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  1. #1
    IronheadMikeTyson
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    Default Shovelhead: Leaky tranny/sprocket & open belt assembly

    So I have a pretty consistent oil leak coming from the front sprocket/tranny area that I'm looking to fix. Bike is a 74 shovel. I'm thinking it's a seal or gasket in there that needs to be replaced and I'm getting ready to get in there and investigate. Before I do that, anyone run into this before? Anyone have any ideas of what I should be looking for?

    Also, since I am going to have to take the belt Assembly apart to get to the leak, does anybody have a good step by step on how to disassemble/assemble a BDL open belt primary? It's been a while since me and a buddy put it on there and a refresher would be good. Photo of the set up attached.

    Thanks in advance

  2. #2
    IronheadMikeTyson
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    Can't post a photo from my phone. I'll post later when im home

  3. #3
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    You'll need to remove the mainshaft support and the sprocket. From there you'll see a large seal. Check to see if that's leaking, if so, pry it out and replace it. There's also a cork gasket that goes in there too that you'll need to replace.



    You may want to upgrade the spacer behind the main seal with one of the ones machined for an oring from saddlebagrail:



    http://www.ebay.com/itm/171564226698...%3AMEBIDX%3AIT

    There's also a seal in the end of 4th gear, but I don't think you can replace it without disassembling the mainshaft.

    This thread is useful:

    http://tearitupfixitrepeat.blogspot....ga-part-2.html
    Last edited by Blackbetty; 12-22-2014 at 2:18 PM.

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    Never heard of a shovel tranny that leaks.?! very rare thing indeed. Even after you replace all those seals, it will still leak, maybe not same spot, but somewhere.
    Been there and done that.

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    ray/saddlebagrail has a how to on rebuilding a leakproof trans. is it ok to post the link to another forum??

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    I would like to see it I need to rebuild mine.

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    Saddlebagrail/ray figured it out. You don't have to live with it, it's not rocket science

    http://www.shovelhead.us/pics/sheets/leakingtranny.pdf

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    I'm sorry but slapping an o-ringed spacer and new seals on a clapped out trans will not Leak proof a four speed. Not saying your's is wore but something to think about.
    Now rebuilding, correctly shimming and assembling everything correctly will help a lot. And why not add the O-ring spacer? It is a good idea.
    And you can replace the seal on the MDG without disassembly
    Get the instruction sheet off of BDL's website and a factory manual. All the info's right there.
    Too tight a belt, too tight a chain, unsupported main-shafts, mis-aligned/loose drive-trains will all kill seals in short order.

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    I can vouch for saddlaebagrail's fix. Adding that, as well as replacing the oil seal in the main gear (the one that goes between the shaft and gear) and the main seal, should keep you reasonably dry, if not completely dry.
    But having said that I've had to deal with a leak coming from the counter shaft on the left side as well. That's just an oring, but slightly more difficut to get to..

  10. #10
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    Quote Originally Posted by Sky View Post

    I'm sorry but slapping an o-ringed spacer and new seals on a clapped out trans will not Leak proof a four speed. Not saying your's is wore but something to think about.
    Ain't that a fact....

    A simply test can be done to see how bad off the fourth gear is running in...

    With the sprocket in place take two screw drivers, one on each side of the sprocket, and pry back and forth.... See by eye how much rocking it does...

    If there is alot to be seen, the gear, bearings, case race, fourth gear bushing and mainshaft has mega ware on them and will need to be serviced....

    The fourth gear may even need to be replaced.
    It's the inside race that bearings roll on...
    If the bearing surface is runable, it can be rebushed with a new bushing and sized...
    Would be a good idea to line lap the case race (If still seviceable) for oversize bearings...
    Running fit is forgiving for a fairly large max. fit. (Specks: 0.0005 to .002)

    The mainshaft may be toast cause of the bushing wearing on the shaft, No choice but to do a repacement to fix that problem..
    Last edited by Dragstews; 12-27-2014 at 4:02 PM.

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