More parts and minor progress.

October 8th, 2011

Again I have been buying parts. Through various contacts I have discovered someone I can buy some good second hand parts off. I got a set of good second hand differential parts so I can rebuilt my rear axle. I also ordered a correct length steering column (more about that in a sec), some brake parts, better rear hubs and a correct period switch panel. They haven’t arrived yet but hopefully soon.

I also went to visit Joss who is just down the road. He was able to show me the differences in steering column and why the correct column/wheel combination is important. He also showed me different sized grilles. He also demonstrated some techniques. Like gas welding thin aluminium! Now this is considered very difficult to do. These days when someone says weld aluminium they generally mean using a TIG welder. I don’t have a TIG welder but I do have oxy-acetylene gear. It seems gas welding aluminium is still done by craftsmen. The sort of people who hand restore million dollar old cars and so on. If it’s good enough for them it’s good enough for me! Back to that in a sec too.

First steering columns. Over the years the steering columns and wheels changed. There were also some differences for certain models of A7 (the sporty/racy ones I believe).

The main differences are the steering boxes, the early ones mounted to the top of the chassis, and the the column length and steering wheels used. Other things changed too such as the rake angle.

The very early columns used a wheel that is clamped onto the column by a bolt. The later wheels are splined. Earlier columns had controls running inside them. If you have been paying attention you’ll remember I bid on and won an early box and column on TradeMe. Unfortunately it is no use to me and this is why…

2011-09-27 21.52.17 Steering columns and wheels.

When I was visiting Joss we laid out the different column and wheel combinations.  The early column and wheel are on the left. This is the same as the type of column I bought. It uses a very dished wheel that clamps to the column. These steering wheels are very hard to find apparently. The box mounts to the top of the chassis rails. The middle one used a longer column and  a flat steering wheel with a spline. This column also bolts to the top of the chassis. On the right is the later column and a ruby type wheel, also knows and an hourglass wheel. This column mounts to the side of the chassis and is the easiest to adjust the rake of (the two earlier ones require wedges or moving the flanges on the box). The rake needs to be adjusted for any sort of  ‘sports’ version of the Austin 7.

Now my car came with the later style column (the one on the right) and the middle style wheel. If you notice above the length of the columns to the wheels in all cases is the same. Using the middle wheel on the right hand column, as my car came, means the wheels is several inches further away from you than it should be.  One interesting thing Joss noticed is my wheel isn’t actually an Austin 7 one. It’s a Blumel’s amazingly. You can just read the mark on it.

The column I won on Trade me is the left hand side very early one. That requires the dished early steering wheel that clamps in place. These are hard to find and wouldn’t be correct on the car I am building. What I need is the middle column then I can use the flat wheel. This I have coming in a my lot of spare parts along with another Austin steering wheel I can hopefully modify and make my own wood rimmed wheel from.

Right, following so far? That’s not all the column/wheel combinations but I think that’s the main ones. Proper Austin geeks (or the usual books) can tell you the years when the changes happened.

The other thing Joss showed me was the difference in radiator surrounds.

2011-09-27 20.42.42 Radiator surrounds.

Now, I am not sure of the years (I need to look in my books to confirm) but here you can see two of the different style surrounds. I believe there was an even shorter one. I have one the same as that on the left. I actually prefer the one on the right. It looks more correct to my eye. And I think it would suit the sort of car I want to build. Most A7 racers are very short and squat. I actually want something slightly taller but not too tall to be unwieldy. The Dixi, my inspiration, uses a totally different surround altogether. Perhaps I could make my own?

Right, other parts I bid on and won were a silver faced Speedo and an original oil button. The early Austin 7s didn’t have a gauge, just this funny nipple like button thing. When the car starts getting it up the nipple pops out. Getting up oil pressure I mean. Then it starts dribbling apparently. I don’t think they were supposed to but they apparently usually do. I am not sure I will use it but I know these things are rare and hard to find so when no one else bid I did.

IMG_0828_1 IMG_0829_1 Oil button.

The speedo took a while to arrive. Not the sellers fault. Seems my building at work doesn’t have a post box at the actual address. Couriered items will turn up but things sent normal post will be redirected to the company PO Box.

Eventually.

It finally showed up so I took it apart. It’s pretty old and worn out. The thing is actually broken in several ways. The  housing has broken but it’s like layers of pot metal have come off the housing without it totally falling apart! It is like layers broke off it.This speedo would actually have come from a different model Austin I think so I am not sure it is even usable on the A7. The ratio might be all wrong.

Also the drive was broken. I didn’t realise until I pulled it apart. I suspect the housing was damaged by someone holding it in a vice trying to pull the unit apart. I didn’t try that. I held it in my hand and gently tapped the housing flange with a soft hammer till it slowly worked off.

