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  1. #1
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    Default BT Swingarm Frame?

    I'm assuming with the round arm and a average weight rider onboard a line would/should intersect both sprockets and the pivot?

    So, my question. When the MoCo went to the square arm was the tranny also raised to keep the alignment? I will eventually find this all out for myself, but in the meantime really curious! I'm wanting to run a final-drive belt with the round arm where it's critical everything (sprockets centers, pivot) be on the same plane

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    Quote Originally Posted by oneuptom View Post
    I'm assuming with the round arm and a average weight rider onboard a line would/should intersect both sprockets and the pivot?

    So, my question. When the MoCo went to the square arm was the tranny also raised to keep the alignment? I will eventually find this all out for myself, but in the meantime really curious! I'm wanting to run a final-drive belt with the round arm where it's critical everything (sprockets centers, pivot) be on the same plane
    Check this out More than yiu prob ever wanted to know https://www.hydra-glide.net/phpBB3/v...hp?f=5&t=15801

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    As you read on, interchanging a round to square swingarm, or vs versa, is not exactly a quick switch and fit.

    Read the entire link closely https://www.hydra-glide.net/phpBB3/v...hp?f=5&t=15801

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    Thanks for all that bud. Much good reading there!.. I have at least two, most likely three and as I recall all very nice. Don't know anything about numbers and such, but I'm not a purist that way anyhow. I'm under the impression they're all the same width between the axle plates, but if there's a widest one I'll use that

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    I belive we are over thinking this.

    I ran a final KARATA belt drive on a ratchet top, Pan motor, rigid frame. And yes, the tolerances where the belt goes past the frame and tire was close... But man, what a great ride and was a simple install. Basically you got a front pulley that mounts right where the front sprocket went, keep the stock clutch basket, put on the rear pulley, and there you go

    Belt drive frames have an kicked out frame offset for rear belts, as the OEM belts are pretty wide. Rear belt drive kits for NON BELT DRIVE frames are very skinny, allowing for the belt to go past the frame with enough frame and tire clearance, w/o having to realign the rear tire

    But that was on a rigid frame. I know KARATA had a kit for swingarms as well.

    In your case, I dont beleive the pivot issue will be a problem, but clearance of the belt as it goes to the rear from the tranny past the frame, or tire clearance MIGHT be an issue as the OEM belts are very wide in comparison

    You didnt mention what make frame, tranny or motor you have, so responses will be really limited at this point

    Also, what belt are you using?. OEM belt or aftermarket? KARATAS kit has a very thin belt that allows for frame/tire clearance on non belt drive frames. I dont beleive a OEM rear belt will pass thru a non belt drive belt frame regardless

    Again, I dont beleive pivot point issue will be your prob. Hit us with more info

    I was going to get another rear belt drive kit for my newest Pan project in a S/A frame from KARATA., but man, times have changed with those guys. Ill be frank, they came off like real A holes when I called them about a year ago by just asking them general questions about thier SA belt kit

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    Last point with the info I have so far: Changing out from square to round swingarm takes some finagling. Im trying to find the post that explained how to do it

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    The Round Swingarm on my 80 involved:

    Different Exhaust. (As the shocks were now in the way, because they mount lower.)

    New, longer, Shocks. (See above) The DS adjustables work fabulous.

    Proper Shock Studs. (I turned down some regular, pan, ones. But there's a "Conversion" stud out there I am told that makes it a bolt on.)

    Axle Locators. I made them. But, I am told "Fab Kevin" (Google him) and some others offer them for a bolt on.

    A different axle. Because the length changes.

    Spacer length bouncing around to put the wheel back where it goes. Easy.. I made mine, but it's the least problematic part of it.

    I built a dog bone type stay for the rear brake caliper. (Used the stock banana) With a spacer for the stay bolt, to keep it all straight, and bolted it to the existing, unused, hole on the right side of the swingarm. It works great. Adjust the length of it to center the axle in the adjuster with the chain set properly..

