Oil to pinion bushing

[DGardner]

http://www.xr650r.us/clutch/

The xr650 has the same problem,

[taber hodaka]

This subject seems to go very deep and technical. The average hodaka rider is not going to have to worry about this. Those that have a repeating problem with this will seek to eliminate or reduce the risk of pinion bushing failure. I think the user group with the primary problem are the racers we all admire and are jealous of. The rest of us country bumkins need not worry, make sure your parts are smooth no rough spots or galled, torque to specification, use the proper length dipstick or measure amount of good oil.-------------------Clarence

[bchappy]

One thing I don't see mentioned here is that the pinion bushing is tightened against a solid piece of metal on each end when the clutch nut is tightened. Effectively it is frozen to the crankshaft. Therefore I see no way that oil can move between the bushing and the crankshaft....so holes in the bushing are essentially dead end. So they just become pockets to hold oil...which is the same as an extra groove like Rich mentioned or dimpling like Danny mentioned. The next thing I want to point out is: the friction is only caused when the clutch is disengaged. So the ones that have the most problem are riders that pull the clutch lever with the engine turning at high rpms. If you set on the starting line with the engine turning 10,000 rpms with the clutch lever in it is smoking the pinion bushing as the bushing is turning 10,000 rpms inside the pinion gear. There is never any friction when the clutch is engaged. I still think the new bushing Paul sells is about as good as it gets until someone shows me differently. Paul, do you want to jump in here and tell us what you have done to the new bushing that is improved over the stock ones.

[DGardner]

The way I see it Your 100% correct on all your points Bill. But I don't race my bike at all and at a stop light I put it in neutral before I come to a stop to help with this problem and I still have the galling. I talked to Danny yesterday and he was telling me that the newer hodaka had a hole drilled in the pinion gear so oil could get to the bearing that hodaka had gone to.....Is this a good option? Is opening up the end of the oil groove at the washer a better option? I don't know....what I do know is it needs more oil for the bushing. I do appreciate all the comment on this subject. P.S. the nut was tightened to spec. Thanks DG

[dcooke007]

Had some spare time today and wanted to research the clutch pinion bushing issue some more. I found a used clutch pinion gear and bushing that is in good condition with no galling on the bushing exterior or gear bore. I do not know how many miles are on these parts or conditions they were operated under. First, the comments about the bushing swelling when over tightened peaked my curiosity. My own repair practice has been to tighten the clutch nut with a torque wrench to prevent stripping the threads and to assure the nut is tight and not likely to loosen....application of thread locking compound is also my usual practice. Torque spec is 250 inch pounds for this fastener. My micrometer has tenth graduations and I carefully measured bushing exterior diameter. Uninstalled diameter is .8239 inch.

In order to observe and measure, I installed the crank bearing, thrust washer, pinion bushing, clutch hub and nut. Tightened nut to 250 inch pounds. This is how the assembly would be installed but with out the extra gears and clutch components blocking my view. As you can see the pinion bushing is secured tightly between the thrust washer and clutch hub with both ends of the bushing closed off. Also, as long as the clutch nut is tight the bushing rotates in sync with the crankshaft. Thrust washer installed with rounded edges toward crank bearing and bushing installed with open ends of grooves toward crank bearing also.

Measured exterior diameter of installed pinion bushing with nut torqued to 250 inch pounds. Bushing measured .8242 inch and had increased in diameter .0003 inch when properly tightened....this amount of expansion would be considered normal. Granted three ten thousands of an inch expansion is not much but it does prove the bushing does expand when tightened. I do not want to damage my usable parts and did not tighten the nut further. I would expect the bushing to expand more if tightened further, reduce required bushing to gear clearance and contribute to galling. So... seems item one on the list to improved bushing durability is to torque clutch nut to spec and do not over tighten.

Added the pinion gear, clutch rotor and the thrust washer between the clutch hub and rotor for observation. With the clutch lever released the pinion gear bushing, pinion gear and clutch components rotate in sync with the crankshaft. When clutch lever is pulled in the pinion bushing rotates with in the pinion gear and this is when wear and possible galling occurs.

