The Hodaka Club Forum

The Wombat 94 runs well now, except that it tends to pop out of Fourth gear at the 3-4 upshift. If I double-shift from 3-5, and then downshift 5-4 it will hold. The shifter case is a rebuilt unit from SH, so there is no wear or play there. I measured and verified the position of the internal shifter arm last year, so that is good. However, this was last year, and this problem only started during the Spring startup this year, so it may well need a readjustment. Every other gear, including finding Neutral, is good.

I know the "two methods" of adjustment and I'm going in and tinkering with it this week, so I'm fishing extra ideas of things to look at.

Have you replaced the ball springs on the shift shaft inside the tranny? Aside from adjustment of the shift mechanism, worn out springs are the next most likely reason the gears won't stay engaged.

There are now two types of springs available,the original style with counter wound left and right springs which use shims or washers between thensprings and ball, and the new "space age" springs which are wound the same direction left and right, and I believe do not use shims. Personal preference is the original style for two reasons, one of which is that the new springs don't locate gear center as well as the original style and can cause missed shifts or impossible to find neutral (your results may vary), and two, without isolator shims, the springs will take a licking from rotational force.

If you haven't replaced these springs, or have not inspected them, pull the shaft and take a look. The shaft assembly can be removed from the clutch side without splitting the cases.

Nope, haven't looked at the shift shaft sproings. This engine is well-worn and they are suspect. I've got maybe 200 miles on since I first got it. I'm planning to split the case during the July-August hot and miserable non-riding season.

I have a set of the NEW shifter springs with the rebuild parts I'm collecting. I hadn't heard a downside to the new springs-- I also get a set of the "stock" springs and reconsider which to use. The clutch also bit draggy and I might go in and do the clutch assembly early as a separate operation. Wouldn't be a problem tp check the shift springs then.
I checked the "bench alignment" of the shift arm in the left case and it is still dead on, so adjustment may be ruled out.
Out riding this afternoon and had the engine die. Poof. Suspect ignition.
Gotta love old bikes.

I share your attitude, Bill. It's all part of the show, isn't it?

Wouldn't ride old bikes unless we can tolerate them!

Right on!!

Not many folks have had issues with the new style spring. I find them to be made of good material, but not designed well in that they don't have a flat bearing surface on either end, so they tend to cock slightly under pressure. Maybe it's just me but I prefer the original design.

In the design process for the new "space age" control shaft springs, two of the factors which were "balanced"/"prioritized" were: 1) the importance of having "square ends" on the springs and 2) maximizing the "storage of movement" of the shifter indexing mechanism.

During discussions, it was determined that ALL control shaft components are well "guided" in their sliding movement on the control shaft - ie, all control shaft components fit on the control shaft relatively closely and "out of alignment" movement is well controlled. Recognizing that factor allowed design decisions which maximized the ability of the control shaft springs to absorb significantly more of the "indexing movement" of the control shaft without coil-binding. Not being burdened with the "dead coils" at the ends of the control shaft springs, provided the last little bit of coil compression needed to vastly reduce the possibility of "coil binding". Since "coil binding" crunches are the main killer of control shaft springs, the "space age" springs directly address a prime reliability factor.

NOTE: Many riders will never have a control shaft spring problem until their shifting mechanism starts to wear so much that shift "indexing" gets out of specification. I am one of those riders. I change control shaft springs every decade or so (just kidding . . . but mostly true) - so the old springs would work just as well for me. (snick your shifts) But if a person persists in a "stomp and hold" shifting style on their Hodie, then the "space age" springs will provide extra life - and a small level of protection to transmission components.

Great discussion, Ed. Now we know some of the rationale behind the design of the new "space age springs".
And the shifter behaves differently than the geared cam.plate of my BMW or the shifter drum of other UJMs. No amount of "preloading the foot lever" or "holding the foot lever at the stop" will help. Once the ratchet wheel is snicked into place it is up to the control shaft and springs to do their job. It is a good system that no amount of finess will affect.
More later.

Oh no Bill! Do not mention "preloading the foot lever" or "holding the foot lever at the top" in the presence of Ed! Yikes!

First thing I tried when the problem started and I can verify it don't woik.
No harm to repeat and say that the Capt'n wuz right.... !!

I got the ignition magneto fixed, so I'm going to ride for this short dry spell and do a little tweaking on the carb mixture.

While the magneto/shifter cover was off I evauated the shift rod feel and I suspect that I have wonky shifter springs. I have the parts, i have the "jeebus clip" tool, and I'll have a rainy spell to pull the clutch cover. First time I've done this. I presume that I can remove the control shaft from the left without the shifter balls getting dislodged and chaotic. I've got a leaky o-ring on the left side I'd like to replace. I figure I can fish out spring pieces with a thin wire hook and a magnet.

I also have a draggy clutch I want to look at and make a parts list (I have minor clutch parts, nothin major, yet)

Old bikes

Here is the status of the tinkering:
I got the shift control and found the springs unwinding and the ball receiver pretty beaten up. I looked at the balls in the output shaft as well as I could and didn't see any chipped balls. In general the engine and transmission bearings look good and the internals are clean. The clutch pack is new so the clutch will not need work.
I'll replace the ball receiver, springs, etc on the control rod and see if that fixes the shifting prob. Anything else I can look at while I'm there?

On the "draggy clutch" issue, there may NOT be a problem. In First gear, engine stopped, if I pull in the clutch and push the bike, there is significant resistance and some gear noise. If it is shifted into Neutral and pushed, there is no drag or noise. I figure that a multiplate wet clutch has more inherent drag than the single plate dry clutches that I'm used to. And the very low first gear ratio would make any drag more noticable.

