Saturday, February 26, 2011

Lowbrow Panhead: Extending the Triumph Fork Stem

As much fun as it is playing mock up, I decided I had better get my ass in gear and get some fabrication work done on this beast so I could actually start it up and ride it down the street under it's own power at some point. I want to knock out the work I need to do to finish the front end, which includes fabricating some fork stops, shaving some lugs from the top tree and lengthening the stem on the Triumph front end to fit the rigid HD frame properly.

If you look carefully down inside that top nut (which is just for mockup, I have a nice stainless one when the bike is getting final assembled) you can see about a half inch of threads showing. That is because the HD frame neck is longer than a Triumph. I need to extend the stem almost exactly a half inch to engage the top nut more fully and stave off a possible tumble down the road.

I kind of got into it and didn't take any photos this evening until I was ready to weld. Nothing too exciting, a couple hours dicking around on the lathe and filing, cutting, etc. The usual drill. I turned down the stepped spacer you see out of 1" OD solid cold rolled steel. A half inch fits into each half of the stem and the center is the extension to lengthen the stem. A heavy chamfer on all pieces makes for good penetration and also keeps the weld flush with the surface so the stem will slide through the bearings still.

V-blocks rule. My buddy George lent me these for this job, and it made it so easy to keep everything in line. Here the stem is clamped in place, ready to weld. The 'V' shape of the body of the clamp keeps the round stem perfectly centered.

Some TIG action, jumping around and rotating the stem until both welds were done. Welded up very nice and easy. It is sitting in the v-block on the bench still, I will let it cool down and go ahead and mount it up on the bike. I am stoked to have knocked this out tonight, lately it seems like everything I try and do becomes problematic, it is nice to check one thing off the list at least!


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