Friday, September 23, 2016

Getting the chopper back on the road.

My BSA, the Rising Star, is the reason I started this old-fashioned blog in the first place.

It is a wonderful little bike, light, nimble and with one of the all-time best frames I have ever tried... by a long shot.

It's had a troubled beginning but I managed to use it for a few outings and even as a daily driver for a couple of months: that was a bit of an epiphany!

I've had to faff around with the carburetter, but not because of the carburetter; that's a story to share over a couple of beers.

There is one thing though that was not well made from the start and that's how the gas tank is mounted to the frame, and it shows because the tank's rear mounting tab broke pretty quickly.

This is obviously because of vibration, and there's not much you can do about that other than try to manage it somehow. Initially we just placed a thick rubber spacer under the tab and just bolted the whole thing down, as was done on pre-OIF Triumphs.

Since this clearly didn't work, I thought that the attachment point to the frame needed to be improved.

As you can see above, it was originally just a piece of threaded bar stuck in the frame and simply welded; my initial idea for improving this is neither my own recipe nor a secret.

I don't know how to weld and I don't have the equipment, but I knew how this should be done so I turned to uncle Fester for help.

After we talked about it for a little bit however, he came up with an alternative solution that would have required working only on the tank, leaving the frame alone and not having to get the bike to his workshop.

This could either be a permanent fix, or at least a major step in the right direction: he fabricated a new tab from a piece of marine grade steel, shaped it and drilled a hole sized for a H-profile grommet. Then, using two metal top-hat bushes, he essentially made an internal bush and external supports for the whole assembly, so that a new sleeve nut can now be torqued down, metal on metal, while the grommet is free to better absorb vibration on all three axes.

Below you can see the old mounting tab compared to the new one, old and new rubbers, and the sleeve nut (unfinished, in the photo):

A beefy, clean set of TIG welds secures the new tab to the tank. Those suckers should be staying put.

Say what you will about uncle Fester, but this cat works just like he rides: hard, and very fast.

Lots of thanks and respect bro.


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