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1940 SS Knucklehead: People's Champ 5 Build"

118K views 327 replies 63 participants last post by  Rigidspeedtwin 
#1 · (Edited)
OK, I know a lot of you have seen my girder fork thread, so a bit of this is rehash, but I wanted to get some of this stuff on here chronologically. If you read the fork thread, you can probably read the beginning of post 1 and then jump to post 4. I posted this over on another (the other) forum that prefers angle grinders to machine tools (but I still love them). It's going to seem like a huge blast right off the bat, sorry about that. I'll update it as I go from now on. Maybe print it out in full color on your company's printer and go read it in the shitter, IDK.

So, a bit of backstory, everyone who knows me knows I talk about this thing all the time. I was trying to keep it on the DL online because I was trying to get invited to a "cool" event like born free or Brooklyn. I've since decided that I'm just a nobody and don't really deserve to be invited anywhere. Maybe sometime in the future. Also I am simply just not good at selling myself on social media, so here's where I'm at and I'll update this as I go.

Basically the whole project started like this, a titled basket 1940 EL motor.



By now I've accumulated basically all OEM (not year correct, though) external parts. I'm going to use S&S/Jims/Andrews internals. The motor will be mostly stock. I don't plan on making it anything other than clean, I want to leave all the "wear" marks in the parts that have accumulated over the last 75 years. Sort of like how I shined up this cam cover:



For the sake of the story, not much has happened with the motor, I've been too busy with other things to really dick with that. Also, for the sake of the story this is going to be a little out of order, but no one's probably reading any of this anyway.
I wanted to build a fork for this build, so here's the story of that:
Drew it in cad.







Got castings made from 3d printed wax off cad models. Material is 316L. This is not inexpensive, but I don't spend much money on things besides motorcycles, so it was within budget. All said and done I have into this what a nice condition early springer would cost.



Had to machine the castings. Fixturing these was often difficult and quite a learning experience for me.























 
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#131 ·
Re: 1940 SS Knuckle

Are you going to have to deflate the rear tire to get it out of the rear stays? It looks that way in the video but may just be an optical illusion.

I guess if a star hub is ~4" wide between flanges, that plus spacers would be a normal 18" rear tire width? Assuming your one-off hubs are in the same zip code dimension-wise...
 
#136 ·
Re: 1940 SS Knuckle

I had the privilege of meeting Christian on the weekend in Toronto ON at the bike show. I will say he is a very humble man. As a person who does this stuff for a living. This man has more talent in his one finger than I do in my whole shop. I've been following this thread quite closely and was blown away when I got to meet the man in person. From all of us at the freedom machine booth, Thank you for stopping in. Letting us waste your time with our mediocre shit. Keep up the good work, because in my opinion you sir are going to be if you are not already. one of the best bike builders in the world.
 
#142 ·
Thanks everybody. It is flattering as hell. I don't think I deserve accolades of this magnitude, but it sure makes me smile and pushes me on.

Last night I spent all night bending up sissy bar parts. I made another one of my wood dies (in 8" CLR) so I had some nice sweeping bends. My original plan was to use 3/4 tube (instead of the "standard" 5/8 rod) to match the tubing on the girder. Well I bent up all the pieces and then took a step back. Too big. Definitely too big. I was thinking it would look beefy, but it just looked dumb, so I am going to remake it in 5/8. It is about 3 feet tall (from the axle plate).

More later. Since the next one will be rod, I will probably just use the standard "bending board" vs the bender.
 
#144 ·
I wrote this up for a DIY forum, so it may seem very simplified, but I just copied and pasted. Deal w/ ittttttttt….

When people hear "Bird Deflector", they probably think it's some sort of windshield or fairing for a motorcycle, colloquially however, a bird deflector is a carburetor inlet cover designed to keep giant things (birds) out of your engine. I run one on my 59 Panhead that looks like this. That little finned johnson between the "pans". There are a zillion of these on the market today, but I wanted something that was just a hair bigger than the small one I have on the pan. (about 10% bigger). There is no air cleaner used, so you suck in all the dirt and dust, but you keep out the pant legs and birds.

Started out with a hunk of 1/2" thick 316SS and a pattern I drew in cad. I punched 3 reference marks.

Then used a compass to make the shape. I decided at the last minute to not round the end of the teardrop.

Cut it out (slowly) on the vertical bandsaw. When cutting SS this thick I run the saw blade at about 90 surface feet per minute. That's essentially the velocity of the tooth.

Then sanded to final shape with a very coarse grit (24) vertical belt sander.

Then I carefully started sanding the edges, taking care to make sure the sanding was symmetrical and consistent.

A little deeper. Trying to make a ridge build up at the point of part. This took extra attention. For this part of the sanding I am using an angle grinder with a 24 grit wheel.

More sanding. Try to use as many reference areas as possible. When doing this i was conscious of both the edge "thickness" remaining, as well as ensuring that new the teardrop of the top plane was evenly offset from the outside edge.

