly.
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        • Moving along with ABS stuff. Threw a spare output shaft on the lathe to test. Measuring up the front hub diameter the ABS ring came off of and the ID of the ABS ring, Nissan wants a 0.002" interference fit:




          Here it is in the diff with the BMW sensor. Perfect clearance (about 1mm) so this method is a go for me:




          Still waiting on my contact to see if he can communicate with the S2000 AP2 ABS unit to see if it can be used as a standalone unit. He's in possession of it and hopes to bench test it this weekend.

          -------------------------------------------------------------------------

          Since I have the diff out, it is time to rebuild/refresh since I'm going to a 3.9 and also explore playing around with the Mfactory clutch lsd in there.

          At the last race the driveline started to develop a very distinct whine proportional to road speed, which is indicative of a diff. You can hear it in my in-car video here:

          https://youtu.be/4o8RcV68MtE?t=29857


          Lo and behold, it was most likely was the diff. We were worried for a minute that it was something on the output side of the CD00A (bought new in 1/2018). Here is the inner pinion bearing cup showing typical fatigue failure of a tapered roller bearing:

          Cup:



          Cone/rollers:




          I've ordered all new bearings and seals for the carrier. I believe this is an R200 carrier, not R200V. There are differences between the two and you will see different sized pinion seals and I believe pinions bearings when you search parts sites for 240sx.

          Here's what I measured and noted on my diff:
          • Inner (larger) pinion bearing, OEM bearing: KOYO TR0708-1R-N
            • ID = 35mm, OD (cup) = 80mm, Width = 32.75mm
            • ISO standard part number: 32307 (i.e.-all bearing manufacturers use this number for this sized bearing)
            • The reason why the OEM bearing doesn't share that ISO part number is because on that specific bearing the rollers/cup are on a steeper angle to be able to handle slightly more thrust load. You can probably get away with the standard 32307. If you search this number in a site like Rockauto you'll see it pulls up a bearing that's labeled for a differential pinion.
          • Outer (smaller) pinion bearing, OEM bearing: NSK 32306AN
            • ID = 30mm, OD = 72mm, width = 28.75mm
            • ISO standard part number: 32306
          • Side bearings, KOYO 57160 "LFT" (Low Friction Torque).
            • ID = 45mm, OD = 85mm, width = 20.75mm
            • ISO standard part number: 30209
            • Nissan spec'd the "LFT" KOYO bearing, which is supposed to be a higher efficiency, lower friction tapered roller bearing. KOYO claims up to 2.5% improved fuel efficiency with the use of these style bearings in a differential. Seems crazy. An equivalent 30209 would probably be a 30209-C or 30209-P5, which means that tolerances are held tighter. Can you get away with a standard 30209 which are less than half the price? Probably, might not last as long.
          • Pinion seal
            • ID = 40mm, OD = 75mm
            • There are two different sizes on this for sure. Pretty sure this might be the standard R200.



          So, because the bearings in this carrier were original from the factory, I got the same ones as that's proof to me. The carrier had 100k miles on it before it started living the race car life that has a couple hundred hours of track time now on top of that 100k.

          -----------------------------------------------------------------------------------------------------


          That brings us to my 1.5 way M-Factory clutch diff setting change. I have a theory with the S-chassis when it comes to track/grip racing. Almost everyone who tracks these cars complains about excessive corner exit oversteer. And, almost everyone who tracks these cars extensively has a clutch/salisbury type LSD.

          The kicker is that the diffs that everyone gets for these cars come by default with "100% lock" under acceleration. I know for sure that Cusco and MFactory diffs come with 100% lock clutch disc arrangements. 100% lock is a recipe for oversteer when coming back onto the throttle. Great for drifting and rallying, not great for grip driving. There has to be more of a balance.

          How the lock builds or comes on with the throttle is dependent on ramp angles, preload on clutch discs, and how many clutch discs there are. My belief that all of it is too aggressive on units that come out of the box for these cars. So, I'm going to experiment with less preload and at the very least 80% lock arrangement on the discs. I may even try 60% based on my research into what top BMW E46 M3 and E36 M3 cars run. I will be measuring preload also so there's no second guessing. Just need to come up with something to measure it.


          Some pictures of the M-factory LSD. There are 10 clutch discs per side. Looks basically identical to a Cusco RS.



          Here you can see there's a choice to run it as a 1 way also:


          The coil springs that you can add or remove to control preload (or the minimum torque it takes to de-couple the sides):


          Spring pockets to have up to 12 preload springs (I believe minimum is 4):


          Closer look at 1.5 way ramp:


          1.0 way ramp:


          clutch discs:
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          • Here's a good tech article from Cusco, which covers most clutch type diffs:

            https://www.cusco.co.jp/en/pdf/LSD%20Guide%20Final.pdf
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            • Checking preload, here's my little bench testing rig I came up with using the output shafts. Not pictured is a digital torque gauge that's inline between the socket and the ratchet to measure the breakaway torque.




