The nut was dremelled off with only slight damage to one thread. The armature casing then cleaned up and rubbed down.
Motor then stripped down. The circlip holding the pinion on has the smallest set of eyes I have ever seen. My circlip pliers would not fit and I did not want to grind down a perfectly serviceable set for this one job so it was out with two electrical screwdrivers. A half hour later the circlip finally came off but not before I had stabbed myself 3 times. Picture below shows stripped motor with bloodstains on the pinion end casting. Brushes still have some but not very much meat on them. The bike is only likely to be used for sunny summer blasts so they can go back.
Armature was then tested for continuity and the commutator polished up with 800 grade wet and dry. Re-assembly is a definitely three handed job, one to inset the armature into the brush end cap and two electrical screwdrivers to hold back the brushes until they are engaged on the commutator (after the end cap bearing had a small dollop of HMP grease and the ball race and seal at the pinion end was similarly treated. There are registers on the pinion end cap and the armature case which line up. oddly the registers on the brush end cap cannot line up with the other two registers which took me about 15 minutes to work out . In the end there is only one way it can go back together. If I ever strip one again I will paint registers on both end caps and the armature case before I strip it. Body was re-sprayed with PJ1 whilst it was stripped.
Further filling of the underside of the tank has also been done this week. This is going to take a long time because a) the convoluted shape means that power sanding tools cannot be used easily and b) I am concerned there is not enough clearance between the front seat support on the frame and the bottom of the tank. Also I discovered that to get the tank off it has to be tilted backwards and the act of tilting it causes other clearance problems at the front. Unfortunately I think I need to remove about 8mm from the section where it is plywood laminated about 50mm deep and I cannot get any sort of saw in there without threatening the nicely sanded top surface.
With some warmer weather I was able to take the tank plug out of the garage and sand down the base. Sanding in the garage is a pain because the dust gets absolutely everywhere.
Whilst waiting for the P38 on the tank base to go off I thought I would tackle a job I have been putting off, namely the oil cooler mount to the rocker cover. When I took the oil cooler off to refurbish it one of the rubber mounts parted company from the washer and stud that screws into the rocker cover casting. I was going to renew them anyway but when I tried to remove the threaded portion from the casting the threaded part sheared in the casting about 4mm below the face of the casting. the end of the sheared thread was of course not smooth but extremely jagged and therefore not good for starting a drill into. The shape and dimensions of the casting meant it was impossible to mount the casting into a machine vice so that a pillar drill could be used, - it had to be held in the bench vice and a hand held 18v battery drill used For the last two months every time I saw it I sprayed it with penetrating oil in the hope it would come out easily. I had 2 options drill a 3mm hole in the sheared stud to put an ease-it-out in and hopefully save the thread in the casting or drill it 6mm then 7 mm and re-tap the hole 8mm, but I was not certain I could get a male /female vibration damper with an 8mm male thread. The ease-it-out option was chosen and a 3mm ease-it out tried but it would not budge and I was frightened of breaking the ease-it-out in the sheared stud. I then tried a 4mm hole and larger ease-it-out was threaded in. the results are in the pictures below.
This is not a complete disaster as the current position of the oil cooler, hung from the top of the front head, puts it in a place that is potentially getting very congested with battery boxes and coil enclosures. Also in this position the oil cooler is effectively pre- heating the air flow to the carbs. I prefer the 900SS position mounted off the lower rocker cover such that the "exhaust" air from the cooler is passed over the front exhaust header pipe. This position also has the advantage of less convoluted oil pipe runs but suffers from the disadvantage of the requirement to provide some form of protection against flints and stones coming off the front tyre. Tomorrow I shall convert the above broken casting into a "standard" rocker cover with the aid of a hacksaw and an orbital sander and devise a method of hanging the oil cooler off a bracket secured to the rear most screws holding the lower rocker cover to the forward facing head.
I cut down some stainless bolts to get the ss studding and turned down 2 ss mounting nuts (from Screwfix), then drilled and tapped some 12mm aluminium bar and then wasted it on the model lathe so that the nuts holding it to the studding could be accessed. Getting the stud length dead right took 2 attempts.
After what we thought was spring it has turned cold again so no resin pouring for this week. I'm pottering about looking for jobs to move the bike forward. I bought a small lathe last year and am trying to learn how to use it , I last touched one in metalwork class over 50 years ago so I have a lot to learn. I plan on machining a carrier for the rear brake caliper to permit a fully floating parallelogram rear brake. This will involve machining to interference tolerances so I need to get some practice. Making some threaded aluminium plugs to go in the frame rails at the back seemed to be a good start. I bought some 25mm aluminium bar from Aluminium Warehouse (good supplier and remarkably reasonably priced). The plugs would be about 25mm long turned down for 4mm to match the frame rail OD (22mm) and turned down again for 21mm to c18mm to be an interference fit in the frame rail. These would be drilled and tapped 6mm to provide a mounting point for the seat or the number plate. I put the bar in the 3 jaw chuck and at the other end had a pointed taper to centralise the work piece and I turned the lathe on to check for run out. BANG!!!! whirrrrrrrrrrr!!! Ooops!!!! At first I thought I had stripped a drive gear on the lathe. Turns out I had left the tool post too close to the 3 jaw chuck and when I pressed the start switch one jaw smacked into the cutting tool in the tool post stopping everything dead. Fortunately it only snapped the toothed belt drive not the helical driving gears. No more lathe work until a new belt is delivered. I thought I would strip and clean the vacuum fuel pump instead. There 2 bolts holding it on via top hat washers and a rubber grommets through c 15mm holes in lugs on the frame. The bottom one was seized with the top hat washer having welded itself to the bolt through corrosion.
