APM Clutch (i.e. Pro Clutch)

[JW113]

I recently installed an APM Comp Master clutch in my '77. It is essentially identical to the Rivera Pro Clutch, and my understanding is that the two were designed by the same guy. While the clutch works, and solved my slipping problem, the force at the lever is off the chart. I called APM this morning, and got essentially zero help. He was convinced that I installed it wrong, or that the cable was binding. If you're at all familiar with this type of clutch, unless you get the disks/plates out of order, there is essentially no way to install it wrong that I can see. Before installing it, the lever force with the stock 10 spring clutch was hardly anything, and I didn't touch the cable when installing the APM. Just for grins, I removed the clutch adjust screw, and the clutch rod moves out with essentially zero effort. It ain't binding. And the cable is teflon lined with a touch of silicone oil. Friction is not the problem.

Also for grins, I used a linear force gauge and checked the clutch lever on my '92 Evo: 8 lbs pull force. Then checked my '04 Road King with SE heavy duty diaphragm: 13 lbs. And the Shovelhead with APM: 32 lbs pull force!

I'm at a loss. Everything that I have read, and what the APM dude told me today, the diaphragm clutch should have much less lever force than the stock 10 spring clutch. It ain't. Much, much more force than the stock clutch. I am at a loss what to do now. Any suggestions, other than pull the freakin' thing out.

-JW

[Ohio HD]

I've never installed one. But what comes to mind is making sure the spring is installed right side out to get the 0.010" to 0.020" bow they speak of. And in case they happen to sell a heavy duty spring, or could have received the wrong spring from their supplier, measure the thickness of the spring and ask them how thick it should be.

Added:
I see they list a spring part number 1-2059-0003 "medium"
That would imply they also have a "heavy" and maybe an "extra heavy"
I'd measure the thickness and call them.

I would think a stock bike, the clutch has 50% more friction surface, that you would only need a very light spring.

[Ohio HD]

I was right, they do have additional springs.


2059-0001 for stock applications color black


2059-0003 competition color silver


2059-0002 race applications color gold

[JW113]

I have the silver spring. Which is what comes with the kit and the dude said was suppose to have a light lever pull. I'm a-thinkin' I need to give the black spring a try. Thanks, round on the ends and high in the middle (O-hi-O). LOL!

cheers,
JW

[Ohio HD]

I have the silver spring. Which is what comes with the kit and the dude said was suppose to have a light lever pull. I'm a-thinkin' I need to give the black spring a try. Thanks, round on the ends and high in the middle (O-hi-O). LOL!

cheers,
JW

Wouldn't that be (o-HI-o)         

[kd]

   O hi O 
       /   
       U

[Ohio HD]

O hi O
    /   
    U

 

[JW113]

Oh you guys!

 

-JW

[72fl]

JW I have the Rivera and clutch pull is minor with no slippage (2 Finger) and does Mark on his 76. The only thing I can think of is the Clutch tightness needs to have a rewverse type Bow contour to the Spring when Installing. I attached Rivera's guide maybe they have something in there that isn't in your guide.

https://riveraprimo.us/pages/installation-guides?msclkid=64dd8918b7e911ecb545bc33d26b1c32

[76shuvlinoff]

When I finally replaced the discs and plates in my Rivera there was one thick plate I think was to go in last. Apparently the design is different now that it was in 2004.  The spring was practically flat and the lever would barely move.  I ended up taking that thick plate out and reusing an old thin one. Life is good.

JW, I have no idea why your's is so tight out of the box with all new parts.  If  you have a thick plate in the stack, and if the design is truly the same, I can send you one of the originals from my Rivera, free to a good home. . When I pulled them out they measured within .005" of the new ones they sent me.

The lever on mine doesn't pull harder than stock does with a well lubed cable.  It is stiffer than my 12 EG.

Here is my thread.
https://harleytechtalk.com/htt/index.php/topic,116382.msg1396314.html#msg1396314

[JW113]

JW I have the Rivera and clutch pull is minor with no slippage (2 Finger) and does Mark on his 76. The only thing I can think of is the Clutch tightness needs to have a rewverse type Bow contour to the Spring when Installing. I attached Rivera's guide maybe they have something in there that isn't in your guide.

Wow, that is trippy. Those Rivera instructions look like a carbon copy of the APM instructions, only with Rivera replaced by APM. It's even the same part number! Is the Rivera Pro Clutch a repackaged APM clutch?

Not sure what you mean exactly by "reverse bow contour" on the spring. The only way that I can see that it would work is to have the "dome" of the spring facing outward.

I got a response from Ben Kudon at APM. Not much help, just re-iterating that it is a two finger lever pull. I honestly don't see how one could install this clutch incorrectly, there is not really anything to it. And the parts are even marked which side faces out.
 

Mark, I might take you up on your offer. So you're saying ditch the .120" inner plate and use a standard plate? That kind of makes sense, as it feels like this thing is overly compressed. I'll ping you. Also, I think I will get one of those black diaphragm springs to give it a try.

Oh, and you were spot on. After a couple hundred miles, the thing is now a lot less grabby and easier to feather.
 

thanks,
JW

[Ohio HD]

JW, that's what I was asking about. That there is an 0.010" to 0.020" bow / curve in the spring. Center outward.

