Transmission sprocket nut question

Transmission, clutch, chains and belts
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doc308
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Transmission sprocket nut question

#1

Post by doc308 » Wed Nov 12, 2008 3:31 am

I recently bought one of those "dual-seal" tranny sprocket nuts and it's about twice as thick as the stock nut. It seems that this might cause a fitment problem with the clutch hub. Has anyone used one of these and , if so, was any modification necessary?
I also see that some vendors sell a nut with a single seal installed. How about these--ie are they bigger ? Any experience with this type?



VT

Re: Transmission sprocket nut question

#2

Post by VT » Wed Nov 12, 2008 4:47 am

All of the dual-seal nuts (Super-Nut®, Duo-Seal®, etc) work with (1936-1964) stock tin primary's. The nuts will not hit the clutch hub.
The seal-nuts will not work on ('65 and later) aluminum primary's.
We covered this before. I posted pix to prove it. A trail has been blazed for you. Proceed. "Super Nuts®" with the single, wide & flattened O-ring are preferred.
Image
SuperNut® with a '55-64 inner primary on a V-Twin '55-57 rigid frame. All the frame tab, inner primary, and oil tank tab holes line up perfectly.

doc308
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Re: Transmission sprocket nut question

#3

Post by doc308 » Fri Nov 14, 2008 3:43 am

Thanks, Vt. Nice picture too. I just tried my duo-seal nut on for size and it caused my clutch hub to sit out about an 1/8" further than it does with the stock nut. Is that a significant amount re: the primary chain line-up?

I noticed in your picture that you're not running the metal splash shield. Could that make the difference it fitment?

VT

Re: Transmission sprocket nut question

#4

Post by VT » Fri Nov 14, 2008 4:17 am

you're not running the metal splash shield. Could that make the difference it fitment?
No shield (for a belt primary) and no it wouldn't make much difference. The '36-64 clutch hubs should just cover the keyway slot on the aftermarket mainshaft. If your hub hits the Super Nut, then you either have an OEM hub and mainshaft or I don't know.
There was some discussion on the Flathead Topic about some aftermarket hubs having too steep of a taper and causing the AM hubs to be pushed 1/8" off or more from seating up on the mainshaft like they should, but post a pic of what you have and we'll take a look.
The '41-64 hub is hand-pushed on to the mainshaft key:
Image
The key is there at the bottom. The hub will only push on about 1/8" further onto the shaft, when the hub nut is torqued to 70 ft. lbs.. The "raised area" (shoulder) on the hub does not make contact with the Super Nut. It's still a clamp-load, from hub nut to (tapered) mainshaft, but there's always a gap between the back of the hub and the exterior surface of the mainshaft nut.
-----------------------------------------------------------------------------------
Wait a minute :lol: .................I know what the problem probably is:
You might have an OEM clutch hub, which has a monster-wide shoulder on the back of the hub. I didn't realize it until someone posted a pic of one. Radically different from the "shoulder" on my Taiwan repop. Yeah, if that's the case, for sure the nut would hit the back of the "shoulder" but not the hub. Check it out.

And further, the appearance of some of my key, even with the hub hut torqued to 70 ft. lbs, is due to the fact that the OEM hubs have the wide shoulder that would normally cover the key. If you sliced away some of that wide shoulder on the OE hub, you'd probably see some of the key as well.
Go to the "Flathead" section and to this topic V-Twin Clutch Hub Woes and look on page 5 You can see how thick the OE shoulder is and how thin the AM hub is (like mine). The SuperNut would probably not work on the OE hub.
It's rare to see any of the OE hubs still around that are serviceable - the thin shoulder hub is what most people consider "stock-Harley" with these days.
Imo, the AM clutch hub is an example of "Harley minimalism" taken to it's fullest extent. Whoever made repop clutch hubs 40 yrs ago, had engineers looked at the original hub and remove every gram of metal "fat". The engineers or "biker machinist" (a society of competent mechanics) knew the AM hubs would perform fine without the thick shoulder on the back of the hub. And that having the leading-edge of the shaft key not completely covered by the hub when installed, wouldn't make any difference at all in hub's performance. Brilliant. Not only did they make a lighter clutch hub at an affordable price, the hub later created a market for mainshaft seal nuts.
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Stett TiG welds a puddle to the base (back of the hub) of each stud to keep them from snapping-free and turning once the hub is all installed. Cures the problem before it can happen.
Building motors and transmissions @ http://stettsironhorseranch.com/" onclick="window.open(this.href);return false;
Last edited by VT on Fri Nov 14, 2008 7:14 pm, edited 5 times in total.

john HD
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Re: Transmission sprocket nut question

#5

Post by john HD » Fri Nov 14, 2008 4:48 am

this thread will tell the rest of the story. viewtopic.php?f=5&t=2656

bottom line, pre 65 oem hub plus super nut does not work.

john

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Re: Transmission sprocket nut question

#6

Post by Cotten » Fri Nov 14, 2008 1:38 pm

Just to add to JohnHD's bottom line for clarity:

Pre 65 oem hub, or pre-'65 OEM main drive gear, plus super nut does not work.

....Cotten

doc308
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Re: Transmission sprocket nut question

#7

Post by doc308 » Fri Nov 14, 2008 1:46 pm

OK--that's the problem. I have an OEM hub and mainshaft. The hub slot complee=tely covers the key and is flush against the nut. As I mentioned, it's 1/8" off after tightening down. Oh, well--back to the OEM nut.

Thanks for all of the input, guys.

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