Gear Set Identification

[Charlie R]

I ran across a gear set that is stamped "91" on each of the counter shaft gears. It seems like I remember that designator but old age is sneaking up on me. Any ideas or info appreciated. Thanks!

Charlie R.

[Zyx]

I have noticed that there are few identical sets of gear ratios between models. What is the tooth count on either the main shaft or the counter shaft gear with the 91 on them? And, would you know at a glance if the tooth module is 1.75 or 2.0?

[taber hodaka]

Never heard of a tooth module, sounds like a tooth extraction team from the army. 91 series parts were the racing items for the ace 90. Heads, cylinders, pistons, 5 speed transmissions and other items.-------------Clarence

[hodakamax]

Hey Charlie--how complete is the gear set? Seems like the 91 gear set had a matching kick start gear and a countershaft with a snap ring instead of nut to hold the sprocket on. I might be interested in part or all of what you have. By the way I only live two hours from you and visit a good friend and Hodaka nut in Jenks. You can see his project several pages back on the forum I posted as "Road Toad Project." He has some old flat track stuff from our past and other weird parts. Contact me through this site or the Hodaka Club if trading parts or stories with us is in the future on the next trip to your area.

Later--Max Good-- Hodaka dealer in Parsons Ks in the day.

[Charlie R]

Thanks guys! That was what this old brain needed! I had torn down an old motor that had been fitted with a Webco 125 kit and set the transmission assembly aside until I could machine another set of cases for the cylinder. The old cases were broken around the studs. Life and other projects come along and well, you know the story. Max,I will PM you later. Thanks again for the help!

[Zyx]

Never heard of a tooth module, sounds like a tooth extraction team from the army. Clarence

All cut gears have a relationship between angle and depth of cut so that they engage and disengage during rotation with a predetermined amount of surface slippage. Gear teeth of matching count but different module will not mesh. Nearly all ( or perhaps all, haven't checked ) of the primary gears for Hodaka 100's and 125's use a module of 1.75. The mains and secondary gears for the 100's are, I believe, all 1.75. For the 125's, the main and secondary gears are a 2.0 module. Compare a ten tooth main shaft first gear in a 100B or model 93 in a 1.75 module with the ten tooth main shaft first gear in a 2.0 module for the Super Combat and you will immediately see the differences. Even though the tooth count is the same, the 2.0 module gear is larger in diameter and the teeth are more robust than those in a 1.75 module. Since all of the gear specs are listed in the model specifications listings, including tooth count and module, I thought perhaps we could identify the gears with certainty by counting teeth and knowing their module profile. Not all of the secondary gears I have seen have a number stamp on them of any kind, so without manufacturing data identifying what the numbers were always or never used for, I thought perhaps the numbers alone would not be conclusive as to their application. For example, the gears in the model 92 and the model 93 are identical except for the primaries. Are model 92 gears stamped with a 92 and model 93 gears stamped with a 93?. If they are identical and interchangeable, why stamp them differently? The numbers stamped on the gears may not have any relationship to the model number used for the Hodaka line of bikes. So I thought I would ask.

[Zyx]

http://www.metrication.com/engineering/gears.html

Gear tooth module is explained in this link. Probably more than we ever need to know.

[taber hodaka]

Shorty looking at the tooth module "Metrication.com" is why I would not be able to identify by looking. It is good to know there are folks like you that savvy this technical stuff, as you are there when we have tech questions. Charlie could you post a picture of the 91 gear? I may still have some. ==========Clarence

[Zyx]

Hard to tell just looking at one, but if you have one of each the difference is there to see. Once you have seen examples of each and know what to look at, the next time you will probably see it right away. The approach and departure profiles of the two sized teeth are the same more or less, because they are both metric spur gears of similar origin, but one is the big brother of the other. If two gears had ten teeth, but one was an inch in diameter and the other was two inches in diameter you would expect the teeth to be bigger on the larger gear. And so it is, but with our bikes, the differences are a quarter millimeter apart. Now that you know to look, it will be obvious.

