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Zundapp KS601 - Making The Battery Strap

   Until just the last year or so, I never felt I could justify putting very much time into working on the Zundapp. There were just too many other projects of higher priority. Still, I wanted to ride it, at least a little.

Obviously, it needed a battery to ride it. I therefore purchased one, but there was nothing to hold it in place. The parts list showed an odd strap like thing, but did not provide any detail of how it was made, or even what it was made from. As a temporary, and very crude field expedient, I just bent up a chunk of 3/4" x 1/8" cold rolled strap and held everything in place with two lengths of 1/4-20 threaded rod. I considered it so temporary that I didn't even file the saw marks off the ends. You know how that goes; rode with that unsightly piece of shit holding my battery down for a number of years.

While it did effectively hold the battery in place, the "temporary" strap was as ugly as hell. But, when I decided to attend the first annual North American Zundapp Rally held at Kevin Johnson's beautiful farm in Spring Valley, Ohio, September of 2013, there was no time to replace it.

Of all the things on the bike that needed improvement, this was the one I primarily found myself wanting to make excuses about. So, as I cleaned the bike up for the second annual Spring Valley meet, getting rid of that ugly-assed battery strap seemed more important to me than just about anything else on the long list of things that badly needed to be addressed.

At the first rally, I had seen the battery strap on Daniel Ayres' beautiful all original '52 KS601. His brother, Joe, who had made the strap, was quite proud of it, understandably so. I was determined to make something which, if not as nicely refined, was
The Zundapp KS601 battery strap, first (and current) incarnation.
The Zundapp KS601 battery strap, first (and current) incarnation.
substantially of the same ilk. Unfortunately, hustling at full speed all the way to the deadline on all the other parts of the bike, and realizing I wasn't going to get the carbs properly cleaned up and reassembled in time and therefore wasn't going to get to ride at the rally, it wasn't until the night before I had to leave that I was able to start on the battery strap.

Let me briefly change the topic and direct your attention to the air intake tube, in the picture above. I wish I had taken a detail shot of the tube prior to wire wheeling the rust off of it so you could see the tremendous flaking and ugly corrosion. After cleaning it up, I swear to you this is a surface finish I would intentionally apply to old chrome if I knew how.

What were deeply pitted rust spots are now little islands af beautifully patinated steel run through with veins of shining chrome. The texture is pure pleasure to run your hand over. The handle bars, basically in the same as-found condition, responded substantially the same to the wire wheel. Wouldn't change any of them for the world! The picture totally fails to capture the effect.

Also, as an aside, what little you can see of the shifter and kick start lever are basically in as found condition, just degreased in situ. Didn't have time to pull them off and clean them up properly. Haven't figured out how to deal with the frame yet, so it's pretty much as found.

Making The Battery Strap

The Zundapp KS601 battery strap in the vise on the workbench.    A closer view of the end of the Zundapp KS601 battery strap, ready for a rivet.
A glance at the vise end of the workbench. I wrested this beauty off a workbench in an abandoned line shaft driven machine tool works with mine own hands. One can only guess what this chunk of iron has seen over the hundred plus years it was bolted to that bench. I used the same fasteners, old square head bolts and nuts, to mount it on mine. The vise came from the tool maker's part of the factory and looked nearly unused, but that's another story. Still haven't replaced my cabinets above it, after the lightening strike fire. They took a good long time to build the first time. Kind of assumed that would be the last time and just haven't had the spirit to tackle the job again. But so goes life. Maybe I'll get them up this summer.

The image to the right shows the end of the battery strap drilled for the first "rivet." The rivets, as you see below, are just chunks of 1/16" mild steel weld rod. Still, they make remarkably strong fasteners. I need to make some rivet sets out of hardening tool steel, something to form the heads a bit nicer.

I considered slotting the strap in the mill, but couldn't think of a quick and dirty way to fixture it. Clamping it in the vise wouldn't work because it would close up as the cutter removed supporting material, plus it would have dictated a wider band at the edges of the slot to accommodate the step width in the vise. In the end, I just did the time honored drill-a-bunch-of-holes, then file out the webs. It went far faster than any conceivable mill set-up would have.

The Zundapp KS601 battery strap with one rivet, next one waiting.    The Zundapp KS601 battery strap in place.
Above left you see one end with a rivet in place and another ready to go. I wrapped the end around a shoulder bolt of the same diameter of the brass barrels I made to accept the hold down screws. I expected the hot rolled 18 gauge to spring back a bit, but it hardly did at all.

To the right, the strap in place. Screwed up the first brass barrel because I didn't have the correct style metric tap. Thought I could get away with it in brass with a little larger ID hole. Nope. So this is a temporary 10-32 version. I just prefer to keep it all metric.

Note that the grotey looking thing under the battery appears to be a chunk of old Fir-tex fiberboard or something of a similar species. Who knows how long it's been serving the function.

I made the strap and threaded barrels in just a touch over two hours, wrapping it up at 5:00 pm the night before the rally. This attempt is really just exploring the basic idea. I will replace it with a little more refined version, with at least some rubber padding, both to give it a more conforming grip on the battery, and also hopefully to protect the strap from the acid. I might consider using stainless and giving it a black oxide finish, but for now, not too bad for a couple of hours of frantic work.

Last updated 11-16-17
Email:  mechanique at wmol dot com

Zundapp drive shaft, U-joints, and pinions.