Cluttch issues

[wombat dude]

I am changing the clutch in my 125 wombat and I am having issues removing the clutch pack. After I remove the right hand thread nut do I put a 3 jaw puller on the clutch pack to remove it from the crank shaft?

[racerclam]

NOrmally it will just slide off unless someone put lock tight on the splines . If not then a light tap should work.

Rich

[Bullfrog]

Um, I like to remove the left hand thread nut before removing the clutch.

Grab the clutch with one hand and give some whacks with a brass hammer on the end of the crank with the other. The clutch should come off relatively easily by that method.

Ed
PS : Do NOT use a steel hammer on the end of the crank.

[wombat dude]

Cool got it. Thanks guys. Now the next issue The book says to put 4 clutch plates and 3 metal plates in. But I pulled out 4 clutch plates and 4 metal plates....... Anyone know the correct setup?

[Zyx]

Depends on which Wombat you have, but in any case there are never the same number of steel plates and friction discs. It is either going to be four and three, or five and four, respectively. Model 94 uses four and three. 95 and 03 use five and four.

So the question is whether someone stuffed in an extra disc, or left out a plate. It will go together with fewer, never tried with more so I don't know if it is possible. It may also be possible to have an entirely different clutch than what it came with since lots of parts swap back and forth.

[Dale]

Are you working on a chrome tank Wombat (Model 94 or 94A)? If so, then 4 friction discs and 3 steel plates would be correct. There is also a possibilty that someone has swapped out the clutch pack with another model. Even so, I am not sure that any use 4 of each. I would have to research that more.

(Edit) Looks like AZ and I were typing at the same time... I think the 03 Wombat uses 4 friction and 5 steel plates while the 95 Combat Wombat uses 5 friction and 4 steel plates. But regardless, there will be a different number of friction plates compared to steel plates.

[wombat dude]

My bike is the red tank wombat 125. Which model does it make it?

[Dale]

That would be the 03. Go to the Strictly Hodaka web site and look under Shop by Schematics. Then select the 03 Wombat and then the exploded parts diagram for the clutch. You should be able to make out the order of 4 friction discs and 5 steel plates.

[wombat dude]

Next issue now after reassembly the clutch is always engaged. The 7 screws that assemble the clutch pack do those need to be screwed tight or just tight enough to run the wire through?

[Bullfrog]

The 7 clutch screws must be fully tightened.
Ed

[bchappy]

Also when running the wire through the screws try to run them in the direction so that if the screw starts coming loose it will be pulling against the wire. If you run them in the wrong direction the screw can turn half a turn before the wire stops it. Hope that makes sense.

[Zyx]

Next issue now after reassembly the clutch is always engaged.

I am assuming you rebuilt the clutch, assembled everything in the side case, connected the cable, and nothing happens. No clutch. Correct?

While the screws need to be tight, not tightening them enough won't stop it from working, so something else is going on. Thrust button and shims installed? What torque value did you use to tighten the clutch retaining nut?

[Dale]

And... are you sure that you have the Clutch Thrust Washer installed. This is a thick washer that is rounded on one edge and sharp on the other side. The rounded edge goes towards the crank bearing. Without the correct washer, you will not be able to disengage the clutch.

[JayLael]

