Clutch hub

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socalrider
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Clutch hub

#1

Post by socalrider »

Greetings men,
On my 65flh I have a 3 stud clutch hub with a mousetrap. I am thinking it is not the original clutch hub and may be a shovelhead clutch hub reason being the adjusting nuts bottom out on the non threaded portion of the adjusting studs before I get to the manual specified 31/32" adjustment that is measured from the outer rim of the collar to the face of the pressure plate. I know panhead clutch springs are shorter than shovelheads and shovelheads also have one or two more friction plates than a panhead.i do have the correct panhead springs and three friction plates.I am thinking that the shovelhead clutch hub adjusting studs are longer than the panhead to accommodate the longer springs and additional friction plates. I know I can make it work by adding an additional friction plate but would rather not do that. Trying to stay as close to factory as possible.Am I right in thinking that they are in fact different? Thanks for the help.



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Re: Clutch hub

#2

Post by RUBONE »

The studs are identical and the hubs interchange. If you are running out of thread your clutch pack assembly is too thin for some reason. What combination of plates (friction and steel) do you have now? Is the 1/2 plate in place? Are your plates factory or aftermarket? See the parts breakdowns in the parts books listed in the Documentation section.

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Re: Clutch hub

#3

Post by RooDog »

Don't sweat the petty stuff, just go ahead and add an additional pair of plates and be done with it. On my Project Panhead I had the same problem and scored a double thick welded steel plate at a swap meet, Apparently someone else had a similar problem. I inserted it in first followed the standard 3.5 stack, and all worked out well. Who, other than yourself will know what's inside that primary?
....RooDog....
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socalrider
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Re: Clutch hub

#4

Post by socalrider »

Robbie I think you solved the mystery.all the friction plates are aftermarket and significantly thinner than the factory plates,and yes i do have the half plate. Thanks for the help man, you always come through! Roodog, i Hear what you are saying and will do that as a last resort.

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Re: Clutch hub

#5

Post by RooDog »

Yes, Fellas....
The thickness of the fiber discs, and of the steel plates does affect the stack height. There is absolutly nothing wrong with using an extra pair of plates/discs to achieve thee proper height, that will give added surface area to your clutch and added holding power. The softer "eliminater" spring have no place in a mousetrap boosted clutch, and the speced 31/32" is just merely a starting point, one can go softer, like 1", as long as the clutch don't slip. An easy test is to use two pieces of masking tape, one onthe clutch shell and another in line on the spring ring, and then try to kick start it with the key off. If the two markers move out of line the clutch is slipping. If not, you are good to go for a test ride. Adjusting the mouse trap is the next fun thing on the agenda, but then, we all know how that's done, now don't we.
Best Wishes.....RooDog
BTW. I am fond of the green Kevlar friction discs from Barnett.....

socalrider
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Re: Clutch hub

#6

Post by socalrider »

You are right roodog it will work with added plates. Thats how ive had it for the past several years and all functioned properly including mouse trap. I would just rather have it as it came from factory. Sourced some oem plates to get it there. Thanks for the help

Andygears
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Re: Clutch hub

#7

Post by Andygears »

socalrider wrote:
Tue Jan 14, 2020 6:57 pm
You are right roodog it will work with added plates. Thats how ive had it for the past several years and all functioned properly including mouse trap. I would just rather have it as it came from factory. Sourced some oem plates to get it there. Thanks for the help
I think there’s something to be said for less plates in a stock application. If you have a 3 1/2 plate clutch, the pushrod travel is divided by 7 when the clutch is disengaged. But in a 5 plate clutch, that same travel is divided by 10. Closer clearance can make more drag. But more swept area, with more plates, should make a more secure engagement for less slip when engaged. All other things being equal, it would seem a compromise as many things are.

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Re: Clutch hub

#8

Post by RooDog »

With the advent of both MoCo and aftermarket Mousetrap Eliminater clutches came problems trying to balance softer spring pressure with additional discs surface area, and separation clearance issues. As Andygears mentioned, it truly is a compromise, and is workable with 74 inches, but goes out the window with a hot rodded engine. These are not so much issues with the mousetrap boosted releasing linkage. Friction in the cable and throw out lever and bearing was also something to overcome, and this happened in 1985 when the Big Twins adapted the ball & ramp system from the Sportsters. Most of all the pressure, surface area, and separation issues have gone away with with today's modern clutch design. And the sealed hub to basket bearing has totally eliminated the old rattling, and jingling thing, bye, bye! All these modern clutch innovations, except the ball.n. ramp, may be easily applied to your 1941 and newer ride with aftermarket offerings from Barnett's Scorpion, BDL Competitor, or my fave Rivera Primo Pro clutch. There are others, and I have even heard that the unit from a 1990 BT with the tapered main shaft, may fit an older tranny, but I don't know this for sure. Anybody know about this. Remember your original 10 spring clutch is 1940's tech....
....RooDog....

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Re: Clutch hub

#9

Post by RUBONE »

For many it is all about experiencing the bikes as they were designed and ridden in their prime, not what it is possible to make them into. There are very different approaches to what a bike is, can be, or should be. I for one could care less about pushing a Flathead, Knuckle, or Pan to its limits, that holds zero appeal. I use my old bikes to experience a different time. I use modern technology to experience now. As an old 1%er friend said when he saw the Ducati I was riding, "Ah, a thinking man's Harley". And I have to agree. I enjoy my old stuff as it was meant to be, and that is good enough for me. :mrgreen:

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