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setting the pinion shaft 1930 Hudson Super 8


timecapsule
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It all started with a noisy U-Joint at the differential end of my driveshaft on my newly purchased 1930 Hudson Super 8.  When I dropped the driveshaft it was apparent that the U-Joint was shot.  Of course there is no replacement so I had to rebuild that end of the driveshaft with a modern U-Joint.  At the time I noticed that the pinion seal was leaking so I decided to replace it.  While I had the seal out I decided to inspect the bearing right behind it and it was trashed.  So was the race.  So I've ordered new ones which btw are insanely expensive.  The original parts book that I have, shows the same part number as the one I took out and it is a Timken 26112.  The best price I can get in Canada is $200. Wow!  Please don't suggest I get it from Amazon.com  or that will send me off on a long rant about landed cost in Canada, plus a potential nightmare of actually getting it in hand.

So my question is. Is there anyone familiar with setting up the pinion gear once I have the new race pressed into the pinion housing, in one of these early cars.  I have an online copy of the service manual and it is weird to say the least.  No illustrations, drawings, or pictures.  Mostly redundant wording for each topic page after page for 269  pages.  There are only a few short paragraphs that mention the pinion shaft and on 3 pages it says there is no end play and on another page it says that there is end play but it doesn't state what it is.  However it does mention in each case that the pinion back-lash should be .006-.008. 

From You Tube, I'm understanding that I remove the differential back plate and set a dial indicator on the ring gear and move the ring gear back and forth which will give me the pinion back-lash reading.  Is that correct? 

As for the pinion endplay.  The pinion housing bolts up to the differential housing.  Between the two, there are 6 shims ( 3 thick, 3 thin).  Also the last part that slides on to the pinion that the driveshaft bolts to (universal joint companion flange) has 5 shims between it and the bearing.   Are the shims between the differential and pinion assembly dictating the pinion back-lash?  Are the shims between the bearing and the companion flange dictating the pinion end play?

My last question is how much torque should I apply to the castle nut on the pinion shaft?  I think it's 7/8" dia. ( just a guess right now) I'm thinking the cause of the failed bearing is because of a loose castle nut.  It is secured by a cotter pin.  But it only had about 20 ft.lbs. of torque on it.  Hardly any effort at all to loosen it.  Good news is the pinion gear and ring gear look great.  As does the larger inner bearing and race on the pinion shaft.

Sorry for the long explanation but I felt it was needed to explain my situation. I can add pictures if that will help explain what I'm talking about.

 

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39 minutes ago, timecapsule said:

I'm understanding that I remove the differential back plate and set a dial indicator on the ring gear and move the ring gear back and forth which will give me the pinion back-lash reading.  Is that correct? 

Yes, on a typical differential, moving the ring gear side to side sets the gear backlash, but that would be only after the pinion gear depth is set correctly with pinion shims.   Yes, the gear backlash will also be changed with pinion depth re-shimming, but that's not how the final gear lash setting needs to be done.

 

The depth of pinion gear sets the contact wearing pattern to be optimum for gear noise reduction, gear wear reduction as well as using the strongest section of the teeth as contact.

58 minutes ago, timecapsule said:

The pinion housing bolts up to the differential housing.  Between the two, there are 6 shims ( 3 thick, 3 thin). 

These shims sound like they would set pinion depth.  Not to be used for setting gear lash.

 

The other shim locations you tried to explain sound like they would be for pinion bearing preload, but pics would help. Tapered roller bearings when "new" need preloading.  Used bearings are less preload.  I'm talking typical differential designs, I can only assume a 1930 Hudson should be the same.   

1 hour ago, timecapsule said:

There are only a few short paragraphs that mention the pinion shaft and on 3 pages it says there is no end play and on another page it says that there is end play but it doesn't state what it is.

I can't believe that there should be any end play on any typical pinion shaft, makes no sense IMO

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3 hours ago, timecapsule said:

So my question is. Is there anyone familiar with setting up the pinion gear once I have the new race pressed into the pinion housing, in one of these early cars.

Err.... No. I have been where you are though trying to figure it all out.

 

3 hours ago, timecapsule said:

There are only a few short paragraphs that mention the pinion shaft and on 3 pages it says there is no end play and on another page it says that there is end play but it doesn't state what it is. 

 

3 hours ago, timecapsule said:

The original parts book that I have, shows the same part number as the one I took out and it is a Timken 26112. 

Is this a tapered roller bearing? Are there 2 of them pointing at each other like there are in modern cars? If that is the case, I'm with @F&J, there should probably be preload, not slop. In a rear axle, things bend and move under load, failures occur when things are not in the position they should be in. Slop is bad. I might re-read the manual with that in mind, maybe it would make more sense if the slop mentioned is from wear? I think you need to have a look at all the bearings in there.

 

3 hours ago, timecapsule said:

However it does mention in each case that the pinion back-lash should be .006-.008. 

From You Tube, I'm understanding that I remove the differential back plate and set a dial indicator on the ring gear and move the ring gear back and forth which will give me the pinion back-lash reading.  Is that correct? 

Yes. If you think about it, it is a BS measurement. How far out the ring gear you are affects it, and the angle. Try to be at 90 degrees to an imaginary line through the center of the case out to the edge of the ring gear. Do the best you can. Lock or jam the pinion or yoke somehow. You might not think it is moving but it is. Getting a repeatable measurement can be frustrating. Note: in rear axle speak, the "case" is the piece the ring gear is bolted or riveted to. The outer housing is called a "carrier". You will see those two terms used backwards a lot.

