Oil Tanks, Saddles, More Castings and Completion of the Steering Locks

 

Oil Tanks

The Mk 1 KTTs had a different oil tank from the other Mk 1 OHC Velos. The 2 main differences are that the filler cap is on the left side of the bike and provision of a much larger oil tap. The oil tap allows a 3/8” inch bore feed pipe to be fitted and this, in turn, gives a reduced flow restriction for the gravity-fed oil into the engine to the upstream side of the pump compared to a more common smaller diameter pipe.

The picture below shows the 2 original KTT oil tanks to be fitted to KTTs 55 and 305 whilst the other tank is a standard oil tank that will be fitted to the cammy special. The standard oil tank is one of 2 that I had made in India over 10 years ago and was copied directly from an original Model K tank that I took out to Bangalore.

However, apart from the obvious cleanup that is required (and that will be done in the "painting and plating" stage of the project), a couple of repairs were needed to the KTT tanks. The first was to the large boss that supports the oil tap on one of the tanks that had rusted to an extent that the tap would not screw in. It is a large (15/16” diameter) 20 TPI thread and rather than buy a threading tap (to clarify use of the word "tap" for non-English native readers of my blog, "tap" has more than one meaning - here there is an "oil tap" and a "threading tap" - quite different things) to recut the thread – which was pretty expensive and would only be used once, I decided to screw-cut a male thread on the lathe on a piece of hexagon bar and to use that to gently re-form the thread in the boss.

Although some slots were cut into the threaded portion (to replicate a tap) and this approach worked well on a threaded brass filler for the V-Twin this approach did not work here …it simply detached the boss from the tank with very little effort being applied!

I suppose that, being an optimist, it is better that this happens now rather than when the tank is full of oil and on the bike!

Plan B: Make a new one,

screwcut the thread and check the fit with the oil tap while it is still in the lathe

carefully clean up and tin the mating surface of the oil tank and the new insert and soft solder the insert into the bottom of the tank.

These tanks are constructed entirely by soft soldering and soldering the new insert in place has to be done very carefully to avoid un-soldering other parts of the tank.

I can’t remember if I mentioned this before, but my powder coater told me of a customer that brought along a 2-compartment (oil + petrol) flat-tank from some vintage bike to be black powder coated and, in spite of being warned about the temperature used in the baking process (around 200 ⁰C), ended up with a pile of sheet metal and a large blob of lead. A salutary tale!

The oil tap itself needed a couple of repairs: first, the filter had become detached and needed reattaching;

and secondly, the oil tap knob looked like this:

….not a pretty sight! 

A new knob was made in 2 parts, namely a steel centre that has a square hole in the centre (filed to shape rather than spark eroded) to fit the male square on the end of the tapered portion and with “bump stops” for the fully-open/fully-closed positions plus a brass lever, which was machined out of a piece of square bar on the milling machine.

These were silver-soldered together to make a complete and well-fitting oil tap knob.

Last, but by no means least, new viton seals were fitted to both of the filler caps.

 

Steering Locks

In my last blog I mentioned that I had made steering locks but that I planned to replace one part, the head steady clamp (KA-43), that I had used with a modified version that was threaded. I had made a pattern for this by adding a boss to an existing head steady clamp and, together with patterns for saddle clamps (KA-111), these had been taken to the foundry for casting.

These were cast in HTB3 – a high tensile brass. This material is remarkably strong with a tensile strength quoted as 740 N/mm² (see, for example, here). This is in the same range as EN8 steel and more than adequate for these components.

This is the collection of castings that came back from the foundry.

After tapping a 5/16” BSF thread into the boss of 3 of the head steady clamps I now have 3 steering locks as shown below.

One of these (upper right in the above picture) is narrower and shorter than the other two because I had to modify the design when I ran out of square alloy bar. A couple of people that read my previous blog contacted me and asked for the dimensions and so I have annotated a photo, shown below, that should be sufficient to make one.

The dimensions in the picture above are for the smaller design because I think it is actually an improvement over my original version.

 

Saddles

In the 1930 Velocette KTT brochure the saddle fitted is advertised as “Lycette Aero Elastic, three-point adjustable fixing”. I have a number of Lycette saddles in my “store” but all of the stem-fixing design – the type that is supported on a tube that fits into the rear frame tube.

However, I do have a three-point fixing “WRIGHTS” saddle in excellent condition that, with a swap of a badge, will morph into a Lycette saddle.

The saddle that came with KTT 305 was a Dunlop “Drilastic” and the cover was in very poor condition

Luckily, reproduction Dunlop covers of this size are readily available. These are advertised as the “small” variant here in the UK and this turns out, as far as I can determine, to be F89/4S in the Dunlop advert – see below – I had already fitted one to the AJS 33/7 in the last restoration (see here) and although they are a bit tedious to fit – the cover needs riveting to the seat frame, these saddles are quite straightforward to restore.

The other 3-point fixing saddle that I had was another Dunlop “Drilastic” but a larger size. It turns out that these were made in 6 different sizes (!!) as shown in the 1931 Dunlop brochure below.

Acknowledgement to Dennis Quinlan from whose blog this picture was taken. See here for an exposition on early saddles.

The picture below shows the original larger saddle, complete with its frame.

This identifies as F69/4D in the Dunlop advert and I found it impossible to source one of these in the UK. Luckily, I found what appeared to be the correct saddle on the website of a French motorcycle dealer and, although the dimensions given on the advert were incorrect, it appeared to be the correct size that I determined from the ratio of the length and width. I ordered one and it fitted the seat frame perfectly.

