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Thread: Transmission oil level

  1. #1
    Join Date
    Jan 2005
    Location
    central Iowa
    Posts
    105

    Default Transmission oil level

    Could use a little advise on the acceptable level to fill trans on 1968 FLH. Manual directs to fill up to "filler opening" with bike standing up. Says capacity is 11/2 pints. That can't be right as I can't get quite that much in there, and now its leaking out as bike sits (?out main shaft). Thanks.

  2. #2
    Join Date
    Jun 2005
    Location
    Northern Colorado
    Posts
    840

    Default

    Fill the trans until the oil level is just at the bottom of the threads. If you have a later cover, the allen set screw is the correct level.
    VPH-D

  3. #3
    Join Date
    Dec 2002
    Location
    Pennsylvania USA
    Posts
    278

    Default You have a good Motorcycle

    Hey there, The leaking part outta the Sprocket side as you may know is a common after parking and can be fixed with a new seal for as long as that lasts....I have one to do myself. The others that I did have been holding well for a few years of light riding and I also use no less then straight 70W motor Oil in those transmissions, depending on the area temperature of use. Any less and leaks will happen as well as poor lubrication. Those hard working 4 spd transmissions get hot. When you have a leaking trans keep the oil level up before each ride...it doesn't take long to add, just bothersome. Keep riding them, Merlin in Pa.

  4. #4
    Join Date
    Feb 2007
    Location
    Hummelstown, PA
    Posts
    901

    Default

    If your 68 has the same cover as my 71, a pint and a half puts the level right at the top of the opening. As far as I know this is correct for these type covers. Have run it that way for lots of miles and years with anything from straight 50W back then to 80W90 now without issues.As far as the seal leak thing, once they start to leak it's usually from dirt and grime grinding away at the seal and the spacer sleeve (35171-37). Bye the time it needs a new seal the spacer usually has a decent valley wore in it and this causes the new seal to fail in short order. Anything that has had more than about 10,000 miles put on since it was last rebuilt will get a new spacer too around here. When you're replacing the seal, it's right there, only cost a few dollars more.
    Brian

  5. #5
    Join Date
    Jan 2005
    Location
    central Iowa
    Posts
    105

    Default

    Thanks very much guys. I'll try a heavier oil. The bike has low miles on trans rebuild so I'm wondering about that seal. Gear Lube vs. regular motor oil? What's the significance of the manual recommending the same oil in trans and engine? It has the stock oil return in the primary. Sorry about the basic questions, but there's only one way to learn. Steve

  6. #6
    Join Date
    Feb 2007
    Location
    Hummelstown, PA
    Posts
    901

    Default

    The primary is lubed by engine oil that is blown and sucked through the primary case, it is totally seperate from the trans fluid. The manuals of the day called for engine oil because it was readily available , and it works quite well actually. Also it probabally helped to insure it got changed when you had your bike serviced. Modern gear oils have specific additives to handle the high shear forces and control foaming better. I had become very fond of H-D's semi-synthetic trans oil, so of course they quit making it. I guess when that is all I'll switch back to the Bel-Ray 80W90. It gets a little stiffer than the H-D stuff in the dead of a PA winter, but thats not a concern for most.
    Brian

  7. #7
    Join Date
    Jan 2005
    Location
    central Iowa
    Posts
    105

    Default

    Thanks Brian. I've replaced the HD 60 wt. with 80-90 gear lube. We'll see how that works. Yes, I thought the motor oil seemed fine when I tried it, but it sure found its way out just sitting. Somebody made a comment years back about the transmission fluid finding its way into the motor past a bad seal/gasket and for some reason that stuck in my head, even though it defies the logic of the HD design on this model. Thanks for your help.

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