 

In a worn unit, you may not need or want to run as tight as .006-.008, but since the bearings were bad you can't measure to see where you were. New designs run looser. .006 will run hot hot HOT as it breaks in. Sadly, you don't get to just arbitrarily run looser because you want to. It changes the tooth contact pattern. The contact pattern trumps just about anything else. Keep a close eye on the temperature in the beginning and keep the speeds low.

 

3 hours ago, timecapsule said:

The pinion housing bolts up to the differential housing.  Between the two, there are 6 shims ( 3 thick, 3 thin).  Also the last part that slides on to the pinion that the driveshaft bolts to (universal joint companion flange) has 5 shims between it and the bearing.   Are the shims between the differential and pinion assembly dictating the pinion back-lash?

No, those are for pinion depth. If you have no clues from etched marks, the manual or anything to know where it belongs, I would start with 2 new preloaded bearings (assuming this is 2 tapered roller bearings pointed at each other) and put in the depth shims exactly the way you found them. Maybe you get lucky and the tooth contact pattern will be OK. If that other pinion bearing is really OK you might be fine leaving it, but inspect it really, really close. Any wear there is going to change the pinion depth a little.

 

Generally speaking you set backlash by moving the ring sideways. Pinion depth also affects it, but you would not set it at the pinion. Pinion depth is critical for a sane tooth contact pattern, so you can't really use it for a backlash setting.

3 hours ago, timecapsule said:

My last question is how much torque should I apply to the castle nut on the pinion shaft?  I think it's 7/8" dia. ( just a guess right now) I'm thinking the cause of the failed bearing is because of a loose castle nut.  It is secured by a cotter pin.  But it only had about 20 ft.lbs. of torque on it.  Hardly any effort at all to loosen it.

ASSUMING that there are 2 tapered roller bearings pointed at each other, and the preload (or lash) is set by shims, and the shims bottom out as the only thing that affects the setting, that nut should be as tight as you can get away with considering the metallurgy of 1930. On modern cars with shims that nut is usually over 200 foot pounds, and you may have to make a special cheater bar to bolt to the companion flange to tighten it. I'll bet it wasn't 200 foot pounds in 1930, but probably a lot more than 20.

 

You should check the contact pattern. Are these spiral bevel gears? Spiral, but the pinion enters at the center? That is what I would expect in 1930. Honestly it is tough to even guess this stuff with no pictures. You check the pattern using a paint. There is yellow gear marking compound available online, I think GM makes it. In the old days, red lead or white lead were used, but good luck finding any today unless you want to make your own. Titanium White artists oil paint can work too in a pinch, but does not work quite as well as the yellow stuff.

 

Now the annoying part. There are how-tos and videos about gear contact patterns all over the Internet. They seem to contradict each other. After much frustration, I found a document from Dana Corp. that was the rosetta stone, sort of. It explained that there are 2 methods by which the ring and pinion could have been manufactured, hobbing as it was done in the old days, and some newer method. The pattern moves the opposite way as you move the pinion in and out with the newer method. I really thought I had it figured out when I found that document. Nope. Those are all hypoid gears, the pinion is offset, and my spiral bevel gears (no offset) behaved yet differently. They seem to be undercut down at the root. Among other things, the oval pattern never occurs, but you still need the load at the center of the tooth.

 

I eventually found markings for the pinion depth measurement on the pinion, in inches, center of axle to end of pinion teeth. This is how it is usually done today, but in my case contradicted the service manual. I never got a pattern matching any book, but the best centering of the load occurred at the marked setting. It was dubious at best, and I never would have found that spot just moving the pinion in and out and the ring gear right and left for the best pattern like professionals do today. Indeed I had been trying for several days....

 

ASSUMING spiral bevel gears, I suggest you start by using the original pinion depth as close as you can figure it, and move only the backlash setting while checking with paint. You may want to check at about 4 spots in case the gear is not perfectly regular. If you wind up with a bit more backlash than the manual says when you get a good contact pattern, that might be a good thing.

 

Edited by Bloo (see edit history)
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Wow.  Thanks guys.  I'm going to print off everything and study it word for word tomorrow when I'm at my shop with everything in front of me.  I've pulled the differential back plate off and since it's will be a couple weeks before I'm ready to assemble.  Getting the bearing, race, seal , speedi-sleeve in will take about a week.  Then I'll take the pinion assembly back to the machinist to have the old race taken out and the new one pressed in.  While I had the parts at the machinist the first time I asked him to inspect the larger bearing and race and he said they looked fine.  

So I'll start adding some pictures now.  Here is all the components lined up as they would be once it was assembled. The small plastic clamp is keeping the seal upright.  It is a Fitzgerald seal. Thankfully it cross referenced to a Timken seal.  The smaller bearing on the right is the badly damaged one that is worth 2 million dollars. 

pinion parts.jpg

Edited by timecapsule (see edit history)
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This is whats called the U-Joint companion flange and it is really badly worn.  As you can see by the straight edge across the end.  I used a feeler gauge and it's about .020 th.  So the machinist is going to level that off and then make a .020th washer/spacer to compensate for the loss.  This rides up against the 5 smaller shims and the outside shim was also worn.  Those shims ride up against that 2 million dollor bearing. There are 6 holes spaced around the side that is on the bench. In the next picture you will see how it attaches to the U-Joint housing and the driveshaft.

ujoint companion flange1.jpg

ujoint companion flange2.jpg

Sorry for the sideways pictures

 

Edited by timecapsule (see edit history)
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Here is what it looked like when it was all assembled.  The U-Joint is in the middle of the picture inside the shroud/housing.  The U-Joint was unique in construction but it was typically a "+" shape.  Strangely there were no roller bearings on the ends of the U-Joint.  They are metal on metal.   

ujoint assembly.jpg

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Bloo, you mentioned about the use of special paint to identify the area where the pinion rides.  In this picture you can see some red on the ring gear so I suspect that that is the red lead paint you mentioned.  So is it critical that I get the paint designed specifically for this purpose?  Will Napa carry that yellow gear marking compound?  Or do I have to source it out on line?  I'm an old fart and so far I have refused to shop on line.  Old school habits I guess.

