Mousetrap on 1976 Shovelhead

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michigander52
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Mousetrap on 1976 Shovelhead

#1

Post by michigander52 »

I'm trying to make the clutch on my'76 Shovelhead pull easier and other folks have suggested installing a mousetrap will help. Before I go to the mousetrap I wanted to see if I could get the longer #37052-65 arm used on'65-'69 to work with my OEM cable set-up. This probably shouldn't work but my thinking is that comparing it to my Franken Knuckle that has the mousetrap eliminator with the long clutch release arm which works perfectly and the pull is the lightest I've ever felt on any other bike.

The issue I'm having is with the longer arm on the Shovelhead the cable doesn't have enough pull length to disengage the clutch (longer arm = less travel). What's puzzling to me is that the cable pull length on the Knuckle is the same as on the Shovelhead and the clutch release arm is LONGER yet the clutch disengages perfectly. Do you have any idea what is different on the earlier clutch set-up that would work differently (require less push-rod travel) than the later set-up on the Shovelhead? I did cut a new notch on the new arm that has helped but it still needs to be shorter yet.
I'm trying to add pictures but having a problem with that.
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Last edited by michigander52 on Wed Jun 01, 2022 12:52 am, edited 2 times in total.
RooDog
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Re: Mousetrap Eliminator?

#2

Post by RooDog »

Quick dicking around trying to reinvent the clutch system the MoCo tried to make work, to greater or lesser success, and go to the complete mousetrap if you want the lightest pull possible. A MT can be adjusted to such a degree that one can wind up with no lever resistance at all.
....RooDog....
michigander52
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Re: Mousetrap Eliminator?

#3

Post by michigander52 »

Thanks for your help RooDog, I'm sure the mousetrap assembly is where I'm going but before buying the mousetrap kit I just wanted to see if I could get it to work as well as my Knuck set-up. Something is different between the two in the distance of travel required to disengage the clutch.
Not to throw good money after bad I'm going to get the MT kit, guess it's just one more thing in my life I'll not understand. LOL
Thanks again
Steve
RooDog wrote: Fri May 20, 2022 6:32 pm Quick dicking around trying to reinvent the clutch system the MoCo tried to make work, to greater or lesser success, and go to the complete mousetrap if you want the lightest pull possible. A MT can be adjusted to such a degree that one can wind up with no lever resistance at all.
....RooDog....
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Re: Mousetrap Eliminator?

#4

Post by RooDog »

Steve....
Perhaps the difference is in the clutches themselves. Like how many plates & discs, early or late springs. The outer buffer/cushion plate present or omitted. All these factors come into play, and also the preload on the springs. Never mind the book specs. Loosen the springs until slippage occurs, and then tighten them until the slip goes away. That is where the springs need to be....
Currently I am wrestling with three different clutches, a modified 10 spring, a Rivera Primo, and am going to try the Barnett Scorpion I have had laying around here for quite a while. The latter two feature enclosed sealed ball bearings vs the OE loose rollers. They provide modern clutch action over the rollers....
....RooDog....
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Re: Mousetrap Eliminator?

#5

Post by michigander52 »

I do need to take the discs out to see what's up with them. After sitting this winter the clutch has developed a "lurch" when taking off from a stop. I'm guessing there's oil or something on the plates.
Do you think this MT kit from Dennis Kirk will work for my '76?
https://www.denniskirk.com/v-twin-manuf ... 384768.sku
RooDog wrote: Fri May 20, 2022 9:42 pm Steve....
Perhaps the difference is in the clutches themselves. Like how many plates & discs, early or late springs. The outer buffer/cushion plate present or omitted. All these factors come into play, and also the preload on the springs. Never mind the book specs. Loosen the springs until slippage occurs, and then tighten them until the slip goes away. That is where the springs need to be....
Currently I am wrestling with three different clutches, a modified 10 spring, a Rivera Primo, and am going to try the Barnett Scorpion I have had laying around here for quite a while. The latter two feature enclosed sealed ball bearings vs the OE loose rollers. They provide modern clutch action over the rollers....
....RooDog....
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Re: Mousetrap Eliminator?

#6

Post by RooDog »

You will need the 1965-67 arm, and it will work with any big twin with a ratchet lid.
But you will need to drill another hole in the lower part of the bell crank if using that arm, or use a pre-1965 arm with the existing hole for the pull rod....
michigander52
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Re: Mousetrap Eliminator?