I always use an old crank stub and bushing etc and compress the clutch using a drill press (while it's turned off) as an arbor press. While the clutch is compressed turn the gear in the middle, that you used as an assembly/alignment aid. I try to use all the same parts that it has when mounted in the bike, to line everything up perfectly, while I assemble it.
The last steel plate needs to all fall into the cage before tightening screws. It often gets edge pinched and doesn't fall into the cage, thus preventing proper clutch pack clearance and the stamped cover can wobble. (not good) Note this last plate is against the stamped steel cover. This extra steel is a proven improvement to the clutch as it helps to keep it in one piece, as it helps to stabilize the unit from racking at the screws. Screws must be pretty much ridiculously tight, to prevent racking and destruction of the assembly by shock loads. If the clutch rotates freely while compressed, it should rotate freely or release, when mounted on the crank stub in the bike. The center bushing can cause no or poor release, if it's mushroomed or worn oddly in any way. To tell if this is your problem, try loosening the clutch retaining nut until the clutch is just sitting on there basically, then retest for release. If that causes it to release, most likely the center bushing is worn to the point of being effectively too short to do it's job.
The gap in between the center clutch hub (steel part) and the aluminum cover, which can be seen when you remove the release bearing, must be no less than 3.5 mm assembled and tight, and no more than 4mm, to provide the right amount of spring preload for heavy duty applications. Sometime you can make extra thich fiber plates, by carefully sanding off one side of two plates, making them into one thick plate. This is a great use for plates that are knackered on only one side. One clutch I use has two pairs of fibers done this way. As long as there is a steel against the stamped cover, and the gap is correct, the clutch should release and hold without slipping.
When used clutch parts are selected, try the center hub on a crankshaft before you go too far with it, as any amount of looseness on the shaft will cause the nut to come loose repeatedly.

[JayLael]

The early 100 engines use smaller diameter springs, so the spring pockets are smaller in the steel center hub, on early ones, and the aluminum outer cover also. On some the screws are different thread pitch. If you see "ISO" cast into the outer cover, it uses the fine thread more common 5mm screws, but if the ISO is not there, it's probably earlier and has coarse thread holes for the screws. The coarse ones are usually Ace 100 early on. The chrome tank Dirt Squirt uses the same clutch as a model 94 wombat, so it has a bigger crankshaft stub than the Ace 100 type. When mixing and matching the clutch pieces, just be sure to choose compatible spring pockets sizes, so that all items match.
The center hole in the clutch hub is smaller diameter on early vs late clutches, so just pick out the one that fits whatever crank you are using, and pick out the parts that match it, as far as spring pocket diameter.
I use ordinary 5mm nuts with blue loctite, in leu of saftey wire. It add a bit more security to the assembly, especially if you have some stripped threads on the alloy cover. I usually discard the cover if it has any stripped thread holes, as they must be mercilessly tight.
Once the nuts are loctited on I grind the screws off flush with the nuts, and there can be contact with the inside of the clutch cover. (your results may vary)
When using the cushioned drive gear, the rivet heads will collide with the backside of the clutch assembly when the clutch is pulled in. I have had incredibly good luck just grinding off the rivet heads and using a sharp center punch to expand the rivet in it's hole, while supporting the rivet from behind with something like a flat ended punch or drift, clamped in a vise.

[Dale]

Great information Jay. Thanks for sharing. I am with the majority of Hodaka riders that do not ride as hard as you do so your experience with clutch packs is really good to learn.

[Bruce Young]

I too would like to say thank you Jay, that is great information, we need more Hodaka users like you whom have learned what works best and what does not. Weather you race or not, its was great info. I have a customer right now that asked many of those questions and I will refer him to your info posts for the answer. Thanks again, PS are there any other little Hodaka secrets you have found that might help the Hodaka World. Bruce Young Hodakaparts.com IDAHO

[JayLael]

Glad to help. I'll think of some more stuff to say I'm sure. Note these are considered over and above the usual "blueprinting" of the clutch plates as per Ed's informative article in the Resonator. The most important one being to modify the steels to clear the clutch bolts. I use a 1/4 straight burr in a die grinder. Carefully align all the clutch plates and mark them with a sharpie, then cut all the steels at once. It takes just a short time on each one to get a clearance groove cut in the steels. This is important, as the steels will fracture if they contact the bolts, also you may have poor clutch release too.

[JayLael]

Every ninth ? groove or so where the bolts are, not all of them.