It has a different surface finish on the top

and, as can be seen in the picture below, the smaller seat cover actually fits inside the large one.

The next detail to be resolved was the “DUNLOP” badge on the back of the seat - the seat is really not complete without this.

I tried using letter stamps of the appropriate size on a piece of brass strip but this looked pretty crude. Eventually, I found an online engraver that could produce a pretty good approximation to the original – the picture below shows an engraved and blacked badge compared to the embossed original.

I figured that this would be about as close as I could get to the original and after powder coating the frames

buying another batch of bifurcated copper rivets and annealing them

I fixed the badge to the covers and the covers to the frames. The picture below is the smaller cover compared to the one fitted to the AJS with an original badge.

The new badge is a bit shiny but I’m sure that can be fixed!

The picture below shows the smaller saddle on KTT 305. It is important that all rivets, front and rear, as shown in the advert, are used to ensure the cover is properly secured and does not “tear away” from the frame.

The castings for the front saddle clamp have not yet been machined and I’ll get to that in the coming weeks.

Tool Boxes, Steering Locks more Casting Patterns and another Steering Damper

I had fitted new Andre steering dampers to both KTTs but was missing a damper to fit to the cammy special. I had this collection of bits and pieces.

One of the most important parts is the base of the damper – the bit that fits inside the stem of the bottom yoke that supports the entire assembly and I was missing one of those, at least, one that fitted. Rather than make one from a solid piece of steel (which would generate a lot of swarf) I made it in 2 parts

and then silver soldered them together. I have retained the original tapered locking bolt which, importantly, has a small pin that engages with the slot that I machined with a small end-mill in the base to avoid the bolt rotating when it’s tightened.

There were a few more little bits and pieces to make, shown below.

The long hexagon nut serves 2 roles: it locks the base to the steering stem with a 3/8” BSF thread whilst the other half of the nut is threaded 3/8” BSCY (which is a finer thread) into which the stud attached to the damper knob is screwed. Finally, a dome nut (will be plated later) has been made to lock the knob onto the stud and a new star spring (the Banbury Run autojumble) completes the assembly.

Toolboxes

Mark Barker makes the most beautifully crafted toolboxes (the AJS 33/7 has one of his) and he has made me 2 that will be fitted to both KTTs which I also picked up at the autojumble.

These are not yet fitted but this is how one looks just resting in the frame tubes

and which will be fixed in place in due course using stainless steel U-bolts.

These are available in a variety of different sizes, one of which fits the frame tube exactly.

Top Tube Saddle Clip (KA-111)

The front of the seat is supported by one of these and I had  ...none. This is what it looks like in the parts book

I asked in my last blog post and also in Fishtail (Velo club magazine) if anyone had one that I could use to make a casting pattern – and now I have one. This is what it looks like in the flesh.

This one is showing its age – some brazing repair on the top part and some distortion on the bottom; nevertheless, it is quite adequate as a basis for making patterns.

I have described in some detail how I make resin casting patterns using original parts, see for example here and here so only a brief description is given below.

Various gaps and holes are filled in with wood (the large hole is filled with a piece of wood cut from a broken garden fork handle, machined to the correct diameter and cut in half to fit), body filler and thick gasket paper is added to the surfaces that will be machined on the castings to ensure there is an allowance for shrinkage.

Each of these is then suspended (in this case, using a magnet) in a small plywood box and surrounded by screws. All surfaces are liberally coated with Vaseline

before pouring silicone rubber halfway up the parts.

After attaching conical pieces of glossy paper to each

silicone is poured to the bottom of the screws to form the top half of the mould.

The mould can now be dissassembled and used for making resin copies. This is what they look like after setting and removing the top half of the mould

and, after a bit of a cleanup, these are the finished items - 2 of each.

In addition to these resin patterns, I have also modified an existing cylinder head steady clamp (KA-43) by adding a ½” diameter boss.

This will be used as part of a steering lock assembly – see below. All these patterns are now with the foundry for casting.

 

Steering Lock

After fitting the petrol tanks, it was immediately apparent that steering locks were required to avoid damage to the tanks from the handlebars/clamps. It would be a pity to put a dent in these beautifully crafted tanks before they had even been painted!

To this end, I used a piece of square section solid aluminium

that I had left over from some other job to make these

and that, together with some round rubber buffers from eBay (40mm OD, 10mm ID, 20mm thick) and a head steady clamp

makes an effective steering lock.

I have modified the design slightly from the picture shown above by incorporating a boss, which will be threaded 5/16” BSF, into the KA-43 part of the clamp and so eliminating the nut and washer on the inside but I have to wait until the castings come back from the foundry to include this.

 

And Finally…..

I have been out and about on the AJS 33/7 Trophy recently and a buddy of mine drew my attention to a lady by the name of Florence Blenkiron. In particular, he noticed that the bike that she is riding here

Acknowledgement to whoever owns copyright of this picture

is a 1930s cammy AJS – this is the racing version rather than the off-roader that I have (see here and here). This picture was taken in 1933 so would have come out of the factory the same time as mine. To say that Florence Blenkiron was an achiever would be a serious understatement – she was the first woman to break the 100-mile per hour barrier on a motorcycle at Brooklands among other things. More details can be found on Florence here and here.