Belt drive

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Frazier
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Belt drive

#1

Post by Frazier » Thu Apr 25, 2019 3:43 pm

Put a belt drive on the shovelhead and took it for the first test ride , its like a different motorcycle ! Before i wouldnt take it over 62 mph the vibration was so bad i thought id brake it or the motor would blow up or something , now its smooth through all the rpm ranges and i actually had it up to 75 mph with no problems ! Big difference !!



RooDog
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Re: Belt drive

#2

Post by RooDog » Fri Apr 26, 2019 4:55 pm

Sounds to me like you have another issue not related to the belt drive. My 90", '68 Shovelhead, 5 speed, in a OEM swing arm frame is good for 70-80 MPH all day long, until it developed a buzzy vibration. While I had it down for some paint work I discovered the top engine mount, the laminated section of frame hanging down from the backbone, had cracked. And that was the source of my new found vibrations. If I were you I would be check all of your engine and transmission mounting points both for fastener tightness and structural integrity. There could very well be something in need of fixing....
....RooDog....

Frazier
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Re: Belt drive

#3

Post by Frazier » Fri Apr 26, 2019 11:21 pm

Good idea , i will check all those fasteners this evening , also the primary chain was so wore out the owner before me turned the primary adjuster over to get more adjustment , also the engine sprocket was a solid mount 22 tooth and the new belt drive is a better drive ratio with the 24 tooth trans and 48 tooth wheel sprocket

RooDog
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Re: Belt drive

#4

Post by RooDog » Sat Apr 27, 2019 12:17 am

Good numbers on the toot counts. I find old Harleys were typically geared too low for the real world.
...RooDog...

Andygears
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Re: Belt drive

#5

Post by Andygears » Sat Apr 27, 2019 1:28 pm

A really bad primary chain with a solid front sprocket can make a lot of vibration, which will loosen everything, mounting bolts and worse, frame welds! RooDog is right, spend some time going over everything and making sure stuff is tight & look over the bottom of the seat post tube to see if a "typical" crack has started there. Rear chain and sprockets not to be ignored.

Andygears

38ulh
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Re: Belt drive

#6

Post by 38ulh » Fri May 10, 2019 11:57 pm

I'm curious about your belt drive. Who made it, is it in a stock aluminum primary, does it require an idler? I ask all these questions because I had an inclosed Primo many years ago, I like belt drives but I always thought that Primo was wearing itself out from the back side of the belt by slapping the inside of the primary. I don't think I'd like an idler either. I didn't keep the primo long enough to wear out or break a belt. I've often considered trying another belt drive on my shovel.

Frazier
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Re: Belt drive

#7

Post by Frazier » Mon May 13, 2019 1:16 am

Its a BDL 11 mm belt drive in a stock shovel with swingarm frame and aluminum primary and yes there is a belt adjuster , there has to be with this setup cause with the aluminum inner primary the trans is non adjustable

Frazier
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Re: Belt drive

#8

Post by Frazier » Mon May 13, 2019 1:19 am

Yes Roo Dog finally getting around to working on the shovel and so far ive found a loose top motor mount , gonna check the motor mount bolts next , Thanks

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