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  1. #1

    Default Barnett scorpion clutch kit.

    I installed one on my '80, shovel. The directions said use red loctite on the hub nut. It loosened up and lead to a breakdown. Lesson here is don't buy one at $500.

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    Since plenty of those kits have succeeded over many years, I'd wonder what caused the locking compound not to work. Were all threaded surfaces cleaned with a non-oily solvent prior to application? Was the hub torqued to spec with a torque wrench?

    Show us some pics of the parts with any damage
    because a single typed post isn't useful info. There are many ways to secure hub nuts beyond friction and adhesive but I don't own a Scorpion and can't read minds over the internet.

    When you called or emailed Barnett tech support what was their response?
    Last edited by farmall; 06-25-2020 at 12:59 PM.

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    Mine works great other than being really noisy. They are really well made and I think chomoly or some exotic material. I'm gonna go with you installed it wrong.

    I had to file down the woodruff key to get the taper to seat fully. Coat the side of the key in sharpie, place it in the keyway on the mainshaft and scribe a line with a sharp scribe or razor blade. Repeat with the keyway on the clutch hub. File away the difference between the two lines from the top of the key. I would bet the key was too tall and it was never properly seated. A buddy of mine spun his and it welded to the mainshaft. Cutting thru a mainshaft to get the clutch hub off, while still attached to the trans is really not fun, so I made sure mine was right.

    I also lapped it with a little valve grinding paste. just lightly. You can pretty much stick the hub on by hand and still need a puller to get it off. It's the taper that holds it on there, not really the nut or the key.

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    Taper joints get keys to augment the holding power and work as a combo (the other use of keys is timing, irrelevant for a clutch). The higher quality key the better.

    Loctite is specifically intended to augment taper fits but sucks to remove without heat (so I use a pencil OA torch with a fine flame and an IR thermometer). Link because many folks don't know that and may think it an old wives tale:
    https://www.henkel-adhesives.com/us/...compounds.html

    Problems with Conventional Assembly Methods That LoctiteŽ Retaining Products Can Help Overcome:

    Pins, key/keyway assemblies have uneven distribution of mass, an imbalance that can lead to vibration at high speeds
    Splines and serrations cause high stresses due to the “notch effect” that occurs in the area of a key. And have high machining costs
    Clamp rings, press fits, shrink fits, and taper fits rely on friction alone to transmit torque, therefore they are limited by material, surfaces and design. Close tolerances are needed to obtain specific load capacities, leading to high production costs
    Lapping is a very good idea if a dye check (most machinists use Sharpies because Dykem flakes off) shows poor engagement since the only reason the factory used tapers is they were dirt cheap to machine. (CNC brought inexpensive splined shafts.)

    Lapping example for those not familiar, and on 'peds with low HP ditching the key lets the owner tweak the timing (that taper is not transmitting power to the driveline like a clutch).

    https://www.mopedarmy.com/wiki/Lappi...d_no_slip_bond

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    I have to second what others have said. I installed a Primo clutch/shell and the key didnt engage properly.
    3 miles later the hub at mainshaft got fuckered up. Shaft was good. I suspect installer error.

    I shipped the basket/hub to primo for replacement hub and a week later CAREFULLY and PROPERLY reinstalled. Years of reliability was the result.

    Get ahold of Barnett and send it back for repair. Its gonna be on your dime, though.

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    On the stock, taper shaft, shovel clutch hub nut, I torque to 120ft.lb., and don't have any problem. BUT, the stock clutch hub is hardened steel and very robust at the shaft taper. All of these aftermarket clutch hub styles with the ball bearing supporting the clutch shell are thin in the area of the taper, same problem as the late '80s HD hub which design they mimic. And the material, even if alloy steel, is soft relative to the original, and that is a problem. These aftermarket hubs can be treated to a reinforcement ring same as used on the HD hubs with ball bearings. That ring should only have .001 - .0015 press fit, and be heated and dropped onto the hub rather than pressed on. Even at that, the reinforcement ring may distort the hub making the fit on the shaft imperfect. You have to find a nut torque that will overcome the ring and allow good seating of hub to shaft, or further problems will ensue.