[Bullfrog]

Every 4th groove. (28 grooves, 7 screws -- every 4th groove has a screw)

NOTE: I think it is important to acknowledge who had the leap of creativity to come up with the concept of putting a steel plate in the clutch pack as the last item before the outer cover goes on. Long-time Oregon based Expert Tuner of Hodakas, Phil Chapman, came up with that idea. I think it was a brilliant thought! If you review the illustrated parts lists, not ONE of them shows putting a steel plate in LAST . . . while some of the packs have two steel plates next to the cast iron clutch hub. I'm sure this was done to sort of "idiot-proof" the assembly of the clutch -- you can't pinch a steel plate tooth between the outer cover and clutch cage if the last item to go in is a friction disk. HOWEVER -- that last friction disk in the factory set-up rubs directly on the outer cover of the clutch. And the ONLY thing keeping the outer cover of the clutch from slipping on the clutch cage is the STATIC FRICTION produced by the ring of contact between the cage and the cover (and the tightness of the 7 clutch screws have a major effect on that).

But when the last item installed in the clutch pack is a steel plate, suddenly the game has changed. EVERY friction disk now rubs on a steel plate (or the iron clutch hub) which is "keyed into" the clutch cage with 28 teeth. Suddenly, the power transmission through the clutch is ALL handled through the 28 teeth of the steel plates and the clutch cage . . . and NONE of the power is transmitted through the friction contact ring between the outer cover and the cage. THAT is a significant change in the operation of the clutch . . . and it is achieved by moving ONE part, and by being attentive upon re-assembly of the clutch.

NOTE: Average trail riders don't NEED to do this modification. In fact, I've not found it necessary with the state of tune of the engines I ride (generally, blue-printed and only slightly tweaked). But if you are making use of all the capabilities of the tuning arts on your Hodaka engine, you really, really should (ought? Must?) put your clutch together this way.

Ed

[Bruce Young]

Hello experts, is it not also true for the average rider, to keep an eye on the fiber plates inspected once in a while and kept in good condition, no glazing, or falling apart and etc, Replacements new are available and cheap insurance. Now the metal plate should not be discolored or scored and damaged in any way. Also make a habit of changing the eng. oil frequently with good Motorcycle oils. Also inspect and keep all other clutch parts in good working order, springs and etc. Proper adjustment once in awhile is a good practice. When a clutch stops working on the trail or trip its a bummer. The pro type tuning comes later. Better left to an Hodaka eng. expert, like your selves. Bruce Young Hodakaparts.com IDAHO

[hodakamax]

Ed, am I reading this right? I am going to add one additional steel plate to the clutch pack--that's all there is to it? I'm reading "moving one part", should that be adding one part? That IS clever if I'm reading this right.

Max

PS--This is on a 94A clutch pack which shows 4 fiber and 3 steel.

[thirdstone]

Got it thanks. One more thing I might add is that I'm now adding high tensile screws with low profile single use pressed steel lock nuts . Jay are you running 4 or 5 plate clutches ? I'm guessing 5. I've run 4 plate clutches due to the better engine response, lighter. I've never had slippage issues only snapped screws. Now we are upping the power somewhat with the case reed the 5 plate is looking attractive.

[Bullfrog]

Max:

Two questions,

1. Do you NEED to do this . . . or are you just interested in the whole idea and want to "play" with something on the scooter? (More to the point, have you been blowing up clutches? I am curious about the clutch life your machines are giving you.)
2. Since I haven't actually done the modification on a Wombat (94) clutch, I can't give you firm advice. But I THINK (<-- that's a BIG "I think") you can simply add an extra steel plate. I'm sure you'll let us know if the 94 clutch won't accept that, right?

Note that the Wombat (03) has TWO steel plates between the iron clutch hub and the first friction disk. On that clutch, you could move both of those steel plates "out" so they would be the last items to go into the clutch pack rather than being the first. Not adding, just changing the order of assembly. Kewel!

Also note that Jay's message gives some information about the acceptable parameters of the "depth measurement" from the "throw-out bearing contact surface" to the crank end(?). I've got to review that (and print it out!) If I'm reading that right, the measurement will tell you BEFORE you put the clutch cover on whether or not you are going to be able to make the clutch pack work. (Thanks Jay!)

Ed

[hodakamax]

Ed, all is well in the 94A clutch department. I might play with it if I have it apart on the next whatever. Thanks for the info and clarification!

Max