Undocumented Panhead Features

[awander]

I was reading one of VT's posts the other day, about how you can stand the battery up on the bracket/crossmember in the bottom of the oil tank, which allows it to sit levl for checking electrolyte level. Wow! I never heard that before-and it's a great feature.

I started wondering how many other things there are about these bikes that never made it into any of the manuals.

I came up with a couple of them just this week. They may be "old news" to some of you, but I sure never knew about them before.

1) What to do with the seat bar clevis pin?

Usually, when I raise the seat to check the oil or the battery, I have been puttingthe pin back into the seat bar, and snapping the spring over it, so I won't lose it. Occasionally I would lay it down on the frame right near the seatpost tube. I did that yesterday, and noticed that if it dropped off of the frame, I might never find it again.

Then I noticed the hole in the frame(almost under the pin in the phot above). The pin fits that hole like it was made for it!


2) I rode to work today(100 mile round trip) and when I was about halfway there, I noticed that the 45031-41 clutch lever pivot screw was backing out(My bike has identical levers for the front brake and clutch). Instead of pulling over and tightening it, like I should have, I decided to keep an eye on it, but soon forgot about it. When I got on the bike after work, I noticed that the pivot screw was gone, but THE CLUTCH LEVER STILL WORKED FINE! The design of the lever and the bracket allows the lever to pivot without a pivot screw installed!
Here's the brake lever(I took the brake pivot screw out to copy it, and it was easier to photograph) without the screw:

and here's the lever doing it's job without a pivot screw installed. The cable holds the lever in place, and you might not even notice it was gone for a while(happened to me anyway):

Note that you can still see clear through the pivot hole with the brake applied.

I don;t advocate this as a recommended practice, but it's pretty neat.

[VintageTwin]

Yep, the battery support is one of those un-advertised features. It looks like your right about that extra hole on the left side of the frame. Pans have that extra hole-tab on the left like the one on that's on the right for the filter bracket. Of course, a clevis pin holder!
And that brake lever design was no accident.
Wonderful motorcycles. Nothing beats a Panhead for style, reliability, and durability. Good deductions. Never heard the one about the pin holder. Probably no one, since the founders were alive, ever knew about it.
Black is a good color for those '51-53 tanks.

[Cotten]

The "pin-holder holder" hole was originally made for a wiring terminal.

We are free to improvise at will for convenience, but to deify the designers is futile. They engineered as many stupid things as brilliant ones. After all, the put the brake grip on the left for tankshift models!

....Cotten

[awander]

Cotten:

I am not sayingthat they never did anything wrong(the designers), but it would be foolish not to take advantage of the things they did right(or even the accidental things that can be used to advantage)

[Cotten]

Certainly, Andy!

I am only cautioning against assigning divine inspiration to their accidents!

(Of course I am being facetious and sarcastic, I just refuse to use a 'smilie" to make that obvious.)

For example, the steering dampener tab and stops for springer forks remained on the headstock casting through to at least 1984. That makes them too cheap to re-design, not benevolent to those who want to customize!

....Cotten

[VintageTwin]

The "pin-holder holder" hole was originally made for a wiring terminal.

What wiring terminal? Do you mean a conduit for a wiring cable? I've heard the wiring cable "title" before but never heard the story. What was the left hand tab-hole's purpose? Rear taillight wiring cable? I've never seen a rear taillight cable run through there. Gravity and heat and weight (from whatever source) can thin wiring out as it's forced to bend. Electrical cable is always run in soft curves, not radical 90 degree bends, except Romex® household 3-wire. I can see two such bends, once as the cable goes in the tab-hole from the bottom and one as it exits the top.
Surely someone from the AMCA has an opinion or photographic proof of a left side tab-hole in service.

I wonder if the brake/clutch lever working without the pivot screw was an accident, or if some forgotten engineer made it that way on purpose?