The pinion gear and clutch rotor has a slight amount of axial movement on the pinion bushing and measured .009 inch with this combination of parts. No clearance spec is listed but there must be some to allow the pinion gear to rotate independent of the crankshaft with the clutch lever pulled in. This is why if the pinion bushing is to short the clutch will not dis-engage.

At this point I am just getting started. It is important to understand how this system works and then determine the likely approach that may lead to improvements.

Danny Cooke

[admin]

Hello Bill,
I just caught your post. I am totally sold out of the improved clutch pinion bushings I had previously made. Harry had helped with the new design which I am always greatful for his help and encouragement.
Unfortunately at this time we will not be able to reproduce those parts at an acceptable cost to be able to retail to the Hodaka public.Also I am sold out of all the reproduction style bushings we had been selling. I am now back to offering OEM clutch pinion bushings while they last.
Thank you
Paul

[racerclam]

I do think that drilling a couple small holes in the tooth root of the pinion gear would help a bunch ( use a carbide drill ) there would be a pumping action every time the teeth mesh at the drilled point .

Rich

[admin]

Yes I agree with Rich on this. Some of the later clutch pinion gears (994001) did have four small holes drilled to allow better lubrication.
Paul

[DGardner]

This is what I've done just to see if it helps. The pinion gear supply grove is deeper and opened up to the bushing more. Drilled three holes in the clutch gear (or clutch center hub what ever you call it) that lines up with the oil groove in the bushing. I was thinking that if your bringing oil in the end of the gear and with centrifugal force and a hole at the other end would give it a place to go. The grooves in the washer would help (I hope) with oil supply. DG

[dcooke007]

A little more time today to consider this subject. Pictured you can see the beginning of the opening that allows oil to the pinion gear and bushing. The opening is very small with limited opportunity to pick up oil.

This is the bottom of the pinion gear and you can see the machined oil supply groove. The groove appears to serve two purposes;
1. provide oil to the pinion gear thrust surface and thrust washer.
2. provide oil to the pinion bushing groove opening.
There seems to be some short comings in this arrangement. The crankshaft rotates clock wise when viewed from this side of the engine....keep this in mind. It seems strange to me that the pinion gear oil groove goes all the way across the gear rather than stopping at the pinion gear bore. This design would allow the leading end of the pinion gear oil groove to pick up oil and for the oil to exit the other end of the groove. This would not leave a lot of oil for the pinion bushing groove to pick up. Also, there is no oil pumping action when the clutch lever is pulled in since the pinion gear doesn't rotate with the clutch engaged and the machine stopped ....therefore no additional oil is supplied to the pinion gear and bushing when most needed.

As you can see from the pinion bushing, the area where the pinion gear and the clutch gear mesh is not supported by the bushing. The inside diameter in that area of the two gears is larger and could act as a small oil reservoir. As best I can determine, the pinion bushing is designed to pick up oil on the leading oil groove, loop around and exit the trailing groove. Remember the crank is rotating clock wise on this side of the engine.

So taking into account the comments and Doug's grooved thrust washer I thought I would see what I could do. Since the thrust washer is always turning with the crankshaft that should resolve the issue of no oil supply with the clutch engaged and supplement oil supply to the pinion gear thrust surface. Remember the crank is rotating clock wise, with that in mind I fabricated my grooves as pictured.
1. With a fine point Sharpie I marked the outer diameter of the pinion gear bushing on the washer and ground the groove just past that point. I did not want to grind the grooves past that point as it may negatively affect oil delivery to the pinion gear bushing.
2. The grooves are ground at an angle clockwise to the center line to force the oil captured toward the pinion bushing.
3. Also as you can see the groove is tapered to capture oil and with centrifugal force push the oil against the back ledge again to pump oil to the bushing.

I ground the leading edge of the intake oil groove and widened the pinion gear chamfer. The trailing edge of the intake oil groove was left sharp to force the oil up the groove.

[dcooke007]

Assembled and note opening for oil supply to pinion gear bushing. Please note this is in the development stage and you should only under take these mods at your own risk. Engines with properly installed pinion bushings and light use may work well as manufactured......do not over tighten clutch nut. And, no amount of modifications will make up for poor maintenance....change your oil appropriately, repair oil leaks and maintain proper fluid levels, use quality oil.
Danny Cooke

[DGardner]

Great work as always Danny! Thanks DG