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Thread: *DIY ZF Transmission reseal

  1. #1
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    *DIY ZF Transmission reseal

    So today I prepped the trans that will be going into the Touring. It's a used trans that I got from Bavarian Auto for the very reasonable cost of $278.00 shipped! It arrived very clean, but I still found evidence of leaks, so I resealed it all up.

    Started with the front seal. It sits behind the cover, and once removed it seems it had just started to seep. Hard to see in the pics, but there was evidence.


    With the cover removed it's easy access to the front seal.


    Drilled a small hole in the seal for the puller. Go easy on this. Don't want to do any damage inside.


    Puller in place


    and a quick pop of the slide hammer


    next I replaced the pivot and fork retaining clip. I also cleaned up the splines, and the seal cover. Spread a small amount of white grease on the splines and the dimples for the pivots in the fork.



    Leaking shift shaft seal


    It's easy to pry the retainer for the dowel that passes through the shifer thingy with a couple of small screwdrivers.


    That little mess is what's left of the dense foam insert that goes inside the shift thingy. The new one is on the left.


    Old seal out. This little guy puts up a good fight. Small pick and small screwdrivers eventually got it out.


    new seal driven in with a 17mm deep socket


    new seal in


    new foam deeli-whopper in the shifter thingy...



    notice that the retainer is partially installed on the coupler. This makes it a lot easier as the coupler has to be pushed in to compress the foam, so the dowel can be slid into place. Once that's done then slide the retainer till it locks. Rotate it so the opening of the retainer faces down in case it needs to be removed with the trans in the car.


    On to the rear seal. A little bit of heat to break down any Loc-Tite and zip it off with the impact.




    I used a puller to remove the flange. It's possible to "tap" off with care, but if you have the tools use them.


    old seal out with a seal puller


    and all that's left is to drive in the new seal. Don't forget to lube both sides of it. The splines were soaked in oil as was the nut. So I coated the clean splines of the flange with gray RTV and drove it back into place using the 36mm socket and a dead blow hammer. I applied a little Loc-Tite to the output shaft threads and tightened it back up. That's it. Not hard at all.

  2. #2
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    Thanks for the very nice pics. This will help out a lot as my shift shaft seal is also leaking.
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    There is a write somewhere about factory improvements to the transmission. I can't find the write up but it fixes lost R and 5th and notchy shifting.

    Thanks for the write up. I am deciding if I want to replace the seal or not since it is not leaking and the trans is on the floor.

    Also, the reason I found this thread. The bentley says you tighten the output shaft in two stages. First to 140lbs, then (after loosening to 90lbs). So you tighten it more, the loosen it, then tighten it again?

    I know the bentley has been wrong before, and I have 4 stitches in my left finger over the 10 mm glove box nut that the manual failed to mention.
    Last edited by dano670; 03-22-2010 at 02:56 PM. Reason: Automerged Doublepost

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    Louie, what did you use to pop that input seal out?

    I'm heading to HF later today and a seal puller is now on my list. I've replaced the shifter parts, need to get to seals next.

    Glad to see it's coming along!
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  5. #5
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    dano670 I really have no idea why you would have to go 140 then loosen to go 89. Brighter minds than mine designed the trans and wrote the book. I tightened it to 120ft lbs. with Loc-Tite. If it comes loose I'll post up. I think the 5th gear issues are more with the ZF320z, which is stronger trans used in later m3's. This trans is the ZF310z.

    SF, I used a slide hammer with a hook after I drilled a hole in the old seal. This is only applicable to the ZF trans. If your working with a Getrag the nose piece comes off and the input seal is part of it. Much easier. BTW the front seal was, by my definition, a loose fit. It's a small slide hammer and it took one little pop and it was out.

    Teaser... I built my own DSSR for less than $20 and eliminated all but one rubber piece from the shift linkage/mechanism. It has a "notchy" race car feel to it with just the right amount of "click".
    Last edited by LouieD; 03-22-2010 at 06:33 PM.

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    Thanks, I will replace the front seal now. How much lateral play did the input shaft have. My zf trans has about a millimeter.

