The Home Machinist!

I own a 1974 sportster that is chopper and is in a rigid frame. I also own a 1973 sportster that came in a bunch of boxes. The 74 I have had for quite some time, the 73 is a recent acquisition and is meant to be a learning project. Once I learn how to rebuild the 73, I will rebuild the 74.

This post is intended to follow the process of the build. Like I said this is a learning process as I have never rebuilt a motor. With most of my vehicles I usually just bought a long block, and install it in the vehicle.

I have a friend that has shown me the process, for putting the lower end together, for a sportster. Also there is a website where and individual has documented his process of "How to build a Sportster", that I am following.
This is the URL; http://www.ironheadcycle.com/pages/howto1.htm

So we shall see how it goes. The worst that can happen is I ruin the basket case bike, and it becomes a pile of parts.

I have most of the lower end cleaned.
I also flipped the two bushings, that the rods ride against. They are staked in at the moment, but I may do a better job later, before they go together.


I now need to measure my rods, the problem is I only own a set of Harbor Fright inside gages. They will not set properly for me to be able to take a proper reading. They are either locked or loose, nothing in between. So for the moment, things are on hold.

This is the flywheel holder I made from an, exercise machine, weight. The two vertical bars hold it so one can torque the nuts to better than a 100 ft, lbs.


I am not in a hurry to get this done. I do have a 2000 Road King I can ride this summer.
I will post more as I get it together.

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Pat P in the Great NW.

Looks like you are getting the procedure down. I had to replace the rod throw on my 70 sportster 900. As I recall there wasn't much to it but I love your fly wheel holder. I wish I had one back then. Keep up the good work, I will be following this thread.

Jack.

I have a problem I need some advise on.
I am trying to get the run out on this shaft down to an acceptable level. At this time I am not sure what an acceptable level is yet, but at the moment .015 is not it. I have put the shaft in, snugged the nut down to around 60 in/lbs. of torque, knocked the shaft around to get with in .005 of run out, then I tightened down the shaft to the required 100-120 in/lbs. of torque and I end up back at .015 of run out.
Pictures:
Sprocket shaft and flywheel

Sprocket shaft in place.

Set up for testing run out. I have a piece of SS in a collet, turned in place as a center.



The questions are!
Would this always have had this amount of run out because it is a tapered shaft and bore?
Is there a method, with out the use of a grinder to correct this? ie Can one lap it to correct the run out?
Am I just trying to split hairs here, trying to get the run out to a lesser degree?

The main shaft has tapers on both ends, and the flywheels are required to be knocked about until they are parallel to with in .001. That is the reason I figured I could knock this shaft around to get it within .001 of run out.

Any insight would be helpful.

The good news!
I borrowed a telescoping gauge from a friend, to measure my connecting rods, main shaft, and bearings. Everything is within specs.
The next good news is this.
The Sprocket shaft has another shaft that fits over it to hold the compensating sprocket. When the bike was being disassembled, it had to be beat off the Sprocket shaft, because of the tightness of fit. Using my poor-mans bluing (red permanent marker) and the new knowledge I have acquired here, I fitted the two parts together. I used a small file that had its tip ground down, as a scraper. The sprocket shaft is the softer of the two, so it got the work done to it. The two parts now fit, albeit only in one orientation.


More to come!

Update! Maximum run out on Sprocket shaft should be .003 at rim of flywheel!

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Pat P in the Great NW.

Patio and I talked by phone tonight. We're going to attempt to isolate the reason for runout this coming Thursday evening. I expect he'll post the results of our search. As he said, stay tuned.

Harold

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Wise people talk because they have something to say. Fools talk because they have to say something.

I know things have changed a lot but back in the old flathead, knucklehead, and panhead days dealer shops only indicated the shafts to run true within 0.001" TIR. No effort was made to check or align the flywheels themselves. The flywheels were rapped with a lead mallet, squeezed together, or wedged apart to achieve the shaft alignment. As I recall, those shafts did not have the flange or collar found on more modern ones.

Are you sure you are supposed to align each shaft individually to its flywheel? We only aligned the complete assembly. It does seem like 0.015" is too much runout for the flywheel, though.

If a center is not rotating, its presence or lack of runout is not a concern, only whether it fits the shaft well. You might check if your center has a point on it that is too long.

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Don Young

Doug
This is my first time putting together the bottom end of a Harley, so I am learning as I go, with the help of friends and books. Thanks for the comment.
My statement is incorrect, you are right. Once the shafts and fly wheels are assembled, the sprocket and pinion shafts are aligned to within .001 or their axis. The fly wheels are not aligned to each other.
As per the Harley manual, the fly wheels should have no more than .003 of run out with each shaft, measured on the outer edge of the flywheel. This is the part I am having difficulty with. I have been having a discussion with Harold about it. I am going to take the parts and go see him tonight. It may be that the center holes, used to hold the shafts are not proper anymore, from use and abuse. So the run out I am measuring, may not be anything at all.

