My Willys 3A and 3B Community
3A, 3B, DJ Technical Knowledge Base => "Original"-- Technical Questions, Answers, Observations => Topic started by: Tumbleweed on October 05, 2011, 09:27:52 AM
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CJ3A '49
Pulled the front axle off a few weeks ago preparing for my rebuild. When I removed the upper king pin there was the usual shims. I then removed the lower king pin and guess what shims again! In the repair manual it specs. shims under the top king pin only. I am wondering if the last owner just didn't know what they were doing or do I have a 2A axle? What harm is there in only putting shims under the top and not the bottom. Is there any way to measure the knuckle boss and where would the measurement come off of?
Also the tension on the 2A is lower than the 3A specifications on proper preload according to the manual.
Thanks,
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George
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CJ3A '49
Pulled the front axle off a few weeks ago preparing for my rebuild. When I removed the upper king pin there was the usual shims. I then removed the lower king pin and guess what shims again! In the repair manual it specs. shims under the top king pin only. I am wondering if the last owner just didn't know what they were doing or do I have a 2A axle? What harm is there in only putting shims under the top and not the bottom. Is there any way to measure the knuckle boss and where would the measurement come off of?
Also the tension on the 2A is lower than the 3A specifications on proper preload according to the manual.
Thanks,
\
George
George,
The Shims serve 2 purposes in this application, The pre-load and also to align the knuckle, to center it, Now I made a centering tool for a newer type of axle of this design
(http://i739.photobucket.com/albums/xx39/backwoodsgoop/PICT0796.jpg)
It slides into the axle housing, and slotted to expand and tighten in the housing then the install the spindle on backwards and bolt to knuckle housing to find the desired thickness of shim,
Heres the whole speal
http://www.backwoodsgoopinfo.com/goopBB/viewtopic.php?f=2&t=39
Now it is not as critical on these Dana axles because of the location of the axle seal, however still important to center the knuckle, keep things nice and aligned, and the reason you will find shims under the lower cap,
Hope that answers your ?
Thanks Frank
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Thank you Frank - perfect.
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A 1949 CJ-3A front axle should still have the shim packs split evenly between the top and bottom. The change came later but unfortunately I have not been able to determine the exact serial number where it took place. My research leads me to believe the change to top shims only came early in the 1951 model year.
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(http://i739.photobucket.com/albums/xx39/backwoodsgoop/Screenshot2011-06-25at22852PM.png)
Bob,
Are you saying @ some point Old Man Willies dialed in his machining close enough to eliminate the lower shims ?
According to that break down he sure did, no shims on the bottom, although one may add a shim there to align the knuckle housing better, in case its off a bit ?
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Yes, the bottom face of the knuckle was increased by 0.058" to eliminate the need for lower shims.
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Yes, the bottom face of the knuckle was increased by 0.058" to eliminate the need for lower shims.
Neat, Thanks Bob,
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That settles it then I'll go with top shims only.
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That settles it then I'll go with top shims only.
???? For a 1949 the shims should be evenly split between the top and bottom.
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That settles it then I'll go with top shims only.
???? For a 1949 the shims should be evenly split between the top and bottom.
Bob, I am a lil confused about "evenly split"... as I see it to be the shims dial in the knuckle for pre-load and centering, These shims take up errors in machining that evidently Old Man Willies dialed in after a bit, and went with the 50 some thousands extra meat on the bottom knuckle,
Now these shims can be various thickness, So simply evenly splitting them by number ? dont add up, ?? usually the shim thickness can vary from super thin, ,005, to .030
If your concerned about this a alignment tool needs to be fabricated, otherwise its a guessing game,
Regardless, if the thing was happy for years with the shims where they where, leave it the way it was, For sure on the bottom, and dial in the pre load from the top,
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I think it means split the total thickness between the top and bottom. So if the total shim pack thickness is .030, put .015 on the top and .015 on the bottom for a total of .030.
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I think it means split the total thickness between the top and bottom. �So if the total shim pack thickness is .030, put .015 on the top and .015 on the bottom for a total of .030.
