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  1. #1

    Default Panhead BDL belt drive issues

    Hey guys I have searched and searched and yet found anybody to share the same problem I'm having. I purchased a BDL belt drive for my STD panhead. This is my first bike and I tore it completely down to frame and motor and have rebuilt everything because the bike was a loose cannon. The engine has a s&s flywheel in it from what I can tell by the markings through the timing cover. Has a splined front shaft and tapered transmission shaft. I installed the belt drive along with an adjustable transmission plate. Torqued rear engine mounts, shimmed the front and torqued those down, mounted the trans plate and torqued it down, then the transmission was installed and I've ran a straight edge from the front pulley to the rear to check the belt tracking and I've adjusted it the best I can and still having issues with the belt hanging off the clutch drum about an 1/8". That's the closest I can get it, I've heard of guys having the belt rub the back of the basket but haven't seen anybody post about hanging off the basket. Any ideas what my problem could be? This is all mounted in a pre 70s paugcho frame with no signs of being tweaked or bent. Seems like the transmission is sitting 1/4" too far to the left in the frame. I've also made sure the clutch hub is going all the way on the shaft and isn't hanging on the key
    Last edited by Rbrooks1992; 09-24-2018 at 2:23 AM.

  2. #2

    Join Date
    Dec 2014
    Posts
    437

    Default

    Do you know what year the trans came from or out of? Asking because the later four speeds have a longer main shaft, and this might account for the way the belt lines up. You mentioned that the frame is a pre 70's paughco, so if you have a trans with a mainshaft for a 70 or later, later, then the mainshaft is longer than the frame is designed for, which would explain the way the driveline lines up. As I see it, there are two ways to deal with this. Best way would be to get the proper main shaft for the frame. Second method would be to fabricate (or have someone fabricate) a transmission mounting plate with the proper amount of offset. A third option would be to get the insert from BDL fpr tje frponont sprocket to offset it 1/4". They sell them because of the wide tire craze that required trans offset. Hope something here helps, and good luck and keep us posted.

  3. #3

    Default

    Thanks for the input willscb! This is all new to me so I'm lacking all the knowledge of these old bikes. I just had the trans rebuilt by a local guy with a very reputable shop, he's super old school and doesn't work on anything but Harley's evos and older. The guy who had the bike before me apparently tried to put the trans together with all different years of parts. So this could be very possible. It's also an aftermarket case and not sure what brand. I'll see if I can get my transmission mount holes to the frame slotted to the left on a mill if there's enough material.

  4. #4

    Default

    Click image for larger version. 

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    This should show what I'm dealing with

  5. #5

    Join Date
    Dec 2017
    Posts
    2,441

    Default

    Asking because the later four speeds have a longer main shaft, and this might account for the way the belt lines up.
    See post #6 here by Dragstews for mainshaft length tech:
    2015 Thread: Changing mainshaft length on 4 speeds, 48-77, bearing retainer plate screw removal
    http://www.chopcult.com/forum/showthread.php?t=43334

  6. #6

    Default

    Thanks for the response. I'm considering having the transmission plate mounting holes slotted on a mill so I can adjust the plate side to side. I'll keep an eye out for an oem 65 ratchet top case and have it rebuilt with all new parts and the mainshaft I need

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