I'm using 600W axle lubricant in my differential.  As you guys may know it's about as thick as the original STP.  Very difficult to get it off parts and tools.  So when I apply the paint, I'm assuming the ring gear must be squeaky clean so it can accept the paint, right?

ring gear.jpg

Edited by timecapsule (see edit history)
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I hope my pictures answered any of your questions guys.  Like I said I'll study your comments tomorrow while I'm under the car.  I may well have more questions later or perhaps need more clarification.  

Oh btw, from my pictures, does this set up look similar to Ford or Chev back around 1930?  Where I am located, there just isn't any mechanics interested in working on anything this old.  I actually prefer doing as much work on the old boy as possible.  However I am a little nervous about not getting this right, and damaging the rear end.

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1 hour ago, timecapsule said:

Wow.  Thanks guys.  I'm going to print off everything and study it word for word tomorrow when I'm at my shop with everything in front of me.  I've pulled the differential back plate off and since it's will be a couple weeks before I'm ready to assemble.  Getting the bearing, race, seal , speedi-sleeve in will take about a week.  Then I'll take the pinion assembly back to the machinist to have the old race taken out and the new one pressed in.  While I had the parts at the machinist the first time I asked him to inspect the larger bearing and race and he said they looked fine.  

So I'll start adding some pictures now.  Here is all the components lined up as they would be once it was assembled. The small plastic clamp is keeping the seal upright.  It is a Fitzgerald seal. Thankfully it cross referenced to a Timken seal.  The smaller bearing on the right is the badly damaged one that is worth 2 million dollars. 

pinion parts.jpg

The shims on the pinion:  If that's where they were, did somebody add them to make up for the wear on the flange.  In other words, if the flange is too worn, then the part of the pinion shaft just inboard of the last threads, now sticks up put of the flange, then the nut cannot tighten the flange.  That's because the nut tightened against the shoulder on the threaded end if shaft, and is not squeezing the flange.  Hard to out in words.

 

 

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7 minutes ago, F&J said:

The shims on the pinion:  If that's where they were, did somebody add them to make up for the wear on the flange.  In other words, if the flange is too worn, then the part of the pinion shaft just inboard of the last threads, now sticks up put of the flange, then the nut cannot tighten the flange.  That's because the nut tightened against the shoulder on the threaded end if shaft, and is not squeezing the flange.  Hard to out in words.

 

 

I understand what you're suggesting.  I really don't have an answer.  The shims, both the large ones and the small ones, do show in the parts book and it simply says, use as needed.  It doesn't ever specify what thickness they are, just a PN for the "thick" ones and for the "thin" ones.  

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2 minutes ago, timecapsule said:

I understand what you're suggesting.  I really don't have an answer.  The shims, both the large ones and the small ones, do show in the parts book and it simply says, use as needed.  It doesn't ever specify what thickness they are, just a PN for the "thick" ones and for the "thin" ones.  

I just lost a huge post when I saw you just posted a reply to me, and I clicked on it. Dammit, I woke up half hour ago and decided to look for pics.  East Coast time here.

 

Anyways, I'll redo what I lost tomorrow.  >>>>A big part of what I lost, TOTALLY backs up where your book says "Use as needed".  You use them between the small bearing and the pipe spacer, to lessen preload.   Put them all where you show in pic, then I bet the pinion won;t even turn.

 

I will get back in the AM, it's too late

 

 

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The shims will need to bottom out in such a way that is not "just the bearing", yeah, hard to put into the words. The companion flange should bottom out without any help from the bearing, then remove shims until you have a little preload on the bearings.

 

Nothing says you have to have a particular kind of paint. If that is what I am looking at, I am really surprised it is still there. The gear rubs off the paint where it contacts, showing you where all the pressure is going to be on the teeth. Normally you just have it on a few teeth and you can let the oil wash it off. Nobody will sell you red or white lead, so unless you can find some in your grandfather's basement you are out of luck there. The current substitutes are the yellow gear marking compound or titanium white oil paint from an art store. In my opinion, the yellow gear marking compound worked better than titanium white, so that is what I would get. Both sucked compared to lead in my opinion, although maybe that's just rose colored glasses looking back at the past. I don't recall where I got the marking compound. Amazon probably has it.

 

1 hour ago, timecapsule said:

Oh btw, from my pictures, does this set up look similar to Ford or Chev back around 1930? 

No. This car of yours is downright modern compared to either of them. You wouldn't believe how rube goldberg chevy rearends were back then. It's true clear into the early 50s. Ford still had side bells and a banjo housing then, which looks like something from 1910, but to be fair to Ford, they did at least have Timkens in the pinion, I think. They held up pretty good.