The shims on the bottom center the knuckle, align the axle,
(http://i739.photobucket.com/albums/xx39/backwoodsgoop/PICT0793.jpg)
Bob mentioned around 1950 the machining was dialed in enough to eliminate the shim @ the bottom , But when aligning the knuckle to the housing select a bottom shim, and adjust pre load from the top,
Simply splitting the shims evenly defeats the purpose altogether of the bottom shims, they are to center the knuckle housing,
Some sort of alignment tool, is needed, when working from scratch however re using the existing lower shims in a axle that has functioned well for years is just fine,
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Bob mentioned around 1950 the machining was dialed in enough to eliminate the shim @ the bottom
That is not what Bob said, this is what Bob said.
Yes, the bottom face of the knuckle was increased by 0.058" to eliminate the need for lower shims.
Dividing the shims equally between the top and bottom keeps the knuckle centered on the axle for the early knuckles. The change in knuckle machining was done to simplify service by eliminating the lower shims, not because they "dialed it in".
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Bob mentioned around 1950 the machining was dialed in enough to eliminate the shim @ the bottom
That is not what Bob said, this is what Bob said.
Yes, the bottom face of the knuckle was increased by 0.058" to eliminate the need for lower shims.
Dividing the shims equally between the top and bottom keeps the knuckle centered on the axle for the early knuckles. The change in knuckle machining was done to simplify service by eliminating the lower shims, not because they "dialed it in".
Bob, �
Are you saying @ some point Old Man Willies dialed in his machining close enough to eliminate the lower shims ?
"YES"
Bob, I am not mis quoting you , You answered Yes to my question, But now its not that the machining got dialed in, it was ease of service, Maybee So It got to the point that Old Man Willy,s got tiered of guys loosing track of the lower shims, and retooled, ?
Doubt it,
No, Bob I think this is just like the axle end float that is adjusted by shims under the spindle, in the older axles, The machining got better so these shims could be eliminated,
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Frank, your kind of twisting BobW's words. What he is trying to tell you is on '49 and earlier you use shims on the bottom and top and on '50 and newer you only use shims on the top.
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Frank, your kind of twisting BobW's words. What he is trying to tell you is on '49 and earlier you use shims on the bottom and top and on '50 and newer you only use shims on the top. �
I understand that,
I asked if it was improved machining, of which the answer was "Yes" that brought about this change, There is no word twisting, as far as this splitting the shims evenly from top to bottom,
Dont add up,
The shims vary in thickness, So if you tear apart a axle and it has 4 shims, you throw them in the pile and do not keep track of the thickness and simply put 2 on the bottom and 2 on the top,
Its going to be out of wack, more then likely,
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Like I said, divide the total thickness of the shims top and bottom added together and put half of the total on the top and half of the total on the bottom. If it does not come out even buy some shims that equal the old total but that can be divided by two.
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Okay so now I have backtracked a bit on the shim stacking. I am putting the shims in tonight, top and bottom, evenly split.
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Make sure you have the right pre-loading on the King Pins, on the 3A they should be between 15 and 18lbs. You measure this by taking everything including the axle out of the housing, I used a fishing scale, hooked it into the eyelet for the tie rod end, and pull, the scale should read between 15-18 lbs at the point the housing starts to turnn. If its too light or too heavy you may have to adjust the shims to get the right pre-load.
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Like I said, divide the total thickness of the shims top and bottom added together and put half of the total on the top and half of the total on the bottom. �If it does not come out even buy some shims that equal the old total but that can be divided by two.
Okay, So I know for sure the rational on this because its a recipe for "Out of Wack" The last axle I did had a .050 and a .030 shim on the bottom for a total of .080 and the top was .040,
So according to the evenly split theory I take the grand Total of 1.020 and divide by 2 and put a .060 on the top and on the bottom,
putting the knuckle housing, .020 off of what it was from factory, No this just dont add up, Now I dont mean to be a trouble maker but really there is no sense to that,
The shims vary in thickness, best bet without some sort of alignment tool is to keep the same thickness @ the bottom and dial in the pre load from the top, The evenly split theory is a guessing game, @ best,
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Okay so now I have backtracked a bit on the shim stacking. I am putting the shims in tonight, top and bottom, evenly split.
That is correct for your vehicle. �:)
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Frank,
Please answer the following question with a yes or no.
