1953 Crank sprocket... Compensator Alternative?

Production K Models

Re: 1953 Crank sprocket... Compensator Alternative?

Postby Noot » Thu Mar 23, 2017 11:54 am

You need a KH ( solid Gear ) -54 part number. It's 30T. Kinda hard to find, but you might notice it since all the one's I've seen are kinda copper colored. You may also need a modified chain adjuster shoe. I ended up using the old-style, oem shoe with a soft-steel shoe(not plastic) - and that adjuster, for some reason was narrower and fit inside my tin primary cover without hitting. Your splines are smaller, so an XLCH solid 34T gear won't fit. The real problem is removing the steel dowel pins in the bosses(for the cast cover) and drilling and tapping 1/4-20. A couple of my bosses didn't even line up with the holes in my tin primary (make sure you use the actual tin primary you will use as a guide). I had to weld up a couple bosses, but I had my cases split, etc. It's not an easy deal. I can't really notice much difference with the compensating sprocket- truthfully. The cast primary cover seals up good too. Just run it and quit lookin' at it ! Ha ha Respectfully, -Noot :D

Oh crap, yeah 52-53 is smaller. The whole time I'm thinking about my KH. I got too many bikes and too much gray hair ! ;)
Last edited by Noot on Mon Mar 27, 2017 3:35 pm, edited 1 time in total.
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Re: 1953 Crank sprocket... Compensator Alternative?

Postby EKHKHK56 » Thu Mar 23, 2017 12:23 pm

I think the 52-53K shaft is smaller than KH...I'll double check.
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Re: 1953 Crank sprocket... Compensator Alternative?

Postby EKHKHK56 » Thu Mar 23, 2017 12:25 pm

I have a few of the early compensators that have been welded together. One option I guess.
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Re: 1953 Crank sprocket... Compensator Alternative?

Postby 55panman » Thu Mar 23, 2017 12:45 pm

What do you have to get for one of those welded compensators. I may need one.
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Re: 1953 Crank sprocket... Compensator Alternative?

Postby EKHKHK56 » Thu Mar 23, 2017 2:37 pm

Let me check. I don't know if I have extras. These 2 are part of complete engines. I am actually in the process of organizing my parts after stuffing them in containers 12 years ago. Who knows what I'll find :shock: The K Sprocket is definitely for smaller shaft than KH.
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Re: 1953 Crank sprocket... Compensator Alternative?

Postby dr dick » Fri Mar 24, 2017 7:13 pm

52-53 used compensator only.
54-56 used comp or solid sprocket depending on year.
there was major design changes between 53 and 54, mainly the sprocket shaft spline size grew from .875 to 1.000 and the timken position in case shifted. this means you cant easily fit incorrect vintage parts together.

52-53
Image

Image

i dont have any 54-56 comp parts to show.
in 54 all the compensator components grew bigger. (then in 57 they grew bigger again).
here is a -52 sprocket shaft extension along side a -57
Image

Image

here is why you cant use a solid sprocket (30t 54-56, 34t 58-69ch) on the 52-53 sprocket shaft.
-52
Image

-54 and -57
Image

here is the L55-56 solid sprocket
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Image

although time consuming and tedious ohv wheels and sprocket shaft can be fitted to 52-53 motor cAses.
this allows a greater flexibility in motor sprocket selection.
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Re: 1953 Crank sprocket... Compensator Alternative?

Postby sportsterpaul » Fri Mar 24, 2017 9:26 pm

Dr Dick gives the explanation for guys welding the compensator together. I don't think epoxy works in shear, so I doubt you could JB Weld the compensator together and have it work.

Thing is, a compensator sprocket greatly reduces shock loads on the rest of the drivetrain. I had a mechanic buddy that told me "Why wouldn't you want a compensator?" Well, like the OP, I wanted a tin primary. That's no problem on a Sportster, the parts are out there. But note you shouldn't use a solid sprocket on an electric start bike because I have it on good authority that it breaks the Bendix gear in the starter motor.

