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FS5R30A gear runout?

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  • FS5R30A gear runout?

    A couple years back my auto decided to give out under 11psi so I persued the auto to manuel swap in my 84ae. I went with an 87 turbo tranny, 87 turbo driveshaft, 88 turbo flywheel, and an 88n/a companion flange. The transmission had 87k on it when I purchased it from a salvage yard. It was resting upright on the input shaft. The flywheel had an unkown mileage but was able to be resurfaced. It was matted to an ACT Street clutch using the ACT bearing.

    (Don't know if all this info matters but I'm putting everything out there to make sure I've covered my tracks well and haven't missed anything obvious)

    Ever since it was installed the tranny has had a little bit of play. It was never enough to really detract from the driving untill recently. It will cluck, chatter and buck depending on the way you drive it and will always have some evidence of slack. It really makes it hard to finesse the car. therefore I pulled the tranny and had it rebuilt with new syncro's, seals and bearings (New release bearing to replace the ACT one also since I heard they wern't that great). Put it back in about a week ago and the problems still there... maybe even worse.

    I put it on jackstands th eother day and had the guy who rebuilt the tranny listen to it and drive it. He said everything looked and felt normal besides a slight bit of backlash from the rear end. He said the noise was normal gear runout and the tranny was fine, just loud and slack. I don't want to leave it this way so I'm coming to you guru's for your recomendations.

    A. buy another used fs5r30a and transfer the rebuild kit (Min $450)
    B. purchase some spare z32 trannies a friend of mine has and transfer the gear sets to my case and use my rebuild kit on the new gears. (Min 300)
    Catch here is that something in both of those trannies he has are broken.
    C. Pull the T-5 out of my parts car and build the heck out of it (1095 min)
    D. find my old auto, build the heck out of it and throw it back in (900 min)

    So really only option A or B are viable. I just wanted to see what you guys experiences where.

    The big question, can I transfer over the z32 gears to the z31 mainshaft using the z32 countershaft and the z31 rebuild kit and syncro's?

    I was worried at one point that my mainshaft was bent snc eit had been resting upright on it at the junkyard but now the theory seems to be gear runout.


    Sorry for the long post but I've already pulled and rebuilt once and I've about broken my piggy bank. I'm looking for a final solution on this one.

  • #2
    If gear lash form your diff is excessive, it would cause what you described.

    My question is: what's wrong with finding another used 87-89T trans and putting it in as-is?

    I have a 30A with a broken bellhousing and input shaft that sounded and shifted perfectly before the boom, the gearset should be fine internally but I have not had it apart to look.

    Comment


    • #3
      Jason84NA2T wrote: If gear lash form your diff is excessive, it would cause what you described.

      My question is: what's wrong with finding another used 87-89T trans and putting it in as-is?

      I have a 30A with a broken bellhousing and input shaft that sounded and shifted perfectly before the boom, the gearset should be fine internally but I have not had it apart to look.
      I'm assuming this is from your flywheel explosion.

      Anyways i had this exact same problem with a rebuilt T5 that I bought from SteveZ31. I thought it was getting flaky on me so i bought a 71C on ebay to replace it. When i pulled the transmission out i realized that I had forgotten one of the spacers between the engine and transmission. Not sure how it caused the noise but it somehow did and I ended up selling a perfectly good transmission and unnecessarily buying a different one.
      Funny stories!

      Comment


      • #4
        Alright, my friend has a blown Z32TT tranny he's willing to donate to my cause. One of the gears is definitely gone, but as far as the rest goes it could be just fine. 600rwhp and 8k rpm shifts at the strip did it in quick. Is it possible for me to take that transmission apart, use all the good gears from it, substitute in a z31 gear for the blown one, put them all on the z32 countershaft and then the z31 mainshaft and into the z31 bellhousing?

        Comment


        • #5
          The only gears you can get away with swapping between the two are 5th and maybe reverse. The rest part of the countershaft and i dont believe they are removable. You can swap gears on teh mainshaft but it wont do you any good since you cant swap their counterpart on the counter shaft.

          Comment


          • #6
            Jason84NA2T wrote: If gear lash form your diff is excessive, it would cause what you described.

            My question is: what's wrong with finding another used 87-89T trans and putting it in as-is?

            I have a 30A with a broken bellhousing and input shaft that sounded and shifted perfectly before the boom, the gearset should be fine internally but I have not had it apart to look.
            Yeah, you need to look at your diff, diff mount, and subframe bushings before going for another tranny. I've heard plenty of worn out or misaligned diffs make the same sound you have described. I've also heard the same sounds from a halfway broken driveshaft joint.
            [strike:ff0tp92h]1984 300ZXT[/strike:ff0tp92h]
            [strike:ff0tp92h]1986 300ZX 2x2 NA2T[/strike:ff0tp92h]
            2000 Porsche Boxster
            2007 Toyota Yaris

            Comment


            • #7
              Diff only has 56k on it, dif mount looks good, Subframe has brand new poly bushings. Driveshaft was checked out by a driveline shop and determined to be ok. Also have a poly tranny mount on it, poly motor mounts will be going in this next weekend.