Let's say we are setting up king pin bearings a Willys front axle. The knuckle is perfectly centered to the axle and there is preload on the king pin bearings. We have determined more preload is needed to meet the turning torque specification. Removing 0.010" of shim from the upper cap gives us the proper preload. By removing 0.010 of shims from the top only, did the knuckle move off center?
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Frank,
Please answer the following question with a yes or no.
Let's say we are setting up king pin bearings a Willys front axle. The knuckle is perfectly centered to the axle and there is preload on the king pin bearings. We have determined more preload is needed to meet the turning torque specification. Removing 0.010" of shim from the upper cap gives us the proper preload. By removing 0.010 of shims from the top only, did the knuckle move off center?
No Bob,
What I have been saying all along, without some sort of alignment tool, leave the lower shims the same, and adj pre-load from the Top, This for sure is not fool proof if they had been lost track of in a prior service, but when working with a axle that has functioned well for years, leave them the same,
Now this is not as critical for these Dana axles, the axle seal position in the housing allows for more of a margin of error, but still you dont want the axle in out of whack, and housing off center,
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No ....
So with the same initial setup, if we remove 0.010" from the lower cap only, will the knuckle move off center?
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No ....
So with the same initial setup, if we remove 0.010" from the lower cap only, will the knuckle move off center?
Yep, by .010,
The lower shims Center the knuckle, adding a .010 would send it the other way, by .010, I really dont understand how this could even be a question, you take out the .010 shim, tighten up the trunnion cap bolts and it sucks it down that .010 that you removed,
Are you just messing with me ? the trunnion Stud pin, whatever you want to call it bottoms out against the bearing inner race and down comes the knuckle, by .010
Same thing on the top when you removed the .010 to snug up the preload a bit more, the pin squeezes into the bearing adding the additional desired "Squeeze"
Squeezing AKA bearing pre load,
Do not just split up shims evenly, the bottom center the knuckle, adj the "Squeeze" from the top,
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Perhaps this picture will help,
(http://i739.photobucket.com/albums/xx39/backwoodsgoop/PICT0793.jpg)
With the centering tool installed and the spindle flipped around backwards the knuckle is centered with the axle, inserting the lower trunnion cap as far as it will go there is that .040 gap, of which the shim takes up,
Take .010 �away from that shim �then when the bolts are torqued it will pull the housing down, .010 off centering it by, .010
A alignment tool like this here, slides into the axle housing, slotted to expand , and machined out to the ID on the spindle, and since there is a machined ridge on both sides of this spindle, the knuckle is centered to the housing,
(http://i739.photobucket.com/albums/xx39/backwoodsgoop/PICT0796.jpg)
and wouldnt you know it after fiddling around with building and having this center tool made, the shim on the bottom was just right, re used it, but if I would take .010 off of it,
It would not fill that .040 gap and Down would come the knuckle,
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Why would the knuckle only move off center by changing the lower shim and not the upper shim? What is the difference?
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Why would the knuckle only move off center by changing the lower shim and not the upper shim? What is the difference?
Bob You must not be reading this,
Yep, by .010,
The lower shims Center the knuckle, adding a .010 would send it the other way, by .010, I really dont understand how this could even be a question, you take out the .010 shim, tighten up the trunnion cap bolts and it sucks it down that .010 that you removed,
Are you just messing with me ? the trunnion Stud pin, whatever you want to call it bottoms out against the bearing inner race and down comes the knuckle, by .010
Let me try this again,
(http://i739.photobucket.com/albums/xx39/backwoodsgoop/PICT0793.jpg)
Now with the knuckle centered , the lower trunnion cap will only go up so far, till is stops against the bearing, then there is that gap there, of which you select a shim that thick, it takes up that space,
Now if I where to not install that shim, or take .010 off of it, It would draw the knuckle housing down that far, when you tighten the bolts, Off centering the knuckle housing,
This rather easy for me to picture, but must be hard to explain,
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Why would the knuckle only move off center by changing the lower shim and not the upper shim? What is the difference?
Bob, May bee this would be easier to picture if you think of the vehicle sitting on the ground , the weight of the vehicle on the axle, the lower is set, not going to change, whatever that is,
The lower shims center the knuckle, you can take away shims from the top to add the pre load,
Or If you think of it like this, to move the knuckle housing up by changing just a upper shim, you would have to take away the same amount from the bottom,
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Frank, You really need to take a step back and think about what you are saying.
