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Barnett Scorpion clutch

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  #1  
Old 05-10-2008, 12:30 AM
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Default Barnett Scorpion clutch

A while back I was complaining about the performance of my basically stock clutch. The bike is a fairly highly modified 1979 FXS with a 96" S&S EVO crate engine and a Baker 6 into 4 transmission. The clutch would slip at high speed (freeway driving) and would drag in gear at a stop. I was talking to shrktooth on this forum about it and he recommended the Primo/Rivera Pro clutch or the Barnett Scorpion clutch (there were others that mentioned these clutches as well but I spoke at length with shrktooth about it). I emailed Rivera asking some questions about their clutch but got no reply. I also emailed Barnett and very quickly got a response with the answers I was seeking (there were a couple more emails and a couple of phone calls to Barnett as well). For both clutches, the retail cost is about the same ($500)...Jireh had the Barnett for about $450 so I purchased from them. I haven't been riding my bike for about two months now due to surgical recovery (no big deal it's just taking time healing up) so I have been taking my time planning the install, getting the other needed stuff together and making the proprietary puller required to remove the Barnett clutch hub.
Well I finally felt okay enough to roll/crawl around on the garage floor here recently so I installed the new clutch. The instructions from Barnett are lacking only the recommendation to use only one pint of Type F ATF (I found out about that during one of the phone conversations with the Barnett rep.) due to the fact that the clutch is designed to be run dry. So there is only enough ATF in the case to lube the chain and other mechanical stuff but NOT to get up into the clutch shell. Initially, the fiber plates are soaked in ATF for 10 minutes but they are wiped off prior to install per the instructions.
Like I said, I am running a Baker 6 into 4 transmission and that added some additional parts requirements to my install. The Baker tranny uses a proprietary clutch adjustment screw and clutch hub nut seal so I had to get the proper adjustment screw and seal from Baker (no big deal, but necessary).
The adjustment screw from Baker needs to be modified to work with the Barnett clutch (shortened 1/2").
The Barnett clutch hub parts need to be pressed together and into the stock HD clutch shell. This isn't hard to do but you need access to a press and to be careful about supporting the bearing and other pieces to prevent damage whilst pressing them together. It all went smoothly for me and I ain't no genius so I'd say anyone with moderate mechanical ability can do it. Otherwise, I'm sure a shop would do the pressing for a nominal cost (whatever the hell that is these days).
There is no clutch spring adjustment other than a torque setting on the spring retainer bolts. You will need an inch pound torque wrench for these bolts and for the retainer bolts on the clutch hub after the hub/shell parts are pressed together.
The rest of the clutch adjustment is per stock HD service manual.
As soon as I finished the install I fired the bike up in the garage and tried it right then and there without going out onto the street yet. I have had a good feeling about this clutch all through this process and I am optimistic that my clutch woes are history (no drag and smooth engagement).
I have a few pictures but they are probably too big to post. I'll get my son to help me make 'em work here when I post again with a street test review of this baby.
 
  #2  
Old 05-10-2008, 08:21 AM
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Default RE: Barnett Scorpion clutch

Thanks for the post Megawatt,
I've been wanting to know more about the Barnett clutch system. Is this the one you installed ?
Is the clutch hub bearing a sealed unit?
is the clutch basket held in place with something similar to the clutch tamer?
Want is your counter shaft sprocket tooth count?
good luck on your test ride.

 
  #3  
Old 05-10-2008, 11:37 AM
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Default RE: Barnett Scorpion clutch

Rodney,
Yep. That's the one.
Yes, the clutch hub bearing is a sealed, double row, ball bearing. I found spares on eBay for $15 apiece so I picked up two of them.
The clutch basket and hub are an assembly that is all pressed together. First the bearing is pressed into the Barnett clutch hub adapter. Then the Barnett clutch hub adapter is pressed into the stock HD clutch basket. Then the Barnett clutch hub is pressed into the bearing in the clutch hub adapter. There are two snap rings and a retainer plate to keep the pressed parts from coming apart.
I have a 23 tooth sprocket on the tranny for the rear drive chain. Is that what you meant by countershaft sprocket?
I have been running a 49 tooth sprocket on the rear wheel but I've been thinking about going back to the stock 51 tooth. The engine has no problem pulling that gearing in the lower gears but I can't use sixth gear unless I'm above 80 MPH.
I hope to get it out on the street today.
 
