Restoring a 1973 BMW R75/5 Motorcycle

May 13, 2007

Law and disorder

Filed under: airhead, BMW motorcycle, motorcycle restoration, R75/5 — Penforhire @ 8:32 pm

Here’s the VIN plate that was mounted on the steering tube.


It’s a bit messed up and I haven’t found an exact replacement yet. There is a German VIN plate available but it is not the same as the USA piece, out of stock everywhere I’ve checked. Hucky’s is still digging through their physical stock to see if one exists otherwise I’ll probably use the German-style plate.

Most of the work time between my last post and this one was spent polishing that wheel rim I started a while back. This is an unbelievable amount of work, much more area to smooth than control levers, light housings, and such.


That’s the comparison but I can tell I’m not quite done with the polished rim yet, too many scratches in between the spoke nipples. The thing is, the more polished I get the surface the further it seems I need to go. I discovered leaning it against some hard surfaces leaves a noticeable scratch where it didn’t do squat before. Another lesson learned. That polished surface is soft like butter! If I knew how much work was involved I might have bought replacements to start. I suppose sweat equity is best though.

Maybe I’m getting smarter?


I started on the other rim with 60 grit paper. It cuts through the corrosion very fast but I’m going to need several more stages, increasing grits, before getting to the polishing wheel.

Why did I return to the rims? Because my parts, frame and a dozen other miscellaneous pieces, are finally out for powder coating! Yay! About time eh? I’m using Joe’s recommended coater, AAA Coating in South El Monte. We’ll talk about the stunningly low price after I pay for the job and examine the work. They are going to degrease, beadblast, and powdercoat in a semi-gloss black. They’ve also got my hubs to just bead blast. The next hold-up on bike assembly after I get the frame back is the wheels. Can’t spoke the wheels until the rims are ready. So THAT’s why the rims are something of a priority.

That polishing work is mighty dirty work too. Black goo and dust gets everywhere. Sure I’ve been dirtier. I’m thinking of a flag football game played in mud. But that was a long time ago. This is as dirty as I’ve been in quite a while.

I’ve also been dilly-dallying about bead blasting the rest of my cast-finish parts. That aluminum corrosion is everywhere except where grease protected surfaces. For instance, I can’t reassemble the front forks until I do something about the lower cast pieces. Just as I’m about to collect everything and bite the bullet on sending stuff out, look what showed up in my garage…


This top-loading table-top blasting cabinet will fit every part except the main engine casting. Normally these sell for $130-ish, down to $100 on sale or in e-bay. Nope, I didn’t pay that much. Can you believe this particular cabinet is a Harbor Freight close-out for $60? That includes the gun, spare nozzles & venturi’s, spare clear sheets (protects the window), exhaust filter, and an interior fluorescent light. They are discontinuing this particular model and changing manufacturer for its replacement. Couldn’t pass that up. It’ll pay for itself if I can blast just three or four parts clean! Admittedly the instructions on assembly were a bit of a headscratcher and there were a couple of pressure leaks that took ingenuity to fix. I should caulk a few tiny box leaks or else live with glass powder getting everywhere in the garage. There is an exhaust filter and I fitted a Shop Vac to it but it wants to suck the door down into the cabinet. I need to introduce some controlled leaks if I want to use that.

I’m using 80 grit glass beads at 90 PSI and that really cuts through the corrosion without much cutting of the underlying aluminum alloy. Here are the front fork castings. Guess which one is blasted.


I shouldn’t be bragging about how cheap the cabinet is. The process is slow but only for one real reason.


My Chinese 2 HP air compressor is not studly enough. Look on the left side, all this hard work is making it leak some oil. Bead blasting is air-hungry work! If I charge that tank to 125 PSI I get maybe 20 seconds of blasting at 90 PSI before it cycles back on for a minute or more. The corrosion slices off fast but it takes more time to get a uniformly shiny surface. I may need to do some, um, compressor research and my dirt cheap cabinet may cost me more before I’m done. Sigh.

Okay, end of garage activity this week. Sunday was a big event. You won’t care but I paid for it so I get to brag about it. Stepson Brian finally graduated law school! Let’s see, four years at Cal Poly San Luis Obispo… one year off… and then three years at Whittier Law School in Costa Mesa. Phew! Now all that’s left is the California Bar exam.

Look, there he is in the stands.


Most speakers were entertaining but then there was Carlos R. Moreno, a California Supreme Court Justice who must like the sound of his own voice. What a boring blowhard! Julie called him a pompous ass. I pity the lawyers in his court.

Here’s Brian getting the dean’s handshake after getting “hooded.” That’s like getting jumped into a gang but just for academic types…


Big party at my house afterward. Woo hoo. Pretty soon Brian can start charging in 15 minute increments. He wants to practice estate law, taking money from old widows, but is continuing where he interned, in big-project construction disputes. Can you tell that I know an awful lot of layer jokes?


I’ll leave you with one of favorites. What’s the difference between a dead snake on the road and a dead lawyer on the road? Skid marks in front of the snake.


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