Friday, 15 February 2013

Brakes, cams, springs & other mechanical merriment.

Back from Norway, I find a handy bit of tube on my desk.

So here is a nice new bush:

It is made from 5/8" x 16 SWG seamless tube, pressed into the brake plate. I may put an oil hole in it if I decide there is enough access.

So, now I am assembling the brake I find something I didn't expect.

I replaced the brake lever return spring, because the arm makes an angle of more than 90 degrees with the brake rod - i.e. it leans forwards (the arm is upward on the brake cam)

You can see the old spring is quite weak and would put the arm in the wrong place. So now I have a new spring, the arm points backwards and makes an acute angle with the brake rod and can be moved to near 90 degrees, as the brake comes on.

The thing is, I didn't expect the spring to operate the brake with the brake rod disconnected. Because the lever return spring is quite strong, it turns the cam, overcoming the shoe springs and the brake comes on. It's obviously designed that way.

I guess all my previous biking experience has had the brake lever return spring on the foot pedal, not the brake arm on the cam.

Anyhow, some more pics for Chaz:

Wednesday, 13 February 2013

Engine Progress!

I have news on the engine! I spoke to Bernard at Ashpole's today, and we have a progress report:
  • The block, old head, and cases have been degreased
  • The old head has been bead blasted ready for sale
  • The timing side mains are in. Bernard is going to grind the journals 5 thou under since they are slightly oval and tapered - and since he is doing that, which will contaminate the old roller mains, he will fit the new ones.
  • He is dealing with the worn camshaft journal
  • There are two options with the broken fin on the block - one is to make a replacement fin and tack it in at each end; the other is to build it up from the root with weld. He is getting a quote on the second option.
  • Unfortunately, during stripping one of the tappet blocks proved to be stuck. Three of them fell out, the fourth fought to the end:
Fortunately Drags appear to have replacements!

Tuesday, 12 February 2013

Oil Filter

Here chaps & chapesses is a small deviation to our Square Four restoration - an oil filter. This is an aftermarket filter housing intended for a Commando - it uses a standard spin-on filter cartridge.

I'm mounting it under the gearbox, between the frame tubes on a steel sheet metal barcket, mounted on the engine/gearbox tie studs.

It mounts with two 5/16" UNF screws, which I have purchased in stainless.

Right now, it's too high. I want it high, since we have a lot of sleeping policemen (speed bumps) around here, and twatting the oil filter on a bump doesn't sound like a particularly good way of improving engine life. However, having it this high means I can't undo the filter cartridge!

So, I plan to modify the bracket to drop the whole assembly about 1 1/2", such that I have clearance to get the cartridge off but it is also pretty high.

But, all that is going to have to wait for a bit, because I have no oil pipe. and since I have no oil pipe, I cannot decide how to route the pipe and I cannot decide on the final location for the filter.

Another job on hold.

The cartridge I used here was the the EMGO 10-26910 for the Commando (about 55 mm tall); you can use the Champion COF103101S (used on Citroen cars), which is taller (about 77 mm tall). 

And stopping.

With the wheels in motion, we can start to look at the brakes. The front is still on the bike, but the back is off and apart:

There is nothing particularly horrendous to report at first sight. The linings are nice and thick, there is only a moderate amount of greas and gunge around and everything operates as it should.

Closer inspection reveals that the adjuster is missing - easily fixed, from Draganfly; a 1/2" BSC tap can be used to clean up the thread, and the sliding parts degreased. No problem.

But what is this? This little bodge is revealed when the cam is removed. The brake cam shaft measures 1/2" OD and is unworn. The hole in the brake back plate measures 5/8" ID and is unworn, so what is going on? I would have guessed that this little 'sleeve' was doing service to fill up a worn hole, but no. A session with the Ariel parts book and Drags 'List 15' leaves me none the wiser.

However, a chat with Mick at Drags reveals all. Having found me my missing adjuster, Mick goes to look at their stock of brake plates and finds that one of them has a bush pressed into this hole - part of the brake plate, hence no separate part number or identification in the parts book.