  #4  
Old 05-10-2008, 02:24 PM
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Default RE: Barnett Scorpion clutch

Okay, I took it out on the streets around the house and a short blast down the freeway. It performed flawlessly. I have never had a clutch with such a light pull at the clutch lever. It's so light, I wonder if it will slip. It didn't feel like it was slipping on the brief run down the freeway today. I'll be watching it closely for a while until it proves itself to me to be reliable but for right now, I am favorable impressed. I won't be running any "acid" tests on it for a while, I want to get it "run in" first.
If it does slip at some point, there are two sets of springs (six of each) that come in the kit. The gold springs are the lightest tension and that is the set installed right now. There is also a green set that I can install if I feel I need more tension. If, at some point I do want more spring tension, I will probably try three gold and three green to see how that works.
Too bad my son isn't here right now to help me resize the pics I have but I'll get them on this thread when I can. They really may not be much help to anyone anyway but I do have pics of the hub and basket assembly so you guys can see what it looks like prior to install.
I was concerned about chain alignment since the old HD hub is not used but I took several measurements before I disassembled the stock stuff to have a reference to compare to the new stuff installed. I saw only a .030" change in position from the original set up which is not sufficient to warrant a new spacer (spacers are stepped in .060 increments) since it was just about dead nuts on originally. Barnett was only able to suggest using a straight edge to check sprocket alignment. I don't have a straight edge that will fit in there that is long enough to check the alignment that way and would require using a mirror to see unless one tried the whole assembly without the inner primary installed first and that opens up a whole new can of worms.
I realize it's early on in this change but for right now, I'd say that if you have the dough to spend, don't mind the small degree of improvising required to check chain alignment and the other stuff I've mentioned, this looks like it might be an outstanding upgrade from the stock clutch.
My son came home! The best I can do is post one pic at a time so heres the first one and I'll add the other two in more posts.
This pic shows Barnett's new hub installed in the shell.

[IMG]local://upfiles/48871/B697ED07F2304918AC687B4F94E49EE5.jpg[/IMG]
 
  #5  
Old 05-10-2008, 02:30 PM
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Default RE: Barnett Scorpion clutch

Next pic.
This shows the clips and retainer ring that hold the whole hub/basket assembly together.
[IMG]local://upfiles/48871/DD2F7FB410CA45248CD58C18FC91C5EC.jpg[/IMG]
 
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Old 05-10-2008, 02:31 PM
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Default RE: Barnett Scorpion clutch

Last pic.

[IMG]local://upfiles/48871/7ED7F571B7BC4EF5A9AAF5A3E800D852.jpg[/IMG]
 
  #7  
Old 05-10-2008, 03:53 PM
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Default RE: Barnett Scorpion clutch

Thanks for posting the images[8D]
Glad all is working out and havng the lever easier to engage the clutch is a bonus, that alone makes me need to do the upgrade.
 
  #8  
Old 05-10-2008, 07:22 PM
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Default RE: Barnett Scorpion clutch

Looks like a nice set up. Question...do you know if they make that type of set up for a belt drive primary. My 50 pan is set up with a belt drive, kicker only, enclosed tin primary.
 
  #9  
Old 05-10-2008, 11:06 PM
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Default RE: Barnett Scorpion clutch

panz4ever,
If your clutch basket is set up to use the original HD clutch hub and clutch fibers/steels, then I can't see why you couldn't use the same kit I did. Of course, your alignment for the front and rear pulleys is much more critical than with my chain/sprocket stuff. Barnett may have a clutch that'll work for you if you're using something else. I don't recall if they supported any other aftermarket company's stuff.
Check 'em out at:
http://www.barnettclutches.com/
 
  #10  
Old 05-31-2008, 11:08 AM
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Default RE: Barnett Scorpion clutch

Well, I have about 700 miles on this clutch. It is still performing flawlessly and I am very pleased.
I gotta say though, I envy you guys that are able to run the stock clutch without problems.
 
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