Transmission shaft: Too much runout. What to do?

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Model T Ford Forum: Forum 2016: Transmission shaft: Too much runout. What to do?
Top of pagePrevious messageNext messageBottom of page Link to this message  By Steve Jelf, Parkerfield KS on Wednesday, February 24, 2016 - 01:03 pm:


I assume .012" is way too much. How do you fix it?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Stephen D Heatherly on Wednesday, February 24, 2016 - 01:23 pm:

Steve, the flywheel, shaft, and crank shaft can be installed four different ways. Lift the flywheel off, rotate it 180 degrees and bolt it back on and measure your run out. If it's still not acceptable rotate the transmission shaft 180 degrees in the flywheel and measure again. Keep doing that until you find the position where the shaft has the least amount of run out.

Stephen


Top of pagePrevious messageNext messageBottom of page Link to this message  By Jerry VanOoteghem - SE Michigan on Wednesday, February 24, 2016 - 01:48 pm:

Stephen,

I think there's only 2 different ways you can mount the transmission shaft, due to the 2 dowel pins. But still, your advice is valid as to rotating the trans shaft & rechecking.

Steve,

When you have it apart again, look very closely for any small nicks or burrs either on the crankshaft flange or on the trans shaft flange.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Jerry VanOoteghem - SE Michigan on Wednesday, February 24, 2016 - 01:51 pm:

Stepehen,

I think I see where you're going. However, the flywheel plays no part in creating, or eliminating, trans shaft run out. That is strictly a function of the fit-up with the crankshaft flange. (Assuming the shaft itself is not bent)


Top of pagePrevious messageNext messageBottom of page Link to this message  By Trent Boggess on Wednesday, February 24, 2016 - 01:52 pm:

First, see where the problem lies.

Put the transmission shaft between centers in a lathe and check to see if the tail shaft is straight with a dial indicator. Transmission shafts that I have measured this way are frequently bent in the middle of the shaft. A few thousandths run out is ok. More than .004, and I would be looking for a new shaft.

If the transmission shaft is ok, chuck and center the transmission shaft in a lathe with the flange toward the tail stock. Use the dial indicator again at face of the transmission shaft and check to see if the rear face is running true, or if there is a little wobble in the flange. If there is a little wobble, the face can be made true by making a light cut across the rear face of the flange. Better yet, use a tool post grinder if you have one.

Next check the rear face of the crankshaft for trueness. If your lathe has a long enough bed, put the crankshaft between centers, and check the rear flange for wobble with the dial indicator. If you find some wobble, then you can true it in the lathe using the same method used for the transmission shaft.

If your transmission shaft is true and the faces of the transmission and crankshaft flanges are true, then you know the problem is not there. If the transmission shaft still has run out, then you do as Stephen suggested and try installing the transmission shaft and flywheel in the four different ways.

I hope this helps.

Respectfully submitted,

Trent Boggess


Top of pagePrevious messageNext messageBottom of page Link to this message  By Allan Bennett - Australia on Wednesday, February 24, 2016 - 01:59 pm:

Trent, I agree with your suggestions all the way, with just one addition. Set the crankshaft up between centres first, and then fit a steady on the rear main, so that the centre can be removed. It does not take much pressure on the end of the crankshaft to cause some deflection, and using the steady will eliminate any chance of this.

Hope this helps too.
Allan from down under.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Andy Loso St Joseph, MN on Wednesday, February 24, 2016 - 02:17 pm:

Steve. You are into how to videos. Go to model t tips.com and check out the transmission videos.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Steve Jelf, Parkerfield KS on Wednesday, February 24, 2016 - 03:33 pm:

I watched #17, and Mike had runout of only .002", so he didn't have to change anything. Maybe it's in one of the other videos.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mark Strange - Hillsboro, MO on Wednesday, February 24, 2016 - 03:55 pm:

Prior to assembly, Mike chucked the transmission shaft in the lathe and faced off the flange so that it would be perpendicular to the shaft. Hence, the low amount of runout on initial assembly.

https://www.youtube.com/watch?v=q9Oo1lHBfsM

:-)


Top of pagePrevious messageNext messageBottom of page Link to this message  By David Dewey, N. California on Wednesday, February 24, 2016 - 04:23 pm:

Sometimes you have to turn the flywheel around to get it to run true too. I had one where it took a few tries, but I got the flywheel and the shaft to an acceptable runout (I forget what I ended up with, think it was under .004) As I recall, it took 4 tries to get the right combination!


Top of pagePrevious messageNext messageBottom of page Link to this message  By Stephen D Heatherly on Wednesday, February 24, 2016 - 04:52 pm:

Jerry, I don't know the reason why but, when I assembled the transmission for my coupe the flywheel did make a difference. In one position the shaft had about 15 thousandths run out. I rotated just the flywheel and ended up with only 1 thousandths run out. When I assembled the transmission for the my touring it didn't make any difference how the flywheel was installed.

