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308 Gearbox - maintenance, overhaul, rebuild?

Discussion in 'Technical Q&A' started by Mike328, Nov 18, 2003.

  1. Mike328

    Mike328 F1 Rookie

    Oct 19, 2002
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    Boulder, CO
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    Mike
    It's very unfortunate, but I've got a worn 3rd gear syncro and a 2nd gear syncro that's beginning to get tired... Downshifts to 3rd have to be double-clutch, and upshifts have to be really gentle. I was going to live with it, but this really takes the fun out of the car. I guess I'm going to replace the syncros.

    Paul Newman replaced his 2nd and 3rd syncros, and did an excellent job documenting this procedure (review the following links):

    Part 1:
    http://www.ferrarichat.com/discus/messages/256120/227322.html

    Part 2:
    http://www.ferrarichat.com/discus/messages/256120/228401.html


    My question is, if I replace the syncros, what else needs to be done? Do I need seals, bearings, etc. as well?

    Also, this job is definitely too big for me. I've found a shop in town that specializes in transmissions and seems to be very competent. Is this something that where I could give the gearbox and syncro rings to a local shop?

    And finally... Any sources for getting work done on the these transmissions?


    --Mike
     
  2. pma1010

    pma1010 F1 Rookie
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    Jul 21, 2002
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    Mike
    Not sure where you are based. In Midwest, Giovanni at Autosprint or Tod at Continental would be excellent choices.

    Good luck
     
  3. Ferrari_tech

    Ferrari_tech Formula 3

    Jul 28, 2003
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    Mike,

    Depending on how many miles the car has done, obviously the first thing to do, is when the gearbox has been stripped and cleaned is to carefully inspect all components for wear, taking measurments when required.

    I would almost certainly recommend replacing all the syncro rings, "O" rings, oil seals and bearings - remember the majority of the costs will be labour, you don't want to have a bearing failure a 1000 miles after a rebuild.

    Also make sure you strip and inspect the diff unit, measuring the plates for wear and carefully inspecting the bearings.

    MW
     
  4. Mike328

    Mike328 F1 Rookie

    Oct 19, 2002
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    pma and MW, thanks very much for your responses... This is good direction.

    Last night, I studied the transmission layout for several hours. I'm now confident I could build one of these, at least on paper :).

    One question I have is--does it really make sense to replace ALL the syncros, including 4th and 5th? (These are actually significantly less expensive than the 1,2,3 rings, for what it's worth).

    By replacing the syncros, I'm assuming we mean the syncro rings--not the assemblies. Are syncro rings typically considered "wear parts" like this?

    T. Rutlands had some decent pricing on the rings, made by ZF I think, a german parts maker. (sigh) German parts in my Italian transmission? I suppose it's whatever it takes to keep her on the road! :)

    Secondly, will all 308 transmissions need to be opened up at some point? I've got 60k mi on the car (documented), it seems a bit premature for this. I really do hope that doing this now will get it out of the way for a long time.
     
  5. pma1010

    pma1010 F1 Rookie
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    Jul 21, 2002
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    Mike
    Ferrari used Porsche synchromesh. The germans are already in that Italian gearbox of yours!
    Philip
     
  6. Ferrari_tech

    Ferrari_tech Formula 3

    Jul 28, 2003
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    Mike,
    You will more than likely need to replace the hub assemblys on 2nd and 3rd, as these are the gears which your are having problems with. However when the box is stripped and cleaned the way to determine whether the hubs are worn, is to lay a new syncro ring on the old hubs and measure the clearance between the back of the syncro ring and the hub, if it's over the limit then the hub must be replaced - also check for wear / damage on the teeth on the hub assembly.

    60,000 miles sounds about average, but there is no definitive mileage period, because it depends on the driver, what type of oil has been used etc. etc.

    If you need any technical information or parts then please let me know

    MW
     
  7. Ferrari_tech

    Ferrari_tech Formula 3

    Jul 28, 2003
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    Mike,

    Here's a picture showing the method for measuring the syncro ring / hub wear.
     
  8. Ferrari_tech

    Ferrari_tech Formula 3

    Jul 28, 2003
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    Mike,

    2nd page - you may have to enlarge these pictures.

    MW
     
  9. Mike328

    Mike328 F1 Rookie

    Oct 19, 2002
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    Mike
    Malcom,

    Thank you very much for this info; I hadn't consider that the hubs also might need replacing.

    Is there a "best practice" in your opinion for a 60,000mi overhaul of the 308 gearbox? Basically, a list of things that should get looked at, and a list of things that should be replaced if a gearbox with 60k miles is going to be opened.

    Also, where are the pictures above from? They look like pictures from my Workshop Manual, but cleaner and more up-to-date...


    Thanks Malcom!

    Mike
     
  10. Ferrari_tech

    Ferrari_tech Formula 3

    Jul 28, 2003
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    Mike,

    The pictures are from a factory workshop manual, if you need anything else I can always post it on Chat for you, or fax if you want

    MW
     
  11. Ferrari_tech

    Ferrari_tech Formula 3

    Jul 28, 2003
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    Mike

    Sorry, forgot to reply to your other question - basically there are no set guidlines as to what to replace, which it is why it is important to clean and inspect all components and assess any damage / wear.

    The obvious components that usually wear are syncro rings, bearings, selector forks, not forgetting to replace all the lock-nuts, oil seals and "O" rings.

    While the engine / gearbox is out have a look at the condition of the clutch and a good look round the rest of the power unit for any obvious faults that can be easilly rectified whilst the unit is out of the chassis.

    MW
     

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