Oil to pinion bushing

[DGardner]

I find on all of the motors that I pull apart a lack of lube getting to the (#67 and 65) clutch rotor gear and pinion bushing. What is the trick to get oil to this part of the motor? I know people would drill the bushing on some of the old Yamaha's to help with oiling back in the 70's and 80's. What about making the oil groves deeper with a Dremal tool and drilling a oil hole at the crossing of the oil groves? Thanks DG

[Zyx]

Drilling should not hurt, but I would not deepen the grooves. Deburr, and chamfer all holes.

[olddogs]

Paul has an improved bushing design listed in his store. I use them on my race bikes as I had trouble with this bushing getting so hot it discolored and stuck to the gear. I believe the cross x end goes toward the crank bearing.

[dirty_rat]

The open side of the grooves does go toward the crank bearing (away from the clutch) and the thrust washer it fits up to should also have oil grooves machined into it. They face toward the bushing.

[Bullfrog]

I'd have to agree that drilling holes in the bushing ought not to be recommended. Holes might serve to distribute oil in another application, but in this application - where is the oil going to come from that the hole is expected to distribute? In this application, holes would seem only to serve as "drains" to relieve any oil/oil pressure being delivered by the grooved thrust washer and the grooves in the bushing.

Deepening the grooves might (repeat might) deliver a bit more oil, but it will be at the expense of weakening the bushing. The bushing experiences a considerable compression load when the clutch nut gets tightened. So I can't say that I am a fan of deepening the grooves either. It is worthy of note that the lay-out of the grooves in the washer and bushing actually work as a low-pressure oil scoop/pump system . . . and it seems to work reasonably well considering the RPM/loads/etc.

Finally, I guess I'd have to say that I'm not convinced that oil delivery to the bushing is all that big a problem . . . of course I don't use my clutch like one might on a modern bike. The Hodaka clutch system was originally designed in the 1960's (or perhaps the 1950's!). It is a crankshaft mounted unit - not main shaft mounted. It was never intended to be used/abused the way modern small bore dirt bike clutches are expected to perform. I'd have to admit that having an oil pump somewhere on the engine capable of delivering 30-40psi oil pressure to the bushing would be a neat deal, but since I'm into about my 4th (or is it the 5th?) season of riding on the clutch bushing in my engine . . . I don't think I'll be trying to fabricate a pressure oiling system anytime soon.

My advice? 1. Try to adjust attitudes and treat the clutch like the vintage piece of equipment it is. 2. Recognizing that for a "go-fast racer guy" that first piece of advice will only go so far, plan on changing clutch/transmission oil often. 3. Plan on some clutch maintenance which includes checking/replacing the bushing as needed.

Ed

[Bullfrog]

Ooops. I guess I'm not agreeing about the hole drilling. It appears that I am alone on that issue so far in this thread. And on reviewing the opening post . . . a hole where the groove crosses would tend to "drain" the oil before it gets delivered to the "far" end of the bushing.

Ed

[racerclam]

I have been grinding a groove long ways on it for years as a resivoir to hold oil , I havnt had a problem with that , jist dont go too deep as to weeken the bushing since it does create a stress riser ,

Rich

[bchappy]

Rich,
Does your groove end where the stock groove circles back (on the clutch side) and come out on the inside or doesn't come out on either end?

[Bruce Young]

Hello, Ed, this is Bruce Young with a question, I understand all the info you presented in your response to drilling holes and deeper grooves for the pinion bushing, but in reference to the New Improved pinion bushing Paul sells which has an extra grove put into it, what does that extra grove do, and how much better is it than stock. I would also like to know if this bushing has ever been made from another metal, ie bronze, or what ever, with all the new modern types of metals, is there anything better than the one we have now, "stock". Bruce

[Zyx]

Regarding the comment about holes draining oil away, frankly, that is what the holes are supposed to do. But consider where the holes would be "draining" oil from and to. Centripetal acceleration will move oil from the crankshaft to the clutch, in that direction. A spinning assembly will not oil in the other direction. Any oil that makes its way to the gap between shaft and bushing can not get to the gap between bushing and clutch without such holes. Adding more holes only expedites the flow from inner surfaces to outer surfaces, which I would assume is what we would want.

