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S13/S14 SR Transmission Interchangeability?

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  • S13/S14 SR Transmission Interchangeability?

    My question is: Can I run a S13 SR transmission with my S14 engine/ecu?

    I've searched various forums and come up with a lot of conflicting information (go figure). Does anyone have a definite answer on whether it will work and what modifications are necessary?
    Last edited by just_drive; 07-08-2013, 06:40 AM.
    '91 Silvia w/ S14 SR20DET - Track Car
    '07 Subaru WRX STi - Daily

  • #2
    Don't know about the S13/14 JDM'. USDM S14 has a speed sensor at the flywheel that the S13 doesn't but I think it's only for the cruise control. www.240edge.com has the FSM's in PDF.
    Don Johnson (really!)
    Just so you know.

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    • #3
      The speed sensor on the flywheel is actually used for crank signal in S14's.

      You can use an S13 trans, you just have to move the bellhousing from your current transmission to the new one.

      The transmission itself is the same.
      1995 Nissan 240sx SR20DET @ 14lbs

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      • #4
        Originally posted by djsilver View Post
        Don't know about the S13/14 JDM'. USDM S14 has a speed sensor at the flywheel that the S13 doesn't but I think it's only for the cruise control. www.240edge.com has the FSM's in PDF.
        Originally posted by eidas007 View Post
        The speed sensor on the flywheel is actually used for crank signal in S14's.

        You can use an S13 trans, you just have to move the bellhousing from your current transmission to the new one.

        The transmission itself is the same.
        Thanks for the info.

        eidas007: This is where I'm confused. I've seen photos of the vss you're referring to in the S14 bellhousing, however, there is no way it's pulling vehicle speed from the flywheel, that just doesn't make sense. I've read they added the vss to diagnose misfire on the S14s since they were OBDII. Having said all that, looking at the S14 SR service manual I cannot find a sensor in the tranny they would use to to determine speed. It has to be on the output shaft somewhere....
        '91 Silvia w/ S14 SR20DET - Track Car
        '07 Subaru WRX STi - Daily

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        • #5
          Both transmissions are the same except the bellhousing like they said. ONLY difference is that sensor which is actually a Crankshaft Position Sensor used for nothing, literally.

          S14 KA's have them also and when you unplug them nothing happens. I guarantee you there will be no difference is you use an S13 transmission and don't use that sensor.

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          • #6
            I've had cars not run because of that sensor.

            Without having to mess around with assist during my lunch hour (I'm a tech at a Nissan dealer), I want to say that the VSS is on the output shaft inside the tranny.

            That sensor in the bellhousing is reading crank speed. It's primary use is non-essential components, but it is used as a backup and a reference to the primary crank sensor.
            1995 Nissan 240sx SR20DET @ 14lbs

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            • #7
              I think the crank hall effect sensor on S14s is for misfire detection for OBD-II purposes. Not used for tuning.
              '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
                So it seems like that sensor on the bellhousing may be unnecessary, but now I'm curious. Here is a view from the S14 service manual, where is the sensor that provides the speedometer signal? I spot 3 and none of them mention speed (neutral position switch, reverse position check sleeve, reverse lamp switch)

                '91 Silvia w/ S14 SR20DET - Track Car
                '07 Subaru WRX STi - Daily

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                • #9
                  It's on the other side, down low and towards the back.
                  '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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                  • #10
                    Directly from a hard copy of the USDM service manual.

                    "This sensor (CKPS) is not directly used to control the engine system. It is only used for the on board diagnosis of misfire".

                    It says that the CMP is used for the tach.

                    The manual doesn't actually show the location of the VSS, however if you go 2 pages back from where you found that picture (MT-6) you can find a diagram that shows you a connector.

                    VSS data is on EC-216
                    CKPS data is on EC-250
                    CMP data can be found on EC-173

                    Hope that helps.
                    1995 Nissan 240sx SR20DET @ 14lbs

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                    • #11
                      Thanks for the help everyone. Looks like I'm not going to worry about that sensor. I'm happy I'll be able to use an S13 SR transmission because I can't find any S14s localy!
                      '91 Silvia w/ S14 SR20DET - Track Car
                      '07 Subaru WRX STi - Daily

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                      • #12
                        S14 and S13 SR trans have different gearing I think. S14s have a shorter 5th... Which I really wish I had...
                        '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
                          In addition to the S14 SR Trans having a shorter 5th (.838 vs .759) they also had Dbl Synchro Rings on 2nd and 3rd. S13 and KA's only had Double rings on 2nd.

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