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Getrag 260 is leaking - but why?

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    #16
    Why does the tranny pressurize when it's not venting properly?

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      #17
      what does the new breather fix exactly?

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        #18
        Sorry, must have missed some posts here.

        @Digitalwave : I don't have the physical knowledge in this area, but would REALLY like to see or read a scientific paper (from like SAE or similar) around this.
        I've only heard that enclosures with rotating parts should be vented to avoid pressure buildup. But I can't really come up with a physical explanation why pressure could build up. And I don't like or is satisfied with "I've heard", I want to know why.

        For example, my rear differential is not vented - and there is a lot of stuff rotating in there.

        The only explanation I can come up with is when gearboxes are working hard the fluid and gearbox heats up, this will in turn heat the air inside the gearbox and if in enclosure that would for sure increase the pressure inside to such a degree that the radial seals might not be able to handle it properly over extended period of time.




        @LowR3V'in : Good question. The "new" breather simply acts as an height extension of the original breather outlet to avoid fluid overflow.

        You could instead just extend the existing "breather tower" to be 10-15 cm higher, that would be just as effective and solve the problem equally good. However that solution is somewhat impractical :-)

        Fluid overflow happens when the gearbox oil is pushed towards the front of the gearbox and at the same time you have a fairly high RPM.
        Last edited by bmw-slangen; 12-28-2017, 08:57 AM.

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          #19
          Originally posted by Digitalwave View Post
          Why does the tranny pressurize when it's not venting properly?
          Very simple explanation...temperature change. The same goes for diff, transmission etc. We all have seen what happens to closed water bottle when it's sitting in the sun or in the cold. All that would never happen to open/vented bottle

          Sent from my VS985 4G using Tapatalk

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            #20
            Originally posted by bmw-slangen View Post
            Sorry, must have missed some posts here.

            @Digitalwave : I don't have the physical knowledge in this area, but would REALLY like to see or read a scientific paper (from like SAE or similar) around this.
            I've only heard that enclosures with rotating parts should be vented to avoid pressure buildup. But I can't really come up with a physical explanation why pressure could build up. And I don't like or is satisfied with "I've heard", I want to know why.

            For example, my rear differential is not vented - and there is a lot of stuff rotating in there.

            The only explanation I can come up with is when gearboxes are working hard the fluid and gearbox heats up, this will in turn heat the air inside the gearbox and if in enclosure that would for sure increase the pressure inside to such a degree that the radial seals might not be able to handle it properly over extended period of time.




            @LowR3V'in : Good question. The "new" breather simply acts as an height extension of the original breather outlet to avoid fluid overflow.

            You could instead just extend the existing "breather tower" to be 10-15 cm higher, that would be just as effective and solve the problem equally good. However that solution is somewhat impractical :-)

            Fluid overflow happens when the gearbox oil is pushed towards the front of the gearbox and at the same time you have a fairly high RPM.

            the rear differential is vented. when the vent is clogged there will be leaking from the speed sensor o ring area
            OBD1 M54/M52TU swap as a M50b25

            Z4 non powered steering rack fits e30



            Euro e46 2005/6 320d 6mt gearbox into E30 with M20 hardy and beck 1985 327s engine

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              #21
              Originally posted by Wanganstyle View Post
              the rear differential is vented. when the vent is clogged there will be leaking from the speed sensor o ring area
              Interesting - didn't know that. Have been throwing around many E30 differentials, but never seend anything that resembles a vent hole or non-sealed passage.



              @Wanganstyle : Where is that vent hole / non-sealed passage located on the differential?

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                #22
                Originally posted by bmw-slangen View Post
                Interesting - didn't know that. Have been throwing around many E30 differentials, but never seend anything that resembles a vent hole or non-sealed passage.



                @Wanganstyle : Where is that vent hole / non-sealed passage located on the differential?

                thread a few down has a decent photo of the vent itself leaking; if you look inside the cover on bmw differentials there is an interesting block off there behind the vent.

                https://www.r3vlimited.com/board/sho...d.php?t=417708
                OBD1 M54/M52TU swap as a M50b25

                Z4 non powered steering rack fits e30



                Euro e46 2005/6 320d 6mt gearbox into E30 with M20 hardy and beck 1985 327s engine

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                  #23
                  Damn, I thought that was a solid metal post. Actually, when taking a closer look at some older photos of two E30 differentials, it looks like that metal post actually have a small hole!

                  Have a couple of differentials on the garage floow, will take a closer look at this area for sure! Thanks for the info!


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