Steve, I second Andy's advice. Mike Benders videos are very helpful.

Stephen


Top of pagePrevious messageNext messageBottom of page Link to this message  By Richard Black - Dallas on Wednesday, February 24, 2016 - 07:58 pm:

Stephen/Jerry -

I've also pondered this question about what, if any, effect the flywheel can have on runout, and have found it quite interesting.

What I came to realize was that if the face of the flywheel pocket (counterbore) in which the transmission shaft flange seats is not true, i.e. it is not dead perpendicular to the axis of rotation of the crankshaft and transmission shaft, it will show up either as flywheel face runout or transmission shaft runout, depending on how you conduct your check.

So, assuming for the sake of argument that everything is true on the crankshaft and transmission shaft (no runout, no wobble, no flange face out of flatness, etc) but that the face of the flywheel pocket is not true, then...

Case 1: If you conduct your check horizontally by supporting the crankshaft main journals, you would not see any runout on the shaft, but you would see flywheel face runout.

Case 2: If you conduct your check vertically by supporting the front face of the flywheel on a level surface with the transmission shaft pointing up, you would not see flywheel face runout but you would see (what appears to be) transmission shaft runout.

But Case 2 is not reality because it is not simulating the arrangement in which the crankshaft/flywheel/transmission shaft is being supported in the car.

Case 1 does accurately simulate the support arrangement in the car, so if the flywheel pocket face is untrue, the actual result is that the flywheel will have face runout even though the shafts have no runout. This could be detrimental to magneto operation.

If the runout check was done as in Case 2, and a (false) runout was observed, changing the flywheel orientation on the pins by 180 degrees "could" solve the problem if the different alignment of the transmission shaft flange and flywheel pocket face coincidentally happen to result in a pocket alignment which is more true to the axis of rotation. But that doesn't really verify the shaft runout, which should ideally be checked either individually in the lathe, or as an assembly in the horizontal position with the main journals supported, or both.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Tom Carnegie Spokane, WA on Wednesday, February 24, 2016 - 08:19 pm:

There are several reasons the shaft can have run out on the end where you are measuring it. There is a method that I use for narrowing down the problem. First, measure the run-out as close to the flywheel as you can. Then measure it as close to the keyway as you can, but not on the extreme bushing surface. Lastly, measure the extreme bushing surface, as shown in your picture.

If all three amounts are the same, the shaft is oscillating. This problem is easy to fix. Just put a small blob of weld on the high side. Then grind (or turn) most of it off. You may have to file the dowel pin holes a little to allow the shaft to re-enter the flywheel. The blob of weld will shove the shaft over and the with a little trial and error to get the blob right, problem solved. This may seem weird or even Mickey Mouse, but I've been doing this for years and it works every time and is repeatable. That is you can take it apart and put it together and it will come back in every time within 1/2 of a thousandths.

If the close-in measurement and the one near the keyway are the same, but the bushing one is different, this means your shaft is oscillating and the bushing surface is worn. To fix this, get another shaft.

If the close in measurement is less than the keyway measurement, that means the shaft is wobbling. This can be repaired by facing the shaft flange as Trent describes above.

link to Montana 500 article:

http://www.antiqueautoranch.com/montana500/may2002newsletter/may2002.html


Top of pagePrevious messageNext messageBottom of page Link to this message  By Jerry VanOoteghem - SE Michigan on Thursday, February 25, 2016 - 10:27 am:

Stephen,

I have seen weird things like that happen too. If it made a measurable difference for you then I can't tell you it didn't. Maybe through the disassembly & reassembly process some other small thing changed as well. Whatever the case, your suggestion of moving things around and retrying is a valid one.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Norman T. Kling on Thursday, February 25, 2016 - 10:38 am:

Tom,
Could you post some pictures, or draw a sketch to illustrate what you are saying about just put a blob of weld on the high side?

I have no idea were you are referring to. This sounds like a good idea, but I don't understand it.

Norm


Top of pagePrevious messageNext messageBottom of page Link to this message  By Jerry VanOoteghem - SE Michigan on Thursday, February 25, 2016 - 10:44 am:

O.K., I thought about it some more and have a theory. The mounting face of the transmission shaft is not truly ground flat. In fact, it has a very slight concavity. Others have mentioned it in past forum conversations. This potentially leaves a very small void between the transmission shaft flange and the crankshaft flange. If the pocket face of the flywheel has any irregularities, such as raised metal around the dowel pins, caused by press fitting them, it could cause the trans shaft flange to deform slightly into the void when bolting everything up. Such deformation could result in run out.

