locking gas cap assembly

[strichzwei]

I received a bag of parts for a locking gas cap and am looking for some instruction on reassembly.
Anyone aware of a video or diagram on how these parts go back together?
It appears all the parts may be there (?).
thanks,
Scott

[Slash2]

Well.. when I have no idea how something goes together, I usually start by eliminating the parts that are obvious. The key cover and key are the first two. Then I’d look at the rest. The large spring looks to fit into the large disc recess and then you can see the circular marking on the hexagonal piece with the tabs which indicates the spring was likely held between these two parts. Then I’d focus on the internal diameters of those flat discs and use the small and large ID’s to aid orientation and position. I’d guess that shaft with the spring might pass through the key cover first, then the spring loaded onto it from beneath and the internal parts assemble onto it. The knurled edge of the cap likely captures the assembly and will probably need to be slightly curled over to recapture it. The large disc has a circular knob that likely serves a positioning purpose. I’d like to see the underside of the cap and large circular disc.


This sort of job is the sort I love spreading out on the work bench and figuring out piece by piece. Sorry if this wasn’t much help in terms of a schematic. I seem to recall seeing one of these on one of the old bikes in my barn. Maybe I’ll run out and see if I can find it to help out.

[Slash2]

You got me curious so I braved the cold and took a walk to my barn to find the cap. Incidentally it was on my 1961 R50S which is in pre-project state. Otherwise known as rough.

Anyway. It appears that my cap has been serviced at some point and perhaps modified. Here’s a photo of the back which should help you. You may be missing a circlip.

From the looks of mine, I’m suspicious that perhaps it was taken apart and potentially the fasteners put back in upside down. The first photo showing the top side will show you what I mean.

At any rate, now I’m curious enough to fully tear it down and learn something. I’ll report back.

[strichzwei]

Cheers!
Scott

[sherman980]

If you haven't "lived" with one of these, you don't know what you're NOT missing... Definitely in the running for the "least worthwhile/most disappointing" but "cool" accessory I've had over the years. Seemed like a good idea "at the time". If you're actually worried about someone stealing your gas but not your bike, not sure what to tell you. First time you need gas but forgot/lost your key, you'll begin to understand...

[Slash2]

I’ve had a locking cap on my R69US for well over a decade and from memory I’ve only locked it once and that was just to see if it worked many years ago. I see these as more of a cosmetic accessory than a functional one. Besides, if i was looking to steal the fuel from a /2, I’d likely just pull the fuel line from the left side carburetor and feed it into the spout of my fuel can.

[strichzwei]

Maybe it was thought to prevent someone from contaminating your fuel rather than stealing it.......?
S

[strichzwei]

OK, I think I have it figured out.

I am missing the "C" clip in Slash2's foto (thanks for that detailed image Slash2), I assume it broke and blew the cap apart.

Also the bolt going through the middle of the cap is broken, I assume it was sheared when PO attempted to take off the frozen nut. That bolt is a specialty bolt as it has a square countersink at the head to capture the key cover but I am sure I will find a way to make do.

I will post and image of how it goes back together after I have necessary parts.

Scott

[chris@flintworksllc.com]

On the original locking cap I just took apart, the center “bolt” was actually a rivet with a square section that fit in the sliding key cover. I had to drill out that one large rivet which holds the cap and lock assembly to the base. The chrome cap is riveted to the lock mechanism using two smaller rivets. Mine was rusted shut but now works fine. Good luck.

[strichzwei]

OK, after sourcing a new bolt with a square countersink I was able to put everything back together. I used a shock compressor tool with some shims to compress the spring and mount the circlip but if you have a helper you may be able to do it by hand. My key lock was in good condition and riveted to the top of the cap so I did not take that apart. I also lubed everything with "EZ turn" aviation lubricant (if you don't have any of this, get some, great for gasket reassembly and petcock rebuilds). Hope the pictorials below help someone out.
Scott