My attempt to seal the
Commando’s fibreglass tank last year was a disaster – filled with petrol it
lasted less than 25 miles before the thing started to dissolve again. So, since
its tax and MOT 6 months ago the bike has not moved. Smoke billowing from the
exhaust didn’t help either.
Being retired and able to
find the odd minute to tackle little projects I decided I would make a tank
myself. It would have to be alloy of course and perhaps a bit special.
This would also have the benefit of not allowing direct comparison with the shape
of the original. I had in mind something similar to the Gendarmerie Commandos
of around 1970 - the ones with the slab-sided tanks.
So, I put a pattern together
and went to see the Club 71 welder. AC TIG is the only way to go he said.
Unfortunately this sort of equipment is extremely expensive and he didn’t have any
- though thought he might get a rig in future.
And anyway he would need one to work on his own alloy tank too.
In the meantime I felt something
less adventurous, in steel, would be good practice. My plan was to piggy-back a
new tank on to the existing. This would be removable, so retaining the original
Fastback tank and its fairly rare Fireflake finish.
A bag was sourced from
GetGeared and cardboard replica made to take patterns. The shape was fairly
simple - requiring metal bending but no panel beating. Steel sheet
0.9mm thick and filler neck were bought off ebay and a s/h MIG welder through Preloved. I did a
night-school welding course many years ago but not much since - so wire and gas were
wasted before I tackled the real thing.
Tacking the panels together was
easy enough but when I started welding proper it was clear it would be
impossible (for me) to get leak-proof seams. Another problem was distortion. For future projects I know that more frequent tacks will help.
Anyhow, the tank is finished, painted and ethanol sealed (recommended for
steel tanks too now
The project was done for the
pleasure - but costs did mount up: tankbag £25, steel sheet £10, filler neck
and cap £15, tap and connector £10, Tapox £35, wire and gas say £25. So that’s £120
excluding the mig welder which I now have for other jobs. Sounds a lot but
compared to £650 + cap + taps + paint, from a well known Norton parts supplier
it doesn’t seem so bad. Interestingly, the sealant is the most expensive single
item, doubtless because they can charge what they like at present.
And, the smoking exhaust has
been sorted with rebore and pistons. Just another £225.
Hurray, roll on Spring.
2 comments:
That looks really smart.
The 'new' tank looks neat.
Would it pass an MOT like that?
As the tank appears to comply with current Motor vehicle construction regs I hope so. However the machine was registered before 1973 when regulations were more lax and even glassfibre tanks and black and white number plates were permitted. In any event,if I'd have made a direct replacement it would have been similarly constructed - just mounted a bit lower down.
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