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SMG Grinding After Track Session

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    SMG Grinding After Track Session

    This has happened a couple times before. Car is great on track, shifts are reliable and crisp. However when driving back to the hotel it will grind when coming to a stop. Now hearing periodic noises when changing gears even if engine isn’t running.

    Gear actutator?

    I recently relocated a rebuilt SMG pump to drug bin.


    #2
    Gears grinding like a beginner learns driving stick shift?

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      #3
      Originally posted by sapote View Post
      Gears grinding like a beginner learns driving stick shift?
      Yeah. I wasnt able to capture that sound on video. But yes that is what it sounded like when I was coming to a stop.

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        #4
        After relocation mine makes the same noise. Nothing wrong as far as I can tell (and it's been a couple years) and for mine it is the lines vibrating. I think the noise either wasn't present and the longer hydraulic lines have introduced the vibration or when the under the intake next to the block the noise, and perhaps less noise, wasn't able to be heard over the engine.
        3.91 | CMP Subframe & RTAB Bushings | SMG (Relocated & Rebuilt) | ESS Gen 3 Supercharger | Redish | Beisan | GC Coilovers & ARCAs | Imola Interior | RE Rasp | RE Diablo | Storm Motorwerks Paddles | Will ZCPM3 Shift Knob | Apex ARC-8 19x9, 19x9.5 | Sony XAV-AX5000 | BAVSOUND | CSL & 255 SMG Upgrades | Tiag | Vert w/Hardtop

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          #5
          Originally posted by eacmen View Post

          Yeah. I wasnt able to capture that sound on video. But yes that is what it sounded like when I was coming to a stop.
          Gears were engaged so the noise can’t be gears grinding noise.

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            #6
            You know what the answer is.
            2003.5 MT JB/B - CSL SCHRICK SUPERSPRINT EISENMANN JRZ SWIFT MILLWAY APR ENDLESS BBS/SSR DREXLER KMP SACHS RECARO AR SLON MKRS GSP DMG KARBONIUS CP AUTOSOLUTIONS KOYO

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              #7
              That's how mine sounded with my failed GPS.
              17 iO1 i3
              16 F22 M235i
              08 E93 M3
              04 E46 M3 Carbon Schwarz - SMG II - Discovery Automotive tuned - AFE Stage 2 - SS Stepped - SS Metallic Cats - Eisenmann X-pipe - SS Race - 4.10 - ACS CF lip - 6000K Heads & Fogs - Tein S

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                #8
                Originally posted by Da Jemster View Post
                That's how mine sounded with my failed GPS.
                Thanks! This is what I suspect. Is the GPS more than just a sensor? Is there something mechanical inside the GPS that makes the sound?

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                  #9
                  I didn't notice the youtube link. That is different from what I experience from time to time.
                  3.91 | CMP Subframe & RTAB Bushings | SMG (Relocated & Rebuilt) | ESS Gen 3 Supercharger | Redish | Beisan | GC Coilovers & ARCAs | Imola Interior | RE Rasp | RE Diablo | Storm Motorwerks Paddles | Will ZCPM3 Shift Knob | Apex ARC-8 19x9, 19x9.5 | Sony XAV-AX5000 | BAVSOUND | CSL & 255 SMG Upgrades | Tiag | Vert w/Hardtop

                  Comment


                    #10
                    Originally posted by eacmen View Post

                    Thanks! This is what I suspect. Is the GPS more than just a sensor? Is there something mechanical inside the GPS that makes the sound?
                    When it’s grinding, was it still with engaged gear? If it was engaged then a good or bad GPS was not the cause. Bad GPS only affects the shift and not after gear was engaged.
                    GPS for SMG is only an electronic encoder (Edited, was encounter)
                    Last edited by sapote; 07-28-2022, 10:11 PM.

                    Comment


                      #11
                      Originally posted by sapote View Post
                      When it’s grinding, was it still with engaged gear? If it was engaged then a good or bad GPS was not the cause. Bad GPS only affects the shift and not after gear was engaged.
                      GPS for SMG is only an electronic encounter.
                      SMG was in A3 and coming to a stop. So trans was downshifting.

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                        #12
                        Originally posted by eacmen View Post

                        1. Now hearing periodic noises when changing gears even if engine isn’t running.

                        2. SMG was in A3 and coming to a stop. So trans was downshifting.
                        1. engine not running means noise is not gear grinding like a bad synchro or not total disengaged clutch. Is this noise same as the gear grinding noise or something else?
                        2. A3 is slow shift; do you think at faster shift mode, noise will change? There is no mechanical parts in the GPS for SMG as you asked previously. Maybe the slave cylinder needs to be bled and teach the computer again about the slave/clutch position.

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                          #13
                          Update: I did an actuator and clutch bleed procedure and the noise remained. However, after running the SMG adaptations the sound went away. I did run SMG adaptations a week before the track event, not sure what would drift out of spec that would cause that noise though?

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                            #14
                            Originally posted by eacmen View Post
                            Update: I did an actuator and clutch bleed procedure and the noise remained. However, after running the SMG adaptations the sound went away. I did run SMG adaptations a week before the track event, not sure what would drift out of spec that would cause that noise though?
                            Maybe the TOB fork had moved too much -- worn clutch or worn PP fingers?
                            So this confirms that the noise indeed was the synchro gear grinding as the clutch not totally disengage causing the synchro failed to sync the two gears to be meshed.

                            Comment


                              #15
                              Originally posted by sapote View Post

                              Maybe the TOB fork had moved too much -- worn clutch or worn PP fingers?
                              So this confirms that the noise indeed was the synchro gear grinding as the clutch not totally disengage causing the synchro failed to sync the two gears to be meshed.
                              Interesting … I recorded the SMG fluid reservoir while conducting the clutch bleed. When doing the clutch bleed it makes some strange sounds around the 12 second mark in the following video:



                              Does this sound indicate a bad TOB or clutch?

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