 

The 2 timken bearing and shims setup on the pinion was still pretty common in the 60s. Having the depth set by taking the whole pinion and bearing assembly off is kind of old fashioned. That's convenient for setting the depth, but probably cannot be made stiff enough for much horsepower, and that is why you would not see it in modern times. Spiral bevel gears went away in the US in the 30s in favor of hypoid gears, and not for the reasons you would think. They were trying to get the driveshaft lower. Spiral Bevel gears were gone everywhere by the late 50s I think except for Land Rover, who kept using them into the early 2000s.

 

EDIT: @F&J posted while I was typing that. I also believe those shims go under the bearing.

 

Edited by Bloo (see edit history)
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Threads like this one are a major reason I enjoy this forum. Timecapsule, thanks for asking the questions you did. Bloo and F&J, thank you for the in-depth answers. I am learning a lot from this thread.

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11 hours ago, timecapsule said:

This is whats called the U-Joint companion flange and it is really badly worn.  As you can see by the straight edge across the end.  I used a feeler gauge and it's about .020 th.  So the machinist is going to level that off and then make a .020th washer/spacer to compensate for the loss.  This rides up against the 5 smaller shims and the outside shim was also worn.  Those shims ride up against that 2 million dollor bearing. There are 6 holes spaced around the side that is on the bench. In the next picture you will see how it attaches to the U-Joint housing and the driveshaft.

ujoint companion flange1.jpg

ujoint companion flange2.jpg

Sorry for the sideways pictures

 

You are having the shop make a .020" shim if they machine the worn flange.  You don't really know how much is worn off the flange, but that's OK as long as when you put the flange back on after setting preload, that the very end of the spline is not protruding out from the flange where the nut goes.  Meaning the nut needs to be pushing in on the flange and that the nut has not hit the start of the splines instead.    

 

On those shims: When the book says "use as needed", ...Those shims, when placed where your pic shows; that place is where you "store" excess shims.   For the shims to be having any effect on pinion bearing preloads, the shims need to be moved between the small bearing and that long tube spacer.    Shims placed there will spread the two bearing cones apart, causing less preload.

 

IMPORTANT PARAGRAPH:  I don't know why "all" of the shims were in that storage spot.  You'd think that the pinion would have been binding with massive preload.  So did somebody have it apart and messed with it? ...or... We don't know if the factory had the ability to set factory preload by using/choosing different lengths of that spacer tube.  If they did, then they would have added the spare shims there only to be used if the car needed bearing repairs later.

 

That may seem odd, but Rwd GM "integral style" ring gear carrier side bearings are each shimmed with just one very thick machined, predetermined sized spacer when new.  The factory has some sort of test fixtures to determine what exact thickness each of these single shims need to be to get proper preloads and proper gear backlash.   If you rebuild those rear ends, the GM shim kit you must buy during repairs, is a combination of different, much thinner shims, so that you can put some stacked together to make a slight change from the factory one piece shim (if that one is too thick for the new bearings or new gears and lash).  

 

So you need to do test fits (without pressing the new seal in yet).  Use all shims in between the bearing and sleeve, and it hopefully should be super loose after you tighten the nut.  Then take some of the shims from there and move them back to between the small bearing and the flange.  Keep doing this until you can feel a very, very slight drag after you tighten the nut fully, and then try to spin the pinion in it's housing. 

 

Modern days.. an inch pound torque wrench is used to measure drag, but think of it like adjusting super large truck front wheel bearings that also need a preload.  It's done by feel on those.

 

 

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6 minutes ago, F&J said:

You are having the shop make a .020" shim if they machine the worn flange.  You don't really know how much is worn off the flange, but that's OK as long as when you put the flange back on after setting preload, that the very end of the spline is not protruding out from the flange where the nut goes.  Meaning the nut needs to be pushing in on the flange and that the nut has not hit the start of the splines instead.    

 

On those shims: When the book says "use as needed", ...Those shims, when placed where your pic shows; that place is where you "store" excess shims.   For the shims to be having any effect on pinion bearing preloads, the shims need to be moved between the small bearing and that long tube spacer.    Shims placed there will spread the two bearing cones apart, causing less preload.

 

IMPORTANT PARAGRAPH:  I don't know why "all" of the shims were in that storage spot.  You'd think that the pinion would have been binding with massive preload.  So did somebody have it apart and messed with it? ...or... We don't know if the factory had the ability to set factory preload by using/choosing different lengths of that spacer tube.  If they did, then they would have added the spare shims there only to be used if the car needed bearing repairs later.

 

That may seem odd, but Rwd GM "integral style" ring gear carrier side bearings are each shimmed with just one very thick machined, predetermined sized spacer when new.  The factory has some sort of test fixtures to determine what exact thickness each of these single shims need to be to get proper preloads and proper gear backlash.   If you rebuild those rear ends, the GM shim kit you must buy during repairs, is a combination of different, much thinner shims, so that you can put some stacked together to make a slight change from the factory one piece shim (if that one is too thick for the new bearings or new gears and lash).  

 

So you need to do test fits (without pressing the new seal in yet).  Use all shims in between the bearing and sleeve, and it hopefully should be super loose after you tighten the nut.  Then take some of the shims from there and move them back to between the small bearing and the flange.  Keep doing this until you can feel a very, very slight drag after you tighten the nut fully, and then try to spin the pinion in it's housing. 

 

Modern days.. an inch pound torque wrench is used to measure drag, but think of it like adjusting super large truck front wheel bearings that also need a preload.  It's done by feel on those.