              With 6 preload springs and the clutch discs in "100% lock" arrangement, it was about ~55ft-lbs breakaway torque. That is basically the range MFactory said it would be with 6 springs, so that's good.

              What isn't ever really mentioned (but should be pretty obvious) is that this breakaway torque decreases with lower lock % disc arrangements with the same number of preload springs. Preloads are just stated without any consideration for disc arrangement. For ****s and giggles, I lowered to what is stated to be 20% lock arrangement (the minimum possible) and the breakaway torque was 10ft-lbs.

              So, not surprisingly, if you want to make the lock less aggressive, but keep the same preload/break-away, you need to add more coil springs. Then of course ramp angles in conjunction with disc arrangement come into play here with how much lock you can actually achieve.
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              • Originally posted by Def View Post
                I recommend NiCopp 3/16" line for brake lines. Super easy to bend by hand and flare to 37 deg.

                Just realized you managed to comment in between my barrage of copy and pasted posts, ha!

                Definitely using NiCopp. It really makes bending brake lines so much easier.
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                • copy and paste from Zilvia. Some of it is repetitive with my other posts on here:


                  So diff is all closed up. Ended up with "60%" clutch disc lock arrangement and 8 preload coil springs (up from 6) for about 40-45 lbs.ft of breakaway torque. Adding/removing a pair of springs seems to be good for 10 lbs.ft jumps. The car should be smoother when transitioning from on and off the throttle and be less snappy when back on the throttle. Really looking forward to testing this difference (hopefully April 1st test day).


                  Speaking of diffs, just want to share how changing shim thicknesses so little changes things so much for those that may be curious or just don't know. I personally haven't had luck yet re-using pinion height shims that were already in my carrier when swapping used ring and pinion sets. Or maybe because I'm anal due to the nature the car is being used, I need it to be as perfect as I can get it.


                  Setting the pinion preload is very sensitive to thickness changes in the preload washer/shim. It went from too loose to just right with 0.0005" (0.0127mm) difference with the preload shim. For reference a basic sheet of paper is 8x thicker than that.


                  After setting pinion preload, you work the gear pattern by adjusting the pinion height with a shim that's sandwiched in between the pinion head and inner tapered roller bearing.

                  Here's what I started off with:

                  "Drive" side is close. A touch high toward the "face" (top of the gear tooth), and biased toward the "heel" (outside diameter of ring gear) :



                  "Coast" side is also high toward the face, and is very much toward the "toe" (inside diameter of ring gear):




                  The drive side is obviously the more important pattern to pay attention to, but that pattern is pretty close. Increasing pinion height will bring the pattern lower toward the "root" and also move the coast side toward the heel and drive side toward the toe.



                  Here's the pattern raising the pinion height 0.005" (0.127mm) from the above:

                  Drive side. Too deep/close to the root now, and biased more toward the toe



                  Coast side also too deep, but centered up more nicely




                  Here's splitting the difference at 0.0025"(0.064mm). This is also with 0.007" backlash taken at the center of the ring gear. This is what I'll be sending it with for this race season:

                  Drive side is nicely centered



                  Coast side still biased toward the toe, but is centered between the root and the face. Not perfect, but the drive side is pretty close to being spot on that I'm not concerned with this





                  ------------------------------------------------------------------------------------------------------------------------------------------------


                  ABS
                  My contact at Race Harness Technologies confirmed that diagnostic information can't be communicated over the K-line on the OBD2 port on the MK60e1 AP2 S2000 unit like he can on the MK60 BMW unit. That means diags is over CAN, or CAN is still active in stand-alone mode, where that isn't the case with the MK60 unit.

                  Now, that doesn't confirm that the unit can't be used as stand alone. It just means if you are to retrofit an AP2 unit, you won't be able to tell if there's anything wrong or errors being thrown the same way you can on the MK60. You also run the modulator through a bleed routine through the K-line.

                  HOWEVER, he still has some steps to go through to for him to be able to access the diags over CAN so there's still a possibility that the MK60e1 can be used in a similar fashion, and not just blindly.



                  With all that said, I had to abort the AP2 mission because of time and his inability to promise that he can get something working by my Watkins Glen race (4/13). I ended up just ordering the BMW MK60 stuff for now as it's all a known quantity. Out of the sake of trailblazing, I'm having him keep the AP2 unit so he can continue to progress as he's just as interested in getting it to work as I am.