    All that said, I prefer a well sorted stock clutch, even on high horsepower applications. Six plates can be fitted along with more spring, and fewer problems and less expense in the long run.

    Just my 2c,
    Jim

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    Very entertaining and educational ....

    (May be a bit more than 2 cents) ...
    Last edited by Dragstews; 06-29-2020 at 10:38 AM.

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    All that said, I prefer a well sorted stock clutch, even on high horsepower applications. Six plates can be fitted along with more spring, and fewer problems and less expense in the long run.
    How do you set up yours and what plates and springs do you prefer? Three or five stud hubs?

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    Quote Originally Posted by farmall View Post
    How do you set up yours and what plates and springs do you prefer? Three or five stud hubs?
    Preferably HD 3 stud hub, stock hub bearing, not the long rollers, RamJett retainer or clone, Barnett steels with narrow slots and no cushion balls. Cheap Taiwan plates, or Alto red plates (even cheaper). You can thin the stock type plates enough to get six in the shell. Five or six plate carbon fiber kit is good also, but expensive. Barnett foot clutch springs (they are orange/ red) along with a few of the Barnett heavy springs (they are grey/white) if needed. A full complement of the grey springs is too much. Aluminum pressure plate. Early style release bearing if using a lot of spring. The OEM wafer bearing is good if you are using only the orange springs. The aftermarket wafer bearings are no good. Preferably '82 - up clutch perch and lever, for more travel. Chain drive primary with oil circulated from the motor. Do it right and it's a smooth clutch that will last a long time. Oh yeah, NO Kevlar plates. They are an invention of Satan.
    You asked, there you go.

    Jim

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    Soups On

    Dang good recipe ...

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    Pics show why the repop witch hat bearing sucks. The race looks like it was machined with a railroad spike:

    https://www.jockeyjournal.com/forum/...d.php?t=102773

    Too bad the Shovelhead aftermarket is fading. A billet witch hat with a shallow Timken could have replaceable races and be nearly indestructible with no grinding/lapping required.

    Is the Eastern Motorcycle Parts bearing any good? https://www.ebay.com/p/171241166

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    Quote Originally Posted by farmall View Post
    Pics show why the repop witch hat bearing sucks. The race looks like it was machined with a railroad spike:

    https://www.jockeyjournal.com/forum/...d.php?t=102773

    Too bad the Shovelhead aftermarket is fading. A billet witch hat with a shallow Timken could have replaceable races and be nearly indestructible with no grinding/lapping required.

    Is the Eastern Motorcycle Parts bearing any good? https://www.ebay.com/p/171241166
    Long ago I made a release bearing assembly for my pan using a ball thrust bearing from work.

    No, the Eastern wafer bearing is no good, but their thrust washers that are part of the assembly are OK.

    Just get the HD factory part, still used in evos, and earlier twinks (I think).

    Jim

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    Quote Originally Posted by farmall View Post
    Pics show why the repop witch hat bearing sucks. The race looks like it was machined with a railroad spike:

    https://www.jockeyjournal.com/forum/...d.php?t=102773

    Too bad the Shovelhead aftermarket is fading. A billet witch hat with a shallow Timken could have replaceable races and be nearly indestructible with no grinding/lapping required.

    Is the Eastern Motorcycle Parts bearing any good? https://www.ebay.com/p/171241166
    I just got one of these eastern ones on ebay. Going to finish the install tonite. The one you linked to first is gabbage, mine was a bit crunchy new just sitting on the bench. lasted about 500miles, clutch adjusted properly. It was kind of a confluence of events so that may be unrelated but the eastern one appears to be a much better made piece. Doesn't have the little scoops for oil on it though, which I thought was weird and not ideal. The bottom edge rides in the oil anyway it seems.

    Also, may as well ask it here, how much in/out play should the kicker shaft have? Mine seems a bit sloppy? (washer is installed on the outside with the chamfer facing the trans.)

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