 

 

More great food for thought and thanks.  The fit/clearance between the differential housing and the pinion housing is super tight.  It took a lot of time to wiggle it off the 4 studs, using a small pry bar back and forth.  Which is discouraging if I have to try different variations of combinations of the large shims.  But it is what it is.  One curious thing about the large 6 shims is that they look well used.  Like as if they have been on and off many times and perhaps dropped on the floor and walked on, etc.  Like a dog eared old book so to say. 

 

I'll check my parts book for an illustration, but I seem to think that it shows the small shims located as I have them in the picture, which is the way they were when I took them off.

I'm off to my shop now and I'll be back in about 12 hours.  Hopefully with more insight and answers in my head.  

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18 minutes ago, timecapsule said:

I'll check my parts book for an illustration, but I seem to think that it shows the small shims located as I have them in the picture, which is the way they were when I took them off.

If that's true, then we must assume that the factory used a specific/selected length of tube spacer on every rear end they set up when setting preload.  It also means the shims are only there in case they would be needed during rebuilding.

 

on some semi-modern pinions, that tube spacer is collapsible, called a ''crush sleeve".  This enables the factory to quickly preload the bearings by simply keep tightening the nut which makes the spacer tube to be crushed shorter for more preload.  

 

So you may want to try the first test fit with all shims back where they were.  If the preload is too tight, then start to move shims between the tube and outer bearing.  But if the bearings are way too loose with all shims where they were, then the tube needs to be shortened a few thousands at a time.

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Thank you F&J for mentioning that those shims were in the wrong place.  I checked my parts book and sure enough #33 shows where they should be just as you said.  That's always a concern when doing something for the first time, that whoever did it before may not have done it right.  So thank you very much for mentioning that and inspiring me to check the diagram more closely this time.  The first time I was reading the page with all the part numbers and glancing at the page I attached periodically and didn't notice that the shims were in the wrong place.  Had I had the knowledge that you just mentioned about them being after the sleeve and why that was, I would have realized right away once I saw the shims in front of the bearing, that something was wrong.

 

Unfortunately life got in the way of me playing with the Hudson today, but tomorrow I'll read over everything you and Bloo had to say and I'll do a dry run with all the old stuff, and set up my dial indicator, just to get familiar with the procedure.  It's probably going to be at least a couple weeks before I get all the parts and the machinist presses in the new race.  

Thanks again guys, greatly appreciated for everything so far.

pinion diagram resized.jpg

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I started to do a practice try at setting my pinion up with the old bearing.  So I needed to make sure the back-lash was with in specs.  That being .006-.008 th.  As it was pointed out to me by Bloo that .006 might be a bit too tight. So perhaps I should shoot for .008-.010.  So I set up my dial indicator on the ring gear and went to you tube for a better visual.  I watch a video that said that there is a top pinion type  as well as a bottom pinion type, an that the indicator should be pointed in a opposite direction depending on what type you have.

Well to me, my 30 Hudson looks like the pinion is right in line with the centre of the axle.  As for the angle of the teeth on the ring gear.  In the video the ring gear comes out on one side at about 90 degrees to the rest of the gear.  The other side of the tooth is a gentle angle.

Well on mine the tooth is pretty much an equal angle on both sides.  As for attaching the dial indicator, there is only one possible position it can be in to be so it compresses at right angle to the face of the side of the tooth.  

As for the back-lash.  I have around .060th. +.   I even put a piece of masking tape on the outer surface of the ring gear and set up the dial indicator to work as a straight edge and drew a pencil line ( mechanical pencil)  and then moved the gear and drew another line.  Then took a digital reading with my caliper and I got about 7/64"  which is around .109 th.  Now of course these are very rough measurements because had no way of making absolutely sure I was holding the pencil at exactly the same angle each time and I was visually taking a reading from the pencil lines to the ends of the caliper.  But needless to say it's a lot more than specs call for. 

So do I have to remove the gear assembly from the rear end to get this right, or can I adjust the end nuts using a round chisel and taping on the holes around those adjusting nuts one opening at a time until I get it close?  I'll add a bunch of pictures to explain what I'm talking about.  

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It was difficult to get a good picture since the ring gear is circular so lines get distorted the further away from the lens ( left and right) when the camera is this close.  But if you look at the gear closest to the letter P stamped on the gear, it best represents the equal angles of both sides of the teeth.

pinion tooth angles.jpg

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So can I leave the assembly in the differential housing and simply encourage the adjusting nut ( white arrow) to turn with a small round long nose chisel to the next slot?  

Btw can someone explain to me what is actually happening when that is done?  I'm guessing that the gears on the axles are being pushed along the axle closer to the spider gears right?

backlash adjusting nut.jpg

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There isnt enough in that picture to tell what you have there, but generally, those are threaded and have a locking tab you must remove. There is one under each carrier bearing, supporting each carrier bearing in a sideways direction. They move the ring gear right/left to set the lash, and they combine to set the preload on the carrier bearings. There is a dance to get the preload and the backlash both where you want them. You'll probably be screwing with those a lot. My guess is you won't want the clamping bolts quite tight around those while you are adjusting. Not very loose though. Maybe you can get them to turn with everything tight. You might need to make some kind of a spanner. A couple allen bolts threaded into a steel bar can be useful to turn those on some kinds of rear axles. When you get a reasonable paint pattern combined with reasonable backlash and correct preload on the carrier bearings, you put the lock tabs back in.

 

I keep looking at the picture and I can't tell whats going on in there. The only piece I recognize is the one with the holes in it. Parts that look like that are still used today.

