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ORIGINAL: Hog Heaven

I don't know why I keep coming back to this thread (I guess I'm one sick SOB), but I'm glad I do.  There are people here who defend the MOCO regardless of the product they are riding and there are those who rip on the MOCO for the product they have purchased.  All of this keeps everything in perspective for me.  I'm waiting to buy my first Harley ($22000+) and I would suppose there are thousands like me.  Only way to make this problem, supposed or not, go away is to make the MOCO hurt by refusing to buy their new bikes.  So count me as one of the thousands who have held off purchase of a new Harley in hopes that eventually this issue will either fade away or be fixed (depending on your view). 

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ORIGINAL: rbabos

Not the sharpest marble in the package but with helical gears under load one will be thrust one way and the other will be thrust the opposite direction. How can they both have the same thrust direction?

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ORIGINAL: glens

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ORIGINAL: rbabos

Not the sharpest marble in the package but with helical gears under load one will be thrust one way and the other will be thrust the opposite direction. How can they both have the same thrust direction?

In a helical gear pair on parallel shafts, one will thrust one direction and the other the other direction. But I'm talking about what happens when two gears share the same shaft and transfer the power both onto it and back off again. Two gear sets working at the same time with a common shaft.

Look at http://hdforums.com/upfiles/36555/48A20D50ACBB4302B96CB2D2C4C36AE2.gif and follow this train of thought. In the left-hand image, the tranny input is the right-hand end of the near shaft. The output of the tranny is the biggest gear on the right-hand end of the input shaft, the one with the big splines on it (where the belt drive-sprocket goes). That gear has bearings between it and the input shaft. Maybe you know all this already, but please bear with me a minute.

Grab the input shaft with your right hand and spin it clockwise (just for the sake of it). Say you're in 4th gear (the biggest gray one, fourth from the left). As you try to turn the input clockwise, the gear will try to screw to the left in proportion to the opposition it encounters with its mate. Its mate will be turning counter-clockwise and will be getting pushed to the right. Now follow the countershaft to its output gear. It's turning counter-clockwise and in proportion to the resistance it encounters with its mate, it will try to screw to the left. Visualize that carefully. Forget the first gearset for a moment and think of what would happen if you grabbed the countershaft with your left hand and tried to force it to turn in the direction its spinning. Think of what would happen if the gear it was meshing with was immobile. That shaft would screw toward your left.

If the two gearsets transferring power were the same ratios as each other, the thrusts the countershaft sees would cancel out (not exactly, though, because some of the original power was lost coming through the first set, so there's actually some less driving the second set, so its thrust would be some less).

Now, visualize that 4th gearset as having the opposite helix (as the Baker 5th gear pair does). When you turn the mainshaft clockwise, the driver gear would screw to the right, the countershaft mate would be pushed to the left. The output pair hasn't changed, so the one on the countershaft will still try to screw to the left, the same as last time. Now, because one helix is opposite, both gears on that shaft are thrusting in the same direction, one while being driven that way and the other while driving that way!

Does that clear things up any?

Maybe Baker did that on purpose so in 5th gear the shafts would both seek their limits of travel and stay firmly there. Maybe to the extent the countershaft wants to float more freely, with same-hand helixes canceling each other out some, it tends to bounce side-to-side more, tapping its limits and making noise. I don't know, but I think I'd rather have the noise (if it happens) than to have power wasted applying the most force possible against the bearings (not to mention the taps would become harder hits as/when the powerflow changes direction through the mechanism).

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ORIGINAL: Hog Heaven

Buttman:

Couldn't agree more with you.  I know that you can find an issue with any bike, but for that kind of money for a new Hog, I'd prefer to buy a used '06 or older.  Guess I'll have to keep my eyes open, but here in the pacific northwest where I live, it seems that demand exceeds supply on used bikes and they are quite spendy.  Maybe I'll have to bid on an Ebay bike and be forced to ride it home

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ORIGINAL: hnesitd1

Interesting post. One question .............. have you any ideas on just how the IDS reduces/eliminates the clatter? Your ideas were very clear but you used heli gear sets on the main/counter shafts as an example. I'm not sure if I follow you with the spur cut 5th gears .... is the problem the large(r) driving gear on the mainshaft (5th)? Very well written post in my opinion.

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ORIGINAL: glens

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ORIGINAL: hnesitd1

Interesting post. One question .............. have you any ideas on just how the IDS reduces/eliminates the clatter? Your ideas were very clear but you used heli gear sets on the main/counter shafts as an example. I'm not sure if I follow you with the spur cut 5th gears .... is the problem the large(r) driving gear on the mainshaft (5th)? Very well written post in my opinion.

Thank you.

Yes, I have an idea on just how the IDS reduces the clatter.

First, I want to say that I don't agree with Baker's decision to reverse the helix. I would have had the countershaft 5th and output "fight" each other so it wouldn't "hit" so hard from one end to the other when power flow changes direction through it.