Following pictures self explanatory , pump stripped , very clean inside. The aluminium casing was cleaned up with a 4" wire brush in a drill held in the vice. The galvanised steel end plate was treated to a coat of 5 wheel silver paint and the set screws acid dipped and re-plated with my zinc plating plant
Another job tackled today, I bent up some 2mm steel for subsequent brazing to the frame. This is to hold the hanger bracket for the exhaust can.
Also, using some of the 4mm aluminium from the road sign I made the hanger bracket itself. I think the finished product looks too wide so I shall probably reduce it in width by about 10 - 12 mm although now it is bent I will not be able to use a jigsaw easily and I do not fancy filing 12mm. One day when it is raining outside and I am feeling energetic??? The other concern I have is that as it is it is not a "fail safe" bracket; if the vibration mount breaks (not unknown) then the exhaust can is only held on by two springs. Mounting off the rear set is possible, there are two holes to hold the rear brake master cylinder but it will be difficult to get the alignment for the brake master cylinder push rod. I would not want the exhaust hanger bracket to be outboard of the visible machined face of rear set. This is precisely why I want to dry build it before brazing lugs onto the frame and before painting it.
Insomnia strikes again so I will try and get you up to date with progress. I decided the 4mm aluminium exhaust hanger bracket was too flimsy and with a vibration mount at one end was not a "fail safe" bracket so I knocked this up from some 20mm OD x 1mm tube and some 10mm OD x 1mm tube.
I originally intended to use 8mm bore rubber air hose to provide a vibration isolation but when I tightened up the through bolts it was virtually solid. I turned down 2 spacers from 10mm aluminium bar, 4mm longer than the mounting eye tubes and then bored them 6mm. The void between the ID of the mounting eye tubes and the spacers will be filled with clear silicone bathroom sealer to provide the right degree of elasticity.
Trying to fit the rear brake master cylinder revealed a clash between the banjo union and the bolt head for the top hanger bolt.
In reality it will be slightly worse when I fit the brake light pressure switch (necessary because there is no mounting place for a standard mechanical contact switch) which I think has an even larger footprint than the union. In order to maintain lateral alignment of the brake actuator rod and the centre of the brake master cylinder, I can only spacer the master cylinder about 6mm from the face of the rear set which is not quite enough to give the necessary clearance. This will require a bit of pondering, which is, I think, always the best bit about building a modified bike - how best to make the modification safely, in a way that you have the capability to manufacture the modification, and that is elegant (minimalist), durable, functional and aesthetically pleasing and is maintainable. A hydraulic switch is probably more reliable but its positioning is not ideal and there will be a lead to it outside the main frame rail so not aesthetically pleasing. Ducati mechanical rear brake switches are notoriously unreliable, I must have replaced at least one on each of my 4 Ducatis and they always seem to misbehave the on the day before MOT. Also the arrangement of the rear set has no obvious location to mount a bracket to hold the unreliable Ducati switch. If I stare at it long enough I am sure a solution will become evident.
Today was trying to solve the clash elegantly. I thought the problem was the bolt head protruding beyond the face of the rear set. So how to get rid of the bolt head? A mushroom cap screw was considered but difficult to buy in that length also the hole in the rear set was drilled an odd size (slightly less than 7mm). My solution was to tap the hole in the rear set 8mm and machine a piece of steel bar with an 8mm thread for the thickness of the rear set and turn it down to 6mm for 45mm and thread the last 10mm with a 6mm die. It took a long time to make because the only bit of steel I had was 10mm diameter and my lathe will only cut steel about 006" per cut. Also all the calibrations on the lathe traverser and lengthways slide are imperial so it taxed my mental arithmetic to the extent I over cut version 1 forgetting that setting a x 000" cut counts twice on the diameter. The bit of steel bar I had was an absolute bugger to turn down, the swarf kept chipping off and getting between the tool and the work piece causing a very corrugated finish. When I came to zinc plate it, I dropped it in the acid to clean off the cutting oil and it didn't fizz as bolts usually do and when I put it in the Zn SO4 and turned on the current, no zinc plating was taking place. I realised the scrap piece of bar must have been stainless steel. Anyway when I fitted it the brake pipe union still fouled the rear set so I will have to turn up some aluminium spacers.
Had some good and some frustrating time in the garage also this week, focussing on how to mount the tank and the seat. Making the mould for the tank I just rested it on the two rear facing lugs for the airbox/battery box and on the original arch which holds the original tank hinge pin. Clearly there will need to be some form of vibration proof mounting and those split circular ribbed thingies you see on Tritons were considered but they raised the tank too much and actually looked naff. I got some 25mm vibration mounts from TME in Poland for about £1.50 each and screwed them into the relevant holes. They raised the tank too high and caused it to sit inclined forward.
I must have had the tank mould on and of the bike about 50 times (it weighs about 15kg with all the filler in it and it is a snug fit so I had to be careful not to damage the top surface) adjusting the vibration mounts with washers and using different thickness mounts ( I bought 25mm and 20mm male female mounts at the same time but the 20mm mounts were too hard). Eventually I got the tank on an even keel and with a uniform space front to back above the frame rails (but still about 10mm too high). I then bored some 30mm indents into the bottom of the mould to lower it.