The real question is just what signs Flyingdg is seeing that leads to the statement that all machines he has seen show lack of lube, and where the signs of lack of lube are on bushing or shaft. If galling or burning occurs between shaft and bushing, more oil needs to pass from thrust washer to bushing, in which case modifying the bushing won't do much. If the signs are between bushing and clutch, drilling holes will, in fact, help to mitigate this.

Oiling is by fling inside the case. What is flung against the top of the case will generally run down toward the bottom, and some will run over the thrust washer. That washer has to pick up some of the runoff and direct it to the bushing. Oil will be directed to both gaps, but the ability for oil to transfer from the inner to the outer gap is not a crime. Certainly a couple of extra holes won't cause the inner surface to run out of oil, as long as there is enough to go around to start with.

So I stand by my statement that extra holes are okay. But I would first want to analyze where signs appear, and make my choices for modifications based on what I find.

[racerclam]

Bill, I grove the oposite side of the stock loop.

Rich

[taber hodaka]

I just have not had a problem. I only torque to spec on the clutch. If they are burning up blueing ect there are oils that will correct that. If any one continues to have a problems I will share.------also the old wynn friction proofing was good stuff. -------Clarence

[Zyx]

Clarence,

Intrigued by your mention of Wynn's Friction Proofing, I ran a Google search to find out what it was. What I found, in addition to the usual advertisement stuff, was an article compiled and published by Fred Rau of Road Rider Magazine several years back. In an article titled Snake Oil, Fred debunks nearly any and all additives to oil (including PTFE, zinc, and solvent/detergent combinations), and doesn't mind naming names. Wynn's Friction Proofing falls under the "solvents and detergents" type additives. Seems that Wynn's is (or was back in the 90's) 83% kerosene. The rest is presumably detergent and carrier oil.

I have used kerosene (and its cousins diesel and HHO) in gasoline engines, but not as a lubricant. I have used it to flush out crankcases that were rather old and filthy, like my 1949 Willys CJ-2A which had God knows how many miles on it when I got it. It did for me what Wynn's will do for anyone -- dissolve deposits. In my case, I knew it was working when clearances increased in minutes and I could not thereafter get rid of the knock. Seems the deposits were holding bearing clearances within an operable range, like some kind of diabolical plating. I overhauled it.

In the instance in point (clutch bushing), if scoring or bluing or coking is caused by overheated oil, I suppose that a touch of kero would help to wash out the deposits, especially coking. But, engine manufacturers and such have extensively tested oil additives in water and air cooled engines and have found that none do any real good, and most do nothing at all. Quality engine oil already has in it all the detergent, zinc, and whatever else it needs to do the job it is rated for. Adding more never really does anything, except perhaps extend the life of an oil by adding back depleted additives. Not sure how a solvent can reduce friction, but I am willing to learn.

I have my favored oils as well, but in the Hodaka, we also have to deal with a wet clutch. While I prefer to use Diesel engine lubricating oils even in standard gas engines because of the additive package (heavy on the zinc), I have no idea what it would do to a clutch. If you have some experience with different oils or additives that enhance what goes on inside an air cooled motorcycle, please share.

[dcooke007]

I see a lot of worn and galled clutch pinion gears and bushings. "Sometimes" the gear can be salvaged by polishing or honing if the damage is minor. Most of the time though both gear and bushing have to be replaced. By the way, new clutch pinion gears are getting scarce. I have to wonder how much of that damage was caused by poor maintenance such as not changing transmission oil frequently enough or operating the machine with low fluid levels. Oil quality and viscosity comes in to play also. There is no reason to use 30 weight non detergent oil with the modern and better alternatives available. I do not want to start the favorite oil debate again so I will leave it at that.

I am reminded the 03 Wombat addressed this issue by installing a caged needle bearing between the pinion gear and bushing and I have not seen any galling on those parts. The bearing arrangement would allow more space for oil and of course lower friction. You can take a look on the parts diagram for the 03 to see what it looks like.

I am kind of thinking as I type and wonder if shallow oil groves ground in the interior bore of the pinion bearing might be helpful rather than additional grooves in the bushing it self? I am resisting the urge to run out to my work shop and investigate since it is after 1am here. Sounds like a task for tomorrow.