                  Another very important discovery of the AP2 S2000 vs the BMW MK60 is that the BMW unit doesn't split the inputs from the master cylinder across diagonals on the car where the AP2 (and AP1) unit does, as shown here:



                  So input1 = FL/RR, input2 = FR/RL, where the MK60 splits inputs Front to Rear. The diagonal split is very common on modern road cars. This means that if you have any rear mechanical biasing/balancing/proportioning upstream of the MK60e1 module, you'll be doing it across the diagonal of the car, which = bad. That leaves all proportioning up to the EBD algorithms stored for S2000 parameters. The MK60 you can mechanically proportion and balance however you want on top of the EBD for E46 M3 parameters.

                  I *think* this is especially important for retrofits where weight distribution, wheel base, etc, can potentially be very different than the E46 M3. For the most part, the stock M3 parameters cover many of cars most of us race/drive give or take a few % points here and there. And, I believe the stock S2000 would probably cover many bases as well.

                  So, I was about to change out my MC for the Z33 unit, but that is no longer necessary. I hope that keeping the Z32 BMC with the internal prop valve is a decent fail-safe in case the ABS faults as I'll still have proportioning in that case.


                  Got the rear wheel speed sensors situated. Ended up using E46 M3 sensors instead of the Z33 ones. Ended up slotting the mounting holes on the sensor instead of messing with the diff cover. That brass insert molded into the plastic so it'll be sturdy. I mean, it was sturdy enough for me to mill it, should be good. The mounting hole for the BMW sensor is for an M6 and the Nissan is M8, so the hole also needed to be enlarged as well:











                  Next up, getting my custom non-ABS OEM front spindles to work with E46 M3 front sensors. A local S-chassis friend (THANK YOU, CLOTUNING) was nice enough to lend me his spare ABS uprights that I could map out to get exact dimensions. The sensor tips can't be more than a mm away from the tone ring, so this is a huge help.

                  Backside of OEM ABS S14 spindle in vice for probing:




                  I've got the measurements I need now. Time to drill/mill!

                  -------------------------------------------------------------------------------------------------------------------------------------------


                  Also, my V2 front and rear big brake parts arrived. Floating, modular Z32 e-brake compatibilty, front rotor options from stock Z33 brembo track rotor to 355mm x 32mm baller setup....






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                  • Whewe do you pan on getting the connectors for the abs plugs?junkyard? Or they sell them new somewhere?

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                    • BTW - you've got a lot of slotting for hat to rotor CTE. I did the calcs before and generally +/-0.005-0.007" radial slots are plenty.
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                      • Originally posted by Def View Post
                        BTW - you've got a lot of slotting for hat to rotor CTE. I did the calcs before and generally +/-0.005-0.007" radial slots are plenty.

                        Copy that. I went with a bit more.
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                        • Originally posted by clotuning View Post
                          Whewe do you pan on getting the connectors for the abs plugs?junkyard? Or they sell them new somewhere?
                          I wussed out due to time constraints with making my own harness. Iím having Race Harness Technologies make the harness so itís taking all that work out of the equation. ABS unit is going on the passenger rear seat shelf. There will be bulkhead fittings for the brake lines on the vertical wall of said shelf behind the passenger and drivers seat areas.

                          Two inputs from the MC to the ABS module. Brake pressure sensors T into those lines. Then 4 outputs. Itís going to be brake line routing heaven. Starting this week.
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                          • So back to the front spindles. Milled and drilled them based off of what I measured. I think the air gap should work just right.

                            "Probing" that OEM ABS spindle. Picked up the small tooling hole on the back that the factory uses to turn the spindle:



                            Had to mill down the area where the sensor goes to match the thickness. Had to remove about 0.095".


                            All done. Thru hole for the sensor is 18mm and is located 50-50.25mm radially from the spindle centerline. Not having the mounting hole there was actually good since the Nissan pattern doesn't match and also uses an M8 instead of an M6. I had a clean slate to transfer the BMW sensor hole:


                            Air gaps and fitment is just right:





                            Really can't wait to test this system. The harness for the ABS should be arriving this week. I'll be mounting the module on the rear passenger side seat shelf so there will be bulkhead fittings galore.

                            --------------------------------------------------------------------------------------------------------------


                            Here's my first step to making the brake system more rigid. Quickly fabbed up a master cylinder brace that mounts on the strut tower. And, yes, these things do help. I've measured decent deflection on the S14. Any deflection in your braking system is magnified at your foot by the brake pedal ratio. Taking as much of it out is very beneficial to brake modulation, feel, and effectiveness:

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                            • Lots of stuff going on here! I need to fab up an MC brace like that.
                              ~1992 240SX, SR20/Koni track day car
                              ~2016 M3, daily driver

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                              • Originally posted by turtl631 View Post
                                Lots of stuff going on here! I need to fab up an MC brace like that.
                                You have an S13, right? GKTech makes one for you. They make them for S13 LHD & RHD, S14 RHD, but not S14 LHD. Go figure.
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