Misc: Everything Else Complete Restoration of a Black Shadow

[Magnetoman]

I have just started a restoration of a 50 Shadow also. I plan on making as original as possible.

Most people here wouldn't know, but I'm immensely grateful to Keith and his crew for allowing me to use their extensive facilities on the Cannonball two years ago. My Ariel had lost compression when we reached South Dakota due to valve seat recession and significant wear of the exhaust guide. Who knew you could do an extensive rebuild of the top end of an engine in a motel parking lot at night and have the bike ready to ride in the morning? Anyway, without Keith's facilities (and his War Department surplus Norton valve guide), my ride would have ended only half-way across the country.

I enjoy working on bikes as much as riding them.

Me too. Relevant to this thread, I have modern bikes when I want a modern bike riding experience, but when I ride old bikes I want to experience them as close as reasonable to the way they were at the time they were made.

As an aside, in no small part inspired by Keith's trailer on the Cannonball, I bought a trailer of my own this time last year and earlier this year completed modification of it with workbench, vise, LED lights, tie-down tracks, etc.

Enclosed Motorcycle Trailer: Design & Build

And now for something completely different, as Monty Python might say. A search of the 'Projects' forum didn't turn up anything similar to what will follow in this thread, which either means no one will care about what I will post, or that (I hope) it's just that no one has documented suc...

www.britbike.com

Summers in the desert are just too hot for riding, and having the trailer would let me haul bikes into the mountains of the Southwest where it's cool where it would support rides by myself and a few friends. I even have delusions of someday fairly soon organizing a three-flags classic bike ride (Mexico to Canada) with a few friends. However, shortly after I finished the trailer the world changed, so use of it will have to wait until next summer (fingers crossed).

Trying to replicate the stove enamel is my real challenge. We only use paint on Vincents ... Often a bit too shiny.

When I restored a Bultaco Metralla ~20 years ago to be in the Guggenheim's 'The Art of the Motorcycle', a friend who owns a shop in town took it to the guy who did his painting, conveying my instructions that I wanted the paint to look like it was done in pre-industrialized Spain. My friend reported back that his painter said it was the first time a customer had requested "a sh*t paint job."

 

[Robert Watson]

I did a bit of work for a movie props guy. For one movie they wanted a mountain bike with big travel rear suspension, and it had to look like a kid in a junkyard built it.

My reply --- "I can do a kid in a junkyard - no problem!"

 

[greg brillus]

Does anyone on here know how the factory painted shadow crank cases.......?

 

[Marcus Bowden]

After shellac vacuumed impregnated for porosity yellow chromate for aluminium etching then stove-enamelled black
. Mr Vincent hardly made money on shadows because of the extra work and what was the difference in price £50 ? For a lesser product tittivated up and went 10 - 15 MPH faster."That he told me himself."
bananaman

 

[Magnetoman]

Does anyone on here know how the factory painted shadow crank cases.......?

The tabbed section on paint and transfers in my bespoke manual is ~75 pages thick, but a quick flip through it turned up an article by a R. Brunwell in MPH 231 where he provides a detailed description and chemical recipe for the "pyluminizing" process used to prime the cases, which he cautions is "rather more than the 'Do it yourself' enthusiast should attempt". Elsewhere details of the stove enameling of the black paint are given. I haven't reviewed any of this material in that tabbed section myself as yet so can't vouch for its accuracy, but in any case at first glance it appears the answer is known.

If no one else has answered your question by the time you need to paint something, let me know and I'll dig deeper into those 75 pages.

 

[greg brillus]