Danny Cooke

[dcooke007]

Still thinking and I don't think drilling a hole or holes in the bushing will do any good. The oil film needs to be between the bushing and the gear. Since the bushing slips over the crankshaft a hole in the bushing would only allow a path for the oil to flow to the crankshaft with no where to go and nothing to oil. Can't see any improvement in that modification. The hole or holes would have to be in the pinion gear itself to "maybe" get additional oil to the bushing. Dimpling the out side of the bushing with small depressions might help. The same principle as dimpling the piston skirt holds oil.

Conversations like this force me to put my thinking cap on and are a good challenge.

Danny Cooke

[dcooke007]

Just to clear things up a bit more. The clutch pinion bushing does not rotate on the crankshaft. When the clutch nut is tightened the bushing is held tightly against the clutch inner thrust washer and rotates with the crankshaft. Since the bushing is held tightly against the inner thrust washer no clearance exists that would allow any real amount of oil to flow from between the crankshaft and bushing.

Danny Cooke

[Modracer70]

Would dry film coating be something to consider? Swain Tech?
Dave

[DGardner]

http://en.m.wikipedia.org/wiki/Galling

Here is a good definition of galling and this is what I'm seeing. Even the bushing and pinion gear that I had isotropic polished has a small amount of galling. DG

[DGardner]

I did a Google search for motorcycle clutch bushing galling, looks like it happens on some honda bikes. One article talked about a upgraded bushing with oil holes and groves.

[Rusty]

"of course I don't use my clutch like one might on a modern bike" I'd be interested in hearing more about this... as I've just been through my whole clutch system as you remember. Thanks

[Zyx]

Just to clear things up a bit more. The clutch pinion bushing does not rotate on the crankshaft. When the clutch nut is tightened the bushing is held tightly against the clutch inner thrust washer and rotates with the crankshaft.

Doesn't matter. The clutch is a spinning assembly, and oil migrates from inner to outer, not the other way around. If holes did no good, the manufacturer wouldn't bother, same with grooves. If two surfaces were not turning against each other there could be no galling. Follow the path from where oil comes from to the point of galling. That is the pathway that needs improvement. If galling always happens in the same spot, that's a clue. Work on that spot.

What one uses for oil matters of course, but even vegetable oil will work, so modern oil is not or should not be the problem. Galling occurs with metal to metal generation of heat through friction. Boundary layer oil is supposed to stop such contact. If it does not, modify delivery and contact surfaces. Polishing parts is counter productive. A textured surface holds more oil and offers less bearing contact surface. Swiping with 220 w/d paper does more good than a mirror finish.

Assuming the surface that galls only rotates against its neighbor when clutched suggests to me that the area is oil starved, and by the time one grabs the clutch, it is already hot and dry. There could be several ways to fight this, but would need to see the parts that are galled to parse the potential fixes.

[Zyx]

Here's an installation note from the manual on clutch installation: tighten the crankshaft nut to 250 inch pounds. Do not over-tighten, or the pinion bushing will swell and seize.

Something to consider, mechanical deformation of the bushing, which no amount of oil additive or modification to grooves and holes will cure. Just another variable to keep in mind when inspecting parts.

[junker2k]

I'm not sure what the problem is here. I have seen problems with bushing on the bearing end but I think this is from over tight nut. I have polished
the inside and outside of the bushing. ( I guess to much time on my hands) On the flattrackers in the 60's I did slip the clutch in the corner when
the rear tire started to get away from me with out letting off the gas. From time to time I payed the price for this when the teeth on fiber disks would come apart. Today with my trials bike I ride the hell out of the clutch, I ride just like my modern bike and I use fiber disks. The clutch is set up to use only one finger. I do check the clutch at least once a season, no problems yet. Now that I have said that it will most likely come apart in the next event.
Jack K

[Bullfrog]

Arizona, we are getting closer on our thoughts.

The ONLY ingress of oil to the clutch bushing is provided by the interaction of 1) the grooves in the thrust washer, 2) the grooves in the exterior surface of the clutch bushing and 3) the difference in rotational speeds of the crankshaft (and firmly attached thrust washer/bushing) and the primary pinion gear (which is selectively freed from the crankshaft by clutch actuation).