              Hopefully I'll know what I'm going to do by the end of the week so I can attack it over my break. Have to be ready for ZDAYZ in May.

              Thanks for the ideas and info. guys, keep em' comming!

              Comment


              • #8
                ZMIKEMAN wrote: Diff only has 56k on it, dif mount looks good, Subframe has brand new poly bushings. Driveshaft was checked out by a driveline shop and determined to be ok. Also have a poly tranny mount on it, poly motor mounts will be going in this next weekend.

                Hopefully I'll know what I'm going to do by the end of the week so I can attack it over my break. Have to be ready for ZDAYZ in May.

                Thanks for the ideas and info. guys, keep em' comming!
                If the diff has been rebuilt, it's possible that the bearing preloads and gear alignments were not set to spec, making the gear meshing sloppy and noisy.

                You mentioned that you replaced the diff companion flange with a 88 NA type. It's possible that the pinion preload is not set correctly due to under or over tightening of the nut that holds the companion flange to the pinion gear. It has to be torqued to spec, not spun on with an impact.
                [strike:ff0tp92h]1984 300ZXT[/strike:ff0tp92h]
                [strike:ff0tp92h]1986 300ZX 2x2 NA2T[/strike:ff0tp92h]
                2000 Porsche Boxster
                2007 Toyota Yaris

                Comment


                • #9
                  [quote]bemis wrote:
                  Originally posted by ZMIKEMAN
                  Diff only has 56k on it, dif mount looks good, Subframe has brand new poly bushings. Driveshaft was checked out by a driveline shop and determined to be ok. Also have a poly tranny mount on it, poly motor mounts will be going in this next weekend.

                  Hopefully I'll know what I'm going to do by the end of the week so I can attack it over my break. Have to be ready for ZDAYZ in May.

                  Thanks for the ideas and info. guys, keep em' comming!
                  If the diff has been rebuilt, it's possible that the bearing preloads and gear alignments were not set to spec, making the gear meshing sloppy and noisy.

                  You mentioned that you replaced the diff companion flange with a 88 NA type. It's possible that the pinion preload is not set correctly due to under or over tightening of the nut that holds the companion flange to the pinion gear. It has to be torqued to spec, not spun on with an impact.
                  Yeah, differentials are no joke when it comes to little things like that.

                  Terrible idea putting those wheels on...

                  Comment


                  • #10
                    That'll be a good thing to check. I'll go ahead and drop the driveshaft and check the ring & pinon for the proper torque this weekend before buying another transmission. Anyone know the preload spec off the top of their heads. I can probably dig it up pretty easily anyway.

                    Comment


                    • #11
                      137-217 ft/lbs for the pinion nut.
                      [strike:ff0tp92h]1984 300ZXT[/strike:ff0tp92h]
                      [strike:ff0tp92h]1986 300ZX 2x2 NA2T[/strike:ff0tp92h]
                      2000 Porsche Boxster
                      2007 Toyota Yaris

                      Comment


                      • #12
                        Theres a big gap there. I can see why one would be tempted to take an impact wrench to it.

                        Although heres another theory, would over or undertightening the pinon gear cause the problem to start small and slowly worsen over time like mine has?

                        Thanks again.

                        Comment


                        • #13
                          ZMIKEMAN wrote: Theres a big gap there. I can see why one would be tempted to take an impact wrench to it.

                          Although heres another theory, would over or undertightening the pinon gear cause the problem to start small and slowly worsen over time like mine has?

                          Thanks again.
                          not likely, but it becomes a risk of loosening from vibration

                          Comment


                          • #14
                            ZMIKEMAN wrote: Theres a big gap there. I can see why one would be tempted to take an impact wrench to it.

                            Although heres another theory, would over or undertightening the pinon gear cause the problem to start small and slowly worsen over time like mine has?

                            Thanks again.
                            That "big gap" is there because not one differential is created equally and so setting the preload to spec can be anywhere within that region. You're best off reading about how to do all of this in the FSM.
                            [strike:ff0tp92h]1984 300ZXT[/strike:ff0tp92h]
                            [strike:ff0tp92h]1986 300ZX 2x2 NA2T[/strike:ff0tp92h]
                            2000 Porsche Boxster
                            2007 Toyota Yaris

                            Comment


                            • #15
                              Alright so I had a good hour in the car of thinking about this yesterday and came up with some info that will probably help.

                              The car clunks when you release the clutch quickly in nuetral (Not every time, but whever your not smooth with it)..... So doesn't that mean the problem could only be in the tranny. Not only that but that would narrow it down to whatevers spinning in the tranny while its in nuetral.


                              So heres my new question. What gears and shafts are spinning when the cars in nuetral and which would be the most likely canadite for this kind of slack or rollout?

                              Thanks again for your input guys!

                              Comment

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