Why is it slightly concave? Because, in manufacturing, getting something truly dead flat takes a lot of time, care & effort. It is however, far easier to allow the surface to be very slightly concave, (maybe .0005/.0015), especially in a production setting. This leaves a high rim around the periphery of the flange, which still allows for precise alignment and perpendicularity without the danger of a less than perfect "flat" surface being slightly convex and allowing a "rocking" fit between the two flanges.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Tom Carnegie Spokane, WA on Thursday, February 25, 2016 - 11:02 am:

Norm, follow the link in my post above.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Tony Bowker, Ramona, CA on Thursday, February 25, 2016 - 11:45 am:

A quick easy way to align the transmission gear shaft.

By Tom Carnegie

The transmission gear shaft is clamped between the crankshaft and the flywheel. It is secured by four bolts and aligned by two dowel pins. It is important for this shaft to run concentric to the crankshaft main line. If this shaft is off, the three drums will be off and the tailshaft will be out of alignment with the fourth main. The best way I have found to check to see if this shaft is in correct alignment is to do the following steps:

1. With just the crank in the block, invert the block so that the head surface is resting on the bench. The rods should be disconnected, as should the camshaft. If the valves are still in the block, put three short 7/16" bolts in the head bolt holes in a triangular pattern to keep the valves from hitting on the bench. Some people make this test with the motor standing on its nose. This is not the best way to do it as the crank can shift slightly in the main bearings which makes getting an accurate reading difficult. With the engine in a horizontal position, everything is much more stable. Plus, the flywheel is in the position it will be when it is in service, albeit, upside-down. Some people make this test in a lathe by supporting the front main in the chuck and the rear main in the steady rest. This is also not a good way to do it as the center main can flex and throw your readings off.



2. Put some sort of match marks onto the crankshaft, gearshaft and flywheel so that it will be assembled the same way each time.

3. Assemble the flywheel and gearshaft to the crankshaft and tighten the four bolts.

4. With a dial indicator, measure the runout of the gearshaft as close to the triple gear pins as you can. Take another reading out near the end of the shaft. Don't measure the necked down part where the bushing rides, but rather on the larger part, near the keyhole. The two measurements should be very nearly the same. If they are not, the gearshaft is bent, or the flange on the crank or gearshaft is off. There could be a burr or object on the flange causing it to be off. More likely one or both of the shafts will have to be trued in the lathe. The crankshaft should have been trued when it was reground. The gearshaft can easily be trued by a machine shop if you don't have a lathe. If you don't have a lathe, my advice is to get one. They are not terribly expensive, and you'll wonder how in the world you ever got by without one once you get one.

5. With the shafts trued repeat step four. The runout should now be equal between the two measurement points. Typically the shaft will run out from .005" to .015". Note how much the shaft is running out. Mark the high spot on the gearshaft.

6. Disassemble the assembly. Preferably with a mig welder, place a spot of weld on the edge of the gearshaft in line with the high spot. (see ill. 1) Alternatively, you can use brass or a stick welder.

7. Chuck the gearshaft into the lathe and turn off the weld until it is one half as high as the amount the shaft was running out in step 5. If you don't have a lathe, you can grind and file the lump away.

8. Drive the shaft back into the flywheel with a brass drift or rubber hammer. If you find that you cannot drive the gearshaft into the flywheel, you may have to file the dowel pin holes slightly. The gearshaft should now be a tight fit into the flywheel.

9. Reassemble the flywheel to the crankshaft and take new readings. You should find the gearshaft much closer to being true. If it is within .001", I'd call it good enough, if not, you may have to fine-tune your lump of weld slightly.

10. Check the runout on the bushing surface at the end of the shaft. If it is more than .003", I'd say repair or replace it.


Top of pagePrevious messageNext messageBottom of page Link to this message  By John McGinnis in San Jose area, CA. on Thursday, February 25, 2016 - 12:53 pm:

Actually, I can't see how to hold a dial indicator steady while rotating a crank/flywheel mass.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mark Strange - Hillsboro, MO on Thursday, February 25, 2016 - 01:04 pm:

Here's how Mike does it in his video, scroll to about 9:45. :-)

https://www.youtube.com/watch?v=39fpe0TIE4E


Top of pagePrevious messageNext messageBottom of page Link to this message  By Tom Carnegie Spokane, WA on Thursday, February 25, 2016 - 01:11 pm:

John, I struggled with that a bit myself which is why I suggested turning the block onto its head surface rather than standing it on its nose. It seems to be a little more stable that way, although I've done plenty of them that were standing on their nose. Another trick is to measure the shaft close to the flywheel, as the gauge hits the triple gear pins. So, you have to "angle-ate" the indicator.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Steve Jelf, Parkerfield KS on Thursday, February 25, 2016 - 02:33 pm:


As long as the indicator can reach the shaft in three separate places, and all of them measure the same, I wouldn't think you need to get any closer to the flywheel than this. In this case the difference between the low side and the high side is .008" in all three locations, so I don't see how it would be any different next to the flywheel. As I understand Tom's procedure I want to add the blob to the edge of the flange in line with the high side marks I've made on the shaft, then machine it down to a height of .004".