So now I have some 5/8" x 16 SWG seamless tube on the way from eBay.. 
Unworn cam shaft and brake plate hole.

Another mystery, a riveted cover over a hole in the brake plate. This hole is for a lug forged into the left hand Anstey link 'stirrup' which serves to prevent the brake plate turning.
The hole has a sheet aluminium plate and a paper gasket held in place by a few brass rivets, some of which are missing. It appears to be there to stop debris getting inside the brake drum.

Talking of the brake drum, here it is, treated to a coat of Finnegan's finest:

And here is the back plate and shoes. The backplate has a lot of dings and nicks, the worst of which have been dressed. We'll see how it fares on the abrasive mop before deciding what else to do with it.

Rolling rolling rolling...

This week I have started work on the wheels. I've decided to strip and build the wheels twice, since I want to achieve the Phase 1 build (mechanically complete, minimal paint or chrome) and get the on-road shakedown process started. This will let me change stuff and make any modifications I need without damaging an expensive finish.

I had hoped to achieve this without building the wheels, but since the spokes are in a very bad way I will have to replace them before MOT. Since I enjoy building wheels, I am going to clean up the rims and Hammerite the hubs for Phase 1; I will then tear them down and rechrome for Phase 2.

So, I cast around for good prices for tyres and spokes. I've noticed that the drive side rear spokes are single-butted; all the others are plain, so I have asked Central Wheel to quote for stainless spokes and nickel plated nipples to match fuor samples I have removed from the wheels.

Central Wheel have very good prices on Avon AM6 & AM7 tyres as well.

Sunday, 3 February 2013

Wiring, or Muck & Bullets

Regular readers will note that this post was originally published a few days ago. It's been moved to it's own page since it is growing...

Moved by a discussion on cable ties on the AOMCC forum (how many rivets in a BR Standard Class 5?),  I started to look closely at the wiring harness.

It is a curious thing indeed. Whilst it has been modified, there are many original cables left in it. These are rubber covered, used 14 plated 0.030" strands (that's 1.0 mm2) and use small coloured bands at each end to determine the cable colour - insulation is always black. The diameter is equivalent to a modern 2mm2 or 3mm2 standard PVC cable (not thinwall), which I may use when rebuilding.

I've discovered that you can buy single cored HO7 (rubber covered, oil resistant) cable, but getting it in the right size and the right colour is a problem. Since it is specified for trailing mains cable, for frequent handling it tends to be in 3 core brown/blue/green & yellow for single phase mains supply.

We shall persevere with the help of Mr. Google. I might ask this chap who looks he has some useful stuff and is local to boot. Or the 318TQ cable here might do it too.

Connections are made with conventional bullets, with the rubber covered single & double snap connectors. My bullets are solder type as shown in the picture, not crimped:

The real curious thing is the sleeving. There is a short (maybe 1 foot) length passing from the front under-tank area to the headlamp; another, smaller diameter from the headlamp to the dip switch; a bare single strand is provided for the horn push. It appears that from under the tank the wires passing to the regulator/coil battery are uncovered. There is a small (1 inch) length of rubber sleeving tying together the wires that start and finish in this area (dynamo to regulator for example) - and that is it! no more sleeving. I suspect that the wire to the rear light was a single strand, since in 1951 there would have been no stop switch. My harness is pretty mangled in this area.

It must have appeared a bit of a dog's breakfast, with all that loose cable!

There is a wealth of information on the AOMCC forum about cable fastening, HERE. However, here is a picture of my rear mudguard:

Now I know that most normal people will glimpse that picture and instantly lose interest, and those that pause for thought will then wonder why we bother with this obsession of ours, but for those of you that want to know how Ariel retained the cable to the rear lamp inside the rear mudguard, well, here is the picture you have been searching for all those years.

There are about five of these little tags welded around the LHS (horn/battery side) of the rear mudguard, and the cable slots behind them. You bend them a little bit to retain the cable.

Note that my mudguard is of the one-piece variety, that pivots around the forward bolts (the ones that pass through the seat lug).