IMG_0826_1 IMG_0827_1 Silver faced speedo.

Inside I found this.

IMG_0832_1 IMG_0834_1 IMG_0836_1

The main drive comes from a shaft that is meant to engage a small gear that drives the odometer. The actual speedo needle is driven off a kind of fly ball governor arrangement. As the shaft turns a weight flies out because of centrifugal force. This moves a little collar along a shaft that presses on a lever that moves a ratchet that drives a cog that is attached to the needle to make it turn.

I think.

I haven’t actually looked too closely yet. What I have seen is the little gear that engages the work on mine to drive the odometer has been stripped. Well, shredded is more accurate. It is like it seized then the worm gear turned the small cog into dust which is now spread throughout the inside of the housing as brass dust.

The good news is I opened up the other speedo I have (also not correct for an A7 I believe – it goes to 80mph) and the basic mechanism seems the same. I figure if I can find a suitable A7 speedo I can take it’s guts and transplant them into my early housing with my silver dials which perfectly matches the clock I have. Needs further investigation.

Oh, it is worth nothing the trip meter only goes up to 99.9 miles. I guess trips were shorter back in the olden days! If I ever get the thing finished I am not sure I want to go further than that in it in one go.

Right, what else. I went for a drive today to get more oxygen for my welding rig and I also got a reamer so I could sort out my brake bushes. I had previously cleaned up the Girling units and I have bought new cams and bushes. To put these in you first remove the old bushes. I machined up a little pusher from a lump of (horrible to machine for some reason) steel. This pushes into the housing and fits over the existing bush then using a vice and a big socket as a spacer you can push the old bush out.

IMG_0844_1 IMG_0847_1 IMG_0848_1

Brake bush removal.

With the old bushes removed I then used the vice again to push in the new ones. I then reamed them to size using a 7/16s parallel reamer.

IMG_0849_1 Reaming bush to size.

Now I thought this is all I would need to do. But I found when I inserted the new cams they were very tight. At first I suspected I messed up the reaming but no, it turns out it was the top end of the cam binding.

IMG_0850_1 IMG_0853_1 Cams.

The cam wouldn’t fit all the way into the housing. Looking at the new cam (left) compared to the old I could see the new one was slightly larger diameter under the head part. Possibly due to the cam being zinc plated where as the old one was plain steel. I carefully filed and sanded the new cam so it would turn easily in the housing but not be loose.

The cams are all different and so are marked with where they go. You must get the cams in the right places. The difference is where the notch for the brake lever is in relation to the cam position. The other odd thing I noticed is two of my new cams are zinc plated and the other two are plain steel.

IMG_0858_1 IMG_0860_1 Brake unit.

The cams are all stamped with their position. FN is Front Nearside. The others are FO (front offside), RN (rear nearside) and RO (right offside). The nearside is the passenger side or the left sitting in the car (nearest the footpath). The offside is the drivers or right hand side of the car. This is if you are in Britain (or another drive on the left country) only of course. God knows what Americans call it. Something with less vowels? They don’t even have footpaths!

Bah!

One problem when doing the FO cam was I discovered the housing was cracked where the bush fits. This one tended to bind up even more than the other side. Since it was damaged (2 out of 4 now – is this a weak point on the car?) I used the remaining rear unit instead of the damaged front one  (remember the other one I used to replace the front unit that broke around the mounting stud). I have one good second hand one coming in my latest parts lot but now I will need to find another I guess.

As I mentioned Joss also showed me the tricks to welding thin aluminium with gas. I’d generally heard it was impossible or at least very difficult. Now it is tricky but it can be done and in fact is exactly how they did it many years ago. There are a few tricks. You need good flux. The flux keeps oxygen out of the weld and keeps things clean. The flux was tricky to find but a friendly chap at a local welding supply shop ordered some in for me specially. It is a powder that you mix with water. It is terribly nasty, corrosive stuff! You have to be careful where you put it and be careful of the fumes from it.

IMG_0803_1 Aluminium welding stuff.

The stuff I got is Harris Al Braze 1070. It was NZ$50 a container but as you mix it with water (or alcohol apparently) it will go a long, long way. The flux is painted onto the metal you are welding with a brush. Instead of filler rods I am just using thin strips of aluminium cut from the same sheets I am welding. DIY filler rod! You don’t need to worry about what filler you are using then – it’s the same as the base metal.

I also got some stainless steel brushes to clean the aluminium before welding. You want everything really clean.

IMG_0807_1 Stainless steel brush.

