Wednesday 20 July 2022

The AJS 33/7 Trophy Model Restoration: The Petrol Tank, Battery Carrier, Oil Pipes, Gear Lever, Footrests, Carburettor and Wheels

It’s been over a month since my last blog post about the gearchange positive stop. Quite a lot has happened during the past weeks and various longer term sub-projects have come to fruition. I have also spent an unbelievable amount of time on bureaucracy - with which I am not accustomed, sorting out various UK government related issues for our Ukrainian mother and daughter that now reside with us – see previous posting.

But now, back to motorbikes!

The Petrol Tank

The petrol tank that came with the bike is the original tank that would have been made by AJS in 1933. This is a picture of it on the bike before restoration was started.

The tank still has its original chrome plating and I plan to have it re-chromed, BUT there are 2 large dents that spoil the appearance. If the tank was to be painted then this would not be a problem (because the dents could be filled) but chroming requires a very smooth surface finish of the original steel …and free of dents! The 2 pictures below show the damage to the left and right side front surfaces.

The first step was to send the tank to a local plating company to have the existing chrome plating stripped back to bare metal.

As regular readers of my blog will know, I try and do as much as possible in my own workshop but, as I’ve mentioned on a number of previous occasions, I have neither the specialist skills nor equipment to take on complex sheet metalwork projects. One of the difficulties that all restorers have these days is finding craftsmen with the skills required to be able to repair damage such as this. The re-purposed Royal Enfield Bullet tool box into an oiltank for the V-Twin is at the limit of my expertise.

Luckily, I have a good buddy whose brother-in-law has spent his whole life doing complicated things in sheet metal and with some gentle persuasion he took on the job of taking out the dents in my tank. This was not a 5 minute job! The first step was to carefully remove the weld at the seam and peel back the bottom of the tank to gain access to the inside.

Incidentally, the rusty appearance is merely surface rust and the sheet metal is actually in very good condition. The surface rust will disappear in processes to be applied later.

With access to the inside of the tank the dents were very carefully beaten out to give a completely smooth surface for plating.

The bottom of the tank was then reattached with the TIG welder and tested for leaks - I pour in a couple of pints of cellulose thinners because it will find every leak there is and it doesn’t leave a residue. One of the welded-on lugs was found to leak (the one in the bottom right corner in the picture below). This is a common problem with this design of tank fixing because people use a bolt that is too long ….and simply keep winding it through the thread until it goes through the tank. The entire lug was removed carefully with a dremel, the hole repaired and the lug reattached. Again, not a 5 minute job.

I now have a tank that is dent-free, with a surface suitable for chrome plating and holds fuel without leaking. Thank you Jo!

Oil Pipes, Gear/Brake Levers and Footrests

Making the oil pipes has followed the same practice as previous projects, namely bending pieces of fence wire into the required length and shape (as the Kiwis would say, use number 8 wire) and then anneal and bend the pipe accordingly before silver soldering a banjo connector or nipple onto the ends.

Nowhere near as many pipes as the V-Twin! In the last picture, the gear lever shown has been made from a section of 30mm x 10mm steel. The main taper of 0.80 was machined on the milling machine and the lever was silver soldered onto a spare splined section that had previously been used for an external linkage on some racing bike (that’s the brazed bit). Filling the centre hole and a peg for the rubber are yet to be done.

The serrated end of the extension for the footrest can also be seen; there is a similar piece on the other side of the bike. Although simple looking pieces, there is quite a lot of work in making these. The serration requires careful setup on the milling machine with a rotary indexer and a 450 angle plate and the 7/16” square hole in the centre (to fit the 7/16” square bar that passes through the engine plates) is spark eroded.

On the left side of the bike, the brake pedal has been made to replicate an original.

And the battery carrier has been remade in its entirety. The long securing bolt on the top has both LH and RH threads.

The Carburettor

The AJS 33/7 Trophy has an Amal Type 6 carburettor and because of its downdraught fitting has a 150 angled float chamber. Luckily, and although the external appearance changed, Amal did not change much inside the carburettor as it evolved in later years into the Types 76 and 276 and most of the internals are interchangeable – see here. The external appearance of the float chamber is also different between the early and later models. These earlier carbs and float chambers are much rarer than the later models and difficult to find if they are missing.

The carb itelf showed minimal wear and it was sufficient to renew the internals - jets, needle, main slide, adjusters etc with new parts, shown below.

The Wheels

Last, but by no means least, the newly built wheels came back from Wheelwise. As always, Steve has made a perfect job of these.

And, with new 20” tyres and tubes from Vintage Tyres and new (soft) brake linings and springs I now have something that is starting to resemble a motorbike.