'13 A&S Clutch retrofit?

[Constant Mesh]

"I opted not to replace the "Spacer 1" (p/n B88-16181-00-00) because pulling that out meant removing and reinstalling the clutch basket, which otherwise didn't need to be removed. Comparing what I could see of the old one to the new one, I can't see any difference. There are no new holes to allow oil flow, just the two blind, threaded holes in the outer face that you would thread a puller tool into."

Thank you for the new info Fred.

I was referring to the holes in the spacer you can't see looking into the axle. I believe there are at least two holes leading from the axle radially out to the bearing on opposite sides of the axle which port oil from a recessed area in the axle to the clutch housing bearing. I speculated that maybe they added two more radially oriented holes in the new spacer for additional oil flow.

That large washer is an interesting component. The first question I have is what is moving against the washer? Does the washer move as one with the clutch boss, axle, and spacer? I assume that the back side of the washer is where the movement is occurring. Maybe the spacer extends out just a bit farther than the clutch housing and all the axle nut torque is absorbed by the spacer.

I'd assume that there's quite a bit of oil flying out from those grooves. Don't know if any oil flows along the axle between the spacer and axle out to the washer? Oil must be getting to the boss side of the washer along the axle somehow otherwise why put grooves on both sides of the washer?

 

[Fred W]

On the new part there is only one, very small hole that leads from one of the two blind screw holes radially out to the needle bearings. If there were two in the original (which I never got to see) then the new part would be passing even less oil than the old one. I would guess that hole is more about lubricating the needle bearings which are spinning at engine speed than anything to do with getting oil to the clutch plates

The big flat washer with grooves is between the clutch basket and the clutch hub. It would only be sliding against those parts when the clutch is disengaged (lever pulled in) and the two are rotating at different speeds, When the clutch is engaged they would be rotating at the same (engine) speed and so there would be no relative motion. Any oil that does make it's way out those grooves would be on the back size of the clutch hub, so would not really get applied to the stack of clutch plates very well.

 

[Constant Mesh]

My comments about the spacer are based on drawings I saw in the Service Manual. I have noticed some errors on miscellaneous drawings.

In the Specifications section there is a subsection labeled Lubrication System Chart & Diagrams. On one of the pages a cross-section of the main transmission axle is shown including the clutch assembly. The spacer is shown with an oil port from the axle to the clutch housing bearing. It doesn't show an interconnection between this port and the threaded holes used for spacer removal. I assumed there were two oil ports in the spacer for symmetry about the axle. The axle appears to have a shallow groove all the way round just under the spacer. With that groove I assume that the orientation of the spacer - its rotary position about the axle is not critical.

I assumed that oil would exit the needle bearings and be centrifugally liberated by the groove in the large washer.

When I'm sitting motionless in 1st gear at a traffic light with the clutch lever pulled in the clutch housing is turning at engine speed and the main axle, clutch boss, pressure plate, and that large washer are motionless. I'm assuming the large washer is motionless in sync with the axle, clutch boss, etc. So there's an almost 1K rpm speed difference across the washer.

Looking at the clutch housing it appears that there's a small radius on the inner ell where the sides meet the back. I would assume that oil from the large washer would travel radially outward away from the axle, then make a 90 at this small radius and and then go outward across the friction plate tabs. I can see how the tabs would be oiled but not the metal plates on the clutch boss.

 

[Fred W]

Exactly. So there is still no logical path for oil to reach the clutch plate friction surfaces. And yet, they seem to work for thousands of miles once they are properly cleaned and whetted with engine oil. I think maybe it is much ado about nothing. The friction surfaces work as intended with or without a steady stream of lubricant. So long as they are not stuck together for some odd reason, such as a long period of time unused or perhaps assembly paste getting things gummed up, the lack of oil flow is not an issue.

We know that dry clutches are prevalent in automotive applications (whee manually shifted transmissions still survive) and they seem to work just fine also. Why do we think that these motorcycle clutches need a steady supply of oil to make them not stick?

Apparently, the Yamaha design engineers are past that little bit of confusion and do not worry the clutch plate lubrication will be insufficient. Whatever the hypothesis, they do work, and they work quite well. For lots and lots of miles.

 

[eflyguy]

Why do we think that these motorcycle clutches need a steady supply of oil to make them not stick?

I've not had any issues, but perhaps because some owners have, and they were resolved by soaking the plates?

Yamaha does state that the clutch is "wet"..

 

[Fred W]

And they are "wet" as compared to some other designs that have no oil on them at all. In the case of a dry clutch, oil on the plates usually results in the clutch slipping when engaged.

I was thinking about the way these clutches works, and I think some people are a bit confused. In order for the clutch to disengage at all, every one of the friction plates must slip/slide against its two adjacent steel clutch plates. You can't have a situation where any of the plates are "stuck together" and still have any disengagement. So even when people open the clutch and find only a few plates are wet and the others not, they have all been disengaging or else the clutch would have been locked up tight.

 

[eflyguy]

Perhaps the plates are binding on the edges of the teeth they engage on, so without pressure from the springs, they are loose enough to slip but not enough to allow oil to get in between..

 

[simfht]

just wanted to say thanks for taking the time to detail your experience

In retrospect, do I like the new clutch better? Yes. I like the progressive feel and lighter pull better, but am somewhat disappointed in the slipper function. Is it worth ~ $300 and a couple of hours of wrenching to get the slipper assist clutch? Of that I am not so certain.

 

[Fred W]

Sorry for missing your reply earlier. You are most welcome.

Clearly, I enjoy the tinkering and modifying of the machine or I'd not have spent the 3 Benjamins on this upgrade. And sharing the results accurately and truthfully is a big part of that enjoyment.

As a follow up, I've been riding the bike with the new slipper / assist clutch now for a number of weeks. I do like the way it feels a little bit better than the stock '14 clutch, but it is still not an earth shaking experience. I've noticed the "assist" function can cause some grabby-ness of the engagement if you are sloppy with your clutch technique. I try not to be sloppy, but sloppy happens sometimes.

The slipper function has not really changed much, in my case, but maybe I am just not aggressive enough on the down shifts to exercise the ramps enough to break them in.

At this point in my experience I would have to say: "Don't bother". But, as always, YMMV.