Up until now, all of the sanding has been on the same plane. Usually when rounding parts, I'll try to make one major cut on a plane that's tangent to where I need to remove the most material (though this is a big estimate).

Here's an example: For rounding a 90 degree corner by eye, I will take a big cut at 45 degrees

Then two more smaller cuts on the new edges I create

This method works best when you can scribe a circle on the edge needing to be cut, but by eye it's good too.

Using this method gets you a pretty nice shape, even when just doing it by eye. I know this sort of seems obvious, but for a long time when I would try to round corners I would stick the part up against the belt and start rocking it back and forth and my corners always looked a little wonky. Secret message: Helicopter Dick. Doing it this way really makes a difference. The bird deflector was a little different. My first cut was probably around 30 degrees off horizontal, but changed a bit as I got toward the rear.

A little more sanding on a new plane.

Then I started using a dynafile, which is the best tool on the planet for metal fabrication, as far as I am concerned. You can see it in the background here. They are not cheap (about 500 bucks) but it is amazing. There are tons of belts available, but I use 60/120/240/400 and blue scotch brite the most. However, I think this pic was shot after using a 36 grit belt. Note that the electric version of this tool is FAR inferior to its pneumatic counterpart. It just cant spin fast enough to be effective in my opinion.

I use model: 14000

But it's also important to have contact arm: 11234 which allows you to smooth parts better.

More dynafile work. 120 grit.

Then I used a scotchbrite blue belt on the dynafile to blend the major sanding marks and see how my shaping was.

Looks pretty good.
 
#145 ·
Making sure the raised ridge was centered and straight was critical.

It needed a little "flair" so I put it in the bridgeport (non-CNC) mill and cut some little steps in it. I roughed them in with a 3/4 roughing endmill at about 200 RPM (this pic) then radiused them with a 3/8 ball nose endmill.

Ok, I know a few steps got skipped here, but all I did was smooth out my cuts from the endmill with a blue dynafile belt, then used a pedestal buffer...

Like this. It's important to make sure you are running the correct SFM for your buffing wheel, (I run mine about 5000). To calculate SFM take your buffer's output speed and multiply it by your buffing wheel diameter and then by PI/12. In this case 1800 X 12 X 3.14/12 = 5652. I just bought some larger wheels to really get the SFM up there, so I'm excited to try those.

First you use a sisal wheel with black rouge (this will remove the dynafile scotchbrite scratches if you're dilligent and use a lot of rouge).

Then I do final polish with a spiral sewn wheel and green rouge. You can go one step further and use an open buff, but I find it doesn't do all that much on my stainless stuff, which is usually pretty curvy. I think for largely flat things you'd see it more.

Shiny.

Hope you enjoyed the trip! One thing to note is that every bird deflector I have ever seen mounts with bolts through the front, but I'm trying to avoid that and am devising a way to mount it with no visible bolts. It will be mounted with the point facing the rear of the motorcycle.
 
#148 ·
Updates.

So I needed to make a sissy bar. Here's some of the process.

Make a drawing and tape it to some metal:



Punch important holes:



Drill some of the important holes.



Use some marking dye and a scribe for the other ones:



Take some randome shit metal:



And make a bending spool. This will keep your sissy from smooshing around the tight top bend. Note, this was made on a manual lathe by making stepped cuts then sanding:



Weld that shit to your sissy jig:



Make a bending die for the center. Step one, make a pattern and trace it onto a board. Then clamp it to a second board and drill a bunch of holes. This can be easily done on a drill press:



Bolt two boards together:



Sand bolted boards smooth:



If you are using 1/2, 3/4, 1 or 1.5 tube/rod, you can skip this step, but I had to regrind a router bit from R3/8:



To R5/16:

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Use a router to take a 1/4 round out of half of your die:



Then bolt it back together:



Bolt your die to your sissy fixture and start bending. The top bend went great. The die shown in this picture didn't work out:



But this new one did:



Not shown are two more dies I made for the bottom. But it bent up pretty good. The top is super tight and nearly perfect. Not smooshed flat at all.



The top is actually a little long, about 1/4", but that doesn't matter:



Next I scabbed together some scrap to bend the top at the same time. This worked well.

 
#149 ·
Unfortunately no pics before polishing, but here's a video from after polish:



Next I made some sissy bar mounting brackets for the axle plates. Started with 1/2" 316 plate:



Cut a little Z into it, that I would never be able to bend:



Made a socket on the lathe and welded it on:



Then polished them up. L&R:



Then a bunch of stuff happened and I bolted a spare transmission and my engine cases with a flywheel and pinion shaft to the bike and test fit a chain/belt... more on the primary belt in a few days.... I have some issues...



Love this view. I have been sweating whether or not it will look too "gimmicky" with the external drive but in my opinion it doesn't. Much respect to the work that CWZON did on his turbo knucklehead, but I didn't want to have the bike look this "wacky".



I think I have successfully avoided wacky, and in my opinion just made it unusual. What're you guys thinking to that point?





