Restoring a 1973 BMW R75/5 Motorcycle

January 6, 2007

Phew! Exhausting work.

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

Okay, this is a semi-excuse post. Brad asked me if I could figure out a way he could “subscribe” to see new posts instead of having to cruise here daily to see if anything was new. I just created that widget over on the right side and I need to write a new post, here we go, to see if it works. Don’t get the idea I know what I’m doing here. That widget is a bit of HTML blindly following a FAQ answer to this very question on WordPress. Blog hosts like WordPress offer a “feed” that can be handed over to RSS readers, a service that aggregates and “pushes” auto-selected news information to your desktop or e-mail inbox. But not everyone subscribes to a RSS reader. Nobody I quizzed at work has one. I don’t have one. Yeah, we’re all Luddites. Anyway, just in case you have one, point it to to get my new posts (feed) pushed to your reader.

I had to go register over at FeedBurner so I could offer a RSS-to-your-e-mail option. If this works right, you click that link, a pop-up lets you register your e-mail address, and, voila, you get e-mail updates everytime I post something. Or edit something, like even a spelling correction. Sorry, I don’t see a way to distinguish those activities. I also don’t know if you’ll get the pictures or HTML or what. We’ll see and maybe I can reconfigure my FeedBurner preferences to make a difference. Let me know.

So, to get to the meat and potatoes, I worked on a few more things today. The most interesting was removing the exhaust system. Well, I should say, attempting to remove the exhaust system. It was not too hard to remove the rear mufflers. They were only held on with a couple of clamps. Of course I needed to run out and buy a 19 mm socket. Who has a 19 mm socket lying around? I had an 18 mm wrench but, despite some unwilling-to-quit efforts at fitting it, no go. You know, I whipped out a crescent wrench and even had it sized on the first nut before the proverbial angel & devil on my shoulders started bickering. Angel won today and there’s a Kragen just around the corner.

So after I yanked the rear mufflers off I noted the piles of rust-like dry crud that fell. Heres a view of the first pile but somehow the perspective doesn’t do it justice. The pile is pretty hefty.


The mufflers themselves are very heavy. Must be 3x or more the weight of modern sportbike cans. And they are chromed. Naturally the chrome is rusty and the baffles are probably shot. There are some nice stainless replacements I saw in Bob’s BMW catalog but, hoo-eee, cost a bit over $500 for a pair! Joe called while I was staring at something else in the garage. I gave him the sit-rep (situation report, yeah, I read too much Tom Clancy) and he reminded me he has a set of mufflers we should evaluate first.

Remember that nifty exhaust nut wrench I showed you in the last post? It certainly did the business to the left side nut. When I got to the right side progress mostly stopped. That nut was tight! Is tight. I sloshed both sides of the nut liberally with Liquid Wrench, several times. I got it to move maybe one turn by beating the daylights out of that wrench with a hammer. My arm is sore, sing it, “I’ve been working on the railroad all the live long day.” I’d get a tiny motion now and then so I kept at it until I felt something not quite right.


Glad I noticed that problem, a cracked wrench, before pounding on it much more. I was smart enough to be holding the nut with a small towel and pre-loading the wrench while I was beating on it but when hardened metal shatters injuries often result. You might be thinking, “that wrench is defective. Call that vendor and get a new one.” Well, I figure it held up just fine. Here’s the handle I was beating on.


It gave its life in the performance of its duties. And look at it this way, I won’t be cursing as I look for that lost wrench in a few years.

You know how I rag on the Haynes manual versus Clymers? Well this time Haynes came through. They had a note talking about the possibility that the nut would be seized. Clymers must have figured if you’re that much a dope you shouldn’t be wrenching. The instruction is now to cut the nut and a conical sealing ring off. Yeah right, without damaging the header pipes? In my mind’s eye I can see my favorite Dremel cut-off wheels just don’t have the diameter for this job. They won’t reach past the fins. I guess I could cut some fins off but I’m thinking I might dig out that $0.50 air-powered tool that came with my Chinese air compressor. I’ll have to buy a cutting wheel to fit it but just think of the future havok I could raise with THAT sort of tool! I dunno. Sounds like time to talk to Joe again.

Here’s the one-piece crashbar my dad had fitted to the bike.


If I recall correctly, no crash bars were stock in 1973 but this design was very common. I know modern thinking claims these might do more harm than good, dig in and flip a bike during a slide, but I think they look right on the bike. The problem is, once again, this is a chromed part. Was a chromed part. Now a chrome-and-rust combination. I could price a strip-and-rechrome but I’m thinking of a strip-and-black paint or powder coat. Please jump in with a comment if you know for sure but I’m thinking these bars were sometimes originally black.

My final picture is the horn. It weighs almost as much as a muffler! This is a Bosch and I cannot see an easy way to disassemble it. It looks sort of riveted. The helpful Clymer manual says the Fiamm horns are easy to disassemble, clean up, and reassemble. How very helpful. Oh and if you damage something trying to fix it, it is only a horn, buy another. They paid a writer for that advice?


Until next time, keep your shiny side up. I’m still looking for mine.


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