The Hodaka Club Forum

I have a clutch pack that is unlike any that I have seen before. Can you identify it?

It does not have a part number on the clutch plate and it has the smaller clutch hub to fit the Ace 100 cranks. It also has slotted screws which indicates earlier models. I assumed it to be a model 92 Ace 100 clutch until I opened it up.

There were only one set of springs (no inner springs). My first thought was that someone had just omitted them, but on second look, I noticed that the spring recesses in both the plate and the hub are smaller than normal. 9mm vs 11mm. More like an Ace 90 than an Ace 100.

Could this be a very early 92 Ace 100 or possibly a very early Super Rat? I'm stumped!

Here are some pictures:

There were some different clutch numbers as Model 92s came out. My old short-tracker started as a 90 and was updated along the with times. Sure looks familiar! Max

hodakamax wrote:There were some different clutch numbers as Model 92s came out. My old short-tracker started as a 90 and was updated along the with times. Sure looks familiar! Max

Max,
I have studied the multitudes to different part combinations used by the different models. The Ace 90 was smaller in diameter so I don't think it was off of a 90. Perhaps the 91R race parts series?
I have another pack that I believe to be a model 92. It has the 11mm holes for the springs. Also, the 93 Super Rats have the part number embossed on the clutch plate. Perhaps they didn't in the beginning? The 93 clutch plates were used for a number of models to follow.
Dale

Hmm, My 90 progressed through every 91R transition possible. Maybe this is what we have here, possibly a 91R clutch mod. Ya got me, that was a long time ago!

Don't know if it changed sometime in production run, but most of the Ace 90 clutches I have seen only used 6 screws. This one has 7, so I am guessing a 100 part.

Sure looks like that pack has a much smaller hole than the one being compared with. Was the 90 a smaller diameter crank shaft end on the clutch side? I know from dealing with Alan & his 90 that the clutch pack was smaller in diameter across the pack. But I’m curious about the shaft diameter....
Victor

The ace 90 had six single springs. The ace 100 were seven single springs up to engine number 27908. you could update the single spring by installing the 924017 smaller springs inside. Spring 904017 was available for the ace 90 as well as a 91 racing item. ?? Clarence

Clarence,
Thank you! I think that explains it. I don't have any listings for updates on the Ace 100's and I was hoping that you would see this...


Victor,
The crank shaft diameter is the same for the Ace 90 and the Ace 100's. However the Ace 100's used a right side crank half with the 91xxxx part number. In the picture, the hub in question measures just under 15mm. The hub below it is for a 94 Wombat and measures just over 17mm.

OK. That explains the size difference. I thought they were both fire Aces! Thanks!

In the second Photo the top parts are 1967 to 1969 Model 92. The lower Hub is Part #944012. The 934008 ISO Clutch part came out in the Model 93 Super Rats first . Be CAREFUL! They made one 934008 for the 1969 1970 Super Rats (no ISO) on the Cover. That one uses flat head screws. The 934008 ISO uses the screws with a Phillips head and has a finer pitch: more threads per millimeter. So, 934008: flat head screws. 934008 ISO : Phillips head screws. Joe.

Joe Ormonde wrote:In the second Photo the top parts are 1967 to 1969 Model 92. The lower Hub is Part #944012. The 934008 ISO Clutch part came out in the Model 93 Super Rats first . Be CAREFUL! They made one 934008 for the 1969 1970 Super Rats (no ISO) on the Cover. That one uses flat head screws. The 934008 ISO uses the screws with a Phillips head and has a finer pitch: more threads per millimeter. So, 934008: flat head screws. 934008 ISO : Phillips head screws. Joe.

Good point Joe. I did discover the difference in pitch while building several clutches from parts this week. It had me confused for some time. Funny that some old clutches have a mix of flat head and Phillip screws. Not good!

934008 iso were also used at the introduction of the 92B in January 1971. The clutch screws were ace 90 #904009 untill the 93A and the 92B, again January of 1971 for the 92B, the clutch screws then became 904009iso in January for the 92B?? ---------------Clarence

And I think this is the very first time the Correct screws for the clutches has been brought up. Another thing about the early Model 92 Clutch is that the steel plates were thicker and the fibers were thinner than the later ones. The Barnett Clutch Kit was that way. Massive Thick Steel Plates that if mixed with the #934006 Clutch Friction Discs would cause the clutch to not release. That`s why if you are new to Hodaka Motorcycles your best bet at first is to buy a Clutch kit from Terry at HPI. I found out all these things about clutch part variations back in the day THE HARD WAY! Joe.

A little more info to add to this clutch subject after doing some research on clutch screw size and pitch...

The early Aces use an M5 clutch screw with a pitch that is still unknown by me. I believe it to be 0.9mm. I have a tap and die on order to prove this. The later clutch covers (934008 ISO) require a clutch screw size of M5x0.8mm.

I had made the statement that I have clutches with a mix of flat head and phillips head screws. I assumed that the flat head screws all had the same pitch and therefore assumed that this was a problem. Wrong! I found those flat head screws to be the ISO size (0.8mm) and also found some NOS flat head screws that are also the ISO size (M5x0.8mm).

Different screw pitches, different screw lengths, different steel plate thicknesses and different fiber disc thicknesses. Then throw in the mixing and matching of various parts with the different models and no wonder the clutch identification can be confusing.

More to come...

ABSOLUTELY ! Joe.

I have confirmed that the threads on the early clutches are indeed M5x0.9mm. This would be the Ace 90 and the model 92 Ace 100 and any Ace's that either have no part number on the clutch cover or have a part number without the letters "ISO" after it.

Once ISO appears on the clutch cover the threads will be M5x0.8mm.

Early clutches M5x0.9mm
Ace 90 Clutch cover 904008 will not have a part number.
Ace 100 924008 cover will not have a part number.
Ace 100 934008 will have the part number without ISO.

Later clutches M5x0.8mm
Later Ace's, Wombats & later. Cover marked 934008 ISO.

Dale
How about a Resonator piece outlining the very helpful information pulled together in this discussion?
Bob