[Charlie R]

Here are some pics of the transmission. One photo shows the "91" stamped on the gear. Each countershaft gear is marked. Here are some numbers:

Primary=63 T Spur
Pinion=?
Kick= ?
Main shaft= 1st (made onto shaft)-11T
2nd- 15T
3rd- 18T
4th- 20T
5th- 21T
Countershaft= 1st- 34T
2nd-30T
3rd- 27T
4th- 26T
5th- 24T
Max, it does use a snap ring countershaft. I'll fill in the question marks tomorrow. Thanks all!

[Zyx]

Sounds like Clatence could be right. 5-speed close ratio gear set for a 90 with interchangeable gears. Neat idea to be able to possibly build the gearbox you want by picking pairs for each gear. Were various ratios available this way? Close or wide ratios mix and match?

[hodakamax]

Charlie--The first of these kits came with the 914601R snap-ring countershaft and 924702 kick start gear. The standard 924601 countershaft will also work. The schematic for the Ace 100cc on SH shows both shafts. Once the Ace 100s were out the CR kits were probably sold as yours is shown (less the primary gear). Long story but this was the transmission I used in my short tracker of the day. I've restored the bike but this is one of the many missing pieces. The bike is just a display piece but it would be cool to get as original as possible---just thinking!
That also is a great road racing tranny--just thinking again--

later--Max

Edit--back on about page 5 on the forum under "Hodaka and PABATCO" we discussed this very subject. Scribbler even posted the original instructions on machining the 90 cases to accept the new CR trans.

[Charlie R]

Max,
Going back to your racing days-Do you remember a guy in Ks (can't remember what town) by the name of Dick? He and his son short tracked and the Father had a small bike shop selling Hodakas?

[hodakamax]

Charlie--I don't remember any local racers by that name but then again I can't remember what happened last Thursday! There were sure a lot of Hodaka dealers in the area at that time. Seems like almost every town had one and they all raced with a passion. What fun! That was a long time ago but I think I'd remember that team. There certainly were a lot of family oriented teams in that era, I probably met them.

Maxie

[Charlie R]

The reason I brought the name up is I went to the estate sale after his passing and bought a ton of old inventory. This gearset came out of one their old engines they used on their racebikes (according to the son). I guess its entirely possible you raced against this engine. Anyways, It's entirely possible I will unearth another CR gearset. There are bins I have never opened yet. Kinda like Christmas when I do! I'm gonna start another thread here in a minute that I hope you, Clarence and some of the dealers from the day can assist with. I think its gonna be fun!

[taber hodaka]

Max there were about 30+ race items for the Ace 90 they came out quite a while before the ace 100. Every item that was numbered like 914501R was for the ace 90 and the kick start gear for that set was 914701R. As you stated the pictures show the close ratio transmission. If you used the counter shaft with the snap ring you would need 914610R secondary sprocket collar. Installing the racing 5 speed transmission in the 90 also required 914609R the control shaft and 912001R foot change ratchet. All of these race items let the little ace 90 fly and win races. If you build up a 90 engine or a close ratio 100cc engine and need a part or two I might have it if Paul does not. And I must ask is short track flat track? I never got the feel for flat track it felt like upside down to me. -----------Clarence

[tvrc18]

Will the 100 control shaft work for the 90 5 speed set? I have one of those gear sets that has the snap ring holding the sprocket on. My control shaft seems to bind some times and I was thinking of trying the 100 shaft. I had real trouble trying to adjust the control shaft for proper shifting but finally got it to work.
Terry

[hodakamax]

Clarence--Thanks for jogging my memory on the 91 series of parts. I wonder if the kickstart gear, foot change ratchet and control shaft were the same parts for the new Ace 100s and just renumbered? The schematic on the Ace 100 shows both countershafts but only one control shaft--Just thinking.

Short track was flat track. In our three state area at the time there were numerous stock car tracks. Most were about 1/4 mile and a few 1/2 miles. We just called them Half miles and Short tracks. The tracks were popular with both bikes and cars "in the day". You could sometimes race more than one day a week and we tried to hit all of them--Fun times!

Max

[hodakamax]

And Terry---In answer to your question I think the two control shafts are one and the same as discussed above--Clarence?