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Thread: How does the parking lock work internally on a Sportomatic gearbox?

  1. #1

    How does the parking lock work internally on a Sportomatic gearbox?

    The gearbox of my 911s Sportomatic 1968 was leaking and unfortunately the company that overhauled my engine no longer exists so I decided to take the gearbox apart myself to replace the gaskets on both sides of the intermediate plate. After reassembling the main body and intermediate plate and when preparing to assemble the tailpiece, I was surprised to find some parts missing and that concerns the locking of the control shaft for reverse and park.
    The first picture shows what I have, a shortened non-original spring and one 7 mm ball. I have ordered a new spring and a 9 mm ball.
    Meanwhile, I looked at the operation of the reverse and park function but I don't understand the park lock. Can anyone clarify that for me?
    In the third pic, the shift rod is in the park position but the locking lever is too low to lock the gear. (Red arrow)
    In the neutral and reverse position, everything goes as expected.
    Have I mounted something wrong?

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    1968 Porsche 911S Sportomatic
    1959 Alfa Romeo Giulietta Sprint Veloce
    1963 Triumph TR4

  2. #2
    Senior Member
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    How many ESR readers have rebuilt a Sportomatic ? probably zero . Good luck .

  3. #3
    Actually I have done several, but not since the late seventies. I was going to suggest that you really need the shop manual.
    Early S Registry member #90
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  4. #4
    Senior Member teenchy's Avatar
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    Quote Originally Posted by Richy View Post
    How many ESR readers have rebuilt a Sportomatic ? probably zero . Good luck .
    I've not rebuilt mine but I've just recently had it rebuilt.

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    (a) 1970 911T Sportomatic coupe
    (b) 2016 E350 4MATIC wagon; parts hauler for (a)
    ESR #1474

  5. #5
    Senior Member teenchy's Avatar
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    There's a Sporto rebuild thread on the bird that might be of use: https://forums.pelicanparts.com/pors...rebuild-2.html If this linked is blocked, search there for "Ultimate ?maybe? Sportomatic Gearbox Rebuild."
    (a) 1970 911T Sportomatic coupe
    (b) 2016 E350 4MATIC wagon; parts hauler for (a)
    ESR #1474

  6. #6
    Quote Originally Posted by 1968sporto911s View Post
    The first picture shows what I have, a shortened non-original spring and one 7 mm ball. I have ordered a new spring and a 9 mm ball.
    Meanwhile, I looked at the operation of the reverse and park function but I don't understand the park lock. Can anyone clarify that for me?
    In the third pic, the shift rod is in the park position but the locking lever is too low to lock the gear. (Red arrow)
    I don't have your pieces here to check myself, but it appears that your shift fork is over-extended. "In the third pic, the shift rod is in the park position..." but the fork is not.
    With the front cover installed, I don't think the fork can move that far forward.
    The 7 mm ball is inserted into the upper hole of the fork, over a pin. The 9 mm ball belongs in the front cover.

    Jon B.
    Vista, CA

  7. #7
    Quote Originally Posted by Richy View Post
    How many ESR readers have rebuilt a Sportomatic ? probably zero ...
    I suspect that several of us have, but like Ed it was many years ago for me too.

    Jon B.
    Vista, CA

  8. #8
    Quote Originally Posted by teenchy View Post
    There's a Sporto rebuild thread on the bird that might be of use: https://forums.pelicanparts.com/pors...rebuild-2.html If this linked is blocked, search there for "Ultimate ?maybe? Sportomatic Gearbox Rebuild."
    Thanks, I found the thread but those are 925 models and they are different.
    1968 Porsche 911S Sportomatic
    1959 Alfa Romeo Giulietta Sprint Veloce
    1963 Triumph TR4

  9. #9
    Quote Originally Posted by edmayo View Post
    Actually I have done several, but not since the late seventies. I was going to suggest that you really need the shop manual.
    I have plenty but the detail I am looking for is not in there.

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    1968 Porsche 911S Sportomatic
    1959 Alfa Romeo Giulietta Sprint Veloce
    1963 Triumph TR4

  10. #10
    Quote Originally Posted by Jon B View Post
    I don't have your pieces here to check myself, but it appears that your shift fork is over-extended. "In the third pic, the shift rod is in the park position..." but the fork is not.
    With the front cover installed, I don't think the fork can move that far forward.
    The 7 mm ball is inserted into the upper hole of the fork, over a pin. The 9 mm ball belongs in the front cover.

    Jon B.
    Vista, CA
    You are right, the 7 mm ball should be on the other side of the pin. The pin is also 7 mm and the opening in the bushing of the shift fork is 7.5 mm.
    The opening in the bushing on the side of the spring and the 9 mm ball is 8.5 mm.

    Here I measure at what height the bore for the bushing starts. That is 17 mm.

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    Here the shift fork is at its lowest position, which is the reverse. 17 mm is halfway between the 9 mm ball and you can see the worn track of the ball under pressure from the spring.
    On the underside of the opening, however, no worn track can be seen, is it already in the park position?
    Once I receive the ordered spring and ball I can try what happens.

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    1968 Porsche 911S Sportomatic
    1959 Alfa Romeo Giulietta Sprint Veloce
    1963 Triumph TR4

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