 

If those are ball bearings on the carrier, consider replacing them.

 

.060" is way too much lash if they were new gears, and probably way too much anyway. I'd try to tighten it up some, probably a lot, and then get clues from the paint pattern. When it was new, some exact combination of backlash with some particular in/out setting on the pinion would cause it to not make noise and not break teeth off. When there's wear it's much tougher to figure out. It helps a lot if you knew where it was set before, but when there's bad bearings you just don't. Doubly so since someone had those pinion preload shims in wrong. 

 

Edited by Bloo (see edit history)
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26 minutes ago, Bloo said:

There isnt enough in that picture to tell what you have there, but generally, those are threaded and have a locking tab you must remove. There is one under each carrier bearing, supporting each carrier bearing in a sideways direction. They move the ring gear right/left to set the lash, and they combine to set the preload on the carrier bearings. There is a dance to get the preload and the backlash both where you want them. You'll probably be screwing with those a lot. My guess is you won't want the clamping bolts quite tight around those while you are adjusting. Not very loose though. Maybe you can get them to turn with everything tight. You might need to make some kind of a spanner. A couple allen bolts threaded into a steel bar can be useful to turn those on some kinds of rear axles. When you get a reasonable paint pattern combined with reasonable backlash and correct preload on the carrier bearings, you put the lock tabs back in.

 

I keep looking at the picture and I can't tell whats going on in there. The only piece I recognize is the one with the holes in it. Parts that look like that are still used today.

 

If those are ball bearings on the carrier, consider replacing them.

 

.060" is way too much lash if they were new gears, and probably way too much anyway. I'd try to tighten it up some, probably a lot, and then get clues from the paint pattern. When it was new, some exact combination of backlash with some particular in/out setting on the pinion would cause it to not make noise and not break teeth off. When there's wear it's much tougher to figure out. It helps a lot if you knew where it was set before, but when there's bad bearings you just don't. Doubly so since someone had those pinion preload shims in wrong. 

 

Sorry about that poor picture.  I forgot to take an isolated picture of that adjusting nut so I cropped one of the others.  This is a better picture that shows the nut on the left.  Easier to zoom in with this picture.  Yes I do understand how that nut and bolt are loosened and that dog so to say is lifted out of a slot.  I have given some thought o making a specialty tool  but there isn't much room to get it in there.  I prefer not to take the guts out because I'll have to remove the axles and I just installed new axle seals and I prefer not to put any extra wear on the seal by dragging the axle past it.  

dial indicator reading.jpg

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3 minutes ago, Bloo said:

Assuming they are preloaded right in the first place, that is exactly what you do. Loosen the side you want to move the gear toward, tighten the other side the same amount.

So for discussion sake, lets assume I want to end up with .010th.  I now have .060th.  So somehow I need to get rid of .050 th.  How do I determine which way to go? I mean the ring gear  moved back and forth ( clockwise/counterclockwise) if you're looking at it from the end of the axle.  So by tightening the nuts,  That would squeeze the axle gears tighter against the spider gears, not allowing as much ring gear back and forth movement.  Did I get that right?

So you mentioned to tighten one and loosen the other.  That confused me.  Why wouldn't I want to tighten both?  

As far as preload goes, with that much movement (.060+ th.)  I'd be thinking that there wasn't any. Right?  

So would I take out all the movement or back-lash, and then gradually loosen off to increase the back-lash until I get something reasonable like .010th?

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Usually... most of the wear is on the pressure side bearing - that is the one away from the teeth, ( left side of car) so if the crown is loose in the bearings at all, try tightening that one up until you get a bit of preload and see where you are.  If you have a manual for any older vehicle it should have a picture chart showing what to move to achieve different settings. They are usually for hypoid but could be helpful in this too. I could post one here if you don't have one. 

Looking at the pictures it seems you have to loosten the bolt to get the locking dog out, so as Bloo mentioned, that should make the collar turn easier. Also... important... Mark the position with a punch mark BEFORE you move anything so if anything falls apart you know where you started. You can easily tell if you are a thread out (1 turn) so a mark can be helpful.

 

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If these adjustments have anything to do with the spider gears, I cant imagine how. There must be something I am not seeing. In most axles all those do is move the ring gear sideways.

 

If that affects the spiders somehow because of axle shimming or outer wheel bearing preload or something, you are going to have to take all that apart and redo it after these threaded rings are set (I think).

 

So qualifying it by saying that on most rear axles for the last 75 years or more, the dangerously oversimplified answer is you would move the ring gear toward the pinion with those 2 adjustments until you had .010" . Your picture here is the standard way of measuring. Check in about 4 spots.

 

1301218260_dialindicatorreading.jpg.aa39

 

Most axles have a spec for preload too, you would tighten one side a little much, loosen, tighten until no play (make sure the gears aren't touching), and then it is probably a number of notches tight (to preload). Does the book say anything about this? This 1934 Chevrolet for instance is 1 to 1-1/2 notches tight.

 

http://chevy.oldcarmanualproject.com/shop/1934/34crm068.htm

 

Not much else about that is like yours, but it does have the adjuster rings. The bearings are balls, however Chevy kept those same bearings in one of their later hypoid axle designs, and then when they changed to timkens in that later axle, the specs did not change for preload. Odd, because ball bearings and timkens usually require different setup in almost any other application. Ball bearings were a horrible choice in my opinion, and today just about every relatively modern axle of any brand uses timkens, but those adjusters are still about the same.

