Slow going off the line

[matt glascock]

Pay careful attention to the bushing, Go. The deformity at either end may be subtle but if you feel a "ridge" along either mating surface, its shot. Also inspect the inside of the pinion gear. Once it all comes together, you'll love it.

[taber hodaka]

I have never changed the thrust washers. If you install the bushing backwards it cannot get oil. I also oil as I install.----Clarence

[matt glascock]

Agreed Clarence. I kept the thrust washers as they looked fine. I just changed all the components as a unit so they could wear in together as a unit with the end result being a "factory fresh" clutch. Fortunately I already made the bushing mistake before this rebuild. Lesson learned. Moved on.

[Hydraulic Jack]

I mentioned earlier about relieving the clutch rotor the same way the blueprinting suggests doing for the drive plates. Here's why:

Notice the dent in one tooth from contact with the cage screw.

View of the obverse aspect of the same area.

Here's what it looks like when filed with a quarter inch file.


To have something as heavy as the clutch rotor banging against the screws hard enough to make these wear marks cause eventual failure of the screw. When a screw fails, half the screw will end up floating around under the clutch cover in proximity of the primary gears. Not good.

[matt glascock]

Hydraulic, do you have an opinion regarding fully-threaded vs. half-threaded screws for clutch rebuilds? I see a lot of very hilly courses with a lot of deep sand and subsequently, my clutches take a sound thrashing. I (possibly erroneously) operate under the "clutch rebuilding is cheaper than transmission rebuilding" theory. All my clutches are safety wired. I recently scored a sizeable stash of half-threaded screws. Are they equal in terms of strength and durability? Thanks you!

[Hydraulic Jack]

The original screws were about one third thread and two thirds shank within the working length of the screw. The extra threads stick out which is where the safety wire hole is drilled. I would prefer to see bare shank next to any moving part in the clutch, but finding screws with the right combination of shank and thread isn't easy.

Can't say whether fully threaded screws are as strong as or not as strong as an other design, but instinct suggests that full threaded machine screws are weaker than full (or long) shank screws. Not sure. They all have threads somewhere. When clutch screws break, they usually do so right at the margin between threads and shank. To me that's a clue. Put that spot out in the middle of the working length of the screw, and flex and contact over time causes failure at the margin. I would rather move that weak spot as close as possible to the clutch cover, and as far as possible away from the center of flex. But perhaps it makes no difference. Testing a clutch to the point of failure takes a while.

[go_hercules]

Go_Hercules here reporting in:

Today I took the clutch out of my Dirt Squirt to track down the rattling/grinding disengaged clutch. The pinion bushing was absolutely pristine. No mushrooming or damage. Slipped in and out of the pinion gear smoothly. After reading some of this post, I expected it to be the source of the noise. The pinion gear fits good and snug into the rotor gear. The throwout bearing is in good shape, nice and smooth when pressed on and spun. I have not taken the clutch pack apart yet, maybe later, but can't imagine what could make noise in there. I do notice that if I spin the big primary gear I can hear the balls rattling in the primary shaft, but with the clutch disengaged that would not be spinning anyway, so couldn't produce the noise I hear. One last thing, before disassembly, the clutch lever at the motor had about 3/16 free play from bottomed out on the screw boss until contact. What now ??????

[Bullfrog]

Did you re-check main bearing? I THINK (<--- that's a Big "I think") I saw evidence of a loose main bearing in your video (as mentioned earlier).
Ed

[go_hercules]

Hey Ed, you were referring to Sparky who started this thread and put up the videos. This is go_hercules who joined in along the way with similar problems.

[Bullfrog]

oopsie. OK, "go_hercules". The situation with freeplay of the clutch lever at the engine is something like, 1) you've GOT to have some freeplay. No freeplay means the clutch is partially disengaged while just sitting there. But 2) you shouldn't allow too much freeplay. If there is too much freeplay, you'll use up most (or all) of your hand lever travel just taking up the freeplay when you try to disengage the clutch. So, zero freeplay is not enough . . . and about 1/4" (some say 3/8") is probably a bit much. So 3/32" to 3/16" is sort of the "sweet middle ground". And freeplay is not causing noises for you.
Ed

[go_hercules]

Ok Ed, I understand what you're saying there so my free play is okay for now. I just now did some measuring. Here is what I found:

(1) The clearance between the main bearing thrust washer and the pinion is about 0.015", which means the pinion can "float" by that much on its bushing. The only thing affectig that clearance seems to be the small thrust washer between the hub and the pinion bushing. I have one thrust washer there which appears correct in the parts diagram. It measure 0.012" thick. I don't know if excessive axial movement of the pinion could cause noise.

(2) The thrust washers between the clutch face plate and the throw out bearing measure 0.095" in total. Seems like a lot, but that's what it takes to get the 3/16 free play in the clutch arm. To get 3/32 would take even more thrust washer shimming there. Just wondering if that tall stack of thrust washers could rattle around when disengaged.

[matt glascock]

Thanks Hydraulic. I was inaccurate in my description. They are 1/3rd threaded opposite to the head and are drilled for wiring. You addressed my concern - that being where I've seen photos of clutch screws post-failure and the fracture always appeared at the margin of the smooth and threaded portions of the shank. Back to the meat of the thread - some time ago, Hodaka Dave rebuilt the clutch for me on my Combat Wombat using the new and improved plates. It did make a soft Grinding noise at first but after about 20 hours of riding time on the new clutch, the sound all but disappeared. Perhaps this is a feature of these new plates. I assure you the clutch did and continues to work perfectly.