Ok so I do know the answer and it is a simple production method that could be replicated but the cost and level of difficulty is too much....... oh and trying to replicate the actual paint itself is another matter.......Firstly from the bikes I have done it is clear that the paint on the frame and engines has no primer under the outer black surface........well from most all the ones i have done including my own bike that was a Harper's rebuild from the early 60's........you can pick the original paint by the signs of drips off the item at any one corner where the item was hung up and then baked in an oven for several hours at somewhere around 60 to 70 degrees. The crankcase matching halves were bolted together and the major cover/barrel openings blanked of with some form of rigid cover plates or similar..........Now this next bit seems to hard to believe, but I was told this and have discussed it several times with David Bowen........ Ok so the factory used a drum like a 44 gal this filled about 2/3rd's to 3/4 full of water.......Then on top of this was added about 4 to 6 inches of Black enamel paint.........Again assuming this to be the same Pinchin and Johnson black stove enamel as they used on most everything else......the crankcases were then slowly lowered into the paint until fully submerged below the surface........then lifted out and left to drip dry a while.........and then off to the oven room for the final stoving process......... I believe the heads and barrels where dipped as well and the outer covers were spray painted. After the crankcases were dry and cooled off........the blanking cover plates were removed and the designated engine number.......that is the last piece of the number was hand stamped with number stamps and the slight damage to the paint if any was touched up with a small artists brush. So this is where folk trying to repaint an engine have a major dilemma........as with most all modern paints, there needs to be an etch primer used and then perhaps 2 coats of black applied........This process produces a paint finish much thicker than the original........Not only that but this extra paint readily fills in the engine number........And it is also the reason why the engine and the rest of the bikes frame and fork parts look so much better than original because so many tiny defects are hidden under this thick paint.........The reason the first part of the engine number........F10AB gets near lost in the paint job is because this part of the engine number is block stamped before the engine was painted.......you can see clearly how the letters/numbers are not punched so deeply into the alloy casing.......So after the cases are painted now, this first part of the number is nearly lost under the thick paint........It is a double edged sword.......You don't want too thick a paint coating, but a poor thin job might not last so well once the bike is on the road.........The original paint was of extremely good quality and had a very solid colour, plus it bonded to the surface extremely well .......This was typical of the paints available back then.......Modern paints do not have this quality so much.........Just like modern brake linings aren't made of asbestos anymore.........This is one of the big challenges you face when restoring these bikes.........And despite what you might think, there are no easy answers........Only the best compromise you can come up with.......

 

[Cyborg]

And is the Shadow carburetor paint information lurking within your paint and transfers manual?

 

[Magnetoman]

Firstly from the bikes I have done it is clear that the paint on the frame and engines has no primer under the outer black surface

Again, based on zero research so far, and thus even a grain of salt may be too much to take with the following, but it's certainly possible (in principle, at least) that the "pyluminized' coating was so thin, and chemically reacted so completely with the paint during the subsequent stove enameling, that no separate trace was left of it.

However, adding to the mix, on p. 364 of his autobiography Phil Irving writes that "All the aluminium engine components were treated chemically with "Pylumin" to provide a good bond for a rubberised undercoat and a finishing coat of the enamels supplied by Pinchin-Johnson for the frames". Yes, he wrote a "rubberised undercoat," but provided no further clues.

And is the Shadow carburetor paint information lurking within your paint and transfers manual?

Nothing stands in the way of a man obsessed... Some people fall asleep counting sheep. Cyborg falls asleep thinking about hues of carburetor paints.

As I think I wrote earlier(?), my process is to add everything I find to the appropriate section of my manual, but only to look into what might be right or wrong when I'm dealing with whatever is covered by that section. I've never painted a carburetor, and I'm not presently dealing with carburetor paint. However, it's not anything official from Amal, but the only thing in that section is from MPH 730 where Bev Bowen wrote that "Many (most?) old Amal carburettors were painted silver..." He then quotes Ernesto Morales as recommending Eastwood's 'Carb Renew' Silver, part number 10187Z.

I'm also not dealing with applying gold leaf to a tank, but when I do reach that stage, I have a surprising amount of information on it...

So, to summarize everything I've written in this post, I vouch for nothing.

 

[greg brillus]

It could be possible the factory used a primer of some sort, but if they did it was very thin....... The Pylumin process was just a surface etch treatment bath........probably no different to an alodine bath used to treat aircraft alloy parts, and this turns the surface a slightly gold or bronze color. That could be done if you are good friends with someone in the aviation game, but all the steel items would need to be out of the cases first in reality. We use a silver paint on carbs, then coated in a matt clear in Euro-thane based paint....... However, modern fuels eventually attack any paint you choose, and it will start to lift especially around the base cap nut and the float bowl parts where fuel dribbles from.

 

[Cyborg]

MM Not that it matters... at least I doubt that it does unless you end up with a similar affliction (which I thought my post might trigger). Eastwood no longer sells that paint. I suspect their new and improved version wasn’t really improved. “My”obsession with hues is waning and will likely subside completely when I drag the crankshaft out from under the bench. Actually didn’t realize I was obsessing until you so kindly pointed it out.