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    Quote Originally Posted by dano670 View Post
    Thanks, I will replace the front seal now. How much lateral play did the input shaft have. My zf trans has about a millimeter.
    That's about what mine has.

  8. #8
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    Cool, I have a Getrag, no need to drill out the input seal.

    I gotta go through the Bentley's and finish my research.

    I'm interested in your DSSR. I also need to pick a shorter gearshift lever. Damn I can't wait to get the 5 speed in the touring!
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    This should be stickied!!!

    paging MacR or tim.

  10. #10
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    Quote Originally Posted by LouieD View Post
    dano670 I really have no idea why you would have to go 140 then loosen to go 89. Brighter minds than mine designed the trans and wrote the book. I tightened it to 120ft lbs. with Loc-Tite. If it comes loose I'll post up. I think the 5th gear issues are more with the ZF320z, which is stronger trans used in later m3's. This trans is the ZF310z.
    I think it is to seat the flange, make sure that it doesn't get hung up.

    Also, the loctite in the manual is referred to as sealant or loctite 262 or something. I don't think it was thread locker. I am using rtv on my threads.

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    Quote Originally Posted by dano670 View Post
    I think it is to seat the flange, make sure that it doesn't get hung up.

    Also, the loctite in the manual is referred to as sealant or loctite 262 or something. I don't think it was thread locker. I am using rtv on my threads.
    I agree on the "seat the flange" thinking. If the rear seal is not driven in far enough the flange will rub against it and tighten up. When the seal is far enough in the flange will turn freely. Maybe that's what the two step is for. The first 140lbs drives the seal deep enough, the 90lbs sets the flange correctly? I saw the sealant thing too. I used sealant on the splines and thread locker on the nut. It's not going anywhere. Thanks for the input dano.

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    Quote Originally Posted by attack eagle View Post
    This should be stickied!!!

    paging MacR or tim.
    +1. Couldn't agree more. Briliant photos.
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    You're rockin it Louie! Stickie please!
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    Also add if you don't have a 5 mm allen socket don't even try attempting the input shaft seal. Those bolts were extremely tight. I only was able to remove 3 of the 4 so I didn't pull the seal.

    Here is the thread to accomplish the service bulletins on the 320 trans:

    http://www.unofficialbmw.com/phpBB/v...223b64b4459dd2

    All of these steps took me about maybe 3 hours.

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    Quote Originally Posted by dano670 View Post
    Also add if you don't have a 5 mm allen socket don't even try attempting the input shaft seal. Those bolts were extremely tight. I only was able to remove 3 of the 4 so I didn't pull the seal.
    Thread locker? Heat will make it give up.
    Louie, Great post and congrats on another stellar woman in your avatar. I look forward to your choices.
    Last edited by ross1; 03-24-2010 at 10:33 AM.

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  16. #16
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    Quote Originally Posted by dano670 View Post
    Also add if you don't have a 5 mm allen socket don't even try attempting the input shaft seal. Those bolts were extremely tight. I only was able to remove 3 of the 4 so I didn't pull the seal.

    Here is the thread to accomplish the service bulletins on the 320 trans:

    http://www.unofficialbmw.com/phpBB/v...223b64b4459dd2

    All of these steps took me about maybe 3 hours.
    Dano another great point. Those little bastards were on there tight! This is one of those times that having a quality tool will make all the difference. I would not attempt to loosen those bolts with a cheap hex (Allen) wrench. You'll could be in for a world of trouble.

    Thanks for the link for the 320.

    Quote Originally Posted by ross1 View Post
    Thread locker? Heat will make it give up.
    Louie, Great post and congrats on another stellar woman in your avatar. I look forward to your choices.
    I didn't see any evidence of thread locker, but it's a possibility. Thanks for the kind words about the post and the womenz.
    Last edited by LouieD; 03-24-2010 at 11:09 AM. Reason: Automerged Doublepost

  17. #17
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    FYI - the front seal on a Getrag is almost identical to this procedure, you need to punch a hole in it and pry it out. There are two small rubber spots on the Getrag seal to punch through, and a small screwdriver and pick finally popped it out.
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