#7

Post by michigander52 »

RooDog wrote: Sat May 21, 2022 1:30 am You will need the 1965-67 arm, and it will work with any big twin with a ratchet lid.
But you will need to drill another hole in the lower part of the bell crank if using that arm, or use a pre-1965 arm with the existing hole for the pull rod....
Okay great, I do have the 1965-67 arm and it does fit between the primary and oil tank so I should be set once I get the MT kit. I did put an extra notch in the arm trying to get it to work with my cable set-up but it should still be okay.
Here's a picture of the arm I have.

Steve
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Re: Mousetrap Eliminator?

#8

Post by RooDog »

I'll have to confirm that tomorrow when I can get back into the shop. I have a complete transmission out of my '68 laying on the floor...
I don't know if I still have any MT parts left.... Or i'll even be able to find them....
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Re: Mousetrap Eliminator?

#9

Post by Andygears »

I have found that variation of manufacturer and lack of lubrication can make a huge difference in M. Eliminator cables. Hanging a clamped on nipple with a bottle of oil above it overnight, fills the cable and can make a big difference, but a cheap cable may not have enough flex to work easily.

Andygears
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Re: Mousetrap Eliminator?

#10

Post by RooDog »

Steve....
You do know that the pre-1968 springs, 38077-41, are stronger than the eliminator springs, 37077-68, and of course, that makes all the difference in the world. The eliminator also used an extra pair of steed plates & fiber disc to compensate for the lowered clamping force of the softer springs. This increased stack height make the pushrod travel and disc separation even more critical to achieving a clean release. It is truly a balancing act trying to get all the mechanical qualities balanced and working together.... And that is why I like the mousetrap setup.... One gets the clutch adjusted so that it does its job, and the the MT booster adjusted to get the kind of lever feel one likes....
Also, like Andy says, lube the cable....
There are two cable designs. The standard coiled outer housing, and the more modern longitudinally wound, and stiffer, outer cable. It removes much of the slop in the operation of the eliminator motion transfer, a quality not detrimental to the workings of the MT.... Just another turd in the soup....
....RD....
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Re: Mousetrap Eliminator?

#11

Post by RooDog »

Steve....
OEM 1965-67 clutch arm to use with a mousetrap.
Can also use used with a MT and the later eliminator clutch pack & springs.
I hope that is not too confusing....
....RD....
DSC03113.JPG
DSC03111.JPG
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michigander52
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Re: Mousetrap Eliminator?

#12

Post by michigander52 »

RooDogg, not too confusing. My release lever is like the one in your picture. I took my clutch pack out last night to clean it up and it has 5 fiber disc and 4 steel. Also it has a 5 stud hub. The PO had replaced the clutch so I believe it has the later springs but I don't know that for sure without knowing the length they should be.
I'm going to take the clutch pack out of the knuckle to compare but I'm pretty sure it has the 3 disc set-up. I think that the extra discs etc. on my eliminator is what the difference in the required travel. I'm ordering the MT kit so we'll see how it goes from there.

Also when cleaning the old discs should they be cleaned with brake cleaner and lightly sanded?

Thanks for the help....
Steve
RooDog wrote: Sat May 21, 2022 4:55 pm Steve....
OEM 1965-67 clutch arm to use with a mousetrap.
Can also use used with a MT and the later eliminator clutch pack & springs.
I hope that is not too confusing....
....RD....
DSC03113.JPGDSC03111.JPG
michigander52
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Re: Mousetrap Eliminator?

#13

Post by michigander52 »

Well I just had to see what the Knuckle had for clutch discs and it wasn't what I expected. It has 5 fiber and 4 steel discs like the Shovelhead instead of the 3 fiber disc set-up and has the shorter and larger diameter springs like the earlier models. Guess you never know how someone has put these old things together.

Steve
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Re: Mousetrap Eliminator?

#14

Post by RooDog »

The Knuckle's springs should be stouter than the Shovels, but may coil bind sooner, so installed height may also be critical....
I usually just use brake clean and wipe the disc dry. I see no point in sanding them unless they are heavily glazed.
Also, that 5 finger/stud hub does nothing for the clutch's operation. Don't toss it, just don't buy one unless it is really cheap, free is better.....
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Re: Mousetrap on 1976 Shovelhead

#15

Post by michigander52 »

The new Mousetrap Kit arrived today so I started installing it and right now I have a couple of issues to work out.
1) The clutch rod wouldn't fit into the slot in the release arm so I had to file the slot a little wider. Got that done and now the rod seems to be too long by 2-3".
2) This bike is a FXE so the shifter arm on the ratchet top points up not down like the FL so I'm going to have some trouble getting the rod to clear. I have cut another groove in the release lever further in so that might work. I had to walk away from it for a little while so I don't cut something I shouldn't.
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