Is my contention that the grooves and the difference in rotational speeds create a low pressure oil "pumping" system. (repeat, low pressure)

Anything which relieves the oil "pressure" provided by this simple system would not be good. Since holes drilled in the bushing would tend to relieve the (already) low oil pressure . . . holes in the bushing seem to not be a good idea. In addition, the holes could not deliver oil because there is no "source oil" available in the interface between the crankshaft and the ID of the bushing.

Note: I am NOT saying the area is trouble free. It is, indeed, a relatively high wear, high maintenance system. Perhaps improvements can be found, but it is important that the basics be addressed first. Fresh clean lubricant in appropriate quantity, proper clutch nut torque and recognition that clutch reliability of this basic design will never equal that which is offered by modern mainshaft mounted clutches.

Ed

[Zyx]

Ed,

It is hard to agree and disagree at the same time, but here goes. I agree that all of the bullet points you named do in fact create an oil "pumping" from case wall to washer to bearing and out. Whether this happens more at one point in the clutch cycle (clutch in/clutch out) than another I would have to study, although I guess going in that pulling in the clutch does change the dynamic substantially; just don't know in which direction. However, having holes through the bushing only gives the oil somewhere to go. It does not effect the tendency or the degree to which oil will migrate through the components due to mechanical actions, it just changes how many places it has to go. If you have a hot spot, drilling a hole in the center of that spot only permits oil from one place to get to another, right where it is needed. Direct path. No going around the block to get there.

Hydraulic pressure is, as you note, predicated on how many outlets there might be in a closed system, but this is not, per se, an hydraulic system closed or otherwise. The pressure head is too low and too random to call this an hydraulic system. Principals of hydraulics do, however, apply. Assuming for the sake of the argument that oil migrates through the bushing area due to a combination of mechanical forces such as rotation, flutter, heat, or whatever which creates a sort of oil pressure at the source, the question of whether there is enough oil to go around, in such a low pressure environment, would be enhanced rather than hurt by having opportunities for the oil to migrate, because migration is more like what the oil does, rather than classic oil pressure pumping through an orifice, or a tube, or a passage of a known volume. All an extra hole or two is going to do, as long as they are well placed, is give the oil an additional place to migrate to. Since the presence of "pressure" at the beginning of the system is very low, having an even lower resistance to that pressure downstream from the source will enhance flow by reducing the resistance to flow.

Oil pressure is not, per se, a predicate to good oiling. For example, the oil pressure in a Cummins diesel is so low that it is shocking. Something like 4psi. The oil pressure gauge on the dash is BS put there to keep customers from going nuts. It is the volume of flow, not the pressure of the flow, which determines whether there is enough oil to do the job. Another hydraulic example, again from the Cummins system, is fuel pressure. Fuel pressure delivered to the high pressure pump is so low that even Cummins does not have a pressure value for it, and contends that ZERO pressure is sufficient. But what they DO have is a value for volume delivered. The fuel delivery system has to deliver so many ounces of fuel within a stated period of time, and can adequately do this even without creating measurable pressure. Much like the amount of pressure you might find in a syphon system. Liquid flows, but at such a small pressure value that pressure is basically static, yet it does flow and can flow quite a lot of volume.

So in the clutch bushing, what is needed is oil, not oil pressure, and having multiple pathways for that oil to flow enhances the distribution, as long as done within reasonable bounds. Pressure arguments notwithstanding, if there are too many ways for oil to bypass an area, you can expect demand to exceed supply. In our case, we don't know any of the values for supply and demand. We know what Japan thought was enough, and the fact that there is now an "improved" bushing implies that the original might not have been good enough. Compare the old style with the "improved" one and see what it is they did to improve it. Aside from space age materials, I would assume that the changes are in placement of grooves, placement and number of holes, increased dimpling or expanded beveling of holes, or a change in the angle of the grooves relative to the axis of the shaft.

I would agree that improving supply at the case or thrust washer may pay bigger dividends than fooling with the bushing, but I would not put all my eggs in one basket here. I would do everything I think possible to help the situation. In my thinking, adding well placed holes is one of those things, but so then is grooving the thrust washer bearing surface, with the groove or grooves angled so that the spinning surfaces will drive the oil into the grooves.

Makes for interesting discussion. I don't remember who first mentioned not to over-tighten the nut, but that, I think, is the one most important thing so far mentioned.