Anything Goes! Dr. Shop Teacher's Tonic le Moto--Broncco T-XL

#21
Gusset and Tank Mount
So the booger weld at the neck is going to get refilled, but I have to address twisting of the frame which caused the break to begin with. Solution: Gusset.

I made a template to fit snuggly around the triangular shape of the neck.
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Then transferred to some plate and roughed with the sawzall and trimmed the inside with the scroll saw.
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Heated and bent the plate to fit.
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A good amount of grinding to shape to fit. Note the tab to attach the front of the tank.
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And here's a better view: IMG_0113.jpg

Next up is another gusset/mud shield.
 
#24
Ride Height: The bike, as designed, seems too squished together and I think has a design flaw where the swing arm/jackshaft bracket is welded. To fix the look and fix the flaw, the swing arm pivot will be moved back a little over an inch. I'll make new brackets next.
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This pushed the center line of the wheel to the end of the bike and doesn't change the angle of the swing arm much. Then i needed to level the ride height to keep the rake angle correct. You can see how the bike looks more elongated.
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I had left the fork uppers purposely long so I could adjust them. The final length is 3.25" and the lowers slide right in.
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#27
Swing Arm Mount:
I made a cardboard template to layout the relocated bracket. After studying the swing arms on the Gilsons, I realized the jackshaft location had to be on the centerline of the swing arm.
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I transferred the pattern to a piece of 1/4" plate, which is slightly thicker than the original mounting plate, and cut it to rough shape with the sawzall.
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Then shaped them when clamped together.
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I removed the original mounts with the sawzall and cleaned up the frame tubes.
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I drilled the swing arm bolt hole on the press and did not drill the jackshaft hole--this needs to be double checked before drilling the pilot.
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Here the brackets mocked up (some final fitting is still necessary). Now we can add the stretch to the frame.
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#28
Fender Radius-ing:
I picked up a pair of old motorcycle fenders for the bike. They are for big wheels, so they need to be radiused to fit the 14.5" tall Pirellis. Since I only have one shot at doing this, I decided to make a cardboard template of fender to experiment with the cuts needed to shrink the fender. The first pic shows finding the center.
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The cardboard was cut to length and width and centered on the fender.
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Then the center portion was laid out to give a maximum perpendicular cut line.
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Starting in the middle, slots were cut 1 5/8" apart.
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The the tabs were rolled over, cut lines matched and taped together.
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Then the pattern was wrapped in tape to hold the curves.
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An additional piece of cardboard was added to keep the form in the original radius.
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New slots were cut to gradually make the wrap around the tire. These were taped back together. New slots will be cut perpendicular to the centerline, which will give me the proper "V" cut for the fender.
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#35
Rear Sprocket
Using Delta CAD, I designed a replacement rear wheel sprocket. While it looks easy to machine, turns out it wasn't so easy. The sprocket isn't flat, so mounting in a lathe to cut the center out wasn't possible, so it had to be milled. A center had to be machined to rotate the sprocket to drill the bolt holes.
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Here's the original side by side with the new one.
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And with the DB 30 Caliper, which will also be a test to make a bracket for it.
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#36
Stretching the frame (and I'm glad I did......oops).
The frame needed to be stretched to fit me, and I was liking the elongated look. I settled on a 5 inch stretch for now, I may cut it back to 4.
I used a level to set a vertical line to cut the frame and then removed the two upper cross bars (for the seat) which will need to be moved anyway.
I had enough tubing to insert a slightly larger section to replace a pretty badly damaged part of the frame, so I did that, too. I used 3/8" ID black pipe which was the right OD to fit the frame tubes snuggly.

Now the bad news: that booger weld at the neck was original to the frame and was how the three frame tubes connected. All that has to be cut out as it broke as I was manipulating the frame to test the extensions.
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And mocked up with an HS50.... IMG_0200.jpg
 

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