Restoring a 1973 BMW R75/5 Motorcycle

March 11, 2007

Whistle while you work

Filed under: 1973, airhead, BMW motorcycle, motorcycle restoration, R75/5 — Penforhire @ 4:54 pm

I did my impression of a well-trained monkey today. I spent at least another five hours roughing up the rear rim with 220 grit.

First I went out and got some of the 400 grit I was lacking, thinking I’d be on to 400 grit today. Fool! I also got a different abrasive to try.


This 3M SandBlaster stuff is neat. The soft form lets it conform to rounded surfaces like spoke nipple openings much easier but sharp edges tend to tear off the little abrasive squares. Once the surface rips off only a soft sponge is underneath, unlike say 3M Scotch Brite or Norton Bear Tex. I don’t know exactly how grits get rated but my impression of 220 Sand Blaster is finer grained than 220 grit Norton sandpaper. At no time did it leave any gouges similar to paper’s worst scrapes. 3M also sells a little detail handle to hold the Sand Blaster but the issue is how quickly the squares rip off on the nipples of this particular rim. I ended up just hand-rubbing.

I thought about some power assist, like a Black and Decker Mouse or similar detail sander. But I notice the pre-shaped paper only goes down to about 220 grit. Heck, the finer grit sandpaper is never even in the tool section of local stores. I have to browse the paint sections to find it.

Here’s a small section of previously polished rim.


It didn’t look bad at a distance but all the spotches and pits are noticeable close up.

Here’s what the first pass using 220 grit looks like.


This doesn’t convey the dull cloudy appearance very well. The first time you ever polish something like this you have to take it on faith that every grit will remove the scratches of the prior grit and the widget will eventually shine again. I mean, it looks like crap right now but if you don’t make it look thoroughly crappy it will never look spectacular. You need to learn that if you see a spot of something it is not going away when you move down to a finer grit. You may believe it might. I used to. But the wasted effort of, um, trying to polish a turd makes you focus on getting the surface completely right at each stage. Some would call this kind of learning the “hard way” but it seems to be the only way something sticks to the inside of my head.

I may have more than a day’s work in just the 220 grit on this one rim right now but I’m not done yet. I suppose a smarter fellow would realize perhaps a coarser grit is called for. But I was scared about the effort to remove, say, 80 grit scratches. I may get bolder on the front rim because no way do pros take this much time on a rim. Nobody would be able to afford their services.

While I’m working on this rim I’m trying to listen to some short stories on CD’s I borrowed from Brad. He recently bought a 5 series BMW. I like to think my 3 series helped influence his decision. Anyway, as part of his ownership experience BMW sent him these short stories on CD’s, all having a BMW car somehow in the story. This is the audio equivalent to “The Hire” series BMW did in video a few years back, different directors all with Clive Owen as the driver. Those were inspired short films and, while I’m not a books-on-tape kind of guy, these audio CD’s are similarly excellent. Mind you, the Suburban Auto Group Trunk Monkey series ( or remain my all-time favorites. The car division of BMW sure makes a tireless effort to convince you that you made the right choice. Anyway, my garage boombox has decided that today is a good day to die. Oh I can still listen to the radio just fine but these CD’s cause it indigestion (plays for a few minutes and quits). It might be due to the funky copy protection on them (I only tried to rip them to MP3’s because the CD player wouldn’t play, honest). But they play okay in my home theater DVD player? So, back to whistling while I work.

I am starting to have a recurring nightmare where I finally get this motorcycle on the road and an uninsured illegal alien immediately smashes into it. This is only a dream so instead of bleeding profusely in the middle of the road I jump up and insanely attack the fellow who struck me. “Do you have ANY idea of the time it took me to….”

Stress? What stress? Listening to too much talk radio? Is this good stress?


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