Purposeful, imo. - from the same engineers that bought the battery support cutout at the rear of the oil tank. The era in which Knuckle and Pans (up to 1959) were made was to be a "hands on" rebuildable motorcycle, grouped right in there with babbit rod (carve the babbit bearing to fit a crankshaft journal with a pocketknife) Chevys and the peoples car Volkswagen.

[awander]

OK-no divine inspration-at least not as a matter of course.

But I like to think that the many folks who designed these bikes were a little like me-most oif the time they did well enough, sometimes they made mistakes, and othe rtimes, whether through divine grace, luck, or just a love of things mechanical, they came up with some pretty neat stuff.

I wonder if the brake/clutch lever working without the pivot screw was an accident, or if some forgotten engineer made it that way on purpose?

[awander]

PS I can;t believe nobody has pointed out that I don't have the correct grips on my '52...

[VPH-D]

The terminal lugs with holes were used on Big Twin models up thru 47.
Your grips also belong that genre of Big Twin.
VPH-D

[john HD]

What wiring terminal?

that is where a bolt with fiber washers connected the battery to the rest of the bike. this was before the days of the terminal board behind the coil.

take a look at a correct/original knuck.

john

[FlatHeadSix]

almost completely correct John. As Cotten mentioned above, the MoCo didn't bother to change the patterns and casting molds when they made design changes, if something wasn't in the way of any new model features, they left it. Its a throw back to the knuckles and it mounted an electrical terminal. There was a phenolic (insulator) 2-piece sleeve that was a snug fit in the hole. It was sort of top hat shaped so that it insulated the faces of the hole as well as the inside. A bolt with a nut went through the hole, you could attach multiple wires. If you look close on the early frames you will see several other "bosses", undrilled on the pans, where additional terminals where installed in the upper seat post casting.

Like John said, look at a correct knuck or WL, there was no terminal board behind the coil, all the terminals were mounted in holes in the frame casting.

Andy, the brake lever deal is an accident. I don't believe that whoever designed that lever ever intended or anticipated that it would work without a pivot screw. There was no such thing as "fail safe" back then. I might add that it was a lucky accident, that you didn't have an accident! Do you think the rear brake pedal would still work if the pivot bolt came out of the clevis?


seat pivot pin fitting the old terminal lug: coincidence
24 beers in a case, 24 hours in a day: coincidence? I don't think so!

mike

[awander]

Mike:

It may be an accident that the lever works that way-but take a look next time you are working with one of them-it just seems too good to be true.

I don't understand your point about the rear brake lever and the clevis pin missing. Are you saying that if somebody HAD figured out a way to make the hand lever work without the pivot screw, that they would have discarded the idea because they didn'yt have a way to add similar redundancy to the rear brake pedal /

The beauty of all this is that we are only speculating-and I must say, I don't really care if they designed the brake/clutch lever that way on purpose-I do know that I am sure glad it DOES work without the pin.

I'm not recommending anyone get lax on tightening fasteners, though-I made and installed a new pin as soon as I got home.

[FlatHeadSix]

VT,

"Fail Safe" is some old military terminology from the Cold War days, originally associated with deployment systems for nuclear weapons. It was one of those catch phrases that people started applying to all sorts of mechanical and electrical things. Basically it means that when something starts going haywire the system will shut down in the least harmful way, sort of a backup for the system if something goes wrong. Its kind of like all the stupid interlocks that lawyers insist on installing on lawn mowers, if you let go of the bar on a push mower, or fall off the seat on your riding mower, the engine dies.

Andy, when I read your post about the pivot pin it reminded me of something that happened to me a long time ago when I was pedaling a Schwinn instead of riding a Harley. The pivot pin came out of the front brake lever and the lever, still attached to the cable, dropped down and got caught in the spokes of the front wheel. I still have the scars. Like I said, you were lucky.

I was being sarcastic about the rear brake pedal, if the pivot pin comes out of that you're screwed. If the pin comes out of the front clevis, the rod will drop down and dig itself into the pavement destroying the rod and probably some other components of your mechanical brake linkage. The factory had no backup plan for that either, it was up to the rider to do the routine inspection and maintenance.

mike