I will post more when after meeting with Harold. I am open to any insight on this issue.
Thanks

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Pat P in the Great NW.

As things stand at the moment!

I took my flywheels and shafts and spent an evening at Harold's place. We spent some time checking what I had done, and the rest with me talking his ear off. Harold is a gracious host.

Harold did some minor cleaning up of the centers in the end of the shafts and then we checked the flywheel run out in relation to the shafts, on his lathe.
The conclusion we came to is, there seems to be a combination of things, that lends to the fact, that the shafts (sprocket and pinion) do not sit perpendicular to their flywheels, in their tapered holes, as well as they should.
The causes we believe are.
a) Not the greatest of machining of the flywheels, when they were made.
b) The metal may have moved some over the years.
c) This lower end has probably seen some trauma in its days. (Markings on the flywheels that shouldn't be there.)
d) It would take a lot of work to fix a small deviation, and there is no guarantee that, doing so, would not make other thing worst.

So with all that said, I am going to put the lower end together, align the two shaft to each other, (as Doug was alluding to.) and call it good. I don't know that the deviation will cause enough problems to matter.

I hope to get the lower end together this weekend.

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Pat P in the Great NW.

Pat,

Looks like you are getting to be quite knowledgeable on the workings of Haeley. Keep up the good work and X2 on Harold's hospitality. Harold and Susan were kind enough to entertain my wife end I for an afternoon and into the evening some time back, what gracious hosts.

Jack.

Today's progress on truing up the flywheels.

I spent another day, this last weekend, up at Harold's place, with the assemble flywheels. After going over all the measurements, we have come to the conclusion that.
Both the sprocket shaft and the pinion shaft, are not perpendicular to their respective flywheels. The sprocket shaft is farther out than the pinion.

As per the factory manual they should be perpendicular within .003 at the outer edge of the flywheel. Once the main shaft is installed between the two flywheels, the assembly is put between centers, with indicators on each of the shafts, next to the flywheels, and are to be indicated in, to less than .001".

In its present state, I can get the pinion side to .0005 and the sprocket shaft to no less than .005. We believe in this condition the motor may not last very long. I have two options. One is to buy new flywheels, or fix mine. I have nothing to lose in trying to fix these, but time, yet I may learn a thing or two, while trying. So the challenge is on! With Harold's guidance I may actually stand a chance.

The first thing to do is to get the flywheels in a condition to be able to mount them, well enough to be indicated, reliably. We figured the best thing to start with were the outer rim faces. Getting them flat and parallel to to each other.
I have wanted to give scraping a try, and thinking that it is not a large area and can be cleaned up later even, a gave it a go.

Here are the pictures!


This was the worst side, so I started there, giving me more time for the learning curve.

In this picture is the second scraper I made,laying on the cleaned up part. It worked pretty well.


The surface plate, Prussian Blue, height gauge, and a rubber roller.

These pictures, are of the other flywheel, both sides. I have not done anything to these yet.



More to come.

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Pat P in the Great NW.

I am very interested in this project and you are to be commended for the thought and effort you are putting into it. I presume your purpose in working on the flywheel rims is only to establish a consistent reference surface to measure from. If the shafts will not align with each other in spite of each one being true, the problem is in the relative spacing and/or angularity of the holes in the flywheels, including the abutment faces for the shaft collars. That will require careful machining or scraping of those parts which seems very intimidating to me. I don't see how the holes can be moved that much and still maintain a fit with the shafts. As I mentioned before, the trueness and alignment of the flywheels is related to the shaft alignment but is a separate consideration, especially in the axis of the shafts themselves.

Keep us posted on your findings. Can you post a diagram showing how the misalignment shows up?

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Don Young

Hi Don

Your presumption is correct about the flywheels.
I need to have consistent points to mount and measure from.

Being there are 3 shafts. The sprocket shaft, the pinion shaft, and the main shaft. The sprocket shaft is not perpendicular to the its flywheel. It should be perpendicular and on a center axis with its flywheel. With the sprocket shaft set between centers on the lathe, the run out, measured at the outer edge of the flywheel, should be no greater than .003". As it is, it measured 15, if I remember right. Some of this run out would be due to the faces not being flat. That is the error that I am removing by scraping the faces, of the outer part of the flywheel. The flange on the shaft and the shaft seems to be ok. I am going to measure it all again to make sure. I will be able to measure the face that the flange rests on once the faces are in good shape. I am going to take a bunch of measurements in the next couple of days and will post more as I get things figured out a bit.

It is not intimidating to me, only because they are in such poor shape, that I have nothing to loose by giving it a go. Also Harold is helping me with the process. That in itself may keep me out of to much trouble.

If this does not make sense to you Don I could draw something up.

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Pat P in the Great NW.

I understand your situation now. It will be something to be proud of if you are able to correct that kind of error and you sure will learn a lot in the process.

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Don Young