 
#150 ·
I think I have successfully avoided wacky, and in my opinion just made it unusual. What're you guys thinking to that point?
I think its a great balance... and balanced is a very good aestetic ideal IMHO.

So much so that I think many people, especially the uninitiated, will not really "See" it so much as notice the overall effect it has on the bike's stance and feel. Perfect.
 
#151 ·
I hated the idea of sprocky and rotor on the outside when I first saw this comin' together, but I like it in practice much better than in theory.

My taste really sucks. I need to have things jammed down my throat. What's the plan for a fender?
 
#156 ·
At this point they're just a placeholder. Having something there is better than nothing. The top part of the bars will be probably one of the last things.

Did Helicopter Dick help you with this build in some way?
:) meatspin.com

Don't click that.

I hated the idea of sprocky and rotor on the outside when I first saw this comin' together, but I like it in practice much better than in theory.

My taste really sucks. I need to have things jammed down my throat. What's the plan for a fender?
I was a little nervous about it, but I was committed right out the gate so I had to stick with it. I am happy I did, because otherwise I think it would just be more of the same. I like having some engineering involved in the build.

For the fender, I have a twinrib unit from easyriders japan. I don't see them very often. I really wanted to make my own tins for this build, but I think that's going to have to wait for another bike. I won't be modifying this much, but I will be probably do a lot of work to whatever tank shell I start with.

In fact, here is a picture of the fender I took last night after making the seatstay brace/fender mount/oil tank mount. I really need to repolish the seatstay tubes, I really scratched them to hell sitting on the frame and making chopper sounds. Anyway, this part you will never see, but I'll know it's there. I also wanted to try turning something and bending it. I like trying new things. I really wish I had sone something more uniquie for the rear trans crossover.





In case you are wondering how that was made on all manual equipment:







 
#160 ·
Looks great. The frame lines are very good and the bars front and back work well with the frame. I might maybe just lay the sissy bar back a touch more to line up better with the fork, but that depends if the angle works for the seat or not. I really like the outside drive. Can't wait to see what the pipes might look like... This bike is a work of art.
 
#161 ·
A bit of technical information I thought I'd add about the driveline.

The whole frame was designed around being able to run a 40T rear sprocket. Secondly, I really wanted to run a BDL "quiet clutch" drive, because it's substantially narrower than the stock clutch hub, since the clutch goes inside the pulley instead of next to it.

Unfortunately, there are two problems with this. The BDL quiet clutch drive is a 45/68 setup, and it only comes with splined front pulleys. I could get around the spline by running a later sprocket shaft, but I was trying to run the tapered shaft. So I thought, I'll just run a 39T BDL front pulley for a knuck and a mix it with the rear pulley.

My shovelhead (and many other bikes) run a 41/61 primary and a 24/48 final. I like that ratio.

41/61 X 24/48 = .336

Since I was now locked in with 3 of my pulleys, I could adjust the fourth to match.

Turns out that

39/68 * 23/40 = .329

Pretty close.

So I went ahead and designed the frame that way. The size of the front pulley had a lot to do with where the frame rails were located and so on. Also, using a smaller front pulley made the transmission move back to about 13.5" vs the standard 12 13/16

Then, tragedy stuck. This past weekend, when I was installing the drive, I noticed that the belt did not fit on the front pulley. Dang.

I spent a lot of time doing some research (also called BDL but they were little to no help). Turns out the knuckdrives use a gates HTD toothprofile and the other drive style uses a Powergrip GT2 profile.

BDL said they would not make a custom pulley. Where I am at right now is I have a Gates 40T taper lock pulley that I am going to adapt to the knuck tapered shaft. It’s nut ugly, per se, but it’s not awesome looking. I think if I have it plated, it will look a lot better. I am going to try to get it on tonight and see how it looks. More later.
 
#164 · (Edited)
As a cabinetmaker by trade I love your use of wood as a former. Especially Oak being my favorite wood to work with.

I would guess that running the grain from left to right instead of top to bottom meant that the end grain gave the former more staying power under the heat of the metal.
The die actually didn't fail, the radius was just too great for the for do bend smoothly. I was having to heat up 8" of material and it just wasn't consistent enough.

One of those companies sells interchangeable engine-pulley hubs. With that as my inspiration I turned down a worn-out pulley for the splined center, leaving a flange with threaded holes to make a 530 front sprocket. So why couldn't someone of your talents salvage a tapered hub and graft it (welds, bolts or otherwise) to the chosen pulley. But if you spent the time and wound up with a plan to modify a taperlock I am not telling you anything that probably hasnt crossed your mind.
That's basically what I am doing, there's just a third piece involved.

Original turned down hub is inside the taper lock bushing and that is inside the new pulley. I did get a steel taper lock bushing so I could weld it to the old pulley inner if needed.

This may just be temporary until I can come up with a better solution. I need to have the trans position nailed down ASAP so I can start getting the fender mounted permanently and begin construction on the oil tank.
 
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