Continuing with my 1960 Super Rocket swing arm rebuild I purchased a pre-owned hollow spindle off of EBAY. It slid into the frame holes fine but the threaded end didn't protrude through the frame gusset enough to allow the nut to be screwed fully on.
I eventually found measurements for the hollow swing arm spindle on this forum and compared the measurements to mine. I was looking for 10 5/8" from the face of the drive side pear-shaped retainer to the end of the threaded portions. Ooops mine measures about 1/2" shorter than this so which explains why the nut won't go on!
Can anyone suggest what model the hollow spindle I have inadvertently bought might off please?
Also, regarding the silent bloc bushes I have been doing some investigating (You Tube) and I am going to cast my own bushes using either a liquid rubber or tufnol twin pack solution. This is common practice in the auto industry and I can't see why it shouldn't work for this application.
The swing arm bearing is a simple but interesting design but I suspect it's design might be a little misunderstood.
In the late 1960s I was in correspondnce with Stan Shenton of triumph racing fame about my Triton project. The discussions centred around the pros and cons of fitting different engins into the Norton Featherbed frame. Mr Shenton said that he had no experience of fitting a triumph unit into a Featherbed frame and their might be issues with resonance and harmonics.
This took my investigations into a totally different direction unearthing facts like a new factory race bike was brought into the pits with the rider complaining of bad vibration. One of the old school mechanics cured the problem in ten minutes and the bike went on to finish without further vibration problems.
What the race mechanic did was pour molten lead into the handlebar thereby damping out resonance starting at the engine and moving into the frame and cycle parts.
Some years later I was talking to a engineer at Lotus cars about optimum tyre choice for my then new Talbot Sunbeam Lotus. I was advised that the Pirelli Tyres factory fitted were the best option because unusually, they had a tread pattern which was not continuous around the tyre; it changed pattern half-way round.
The Lotus engineer explained that early tests on the prototype cars found that due to the cars light weight and absence of shell cross-bracing the tyre tread pattern on running against the road would set up a high frequency vibration which travelled up the offside suspension into the body shell, across the roof panel and into the diagonally opposite suspension leg causing that wheel to run out of balance!
Back to the BSA A10 Silent Bloc Bushes I suspect that yes they would have provided a degree of torsional damping of the up/down action of the rear wheel as well as lateral stability of the swing arm but I wonder if the rubber also dampens out the resonance set up by the rear chain running over the sprocket which might otherwise have found a sympathetic or harmonic resonance in the frame itself or handlebars or foot pegs?
Vibrations are silent and invisible but when finding sympathetic harmonious structures to amplify or exacerbate them they can become totally destructive certainly very unpleasant for the rider.
And of course they are cheap!
Safe riding.
