3. Front and Rear mounts...

Step by step progress on a recent Frisco mounted King Sportster tank exercise...
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Prof
Founder, Choppers Australia
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3. Front and Rear mounts...

Post by Prof » Sat Dec 15, 2007 9:42 pm

Final fabricating job is now to make the front and rear mounting brackets and hardware...

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This is the complete fromt mount. Each wing is made up of two components... a flat 3mm tab welded to a heavy walled tubing ring.

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The tabs are angled to produce a neat flowing line from the tank. The tubing from which the rings will be made is used to mark out the shape to be cut. Use black texta and a knife point or sharpened spoke as your marker...

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The rings are 6mm wide and cut from thick tubing on the lathe. Using the lathe keeps their width even. If you don't have a lathe, use a verniers to mark a consistant width and carefully cut witha hacksaw or angle grinder with 1mm blade, turning the tube regularly to ensure you stay on the marked line..

The rubber grommets are a bit of a challenge. I could not buy any wide enough, so I bought an extra number of narrower ones. First I ground off one rib of two grommets to give a 7mm wide barrel. Then I cut off the ribs of two others. The two pieces fit together well, supported by a stainless washer on each side.

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Finished job. The tank will be properly supported by the 6mm wide rubber grommets, plus the washers on each side. It is fully insulated fmro the bolt and frame bracket, so vibration through it will be minimal... more comfortable and also less chance of cracks. When making mounts like this, take care not to tighten bolts too tighly and put stress on the mounting tabs...

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Rear tank mounting consists of a curved tab that rests on a wide piece of rubber over the top frame tube. To just bolt it down, would negate any rubber mounting, so the bolt is separated from the metal by a rubber washer.

Rubber washer is cut out of truck mudflap material, using a hole punch specially made for the job... a piece of sharpened tube. Second hole punch is from a cheap harware set. When punching rubber use a block of hardwood or a thick piece of lead so cutting edges of punches are not damaged.

For good looks and neatness, a ribbee washer from an old washing machine rubber mount was used... it was the right size. At other times I have made a ribbed washer from stainless round bar on the lathe.

Rather than run a bolt right through the frame tube, I have machined up a long threaded plug that can be tapped into a hole in the frame and then welded in place. Note the ridge on top to prevent it accidentally falling through before welding. The chamfer on the leading edge is to make it easier to tap in.

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The plug was threaded with UNF being for a Harley. In steel use fine threads and in aluminium use coarse threads. 'Vs' cut into vise jaws are to hold round material for threading. Always use threading lubridcant and stop to clean out ong threads often to prevent thread damage.

Final job on tank was to weld in a plate to close off front of tank, but some how I managed to forget to take any photos of the finished job or of pressure testing the tank... sorry

Tank was pressure tested with filler cap on and using a adapter screwed onto the tap outlet. I use a foot pump and put in about 5psi, hold the tank under water and look for any bubbles. This tank had three small leaks that were quickly repaired... not bad for the amount of welding required...

Next will be some threads by Tex on filling, painting and mounting his new tank..
Chopit'nrideit... Prof

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