[Hydraulic Jack]

Couple suggestions here. 1) Hercules, I appreciate your issues, and that they may be similar to Sparky, but diagnostic assistance specific to your situation should probably have its own thread so everyone is clear. 2) there should be ZERO clearance between the pinion bushing, the thrust washer, and the main bearing. The whole thing about not overtightening the clutch nut is that the bushing is under pressure from the nut. Follow the line of parts under pressure and you go from nut to lock washer to rotor to thrust washer to bushing to thrust washer to main bearing. No clearance anywhere here. They shoulder against each other and are pressed into place with the clutch nut. Not to mention I am not sure how you were able to measure clearance between the thrust washer and bearing as they are pretty much hidden under the casting for the main bearing.

Anyway, if this doesn't fix your situation, you might want to start your own diagnostic thread so we can track along.

[Hydraulic Jack]

Matt, while I don't like grinding, when new or otherwise, a smooth clutch is a good thing. And I would think where the threads meet the shank of any screw or bolt would be the weakest point on that device. I simply like the idea of placing that weak spot somewhere other than against the rotor or drive plates. I like the idea of using 12.9 grade metric screws for the clutch. Has to be better than the original screws.

[matt glascock]

Is it possible to drill them for wiring or do you recommend using nylock nuts. Details details I know, but my usual off-road courses, with deep ravines and deeper sand, necessitate a substantial degree of clutch brutality. Such is life in the river bottom lands of northeast Iowa. Searching for the perfect mousetrap... I'll look into the HD screws. Thank you.

[go_hercules]

Hey Hydraulic, maybe I will start another thread. Just seemed like a similar problem everyone was involved in would let us help each other. Not trying to hijack or anything. But I must have described wrong. The clearance I am talking about is the axial freeplay (in and out) of the pinion gear on the pinion bushing. In other words, with everything cinched up like you describe, the pinion gear has to have some room to move or else it too would be cinched. I measured that amount of clearance on the bench by measuring how much the bushing stuck out beyond the face of the pinion gear. Picture a completely assembled engine, if you could stick a feeler gauge between the pinion gear and the main bearing thrust washer, that's the clearance I am talking about.

[Hydraulic Jack]

Hercules, now I get it. No problem, and you are right, the pinion has to be free to spin. For some reason I thought you were referring to clearance between bushing and bearing, but of course you didn't say that, so I wasn't reading closely enough.

As far as the pinion floating on the bushing and causing noise, I suppose it does. Maybe that contributes to the whirring noise heard with the clutch pulled. Should not be an issue. The Hodaka is not noise free by any means.

Matt, drilling grade 12.9 I suppose is possible. I would not bother though. Look for M5 torsion nuts, What we used to call trochoidal nuts because they were deformed in a sort of triangle shape at one end. These days I think they are just deformed two-sided but work the same. They are an interference nut intended for single use. I would also use locktite on the nuts as well as the threads in the cover, and under the rotor splines. Red or green, not blue under the splines. Small as they are, red should work for the nuts. I don't trust nylock nuts, but here they would simple be a jam nut, and I understand some folks do use them. You can find either nylock or torsion nuts at Home Depot.

[go_hercules]

Matt and Hydraulic Jack, for what it's worth I have had regular nylock nuts on my clutch for the last twelve or so years with no problems at all. For sure, the deformation type nuts are more dependable, but these have worked fine for me.

And thanks for the replies on my clutch. I will continue to search for the cause of that rattling/grinding/growling noise.

[matt glascock]

I think I know what you are referring to Jack. Nuts with a little "punched in" indentation on opposite flats. I'll hit the Home Despot tomorrow. As always, many thanks. Good luck with the clutch, Go. Once dialed, they are a really effective and well-designed clutch system.

[go_hercules]

Matt, this is what they look like:

https://www.fastenal.com/products/details/90679

[matt glascock]

Excellent Go. Very helpful. Thank you. That is exactly as HJ described. I'm on it.

[go_hercules]

One more question before I pull my hair out. How easily should the clutch hub slip through the clutch cage? If everything is in good shape without burrs, washboarding, etc., should it more or less slip on through? Mine appears to have no damage, but you have to sort of shimmy it back and forth to get it to move through the cage by hand. Thanks.

[Hydraulic Jack]

You have to shimmy it. Tolerances are close. If you were to grease the contact points between rotor and cage, it would likely slip right through, but steel against aluminum is pretty grabby. Once everything is all bolted together, the rotor can't cock in the cage, and everything starts to work smoothly.

[go_hercules]

Good to know, thank you. I could not find the source of the rattling/growling noise in my clutch. So I took a closer look at the throwout bearing. I could push on it to load it and spin it. It feels fairly smooth. But I decided to take it apart. After about an hour I manged to get that tiny clip off. The balls are good, but there is some small indentations in the race. We are talking very small I can feel, and hear, when I drag a pick across it. I think this is causing the crunchiness and the noise. I will order a new one and see how it goes.

[matt glascock]

This will be cool to know. Good luck!