[JW113]

OK, full disclosure here. I did see that in the instructions, but indeed I did not measure it. Not because I'm lazy (don't ask my wife about that though), but because I could not figure out a way to measure it. Guess I need to put my thinking cap on. It looks easy in cross section view drawing, but in reality, not so easy. As in, how to get something in there to touch the top of the diaphragm and keep it perfectly perpendicular? Or maybe I'm missing something obvious?

You cannot view this attachment.

-JW

[JW113]

OK, here's a big DOHHH!!! I no sooner hit send above, and a light went off above my head: measure it as you would a primary chain, i.e. the depth from the hole in the outer primary. DOHHH! Running out the garage right now...

-JW

[JW113]

Hmmm. So that black spring retainer overhangs the inner end of the diaphragm, so you can't really get right up to the inner edge to measure the exact compressed thickness, but measuring from the outer edge to the surface nearest the spring retainer, I am getting .026". So it's a little more than that, maybe .030"? Which is .010" less compressed than they spec, with a monster for clutch lever force. WTF? I can only imagine what my poor throw out bearing is going through, guess it won't be long for this world.

-JW

[david lee]

im interested in the fix jw

[76shuvlinoff]

So you're saying ditch the .120" inner plate and use a standard plate?

I know it worked for me but I have an older Rivera hub. As I understand it the new ones are deeper and should accommodate that thick plate. As mentioned previously, with all the surface area in these clutches you do not need a performance spring in a stock bike.  I think I'd be looking at that but the offer of a used thin plate stands.

 If you read back through my thread on this topic billbuilds  dug into this issue, even contacted the manufacturer.  It reads to me like the new hubs will take  the thicker stack up of 1.7".

[ghostrider]

Did the kit come with any of the adjustment shims?  If it did you could always try using them and see if it helps.
To measure the arch you could try a short straight edge, like a full blade from an Olfa knife, and lay it accross the spring just south of the retainer, if you know what I mean. It won't be real wasy to see or measure the arch, but if its way off it should be obvious.  I've got my sitting here in front of me and I think that would work ok?   

[turboprop]

Rivera

JW I have the Rivera and clutch pull is minor with no slippage (2 Finger) and does Mark on his 76. The only thing I can think of is the Clutch tightness needs to have a rewverse type Bow contour to the Spring when Installing. I attached Rivera's guide maybe they have something in there that isn't in your guide.

Wow, that is trippy. Those Rivera instructions look like a carbon copy of the APM instructions, only with Rivera replaced by APM. It's even the same part number! Is the Rivera Pro Clutch a repackaged APM clutch?

Not sure what you mean exactly by "reverse bow contour" on the spring. The only way that I can see that it would work is to have the "dome" of the spring facing outward.

I got a response from Ben Kudon at APM. Not much help, just re-iterating that it is a two finger lever pull. I honestly don't see how one could install this clutch incorrectly, there is not really anything to it. And the parts are even marked which side faces out.
 

Mark, I might take you up on your offer. So you're saying ditch the .120" inner plate and use a standard plate? That kind of makes sense, as it feels like this thing is overly compressed. I'll ping you. Also, I think I will get one of those black diaphragm springs to give it a try.

Oh, and you were spot on. After a couple hundred miles, the thing is now a lot less grabby and easier to feather.
 

thanks,
JW

Rivera shut down. No more. Ben was the guy at Rivera, he formed APM, same building, designs, suppliers, bad attitude, etc.

[turboprop]

There are really two versions of the pro clutch. I will call them, old and new. The difference between the two is the center hub. The old hub had a flat surface that functioned as a steel plate. The new hub does not the flat plate are. Instead it has small nubs that protrude from each of the splines. The clutch pack for the new hub includes a thick steel plate. It goes in first and functions as the plate area that is integrated into the old hub. The remainder of the clutch pack uses the standard steels and frictions.

[72fl]

Rivera Pro, APM,

American Prime is who is Manufacturing them Now.

JW I guess I misworded but the outside of the spring Bow back at you, you could try like a 6" scale to lay across it. Or I guess anything that is flat and you can lay across the spring and measure the deflection. Check Marks out he is why I installed mine. Dave

[FSG]

[JW113]

Thanks Gary! Although that is the video for the Evo clutch, it inspired me to go find the 4 speed clutch as he mentioned.

https://www.youtube.com/watch?v=Wd-ttSzm7Ro

Sure wish I knew how you guys embed videos into these posts! That is a neat trick.

At the end of the day, as you can see, there is not much to this clutch and not any way that I can see to screw up the installation. However, at time 7:25 of that video, I see something quite NOT what the claim is for the diaphragm compression measurement.

You cannot view this attachment.

I could drive a Volkswagen Beetle between the gap of that ruler and the outer edge of the spring. .020??? Say what??? What I'm am I missing here?

I'll be giving him a call in the morning...

-JW

[billbuilds]

    That measurement is the compressed spring measurement. I don't see where you are compressing the spring.

[ghostrider]

I don't think he had the 4 bolts tightened down,  it was just for illustrative purposes.  Thats why the gap looks so big.  Why don't you just bend the lock tabs back, then back the 4 nuts off a turn or two and see if this changes the feel at the lever.  If it does, get some shims.