Now note the early K had a much weaker set of gears in the transmission. So if you run a solid sprocket you run a great risk of breaking gears which would then grenade the case. Now maybe the race guys got away with it in 1952 and 53, but I wonder if they also ran the aluminum primary and compensator that fits under it.

As Dr Dick points out, you can adapt a later model set of wheels to the early K, but if you do, then you should also look at converting to the 56 set of gears which are the same as in an Iron Sportster. If your bike is for display and some easy parade duty, then you can probably get away with welding up the early compensator sprocket, but don't hammer it on the street if you want to keep the tranny together.
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Re: 1953 Crank sprocket... Compensator Alternative?

Postby dr dick » Sat Mar 25, 2017 6:34 am

sportsterpaul wrote:Thing is, a compensator sprocket greatly reduces shock loads on the rest of the drivetrain.

though logical, this is street legend.
in cases of high load the comp bottoms out. its then the same as a solid.
so it doesnt reduce the shock on the drive train downstream of the sliding cam.
where the comp does its work is when cruising, it absorbs and releases most of the forces created by harmonic vibration of lightly loaded chains.

we all have ridden along side another bike and watched its rear drive chain.
under acceleration the chain acts as would be expected.
also acts as expected under deceleration.

when cruising it misbehaves.
*the top run of the chain whips (vibrates like a guitar string) while the 'no load bottom run' acts very civil.*
what you see on the top run is harmonic vibration.
this whip create forces that are magnitudes above what you may expect from your observations.
that whip force is transmitted both upstream and downstream.
newton stated force = mass multiplied by acceleration.
remember acceleration can be positive or negative.
your chain accelerated and decelerates with each flywheel revolution, because your flywheel accelerates and decelerates in lockstep when cruising.

when accelerating the flywheel rotation increases more then it decreases each revolution. you speed up.
when decelerating the flywheel rotation decreases more then it increases each revolution. you slow down.
this bring up the inevitable question 'what happens when im neither accelerating or decelerating? in other word when im cruising.'
well you know the answer. see asterisk above.

why does that cruising whip happen happen?
because the flywheel rotation not stable during each revolution.
its accelerates when piston pushes on the crankpin, and decelerates when the piston does not.
we all know the piston pushes for only a fraction of each firing stroke.
that leaves the remaining portion of the firing stroke and the other 3 strokes unpowered,hence the flywheel decelerates.
the flywheel accelerates and decelerates with every other revolution.

this hopscotch movement of the flywheel transferred to the entire bike mass.
and it shows up in your chains as whip.
whip, in turn, is turned into "vibratory" force, just as newton stated.
we all know how badly vibration induced forces affects both man and machine.

what the compensator does is allow the variations in flywheel rotational velocity to be absorbed and released thru the compensator spring.
this insulates the destructive effects of flywheel rotational oscillations that your pistons make when they are lightly loaded .
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Re: 1953 Crank sprocket... Compensator Alternative?

Postby sportsterpaul » Sat Mar 25, 2017 6:07 pm

I would have to respectfully disagree that a compensation sprocket is there to reduce chain whip. This would not explain why only electric-start Sportsters got the compensator sprocket. Chain whip was not so big a problem if Harley could get away with a hard sprocket on the Iron XLCH.

In cases of high load the comp bottoms out. its then the same as a solid. So it doesn't reduce the shock on the drive train downstream of the sliding cam.
Quite true that it becomes "solid" at times, but shock loads are not the same as peak loads. Its how sharply the load increases or decreases. So the compensator cam running out to "solid" adds time to the event and reduces the shock, despite the peak load being the same. An impact wrench is a perfect example of shock loads doing things to nuts and bolts that steady torque will not.