    I drilled a small hole in the caliper and turned an aluminum stud to press into it. This holds a rubber shock mount that goes to the swingarm to prevent the caliper from bouncing around and rattling. Barely noticeable and works well if you like the old looking caliper and want to keep it.

    And I think I ended up throwing a disk brake spacer behind the sprocket to get it to line up better?



    Anyway.. It all worked out and wasn't a problem at all. But, these are the issues you'll be dealing with if you want to go from square to round.

    Hope this helps.
    Last edited by confab; 10-09-2021 at 2:53 PM.

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    Quote Originally Posted by docmel View Post
    I belive we are over thinking this.

    I ran a final KARATA belt drive on a ratchet top, Pan motor, rigid frame. And yes, the tolerances where the belt goes past the frame and tire was close... But man, what a great ride and was a simple install. Basically you got a front pulley that mounts right where the front sprocket went, keep the stock clutch basket, put on the rear pulley, and there you go

    Belt drive frames have an kicked out frame offset for rear belts, as the OEM belts are pretty wide. Rear belt drive kits for NON BELT DRIVE frames are very skinny, allowing for the belt to go past the frame with enough frame and tire clearance, w/o having to realign the rear tire

    But that was on a rigid frame. I know KARATA had a kit for swingarms as well.

    In your case, I dont beleive the pivot issue will be a problem, but clearance of the belt as it goes to the rear from the tranny past the frame, or tire clearance MIGHT be an issue as the OEM belts are very wide in comparison

    You didnt mention what make frame, tranny or motor you have, so responses will be really limited at this point

    Also, what belt are you using?. OEM belt or aftermarket? KARATAS kit has a very thin belt that allows for frame/tire clearance on non belt drive frames. I dont beleive a OEM rear belt will pass thru a non belt drive belt frame regardless

    Again, I dont beleive pivot point issue will be your prob. Hit us with more info

    I was going to get another rear belt drive kit for my newest Pan project in a S/A frame from KARATA., but man, times have changed with those guys. Ill be frank, they came off like real A holes when I called them about a year ago by just asking them general questions about thier SA belt kit
    Interesting!

    Frame I'm talking about is a 80-81 but not exactly 100% sure. Guy who gave it to me is standup and said he was pretty sure it's a beltdrive frame. It looks bowed on the right so you could shift the drivetrain that way to make belt room on the left. Otherwise most of the measurements are pretty close to the earlier chaindrive square arm frame I'm comparing it to

    All the forgings on it are beefier and the tubing on it is a slightly larger O.D. and (thicker) wall. All measurements on it are metric!!!

    I could only find one not too good pic of a bare 80 Sturgis frame and it looks like the same one to me? I don't know anything else.

    Maybe somebody knows how to correctly measure a beltdrive/Sturgis frame?

    My 06 Dyna was the last year for the 30mm belt, what people call 1 1/4 I think. 07 went to the narrower belt, 1 inch maybe? Took me a while to find a 30mm international pulley for the rear. I like cruising it at 85, just wee bit out of it's comfort zone. Haven't installed it yet though. Anyway, back to the 81.

    I was thinking, why couldn't I use one of the current narrower 1 inch belts on it? I would find a way with the front pulley O.D. if clearance there was an issue

    How wide is the KARATA belt?

    Edit: At first I was thinking a 48 Pan motor, maybe a small chance of a Shovel top on it, but now I'm also considering other more powerful motivation?
    Last edited by oneuptom; 10-10-2021 at 11:50 AM.

  10. #10
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    Quote Originally Posted by confab View Post
    The Round Swingarm on my 80 involved:

    Different Exhaust. (As the shocks were now in the way, because they mount lower.)

    New, longer, Shocks. (See above) The DS adjustables work fabulous.

    Proper Shock Studs. (I turned down some regular, pan, ones. But there's a "Conversion" stud out there I am told that makes it a bolt on.)

    Axle Locators. I made them. But, I am told "Fab Kevin" (Google him) and some others offer them for a bolt on.

    A different axle. Because the length changes.

    Spacer length bouncing around to put the wheel back where it goes. Easy.. I made mine, but it's the least problematic part of it.