Top of pagePrevious messageNext messageBottom of page Link to this message  By Tom Carnegie Spokane, WA on Thursday, February 25, 2016 - 03:31 pm:

Steve, I agree with everything in your above post.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Norman T. Kling on Thursday, February 25, 2016 - 04:13 pm:

Thanks, Tom and Tony. Now I understand.
Norm


Top of pagePrevious messageNext messageBottom of page Link to this message  By John McGinnis in San Jose area, CA. on Thursday, February 25, 2016 - 05:22 pm:

What are all of those flywheel balancing holes....before or after magnet installation???


Top of pagePrevious messageNext messageBottom of page Link to this message  By Steve Jelf, Parkerfield KS on Thursday, February 25, 2016 - 10:54 pm:

After. I made all the magnets the same weight before they were reinstalled, too. I had to replace a couple of bad magnets, and that undid the previous balance.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Kurt Baltrusch on Friday, February 26, 2016 - 09:05 am:

My machinist just finished addressing my crankshaft, flywheel and transmission shaft. Both faces had run-out, but the best of four trans shafts I gave him was .020" non-concentric. He lined it all up, reamed the holes and made oversize locating pins.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Kurt Baltrusch on Friday, February 26, 2016 - 09:06 am:

My machinist just finished addressing my crankshaft, flywheel and transmission shaft. Both faces had run-out, but the best of four transmission shafts I gave him was .020" non-concentric. He lined it all up, reamed the holes and made oversize locating pins.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Steve Jelf, Parkerfield KS on Friday, February 26, 2016 - 12:29 pm:


This morning I installed the Carnegie blob, reassembled, and checked alignment.


With all the bolts in and tightened, there's this much difference at all three measuring spots. I'm declaring victory in this battle and moving on.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mark Strange - Hillsboro, MO on Friday, February 26, 2016 - 12:49 pm:

Well done! Looking forward to seeing many T driving videos from you this coming season. :-)


Top of pagePrevious messageNext messageBottom of page Link to this message  By David Dewey, N. California on Friday, February 26, 2016 - 12:54 pm:

The shaft could be that much out of round! Think you've got it!


Top of pagePrevious messageNext messageBottom of page Link to this message  By John McGinnis in San Jose area, CA. on Friday, February 26, 2016 - 03:10 pm:

Does anyone think that Ford checked any of this....I sure never have....but now I am spooked.????


Top of pagePrevious messageNext messageBottom of page Link to this message  By Jerry VanOoteghem - SE Michigan on Friday, February 26, 2016 - 03:44 pm:

John,

No, probably not, but Ford used brand new parts that were individually inspected. They had every right to expect good alignment at assembly.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Tony Bowker, Ramona, CA on Friday, February 26, 2016 - 04:34 pm:

Great, the rest should be easy.....


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mark Strange - Hillsboro, MO on Friday, February 26, 2016 - 04:48 pm:

Steve, you already know this, but before you install the triple gears, please check to make sure that the thrust flange of the triple gear bushings stand a bit proud of the surface of the gears - based on the witness marks on your flywheel, it looks like the triple gears were rubbing on the flywheel surface at some point in its history. :-)

Scroll to the three minute mark in this video:

https://www.youtube.com/watch?v=K4cw_Wl-hKY


Top of pagePrevious messageNext messageBottom of page Link to this message  By John McGinnis in San Jose area, CA. on Friday, February 26, 2016 - 06:56 pm:

There could be great variation in what Ford used as an inspection process as many of these parts may have been outsourced. There are a lot of parts and tolerances in that string of components....and what would a tolerance study disclose. ...and what would be acceptable. I really wonder (and Ford too) what the allowable runout for the output shaft (at the 4th main)would be.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Steve Jelf, Parkerfield KS on Friday, February 26, 2016 - 09:20 pm:

Mark, yes. There's plenty of triple gear clearance. I don't have the paper work handy, but I'm pretty sure Mike installed new bushings when we had this apart before.

I digressed from one bit of conventional wisdom today. The usual recommendation is to tie the triple gears in place with wire during reassembly. I wasn't talented enough to make that work. They kept falling out of the wire.


So I used Gorilla tape to hold them together. That worked very nicely.


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