What they did was the equivalent in 120 VAC service of sending a separate, full-current-carrying, neutral wire to each of two loads when they could have been balanced with a single neutral wire that would only carry current whenever there was a difference between them. If both loads are the same, the neutral wire carries no current, (the countershaft itself being the neutral wire(s)) and at most the neutral carries only the current of one of them. With separate neutrals, instead of zero neutral wire heat at dual full loads you'll have twice the wire heat running back to the panel.

I think the noise arises in 5th gear for two reasons. First is simply because the spur gears are plain noisier, no matter how carefully they're made, compared to the helical-cut gears (assuming equal fabrication care), which actually slide in and out of mesh. I suppose sloppily-made helicals would be noisier than meticulously-made spurs, but we can probably agree that reasonable care was taken with both in our case, so in comparison to 5th (and 1st, of course) the rest just don't get our attention much.

The second reason is because while in 5th there's no balancing of thrust on the countershaft, for one thing, and since there's no side-thrust on the driving gear, it won't "ride" snug to one side or the other of its space on the mainshaft, so perhaps it walks side-to-side a bit there (I don't know first-hand how much sideplay it has that way).

So we've got the opportunity for it to make a different noise than the other gears which "freewheel" when not in service.

The IDS softens each impulse that reaches it, spreading the shock out over a longer time-frame. Think of a sawthooth waveform being transformed into more of a sine wave. Since the noises being made by the gears mating and the shafts thrusting are directly in proportion to the loads passing through the gears, the softer load peaks with the IDS will reduce those effects.

Without it I believe there's also more of a tendency to have the harder impulse reflect back toward its origin. When something like that happens, there'll be moments of slack when the wave coming back meets one of the same strength but opposite polarity going forward, and moments of increased energy where the waves are in sync, complementing each other.

Visualize the complex waveforms which develop when you toss a pebble into still water and the wave expands circularly, then hits a concrete wall, bouncing back again. Where the ripples meet coming and going; visualize that. Now, put a layer of open-cell foam on the wall and visualize what will happen with the reflected waves. They'll be much subdued and all the little local disturbances will be smoother. Maybe it would be safe enough to compare the IDS to that layer of foam.

Also part of the noise is that conventional drive chains are not smooth operators. The primary is such a critter. The effect is lessened the larger the pitch diameter of the sprocket in relation to the pitch of the chain. The pitch diameter (the diameter through which the centers of the chain link pivots pass) actually is effectively two sizes at the points where the chain is picked up and fed

(in reply to glens)

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ORIGINAL: Dogdoc

I Think the noises in fifth and sixth gears have a totally different origin.  I am NOT an engineer, this is just from my observation over 2500 miles on my Ultra.  The fifth gear noise is definately a gear whine.  Sixth gear noise is totally different. It sounds like someone is doing a drum roll with two ballpene hammers on the engine.  The noise gets significantly worse under two conditons:  First when the engine loads up when going up an incline and  secondly, when you are going down hill.  The tapping noise coincides with a power pulse.  So what I think is this:  Take your bike with the engine off and put it in gear and grab the drive belt and as hard as you can shake it back and forth.  There is a little play between the gears engaged on the front side and the gears when they engage on the back side. As you vigorously move the belt back and forth you are gonna get some noise .  As the power pulses get stronger when the engine loads up, the tapping gets  louder.  Now imagine what the IDS sprocket will do to the tapping when you cushion the power pulse with massive rubber grommets.  It now is not metal against metal, it is metal against rubber.  SO I feel the power pulses are still streaming down the drive train and hitting the sprocket, and the IDS sprocket absorbs them.   I still feel the Compensator is not doing its job. Please let me know what you think.  I am totally wrong?? 

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ORIGINAL: hnesitd1

As someone mentioned, if they'd have used spur-cut throughout, there probably wouldn't be this particular problem. The reflected wave is present in all gears, but generates the clatter when 5th is selected, eh? Why? The reason seems to be HD's use of spur-cut gears in 5th only. The power transfer (main-countershaft) remains helical. As I understand it, there is no equal-opposite gear set to maintain the seating of the mainshaft-countershaft (axial)... the pulse plays havoc here but most likely is transmitted throughout the drivetrain (back to the compensator).

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ORIGINAL: rbabos

The only major fault with the whole mess is that the IDS should have been part of the drivetrain package in 07 on all softails and touring models once they went with the 96" engine and 34 tooth engine sprocket. 

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ORIGINAL: hnesitd1
OMG this is TOOO Freaking funny!!  This is post says it all!


 With the understanding that all things are not equal (08 vs.07) I'd be veeeeeeeeeery curious in knowing whether the 2008's clatter with the IDS removed. If they do, then the IDS was intended to be the fix for the non-existent problem. If the 08's do not clatter (sans IDS) then the component changes within the drive train provided the fix (for the non-existent problem). Of course the question then becomes, what component changes were made!! Maybe we can ask the MoCo to conduct these trials and then reveal their findings ... with (of course) the understanding that we all understand that no problem exists. Do ya think?