Friday, 28 December 2012

Very Flat, Norfolk

We can muse over what the oft-quoted Noel Coward meant by this line from 'Private Lives', which premiered at the Edinburgh King's Theatre 1930. However, keen observers and students of geography will know that Norfolk, whilst undeniably low lying compared to some parts of the country is positively undulating when compared to others, notably the fens, at least in places.

Undulating is also a word that could be used to describe Amelia's sump plate, which won't be doing any sealing anytime soon:


Anyone got a spare one?

Wednesday, 26 December 2012

Ever deeper - Coupling Gears and Bearings

Under the guise of clearing out the workshop (I was - I was trying to finish off the primary case polishing, but Mrs H was surfing and wanted some Boxing Day P&Q) I ventured into the shed to retrieve the coupling gear cover.

The idea is that once the coupling gear cover is off, I can polish it and the primary case.

The nuts and screws came out relatively easily, but the cover was a b****r to get off, as we say in Norfolk.

Turns out that the cover has a steel locating sleeve around two of the studs, which corrode and resist the removal of the cover. A few minutes with the hide mallet and a soft drift had it shifted (seized at the front, where the steel sleeve meets the weather).

Anyhow, here it is, off:


No drama there, all present and correct - though I expected the coupling cover main bearing to slide out of its journal and stay on the shaft. The peculiar face-type oil seal is cratered - bits of the seal are completely missing.


Here is the cover, complete with bearing. There is a fair bit of gunge in there, which will be ferrous material from the wear on the gears I expect.

The bearing is in there, and for some reason refuses to turn. The story is that this bearing, which is essentially similar to the other drive side main roller bearings, has a inner race which is 0.001" smaller than the roller bearing in the crankcase, so that the corresponding journal on the crankshaft is also smaller. 

This means that when the engine is assembled, the smaller outer journal (the one for the coupling gear cover bearing) will pass through the main bearing in the crankcase.

This bearing is also lipped on the outside of the outer race. It's not entirely clear why they did this, since the crankshaft is located axially at the timing side.

Anyhow, this went back into the workshop to be cleaned up. It turned out that someone had fitted two paper gaskets to this cover for some reason.

The bearing came out with some gentle persuasion (a hammer and a socket in the time honoured fashion) but a look inside the outer race revealed it was junk:

A massive pit and some odd wear marks in the outer race. There were possibly some wear marks on the inner race as well, but we need to look further before passing judgement on those. 
All in all, a jolly evening's work.


Shock Horror!!!

To get further into the engine, we have to remove the crankshaft shock absorber. This consists of a sleeve splined to the rear crankshaft and hence driven by it. The sleeve has a external spline as well, and a section of it's length which is a plain bearing surface. The engine sprocket runs on this plain section, and is machined with a face cam. The corresponding cam profile is machined onto a further part, which is splined internally and is driven by the sleeve on the crankshaft.

In order for the crankshaft to drive the engine sprocket, and to prevent the face cams from riding over each other (resulting in no drive) the whole assembly is held together by a heavy spring.



Hence if the system is running smoothly, the cams are held together by the spring - but if there is a sudden high torque the cams are free to slide over one another and compress the spring. This thus forms a transmission shock absorber, rather like the rubber cush drives commonly found in more modern machines in the centre of the clutch.



I guess that at the time these engines were designed rubbers were not ably to withstand the heat & oil found in the primary drive.

Anyhow, it is all in pretty good shape, with no evidence of wear anywhere. Even the sprocket is good. It has 25 teeth by the way, just for the record. This strikes me as a little odd - Drags list 26T and 27T sprockets; my '52 Ariel Owners Guide says 24 solo and 22 sidecar; the '51 SQ4 parts book lists 22T, 23T and 24T.

Mr Waller however lists 25T, so it must be OK!

The only thing I could find at fault was the retaining nut, which is pretty mangled and the split pin was missing.



Bracketry

Brenton Roy posted this picture on the AOMCC forum to help out us poor souls restoring Mk 1 Square Fours:




It shows, rather obviously, the top of the oil tank with the breather tower, the filler and a mystery bracket.

I had no idea this bracket was there, but since I have had a mystery hole in the top of my tank I suppose I should have figured it out. Anyhow, it was a simple matter to make one out of a bit of steel strip that was laying about in the bits box:



I'll fill in that hole next time I have the welder out.



Friday, 21 December 2012

Monday, 10 December 2012

Still Cold Outside


So we have to find another job that will  bring us indoors.

I don't have many of those left now, but one thing I haven't touched is the oil tank.

Its the right tank, but it has a number of problems:
  1. The filler neck is bent, and the thread damaged on one side. It looks as though some clumsy oaf has dropped it neck down on a hard floor.
  2. The breather connection is bent, caused by said oaf probably in the same floor-dropping activity. The picture above shows this one, and the filler neck, though I had started work on it when I took this shot (as witnessed by the 38 mm socket acting as a former)
  3. The filter is missing
  4. There is a hummungous dent in the side that is hidden by the battery
The first of these little gems that I tackled was the damage to the filler neck. The bend was on one side and had splintered the crests of some of the thread away from the base material. Looking closely at this I decided that the material must be relatively hard, so I elected to normalise the metal.

Normalizing is the heating of steel to above its critical temperature followed by cooling in air. The piece is usually left somewhere warm. Normalizing is a quick method of softening a piece to the point where you can harden and temper it for use for your chosen purpose.

I used the trusty Rothenberger Superfire 2 to heat the area to bright red, and played the flame at a distance to bring the temperature down as slowly as possible.

Then, using a large socket in the vice, I placed the neck over the socket to use the socket as an anvil. I used a 38 mm socket, which supports the neck nicely and is a close fit.

With the material cooled & annealed, I was able to push the bent neck back into shape with a variety of drifts & chisels. This went very well, which just left me with the thread to fix.

I did this in two stages, possible needlessly. I started by grinding out the damaged part with the Dremel, since it was confined to about 15 degrees of the full circumference and maybe 6-7 pitches. I cleaned it up using a 1/2" CEI plug tap as a chaser.

Looking backward, I could probably have saved more of the original material if I had started with the tap. Still, the cap will now happily go all the way down to the seal!

The next job I had to tackle was the breather tower. I had a very good picture of what this is supposed to look like from (The Ever Helpful) Brenton Roy of the AOMCC.

As you can see from the pictures, the delightful minaret shape of the breather was a pale shadow of it's former self after the short bungee-less jump onto the garage floor, and I was afraid that much grief provided by attempting to cold form it back into shape would:
  • Squash the tube flat
  • crack the material of the 'minaret'
So, I figured some hot work was called for, though at this point I hadn't decided if I might do this with the breather detached from the tank. Holding the tank by the lower mount (so I could pull up on the breather connection) I heated the breather bright red and held the little tube in a mole grip, with a suitable rod (actually a masonry nail).

I found that the tube would move from side to side quite easily once the material was hot enough, and this with some upward pressure was enought to roll the minaret up and out of it's inverted position. A couple of cycles of this and it was back to a very passable representation of it's former self.

Next job: the dent in the side.