Different Length Clutch Screws

[DesertRat54]

I'm re-building a Combat Wombat clutch using some parts from my "clutch box." I'm noticing that there are at least two different lengths of clutch screws: a shorter set (Part # 904009) for the Ace 100, B, B+, early Rat, early Wombats and early Dirt Squirts, and (I THINK) a longer set (Part # 954009) for the Combat Wombats, late Rats, Super Combats and 03 Wombats. Then there's another set (Part # 994009) for the Road Toads and late Squirts. My question is, "Are the 954009 screws the longer ones?" Also, are the 994009 screws a different length from either of these others, or do I count them as either a long or short screw?
Thanks,
Bill in VA

[dirty_rat]

Can you measure all three and let us know what the measurement's are. I have the first two sets and I can give you the lengths for them to see if what you have are close or the same. The third set I do not have, but I'm sure someone else can help there.

[DesertRat54]

Thanks for responding, Dirty Rat. I have only two of these screws. One size is about 34 mm long; these came from both an Ace 100 clutch and a Wombat clutch. The other size I have is about 37mm long; these came from a clutch labeled "Combat Wombat." There are two different part numbers for these screws: 904009 for Ace 100, B, B+, early Rat models, while the Combat Wombat screws have the part number 954009. Since my box of clutches is full of used clutches from previous owners, I want to match the screws with their correct part numbers. I found the the 994009 part number in my manuals and on Paul's site while looking for the other two, and I have no idea of these screws' dimensions or description. Any help here would really be appreciated.
Bill in VA

[taber hodaka]

The part number 904009 is a ace 90 part number and that same part carried over to the ace 100. -----------Clarence

[dirty_rat]

The ones I have for the early bikes (the 904009 screws) are just over 34 mm long and the ones I have for the Combat Wombat, etc. (the 954009 screws) are just over 37 mm long. I do not have any of the later style (the 994009 screws), so I don't know if they were a different size for one of the first two.

[DesertRat54]

I think I've found the answer to my question, and thanks guys for helping me along with it. In case anyone's interested, there are three lengths of Hodaka clutch screws. The shortest (994009)are those for the Road Toad, with only three friction discs and two plates. The next up are those used in the Ace 100 motors, early Super Rats and Wombats (904009). The longest of the three are found in the Combat Wombats, Super Combats, M98 Super Rats and 03 Wombats. The 994009 screws measure a tad over 31 mm long, and yes the 904009s are "just over 34 mm long," while the 954009s "just over 37 mm long." So for those of you who have a box of random clutch parts and you are wondering where to begin, here's a little to help with that.

All of this makes sense, with the clutches being more robust as a reflection of the greater loads placed on them (load increasing as displacement increases). The most curious thing about all of this is what appears to be the "lightweight" design (as in not designed to take much stress or abuse) of the Road Toad clutches--and that even the 02 remained fitted with the earlier clutch while the 03 Wombat's was upgraded from the 94 and 94A models. I would think that the 02 Road Toad would've gotten the same sort of upgrade. Were the Toad Toad clutch components of a better design so as to "do more with less?" I dunno.

Bill in VA

[RichardMott]

Are these overall lengths or just the threads. I think since these are similar to flat head screws, they might be measured using the overall length. But I am just asking since I don't know for sure if these are technically flat heads.

[---]

I am assuming overall is the stated length.

[dirty_rat]

The ones I measured were overall length (measured from one end to the other - not just the threaded area).

[DesertRat54]

Yes, they are overall lengths. Also--all are, of course, flat-headed screws, but the 994009 and 954009 are phillips heads while the 904009 are slotted. And now, as I'm thinking of it, I might have some 904009s that are phillips-headed. I'm too tired ot look right now.
Bill in VA

[dirty_rat]

I have both slotted and phillips-headed 904009 screws. The early ones were slotted and later ones were phillips-headed.

[DesertRat54]

Yes, I was thinking the same thing re: the 904009 screws. It seems like the phillips would be an improvement over the slotted heads.
Bill in VA

[matt glascock]

While we are on the subject, I'm rebuilding a model 95 Combat Wombat clutch. I would be really interested in hearing your experiences regarding the use of safety wire vs. self-locking (nylock) nuts vs. typical nuts with blue loctite vs. nuts with spring lock washers as the best technique for stabilizing the clutch screws. For any safety wire advocates, what gauge do you recommend and how many windings on each screw do you use? Thanks to all!

[bchappy]

I am a nylock nut fan. I have used them in all my 3 rebuilds and have not had any problems. I would say that I am not a racer anymore so someone that had been abusing their engines may want to chime in.

[matt glascock]

Thanks Bill. I use nylock nuts on many chassis components on my modern race bike but they are easy to see hence check before races and between motos and are not subjected to several zillion revolutions in an out of sight location. I've never had a failure. I'm starting to lean toward using nylock nuts on this clutch rebuild unless someone presents an horror story. When I pulled the clutch, the DPO had nothing on the screws and all were loose and backed out a couple millimeters Scary!! Thanks for sharing your experience.

[taber hodaka]

I never used anything but what came originally, tightened and wire threaded not wrapped. But nylon lock nuts would be good. ---------------Clarence

[matt glascock]

Have you experienced a failure? Thanks!