    I built a dog bone type stay for the rear brake caliper. (Used the stock banana) With a spacer for the stay bolt, to keep it all straight, and bolted it to the existing, unused, hole on the right side of the swingarm. It works great. Adjust the length of it to center the axle in the adjuster with the chain set properly..

    I drilled a small hole in the caliper and turned an aluminum stud to press into it. This holds a rubber shock mount that goes to the swingarm to prevent the caliper from bouncing around and rattling. Barely noticeable and works well if you like the old looking caliper and want to keep it.

    And I think I ended up throwing a disk brake spacer behind the sprocket to get it to line up better?



    Anyway.. It all worked out and wasn't a problem at all. But, these are the issues you'll be dealing with if you want to go from square to round.

    Hope this helps.
    Thanks

    All in all that sounds like a walk in the park to me because I've dealt with situations where I've had to offset the whole drivetrain, widen the swingarm for a wider tire & belt, rubber mount the works.

    I suppose 12.5 shocks would be too short? I have some nice NOS chromed aluminum adjustable progressives made for Arlen Ness I'd like to use

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    I give up trying to figure out exactly what this frame is. Based on what I've seen so far I'm gonna say it's a 1980. And it doesn't matter if it's a beltdrive frame or not because my measurements tell me I can run a one inch belt and a 160/70-17 on it with plenty of room between the tire and the frame, at least 1/4 inch in both places. 160 = 6 5/8" measureing the rear Dunlop on my Dyna

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    Quote Originally Posted by oneuptom View Post
    Thanks

    All in all that sounds like a walk in the park to me because I've dealt with situations where I've had to offset the whole drivetrain, widen the swingarm for a wider tire & belt, rubber mount the works.
    Yeah, you won't even break a sweat on it.

    I suppose 12.5 shocks would be too short? I have some nice NOS chromed aluminum adjustable progressives made for Arlen Ness I'd like to use
    I dunno? I like big, fat sidewall, back tires. And I have an old fender on it with wiring on the top side. (Stock for the fender, I think? Gonna fix that this winter.)

    I measured it, and the shocks are extended to exactly 13.25 center to center, sitting on the side stand, installed on the bike.

    My bike would rub on bumps at 3/4" lower. But, yours might not? Depending.

    I would give you the exact part number I used to compare, but Dennis Kirk won't let me view old orders right now.

    Here's a pic from today if it helps. if you have a different, more accommodating, tire and fender setup? it may work.

    it was a great day to ride, btw. We put about 130 back road miles (Which is like, ten million highway miles.) on them today. Had a blast!

    Attached Thumbnails Attached Thumbnails shocks.jpg  
    Last edited by confab; 10-10-2021 at 9:06 PM.

  13. #13

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    [QUOTE=oneuptom;851444]Interesting!

    Frame I'm talking about is a 80-81 but not exactly 100% sure. Guy who gave it to me is standup and said he was pretty sure it's a beltdrive frame. It looks bowed on the right so you could shift the drivetrain that way to make belt room on the left. Otherwise most of the measurements are pretty close to the earlier chaindrive square arm frame I'm comparing it to

    All the forgings on it are beefier and the tubing on it is a slightly larger O.D. and (thicker) wall. All measurements on it are metric!!!

    I could only find one not too good pic of a bare 80 Sturgis frame and it looks like the same one to me? I don't know anything else.

    Maybe somebody knows how to correctly measure a beltdrive/Sturgis frame?

    My 06 Dyna was the last year for the 30mm belt, what people call 1 1/4 I think. 07 went to the narrower belt, 1 inch maybe? Took me a while to find a 30mm international pulley for the rear. I like cruising it at 85, just wee bit out of it's comfort zone. Haven't installed it yet though. Anyway, back to the 81.

    I was thinking, why couldn't I use one of the current narrower 1 inch belts on it? I would find a way with the front pulley O.D. if clearance there was an issue

    How wide is the KARATA belt?

    Youy can go to thier website for sizes. They are 1.125 to 1.50, depending on application

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