The flux is great stuff. It keeps the weld clean and allows everything to flow without oxidising. The problem is when you heat it it gives off a very bright orange light. This is so bright you can see what is happening behind the flame and with aluminium welding you have to watch things very carefully. Welding aluminium is hard because it behaves so differently to steel. When you heat steel it changes colour. Everyone knows what red hot steel is. Aluminium doesn’t behave the same. You heat it, it stares at you looking the same then all of a sudden it turns into a puddle and you have a hole! Now there are subtle changes. It’s hard to describe but you can see when it is just on the verge of melting. The texture and appearance do change very slightly. With the flux there though the orange glow hides all this.

IMG_0805_1 Orange glow from flux.

The picture above doesn’t show how bad it is really as the camera stopped down to contain the brightness. When seeing it in person it is very orange. Normal welding glasses are dark to cut down the very bright light from the oxy acetylene flame. When using this flux you need something to cut out the orange. Joss put me onto using blue lighting gels. This works great! It totally removes the orange and also cuts down the brightness from the gas flame too. I got some gels from Surplustronics as used on stage lights. I think it was $3 for a sheet and one sheet is more than enough. I took my normal gas welding goggles and removed the dark filters and added my own made from blue gel (two layers) and a disc of thin acrylic. The goggles usually have a clear plastic impact disc over the darkened glass. I reused these plastic discs and sandwiched my blue gels between them and my acrylic discs in place of the welding glass.

IMG_0819_1 IMG_0823_1 Making my own welding goggles.

These are only a temporary solution. The problem with these goggles is they won’t help with UV at all. I thought UV only happened when you were arc welding (MIG/TIG etc) but the oxy-acetylene flame also gives off UV. There are proper aluminium welding goggles available but I will have to get those from overseas. As usual NZ either doesn’t have these things available or they do but at exorbitant prices.

The torch I use is a BOC light set I bought a few years ago to do steel brazing with. It’s quite small and so is ideal for thin aluminium work.

IMG_0818_1 Gas torch.

I am still learning the optimum settings to use and practising. After a quick try with Joss, where all I really did was make puddles, I came home and after making my goggles tried it myself.

The very first attempt went amazingly well!

IMG_0809_1 IMG_0811_1 IMG_0814_1 First attempt.

To weld you clean the metal with the stainless steel brush. Then you paint flux paste onto the aluminium and your filler rod. Using the torch you tack the two pieces together then you run a bead by pushing the torch along creating a weld pool that you sort of wipe the filler rod into. It is very hard to describe! It is also VERY hard to do. It is very easy to get too much heat into the metal and melt a hole in it. On my first go above you can see a hole. After welding the flux will leave a slaggy mess you can see in the left picture above. You have to clean this off as it is very corrosive (as is the flux paste – anything metal left in it will die). Hot water and a Scotchbrite pad clean it up well. I didn’t tack weld this at both ends so when I started welding heat distortion made the plates move so I didn’t end up with a flat weld.

For a very first attempt that was damn good! Actually that was a total fluke. Today, after going off to get a new oxygen bottle (first refill since 2003!) I did some more practice and wasn’t quite as good. Well, wasn’t as consistent. It is very hard. But like anything I think with practice I can get it.

IMG_0841_1 IMG_0842_1 Best attempt today.

This is my best attempt today. The front side on the left and the back on the right.  Pretty flat weld. Good penetration. Just blew a hole in the end. It certainly isn’t coming apart in a hurry though. But more practice required. I need to get to the point where getting that result is the norm, not a fluke.

After welding practice I decided to sort out the drag link  grease nipples.  It seems the early oil nipples are impossible to get. Actually I am finding it damn hard to get the later style even. No one seems to have them any more so I ordered some 5/16ths angles ones from the VAR spare department. These use a 5/16ths BSF thread so when I was out buying gas and the reamer today I also got a 5/16ths tap. The existing holes in the drag ling ends were pretty knackered. I made up some brass inserts to solder in place that I can then screw my more modern grease nipples into.

IMG_0861_1 IMG_0863_1 IMG_0866_1

Grease nipples.

I would have used a convenient piece of of brass stock to make the little mounting bosses but I didn’t have any convenient! Instead I used some brass dome nuts I had. These I drilled out then re-tapped to 5/16ths BSF to take the nipple. I then used the lathe to turn down the dome so it would fit into the boss on the drag link. I soft soldered the boss in place then painted them. Tomorrow I will reassemble the drag link. I would like to get some straight nipples to use if I can find somewhere that sells the damn things these days and doesn’t need you to have a business account to buy from them and is open on Saturdays! I used to know a lovely girl who worked at Paykels…

Ah, my front axle! Bah! Now that’s turning into a story. Will talk about that later.

The final thing for now is last weekend I took a little trip and in the front window of an apparently disused shop I saw this.

2011-10-01 14.59.54

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