Open Primary options

Transmission, clutch, chains and belts
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MS-Geek
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Open Primary options

#1

Post by MS-Geek »

Hi all,

I looked in the knowledge base but didn't see an answer on this.

I've got a '48 motor with 4 speed ratchet top tranny on a '57 frame. I'd like to convert to an open primary, I see most options are just the pulley's and belt where hte options for softtails and newer bikes have backplates and covers. I see posts say that without a backplate the belt drive puts stress on the bearings while others say the torque of a 74" panhead shouldn't matter to the belt drive.

I kindof like the look of some kind of cover on the belt drive, and saving my pants from being chewed up. Does anyone know if there are any available for the setup I'm looking for?

Also I see the panhead ones don't usually include a clutch, does that mean it should work with my clutch basket?

Any help, opinions or pictures would be appreciated.

Chris
Hauula Pan
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Re: Open Primary options

#2

Post by Hauula Pan »

There are many options from different manufacturers available, from narrow belts that will run inside the primary to wide open ones. Before I put my 52FL back to stock I ran a 3" wide BDL for a while. It came with front & rear pullys & a top cover. No back plate used & used stock clutch with a polished cover over the spring plate. Nice set up which I later re-sold. As long as the tension is set properly there shouldn't be any issues. Remember the early primary chains didn't have tensioners either. If you want the wide belt open look BDL, Primo, and a few others are available and not very expensive for the basic pullys & cover. The price goes way up when you get into the fancy billet stuff.
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Re: Open Primary options

#3

Post by Hauula Pan »

Sorry I don't have a picture of it all together but here is one that shows the pullys & clutch hub cover.

Image
caschnd1
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Re: Open Primary options

#4

Post by caschnd1 »

For a mostly stock panhead, the 1-1/4" wide belts are plenty strong. I'm not a fan of the 8mm belts with aluminum pullies. I ran one of those for about 8K miles when I first rebuilt my panhead back in 2004. The belt and pullies showed lots of wear after just those few miles. I did some further reseach and went with a SuperMax Silent Drive to replace the 8mm Primo. The SuperMax uses polyurethane pullies (like the hard skateboard wheels) and a 14mm pitch belt. I've put over 85K miles on the SuperMax drive. I've cut one belt when a piece of wire got wound around it. Another belt broke when I hadn't tightend my transmission to the mount plate enough and it cocked slightly sideways. My last belt I put about 60K miles on and wore it out. The pullies show no signs of wear at all after 85K miles. No "inner plate" is required for a 1-1/4" belt. I run the stock inner and outer covers. I prefer the stock look of the primary.

-Craig
DSC_0887.jpg
DSC_0887.jpg (115.3 KiB) Viewed 2361 times

With the cover in place...
DSC_0984.jpg
DSC_0984.jpg (115.12 KiB) Viewed 2361 times
JR JOHNSON
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Re: Open Primary options

#5

Post by JR JOHNSON »

hi,you only need a 1 1/2 8mm belt drive,unless you you want a 3 inch for looks,to me it just ads weight,and pressure on the main shaft on the transmission,also there's no seal on the crankshaft,and if the transmission is a 48,no seal on the main shaft,also you have to relocate your crankcase+chain oilier,which you'll shut off.belts don't like to much. on the pant leg guard,I'm sure somebody makes them,but i think you can do better doing it on your own. ...........just my opinion..........with respect.........JR
1964FLDUO
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Re: Open Primary options

#6

Post by 1964FLDUO »

caschnd1 wrote:For a mostly stock panhead, the 1-1/4" wide belts are plenty strong. I'm not a fan of the 8mm belts with aluminum pullies. I ran one of those for about 8K miles when I first rebuilt my panhead back in 2004. The belt and pullies showed lots of wear after just those few miles. I did some further reseach and went with a SuperMax Silent Drive to replace the 8mm Primo. The SuperMax uses polyurethane pullies (like the hard skateboard wheels) and a 14mm pitch belt. I've put over 85K miles on the SuperMax drive. I've cut one belt when a piece of wire got wound around it. Another belt broke when I hadn't tightend my transmission to the mount plate enough and it cocked slightly sideways. My last belt I put about 60K miles on and wore it out. The pullies show no signs of wear at all after 85K miles. No "inner plate" is required for a 1-1/4" belt. I run the stock inner and outer covers. I prefer the stock look of the primary.

-Craig

Image

With the cover in place...
Image

No rattlers on your clutch drive disks, Craig? I must be the only person who still runs those. Also looks like the gaps on the plates are huge, they look like they have atleast 1/4" play on the basket dogs. Did you mill them out yourself for some reason or am I seeing things.

Image
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Re: Open Primary options

#7

Post by Hauula Pan »

The BDL I ran came with a belt guard (most of them do) its just not installed in the picture, just as the belt isn't installed either. I used to have pictures of the thing all finished I just can't find them. All I had to do was shut the oiler off at the pump to run the belt dry. There are many options available it really depends on what look you want & what your budget allows. I'll bet if you look through the gallery you'll find some pictures of different ones.
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Re: Open Primary options

#8

Post by MS-Geek »

Thanks, I may lean towards the belt in the tin, it does have a more classic look. Awesome bike you've got there.
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Re: Open Primary options

#9

Post by caschnd1 »

1964FLDUO, look at your plates with the rattlers, then imagine what they would look like without the rattlers. You remove the rattlers and you get those big gaps on every other slot. But they are not on the drive side of the gap so it makes no difference.

Here is a more clear photo of the plates I use. They are basically identical to your plates with the rattlers removed. Only half the slots are larger in size.

-Craig

Image
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Re: Open Primary options

#10

Post by 1964FLDUO »

Ahhh...I See, Craig. I thought all of the slots were huge. I have gathered a lot of those barnett and other aftermarket disks without rattlers over the years and they all have no gap. I've never seen disks like yours other than the rattler disks. Interesting.
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