 

Modern rear axles usually specify more preload. As I mentioned earlier, the biggest problem is the parts and cast iron stretching and moving around, letting the gears get out of line enough under power to put the load in the wrong place and break teeth. Some modern axles have you put a dial indicator on the carrier and keep tightening those rings until the carrier is a certain amount wider! It takes quite a bit of force. In another tech article I read, a respected axle builder, talking about one of those modern axles, said he "didn't think it was possible" to overtighten those rings.

 

Now I am NOT suggesting you tighten the snot out of an old axle like that, use the original spec if you can find one. The point is slop is bad, and the most important thing is keeping the gears properly aligned with each other, and a little too tight is better than a little too loose.

 

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2 minutes ago, Oldtech said:

Usually... most of the wear is on the pressure side bearing - that is the one away from the teeth, ( left side of car) so if the crown is loose in the bearings at all, try tightening that one up until you get a bit of preload and see where you are.  If you have a manual for any older vehicle it should have a picture chart showing what to move to achieve different settings. They are usually for hypoid but could be helpful in this too. I could post one here if you don't have one. 

Looking at the pictures it seems you have to loosten the bolt to get the locking dog out, so as Bloo mentioned, that should make the collar turn easier. Also... important... Mark the position with a punch mark BEFORE you move anything so if anything falls apart you know where you started. You can easily tell if you are a thread out (1 turn) so a mark can be helpful.

 

The only reference I have to a service manual is a free online copy through HET.  But it seems to be a copy of the original but it is a very strange manual.  295 pages  and almost every page is redundant for the most part except for a small paragraph or 2.  That is where I found that the back-lash should be .006-.008.  Other than that, there are no pictures or illustrations at all.  Here is a link and you can see what I mean.  http://hudsonterraplane.com/tech/1930/1930-1933Hudson8ServiceOperationsManual.pdf

 

Yes a very good point about making the nuts before I move them and keeping track of how far and what direction.

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4 minutes ago, Bloo said:

If these adjustments have anything to do with the spider gears, I cant imagine how. There must be something I am not seeing. In most axles all those do is move the ring gear sideways.

 

If that affects the spiders somehow because of axle shimming or outer wheel bearing preload or something, you are going to have to take all that apart and redo it after these threaded rings are set (I think).

 

So qualifying it by saying that on most rear axles for the last 75 years or more, the dangerously oversimplified answer is you would move the ring gear toward the pinion with those 2 adjustments until you had .010" . Your picture here is the standard way of measuring. Check in about 4 spots.

 

1301218260_dialindicatorreading.jpg.aa39

 

Most axles have a spec for preload too, you would tighten one side a little much, loosen, tighten until no play (make sure the gears aren't touching), and then it is probably a number of notches tight (to preload). Does the book say anything about this? This 1934 Chevrolet for instance is 1 to 1-1/2 notches tight.

 

http://chevy.oldcarmanualproject.com/shop/1934/34crm068.htm

 

Not much else about that is like yours, but it does have the adjuster rings. The bearings are balls, however Chevy kept those same bearings in one of their later hypoid axle designs, and then when they changed to timkens in that later axle, the specs did not change for preload. Odd, because ball bearings and timkens usually require different setup in almost any other application. Ball bearings were a horrible choice in my opinion, and today just about every relatively modern axle of any brand uses timkens, but those adjusters are still about the same.

 

Modern rear axles usually specify more preload. As I mentioned earlier, the biggest problem is the parts and cast iron stretching and moving around, letting the gears get out of line enough under power to put the load in the wrong place and break teeth. Some modern axles have you put a dial indicator on the carrier and keep tightening those rings until the carrier is a certain amount wider! It takes quite a bit of force. In another tech article I read, a respected axle builder, talking about one of those modern axles, said he "didn't think it was possible" to overtighten those rings.

 

Now I am NOT suggesting you tighten the snot out of an old axle like that, use the original spec if you can find one. The point is slop is bad, and the most important thing is keeping the gears properly aligned with each other, and a little too tight is better than a little too loose.

 

Thanks for that Cheve link.  I'll study that in the morning.  I may have to remove the whole assembly to get a better look at it even though I'm reluctant to.  Because, like you I don't see any way that the ring gear can move sideways and there aren't any shims to be added like I've seen in more modern assemblies.  That's why I asked what was going on when those nuts are turned.  I only have a illustrated diagram from the parts catalog.  I posted a partial picture of it earlier but I cropped it in the wrong place.  If you scroll back to that picture, there is an arrow at the bottom right, and it is pointing at that adjusting nut.  I'll take a better photo of it and post it tomorrow.  But the illustration really lacks detail and leaves me scratching my head. 

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Here is that diagram I just mentioned.  #20 is listed as "differential adjusting nut".  But there just doesn't seem to be enough detail in the diagram to figure out what moves when the nut is adjusted.

#16 is the "differential gear"

#17 is the "differential pinion"

#18 is the "differential spider"

diff diagram.jpg

Edited by timecapsule (see edit history)
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The Chev link is interesting, but don't put much stock in what you see there because outside of those adjusters, not much is the same. I'm quite familiar as it is almost identical to my Pontiac. It is a real screwball.