Putting compliance in the drivetrain does not reduce chain whip, but can make it much worse, to the point of catastrophic failure. I learned this when at Ford during the Escort engine camshaft belt fiasco. The belts worked fine when the engines were hard-bolted to the dynamometer. It was only when they bolted the engines into experimental prototypes that the belts would snap. This was a harmonic problem. The shaking of the engine on the rubber motor mounts would add to the lumpy load problems of a camshaft. This created standing waves in the belt, to the point it would snap. I told the engine guys to make the tensioner spring-loaded. They explained that was the wrong thing to do. The springiness of a moving adjuster would guarantee that the belts would break. The engine guy told me the problem is that a car engine goes over a decade of RPM, meaning it runs at 700 RPM and it runs at 7000 RPM. With a factor of 10 in the running speed, it was guaranteed that there would be dozens of harmonic interactions over the RPM range. A spring-loaded adjuster would be guaranteed to interact at some RPM and break the cam belt. I got the impression he knew this because they tried it, as a cheap fix.

The compensation sprocket is a cush drive that reduces sudden drivetrain loads, especially on up- and down-shifts. The Wikipedia entry states: “A cush drive is a part of a motorcycle or scooter drive-train that is designed to reduce stress from engine torque damaging other components during gear or throttle changes.” Like so many things in complex mechanisms, that is not all it does. I have seen the starter Bendix break if you use a hard sprocket on an electric-start Iron XLH. All the forum posts about cush drive says the bike runs and feels smoother, and is quieter. I was also told by a racer that it lets the clutch transmits more torque. Since the 45-degree engine is like an impact wrench to the clutch, lowering those sharp torque pulses keeps the clutch plates stuck together, whereas a higher peak would start them slipping, which once started, is maintained at a lower torque than the breakaway torque. The compensator also reduces noise, a critical advantage for a Harley trying to pass noise regulations.

Now I am perfectly happy to concede that the compensator might reduce chain whip at some RPMs and loads, but a whipping chain might be visible, its only an indication of torque pulses, not something that needs fixing compared to the damage from shock loads to the drive-train during shifting and transition.

I have heard many people say that a rear chain spring-loaded adjuster is a bad idea as well. It is guaranteed to have a harmonic that will damage the chain. Same deal when I was a VW mechanic. The Porsche guys told me how a 911 had cam chain adjusters that worked under oil pressure. Very over-designed. Very German. The oil added damping to the adjuster, unlike if it was a simple spring-loaded one. The wrenches on that side of the service bay said the smart people paid 400 bucks to put a hard-stop aluminum billet manual adjuster in, and just adjust it during the valve lash service.

That was how the Escort cam belt adjuster worked. It was spring-loaded, but the procedure was to unlock it so the spring applied the correct pressure to the belt, and then bolt it back down so it was fixed position. Interestingly, the German group just told the engine guys to make the belt 25% wider. This required a new timing cover and major changes just 6 months before release. The Americans wanted to understand it, and wanted dirt cheap, so they studied it for a couple months, ended up increasing the adjustor pressure so the belt had a larger static load, and then lived with heads that grenaded periodically.

Of course, Ford’s first attempt was trying to convince the EPA that the cam belt was not “pollution related” equipment and hence, did not have to be designed to go 50,000 miles. The EPA told Ford to bugger off with that nonsense, and then the crisis really went into overdrive. That is why a guy like me in Light Truck Engineering got involved, Ford had authorized 24-hour overtime for any engineer that wanted to work on the Escort cam belt. I never took them up on it, but the engine guys were walking the halls of all the buildings asking people if they had a theory. The Gates belt people would hand out a design guide to anyone that wanted to use their new notch belts. Turns out Ford had violated about 5 of the 10 recommendations.
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Re: 1953 Crank sprocket... Compensator Alternative?

Postby EKHKHK56 » Sat Mar 25, 2017 7:37 pm

I'll guarantee a green light full throttle dump will hit the transmission like it was direct drive. That compensator would bottom out and become direct in about .005 seconds ;) I agree with the Doc. The design was intended to smooth out pulses primarily. This is what the old guys told me way back...
Last edited by EKHKHK56 on Sat Mar 25, 2017 7:56 pm, edited 1 time in total.
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