Paugho frame for 45"

[kitabel]

W/r/t there is now a 4-speed handshift aftermarket transmission available
This one? https://tinyurl.com/y7a7ls29
The price is very good, considering that you don't need the original box at all.
In my opinion, the ratios are an improvement over the original 3 speed, but nowhere as useful as the stock BT transmission (not to mention the hand clutch). The first gear is much taller and the 3-4 shift is much farther away, the opposite of my preferences.
45 4-speed:
1st 2.664 (only 8% stronger than stock 3-speed at 2.469)
2nd 2.019 (the very close 76% RPM recovery is nice, but it's in the wrong place)
3rd 1.421
4th 1.000 (recovers only 70%)

BT:
1st 3.004
2nd 1.820
3rd 1.228
4th 1.000 (recovers 81%)

The BT is a far more $$$ and complex project, it's up to the builder.

[nanonevol]

Project is moving along slowly. Building up a 3:1 transmission as recommended here.
I've got a 20 tooth engine sprocket and a 51 wheel. I have on hand a 22 and a 25 transmission sprocket giving me either 3.77 or 4.28 final gearing.
The engine will be pretty much stock except for the carb (prob a Mikuni, maybe an Amal) at least in the beginning.
Would love to stroke it though later.

Trying to figure out what clutch parts I need. Hoping for a dry primary, chain, and hand lever operated.
I got this in basket of parts, but it looks like the part for a 45". I would think I would need BT clutch.

[kitabel]

Nothing but a 1936-* big twin (OHV or SV) clutch will fit the transmission mainshaft.
Your math is correct, all chain drive big twin clutch drums are 37 tooth.
Primary drive 37 ÷ 20 = 1.85
Secondary drive 51 ÷ 22 = 2.32
Overall 1.85 × 2.32 = 4.29:1.
I suggest you use this at first, as equivalent to a 33 tooth (tall) original 45 ratio. The small engine won't like pulling a taller ratio. The 3.77 is far above any original 45 ratio, even tall for a Sportster.
The 4.28:1 drive + 3.00:1 1st gear will give very good low gear acceleration, and still reach 90 mph.

[RUBONE]

That is a Big Twin clutch hub. They are tapered with a keyway, 45 are splined.

[nanonevol]

Thank you, thank you.

Now I'm hoping I can use the Super Nut because my Main gear is an earlier one that did not use the small seal on the main shaft.
I should have just bought a new main gear but I had already paid a machine shop to size the bush (which they got a nice close fit on).

Apparently the Super Nut won't work with certain clutch parts. Which, I don't know.

Still putting together the transmission.

[nifty]

To advise on supa-nut fitment, need a pic of the other side of your BT clutch hub
Nifty

[RUBONE]

Apparently the Super Nut won't work with certain clutch parts. Which, I don't know.

Look at the back of that hub. If the center tapered portion extends back it will contact the supernut. If it is flush it will not. I personally have never used a so called supernut and never will.

[nanonevol]

Here it is.

[RooDog]

I had the interference problem on my '50 Panny and just simply ground back the enter of the hub until it cleared.
Or just use a later model hub.....
Or get someone with a lathe to cur it back for you....

[nifty]

Bit hard to tell, if rear face is more or less level with area surrounding taper bore you should have room for supa-nut/duo seal. Looks like it might be good for you.
The actual seals used in supa-nut/duo seal are more robust than the 65up shaft seal, where I can I use both.
Nifty

[RooDog]

The Buell fork fits. No frame modification needed.

I would prefer a hand clutch, foot shift like a modern bike if possible.
S'pose I need a mousetrap for that.
I'm finding it harder to find answers in the Harley world compared to the Triumph/BSA world.
The parts and repair manuals also harder to decipher but some of that is learning curve.

Ia that fork tree set on backwards for a reason?

[RooDog]

Do you have a transmission yet?
If so, how about some pictures?
How can we help if we can't see what you are doing?

[RUBONE]

Do you have a transmission yet?
If so, how about some pictures?
How can we help if we can't see what you are doing?

Read his previous posts. The bike is a Paughco frame for a 45 engine with a BT drive train. For his purposes a '68 up type direct pull will work with his ratchet top gearbox. A mousetrap not so well with a single downtube frame.

[RooDog]

Do you have a transmission yet?
If so, how about some pictures?
How can we help if we can't see what you are doing?

Read his previous posts. The bike is a Paughco frame for a 45 engine with a BT drive train. For his purposes a '68 up type direct pull will work with his ratchet top gearbox. A mousetrap not so well with a single downtube frame.

Are you building this for him, Robbie?
I saw the original pic and knew it was going to be a can or worms, probably why the first guy sold it in the first place.
Excuse me for asking for current pictures.
I would like to see his progress, if there is any....

[RUBONE]

No "can of worms" about a project like this. Just a new guy trying to learn, and badgering never helps. The concept is straightforward, been done many times (why else would Paughco offer a frame?), and easily accomplished with used or off the shelf parts. He is facing a learning curve that is unfamiliar. But my guess is he will easily succeed.
Other than support I have no part in this project. I only work on my own stuff and any more not that often. Too many projects, not enough time or money, and with age, not enough ambition. Too many other interests vying for time...