Rear drive belt length

Like it says above.
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smnmuller907
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Location: Anchorage, AK

Rear drive belt length

Post by smnmuller907 »

So I'm in the process of laying out my frame to the new axle plates and the rear tubes bend at compounding angles to accommodate a 280 rear. My problem is when all was sead and done I ended up parallel to the plates but about an inch below them. I could fix this by just moving the axle plates back about 3.5 inches but I want to make sure I can buy a belt when I'm all done. I'm thinking I could use the extra room to drop the seat a little.Right now the belt is 139 tooth. -118. I'm having trouble finding longer ones. Is this something comment to find and I'm just not looking in the right places? Option 2 would be to add another bend to get the elevation but I wouldn't be running parallel and would need to make new plates plus I did this on a sample and it looked horrible. Option 3 is move the neck forward but I'm not fond of seeing another 3 inches between the row tubes and the motor. Any thoughts ????
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gww25
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Re: Rear drive belt length

Post by gww25 »

Try to post some pictures. There are a couple of ways to work around this if I understand your current positioning but I need to see you setup. Finding a long belt shouldn't be a problem however since we've been doing frames with 4-inches of rear stretch for a long time.
smnmuller907
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SELF INTRODUCTION: Hi my name's Simon. Journeyman Sheet metal worker /welder / fabricator. Lots of metal fabrication experience I'm hoping to carry over into Motorcycles. just starting my journey into chopper building.purchased a donor bike and am starting a build from the frame up. (ambitious i know). 80" evo, 280 rear, Ultima RSD transmission, Ultima 3.375 primary, DNA springer front end.
Location: Anchorage, AK

Re: Rear drive belt length

Post by smnmuller907 »

gww25 wrote:Try to post some pictures. There are a couple of ways to work around this if I understand your current positioning but I need to see you setup. Finding a long belt shouldn't be a problem however since we've been doing frames with 4-inches of rear stretch for a long time.
Ok here's my first shot at a video on this thing. Let's see if it works. looks like you may have to click the link or copy paste to browser. I read the forum and still can get it to work


https://www.youtube.com/watch?v=vR3w1OvbvII
hansgoudzwaard
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Re: Rear drive belt length

Post by hansgoudzwaard »

Bigger Axle Plate.
Bigger Axle Plate.
AXPLA.JPG (23 KiB) Viewed 4642 times



I would make a new axle plates. They would need to be a little larger to fit into the frame tube slots with the rear axle in its present position.

The top frame tubes are not shown in the video, so you may want to mock those in before you cut the slots.

Good Luck.
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gww25
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Location: Murphy, Texas
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Re: Rear drive belt length

Post by gww25 »

You're actually pretty close based upon the video and I've seen a lot worse. In a situation like this we've often just used brute force to 'tweak' the lower bends by clamping the lower rails down firmly (just ahead of where the bends start) and then using a cheater tube over the full length of the rear upsweeps you can usually close the gap by at least .5-inches, sometimes a lot more. Also nothing wrong with an oversized plate. Any luck yet on finding s good source for a longer belt. Maybe a combination of tweaking, oversize plate and longer belt, all three will give the best results.
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Re: Rear drive belt length

Post by krymis »

gary and i spoke about this today.
One issue is pulley ratio and belt length and RPM. To remedy this i just switch to chain. if this is for a harley look at zippers and they will have a direct chain conversion.
Issue two is the clamp and bend. When I was starting out I found that this was doable but I had to clamp better than what i did have it. I am not adverse to using heat for bending also. some may disagree but these are some of my ways.
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