All by design
Assembling parts already made and generally regarded as ‘for the machine’ is a relatively simple thing… the problems start when deviating from the manual.
There will be enthusiasts reading this who are designers, trained in the art of visualizing a concept, able to turn their vision into reality as they create wondrous forms – in this case to put an old motorcycle together. They glance, almost casually, at the space between part A and part B, their pen or pencil leaps into their hand, a sketch is created, turned to a drawing which becomes The Part. Their designed parts fit, look as though they should be part of the machine and meet the form and function requirements needed for something pleasing to the eye. Then there’s me…
There are loads of reasons for deviating from what has gone before, manufacturers for instance will update, redesign, improve for reasons of sales or production purposes, competition riders will alter and modify to make their machine work for them. Again, then there’s me…
Arguably anyone who chooses to make something which deviates from standard is entering into the design field, we may not feel we’re designers but whenever we have created a bit which mates part A to part B and isn’t a standard bit then we have ‘designed’ something. Okay, this may be a much more organic, trial and error process than a route taken by someone with design skills, but even if all you’ve done is file a piece of metal and offered it up to the machine in question then thought “it needs a bit more off the corner..” then design has happened.
This was pretty much where we left off last issue when things came to an abrupt halt and I checked out the service of the NHS – which was excellent – but meant I wasn’t able to do a great lot of manual work. Even worse, despite several creative ideas, I couldn’t design a viable cover for the bandage to allow my involvement in the Christmas washing up… I was truly gutted.
Once the bandage was gone and I could handle tools again, the work on the oil tank continued and a simple mounting method was needed. With the wooden former able to be lifted in place, rider leg/tank clearance was checked by putting the rider in the correct position and seeing what the gap was like. Quite a big gap… this means the
tank can be repositioned slightly to give a little more room around the carburettor intake. This is a good thing as I chose to use the sub-frame I had altered in 1990 or thereabouts – in those days, the idea was to build a pre-65 trials bike and the frame was slimmed where my knees would catch. I do have a standard sub-frame but it needed a bit of work too; if I’d used it then more standard stuff would have fitted but where’s the fun in that, eh?
With the wooden buck wedged in place, I could mark the position of the brackets and was able to gauge the clearance between legs and tank and adjust as necessary. I’ve mocked up some brackets to cope with the modified frame and in light of the tank position, I’m going to move them slightly so a rubber mount can go between the alloy and steel, which will slow down any vibration problems. It doesn’t take much to insulate such a tank as this – good old tap washers will work and are easily available.
There are an almost bewildering number of anti-vibration mounts available out
in the open world as lots of parts require some form of insulation from the surface they stand on or attach to, in order to remain in working order.
Elsewhere in my workshop a Can-Am enduro – currently taking up space and time as a sidecar is fitted – has the exhaust mounted on bobbins which insulate it from vibration. I did look at these mounts as a possible solution but I don’t have any narrow enough – they probably exist, given the range of products out there – but they don’t exist in my stores… by ‘stores’ I mean the box with all the small bits in.
A lot of choices are made in such projects as this depends on several factors – cost, availability of bits, plus skills and determination of the person doing the job. Like many in this uncertain time, the resources are just not there to fling money at this project, the availability of bits for the modifications is less of a problem as the availability of skills means while I could cut and fabricate a piece of tube and a bracket so a Metalstik bush could fit I couldn’t weld it on and such tasks would mean taking it to someone else.
In pre-pandemic days, I’d slip the bike in the van and take it to a mate with welding skills far in excess of mine – this is what was done with the sub-frame suspension mounts, said mate cut them off, flattened them then rewelded them like they’d never been off. What I can do is alter a bolt, drill a hole and make sure the oil tank has some slight movement on its mounting.
So, the tank former is created from plywood and some temporary brackets are
screwed in place and some tweaking to position will occur. Some paper templates were cut by plonking the tank buck on the paper which comes in the boxes when stuff is ordered from a well known online super store… A sheet of aluminium has been available for a long time and placing the templates on the sheet I drew round them with a felt pen and cut the shapes out using my band saw, leaving a few millimetres over size. I could have cut by hand using tin-snips but the pair I have are very old and not great, which is possibly why they were given to me. Not being au fait with the intricacies of tank construction, I don’t know if the future welder will require the pieces cutting to exact size or prefer to do this as the tank is constructed, so erred on the generous size. It wouldn’t be a problem if the tank is not to exactly the size of the former – it’s not mating in with anything other than the brackets and adjusting where the holes are isn’t a great problem.
Bigger problems have been caused by a lack of fittings to allow the oil to return to the tank, the feed union and filter are easily available and I have one anyway, I also have a filler cap and a breather isn’t difficult to make. What has defeated me until recently is the oil return fitting.
My BSA B40 tank has a nice cast fitting which screws in to the tank, allows the oil to return and provides a rocker feed. All attempts to find this feed have failed yet I’m certain it used to be commercially available at one time. On standard Triumph tanks, the return is via a steel tube with a smaller tube brazed in as a feed to the rockers, not a problem to make I agree, but see the ‘lacking skills’ bit earlier.
I’d almost given up hope on finding such a thing then looking at a forum about woodworking of all things there was a picture of a ‘T’ piece which, when questioned, the forum poster said ‘…oh it’s a feed thingy for a vintage motorbike, my neighbour’s into them and it’s just the job for feeding lube to my saw…’ Said bit was sourced… or will be when the supplier has new stock coming in… The ‘T’ piece isn’t exactly as I wanted but is for the exact job I need, so will do nicely.
Slightly easier to solve is the feed into the tank, a boss welded on and drilled will be the first stage then a special fitting will be fabricated to ensure there’s a bit of back pressure so the oil will be forced up the rocker feed but not too much back pressure so, no pressure then… or perhaps just the right pressure…
The bosses needed for the filler cap and oil feed to screw into are bigger bits of alloy than I have in the scrap box, they also need a screw thread for which I don’t have a tap so this is a job I will farm out to the welder probably. Yes, I could probably screw cut internally on my lathe, but as of this point in time, I’ve not tried external screw cutting yet and only have a few of the change wheels needed for various pitches of thread in any case.
With the pieces of aluminium cut broadly to shape, the back now has a step pressed in and the edges have been formed around the buck and I’ll be able to present the lot to a welder to do the easy bit of sticking it all together.