 

The specs in that HET manual are brief, but sound fairly normal to me. Page 20: "Remove endplay, tighten each nut one notch". So, 2 notches of preload altogether. "backlash .006-008". OK, I'm fine with that. Pinion bearing "should exert drag". Ok, so its preloaded a little. That is expected, and is just like a modern axle! We have tiny torque wrenches now, but in 1930 they didn't even torque head bolts. Axle end shaft play ".005-.010". I can't say for sure, but combined with their description of how to set the axle shims, it all sounds normal and relatively modern. Your spider gears (not mentioned) are probably modern and normal too, and unaffected by any of this. They probably have no adjustment other than their own wear and tear, and maybe some bronze thrust washers (and you wouldn't even get those in a modern one). The axles just slid into the side gears splines, float in there , and bottom out on something. The .005-.010" slop is because the axles lengthen a lot when they get hot. Shims between the outer bearing race and the cap holding the bearing in set the endplay. Chrysler used this exact setup until 1964 (and the one they replaced it with is not terribly different in concept).

 

 

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7 minutes ago, timecapsule said:

Here is that diagram I just mentioned.  #20 is listed as "differential adjusting nut".  But there just doesn't seem to be enough detail in the diagram to figure out what moves when the nut is adjusted.

diff diagram.jpg

Oh yeah, modern and completely normal. Don't worry about spiders. 20 is side-to-side ring gear adjustment as discussed. You want a total of 2 notches (they stated it as one notch per side) of preload with the desired backlash.

 

Unfortunately we haven't said too much about the elephant in the bathtub. We don't as far as I know have a spec for pinion depth. In your case, to start, I would ASSUME (never do that but you don't really have any choice) that the stack of shims that sets depth is the original stack, and that the rear pinion bearing, the one you didn't replace, has basically no wear. Then I would try a paint pattern at .010" backlash, and at .006" backlash, and at .014" backlash, and see if you can get a handle on how the contact pattern is moving around. If that pinion depth is still exactly where Hudson put it in 1930, you might get lucky and this might be pretty easy. I'll warn you, it is often frustrating. You'll probably never get perfection, but you do need to keep stress away from the edges and the root of the teeth. You'll need to make the pinion or ring drag somehow in order to get some torque to rub the paint off at the contact points.

 

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12 minutes ago, Bloo said:

The Chev link is interesting, but don't put much stock in what you see there because outside of those adjusters, not much is the same. I'm quite familiar as it is almost identical to my Pontiac. It is a real screwball.

 

The specs in that HET manual are brief, but sound fairly normal to me. Page 20: "Remove endplay, tighten each nut one notch". So, 2 notches of preload altogether. "backlash .006-008". OK, I'm fine with that. Pinion bearing "should exert drag". Ok, so its preloaded a little. That is expected, and is just like a modern axle! We have tiny torque wrenches now, but in 1930 they didn't even torque head bolts. Axle end shaft play ".005-.010". I can't say for sure, but combined with their description of how to set the axle shims, it all sounds normal and relatively modern. Your spider gears (not mentioned) are probably modern and normal too, and unaffected by any of this. They probably have no adjustment other than their own wear and tear, and maybe some bronze thrust washers (and you wouldn't even get those in a modern one). The axles just slid into the side gears splines, float in there , and bottom out on something. The .005-.010" slop is because the axles lengthen a lot when they get hot. Shims between the outer bearing race and the cap holding the bearing in set the endplay. Chrysler used this exact setup until 1964 (and the one they replaced it with is not terribly different in concept).

 

 

You were asking about the axle and setting the end play.  If you look at #38 in the illustration, that is what's called a "thrust button"  So the axles touch each other and over time they wear down that thrust button on the end of each axle.  So the procedure is to add "hard facing" to the end of that thrust button.  Which I did, and now I am at between .008 and .009. 

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2 minutes ago, Bloo said:

Oh yeah, modern and completely normal. Don't worry about spiders. 20 is side-to-side ring gear adjustment as discussed. You want a total of 2 notches (they stated it as one notch per side) of preload with the desired backlash.

 

Unfortunately we haven't said too much about the elephant in the bathtub. We don't as far as I know have a spec for pinion depth. In your case, to start, I would ASSUME (never do that but you don't really have any choice) that the stack of shims that sets depth is the original stack, and that the rear pinion bearing, the one you didn't replace, has basically no wear. Then I would try a paint pattern at .010" backlash, and at .006" backlash, and at .014" backlash, and see if you can get a handle on how the contact pattern is moving around. If that pinion depth is still exactly where Hudson put it in 1930, you might get lucky and this might be pretty easy. I'll warn you, it is often frustrating. You'll probably never get perfection, but you do need to keep stress away from the edges and the root of the teeth. You'll need to make the pinion or ring drag somehow in order to get some torque to rub the paint off at the contact points.

 

Thanks for that warning of frustration.  That's one of the reasons I may pull it all out and do it on the bench.  The gas tank is right up tight against the back of the differential and I can't even see the adjusting nut on the ring gear side.  So working off a creeper would only add to the frustration I'm thinking.

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5 minutes ago, timecapsule said:

Thanks for that warning of frustration.  That's one of the reasons I may pull it all out and do it on the bench.  The gas tank is right up tight against the back of the differential and I can't even see the adjusting nut on the ring gear side.  So working off a creeper would only add to the frustration I'm thinking. 

As for the pinion depth. Yes I couldn't find any mention about that spec.   The 3 thick and 3 thin shims ( the large ones that were in the correct place) that were between the differential carrier and the pinion housing add up to a fair thickness.  It will be interesting to see if I need more or less shims there.  I should try to take a reading off each shim and see how much they total.  If I need new ones, there is a CNC machine shop that does water jet cutting only a couple blocks from my shop, so they may be able to make new shims for me.

 

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