Ducati Elite 204cc
Making a few unobtainable parts
Although a great many parts are still available - usually as an assembly, some minor parts are just not to be found, not surprising for a 60 year old machine I suppose! While stuff was away being plated, I started looking at what I could reasonably salvage, even if that meant making small components.
First up was the choke lever which bolts onto the right hand clip-on handlebar which although complete was really poor cosmetically. The chrome cup which holds down the spring was seriously rusty, as well as dented, so no way was this usable.
It's a thin pressing, so I could have turned one from solid bar but I decided to spin one from sheet stainless and the first part needed was a former to shape the cup from. This needs to have dimensions matching the INNER surface of the cup:
After cutting out a suitable disc with the angle grinder it's time for spinning! I used a small bar of dural, mounted in the tool-post to 'persuade' the metal to the required shape - with lubricant to reduce friction.
This is the rig I used - the bolt could have been threaded into the forming bar but I just drilled it clearance and used a revolving centre and centring pad to keep the pressure on.
Held onto the bar end with double sided tape it was a simple matter to polish the outside to an acceptable finish/
......and this is the finished article with the original for comparison.
.......and the assembled lever which just needs a stainless bolt making - might be available but it's 7mm diameter with an 11mm head!
The Speedometer bezel was next - it's a chromed brass ring with grooves around the top face but is crimped to the speedo casing. It is usually possible to carefully 'uncrimp' the underside of these bezels but this one was crimped over, right to the body of the instrument. I really had to get inside this unit, firstly it was seized, secondly the little celluloid window which allows illumination from a festoon bulb INSIDE the headlamp had become detached and was almost opaque. I decided to cut right through the ring - made of course from Unobtainium - after first checking that I had a suitable piece of dural tube to make another.
It had to come off - even if it had been good enough to re-plate, I did see a speedo on eBay but it was mega money and (most of) mine is the original.
Polished alloy will make a good passable copy of a chromed ring, except perhaps for rivet-counting purists! When I got inside the thing, I was glad I had taken the trouble - it had been wet inside and all lubricant had long since gone. Careful cleaning soon had the mechanism working again so I stripped and zinc plated the casing again. With a small square bar in the drill chuck, set in reverse, the needle moved smoothly up to about 60mph (full speed on drill) and I added about 6 miles to the odometer as a final check.
The first stage of making the bezel was to machine the inside form to fit the casing, then parting off with a bit of excess material for finishing cuts. Once detached from the chucking spigot, this was then machined to accept the bezel for final finishing - I actually made it a shrink fit as there was not much area for double sided tape to grip. Heating with a hot air gun was sufficient to fit it and allow to cool and grip. Only very light cuts were taken, in order not to disturb the bezel from the chucking piece. With both parts made from the same material it would be a challenge to remove - but I had a shoulder to gently lever against and was not about to start again with a steel chucking spigot to get enough expansion!
The alloy chucking piece came in handy again and was machined to securely locate the completed bezel for crimping to the body.
This was the set up I used to roll the crimp onto the newly plated speedo casing, having first put a thin bead of clear sealer between the glass and the bezel, left overnight to dry. I didn't think it necessary to roll the edge right down as on the original - there is no way it can come apart in service. I used a small bearing to roll the edge to reduce friction and provide a neat edge.
The finished bezel with the grooves almost as original
Refurbishing the Rear Spring/Dampers
Part 2 Rear brake-light switch and headlamp bolt spacers
Part 3 - Speedometer drive