Wet clutches do drag. With the Hodaka, the clutch is mounted on the crankshaft (175's and 250's not included) which puts the draggy clutch on the wrong end of the mechanical advantage when pushing a dead bike in gear. The wheel and chain drive the transmission, the transmission main shaft holds the large primary gear, and the clutch is on the crankshaft with the small primary. This means when you push the bike in gear, you are fighting the primary (and overall) ratio backwards. If the primary gear ratio is 2.8:1 with the engine driving the system, then the ratio is 1:2.8 when pushing the bike. Add whichever gear you are in and it only gets worse. If you must push the bike in gear with the motor off, shift to fifth gear.

One example, using the 94 Wombat: final drive 4:1, primary ratio 2.75:1, first gear 3.44:1. Multiply all together and you have an overall ratio in first gear of 37.84:1. This means when pushing the bike in first gear with the clutch held in, engine stopped, the clutch must turn 37.84 times for every revolution of the rear wheel. In fifth gear, the clutch needs to turn only 10.45 times for every turn of the rear wheel.

Most Japanese bikes have the clutch on the transmission main shaft, which is why they tend to push in gear a whole lot easier than a Hodaka.

Easiest is to pop it into N, which is not hard to find, even w/o a neutral light.

OK - clutch issues have been thoroughly discussed, so I'll comment on the control shaft springs. First thing up is a nit-picky correction. The control shaft springs do NOT un-wind. The spring ends get flared out by being "hammered" by shifting situations which coil bind the springs. The correction is both nit-picky AND important because . . . they surely do "look" like they have un-wound so anyone and everyone who has seen that and thought that can be forgiven. BUT, if you believe something which is not true and then go to work to fix it, the odds are you will not be "fixing" the true fault. So it is important to understand that it is the crushing forces of coil binding which flare the ends of the springs, then a proper solution to the problem can be applied.

You are embarked on the correct first step - replace the flared springs. But that is ONLY step one. Then you must address the what/why/where of the situation which caused the coil binding.

Check the shifter mechanism for excessive wear/"slop". Repair as needed. Especially - grab the outer end of the foot change shaft and check for sloppy fit in its bore. Excessive wear/"slop" here is common and contributes to poor shifting (and flared ends on control shaft springs).

Follow the manual and check for proper adjustment of the shifter mechanism. The shifter may have been adjusted in an attempt to get it to work with the collapsed/flared springs. If so, it will almost certainly be out of adjustment with the new springs installed.

NEVER, EVER try to shift gears forcefully with dead engine and bike not moving. The gears in the transmission MUST be moving (simply rocking back-and-forth will provide enough gear movement) to allow the ball receiver and control shaft balls and counter shaft gears to move into positions where shifts are possible. It is quite possible that more control shaft springs are ruined with dead engine in the garage than on the street, trail or track.

Finally, snick your shifts. No "stomp and hold"! NO! Snick the shift lever up or down to the stop AND GET OFF OF IT. The mechanism is made for that way of shifting. Stomp and hold will crunch the control shaft springs AND will not work nearly as well as . . . . . wait for it . . . . snicking your shifts. Snick. Yes.
Ed

Vector and rotational forces do in fact cause springs to unwind. High School physics.

Wear and tear.

Stomp and hold.

Good guidance, Ed.

I call it "unwinding"of the springs 'cause that is how I've heard it described. But whatever the cause, the worn parts will be replaced. The shifter cover is properly refurbished and adjusted. I'll check the adjusemt with the new shift rod parts.

On the Beemer, the shift cam and mechanism lend themselves to the preload-and-hold method. But the Hodaka ratchet plate works best if you "snick" it to the next detent and let the shift rod/springs follow their sequence.

Do you use the clutch at all when you snick or just roll off the throttle, click it up, then roll on the throttle to index the next gear?

What they are referring to is shifting without using the clutch. The Hodaka transmission is a constant mesh unit. Every gear is always engaged with its mate. The only thing that moves around and changes which gear drives which shaft is the spring and ball system. Since all gears are being driven, shifting without the clutch is not really all that big a deal. However, as with any such transmission, the rate of rotation of the undriven gears is determined by the gear that is driven, so it isn't a net-neutral equation. Backing off the gas for a moment while shifting mitigates most of the potential for shock to the gears and balls. It also results, most of the time, in positive shifts which is a plus, but only as long as your springs are in good shape.

Jack, based on that I assume this technique is applicable for both up- and down-shifting and that the clutch is really only necessary for engaging first gear from neutral and for slipping purposes to keep the revs up. Does the actual shift occur when rolling on the throttle after the "snick" and thus, loading the transmission? Sorry about all the noob-like question. I've always been in the 'hey, the thing has a clutch engage/disengage hand lever - it must be there for a reason. In fact, I keep a finger or two on the clutch lever continuously. I've discussed this topic with The Captain before but I'm not quite clean on the physics involved just yet. Thanks!

Do I use the clutch or shift clutchless? The answer is yes. I admit that I just don't care for the "feel" of down-shifting clutchless (mayhaps I'm not very good at it?) Up-shifting with or without clutch is sweet. And I change control shaft springs once a decade or so. While the previous sentence is a bit tongue-in-cheek, it IS true that I can remember having to replace the control shaft springs exactly twice in engines that I have run during the periods 1971-1978 and 2005 to the present. (I took a loooooonnnnngggg vacation from motorcycles in the middle there.)

Matt, there is just no time to tap out the operations/physics of being "locked" in gear and what MUST happen to allow the shift to take place.

Hydraulic, run the rotational and vector numbers you were speaking of if you'd like - some springs may indeed un-wind in use . . . just not Hodaka control shaft springs. The force vectors which flare the ends of the springs result from the slight mis-alignments between the cylindrically shaped sides of adjacent coils (particularly at the ends) when the springs experience crushing coil binding compression extremes.

Ed