For everyone else, just use the appropriate Willys service manual for your vehicle and you will be fine. On pre-1951 Jeeps the front knuckle will be centered on the axle when the shims are equally divided between the top and bottom. Unequal shimming will cause the knuckle to move one way or the other slightly. Of course there is a lot of leeway in these axles so it probably won't matter much either way.
Here is a cut from a 1950 Willys service manual.
(http://www.cj3a.info/temp/kingpin.jpg)
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Frank, You really need to take a step back and think about what you are saying.
For everyone else, just use the appropriate Willys service manual for your vehicle and you will be fine. On pre-1951 Jeeps the front knuckle will be centered on the axle when the shims are equally divided between the top and bottom. Unequal shimming will cause the knuckle to move one way or the other slightly. Of course there is a lot of leeway in these axles so it probably won't matter much either way.
Here is a cut from a 1950 Willys service manual.
(http://www.cj3a.info/temp/kingpin.jpg)
Likewise Bob, So dont worry about the shims, lots of leeway in the axle, run the axle croooked,
3-5 lbs pre load, and some books up to 18 lbs ???
Quite a spread really, So I am going to attempt to explain one more time Bob, Take just the bottom trunnion cap and bearing and stick it in the race on the axle housing,
The flat part of the trunnion cap is the bottom of the knuckle, start adding shims, little building blocks if you will, this will raise the knuckle housing,
Bob, there is quite a bit of thought going in to what I am saying, your just reading a book, not understanding what is happening here,
The lower shims, the little building blocks set the height of the knuckle housing, center it as best as possible,
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So obviously the last sentence of paragraph #4 of the Willys manual is wrong, according to Frank.
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So obviously the last sentence of paragraph #4 of the Willys manual is wrong, according to Frank.
Ventport, These old books are the best written well worded manuals that for the most part are very accurate, one this subject however there are a couple things that following the letter of the law if you will that dont really add up,
Now that book quoted for instance has a lighter pre load listed, 3-5 lbs, Which is what I like to lean towards on setting up these axles, rather then the tighter 12-16 or 18 ?
That is a good example, 10 lbs is quite a bit more squeeze, essentially loading the bearing before it even sets down on the ground, and you wonder why the bearings brinnell, theres your pressure, and vibration well just not pay any attention to the centering of the axle, theres your vibration,
What I will do next axle I work on is try to get a comparison between the weight of the pull per .001 of pre load, I am thinking that .002 preload on this bearing would be just fine, and see what that relates to pull,
I have also seen a spec of 80 inch lbs spec pull @ the trunnion stud,
No I follow the books to a point , but sometimes and in some cases its not always 100 % accurate, Its just the nature of the subject, there is sometimes a disconnect between the writers and the engineering ,
Now the original question was if the shims on the bottom trunnion cap where there because of some one who may have not known what they are doing, well at this point if they add up to a selective number that centers the housing,
They did, and leave them the same. and adjust the preload from the top, 3-5 or up to over 15, depending on what book you want to follow,
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"Of course there is a lot of leeway in these axles so it probably won't matter much either way."
Yes Bob, These axles could be taken apart and repaired in the middle of nowhere with a hammer Rock and a screw driver, and maybee a set of vise grips, in a mud puddle,
Filled with just about anything that resembles a lubricant and get you where you need to go,
They also can be carefully cleaned and set up with new components , knuckle housings centered, pre load set, filled with a correct lubricant, and get you where you need to go for 30 plus years without ever messing with it,
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"Of course there is a lot of leeway in these axles so it probably won't matter much either way."
Yes Bob, These axles could be taken apart and repaired in the middle of nowhere with a hammer Rock and a screw driver, and maybee a set of vise grips, in a mud puddle,
Filled with just about anything that resembles a lubricant and get you where you need to go,
They also can be carefully cleaned and set up with new components , knuckle housings centered, pre load set, �filled with a correct lubricant, and get you where you need to go for 30 plus years without ever messing with it,
The question is how much improvement is there going to be when you center the knuckle housing over the factory method....will it be noticeable, all other things equal? After all ...when you turn the wheels, the knuckle is no longer aligned perfectly and the joint takes care of it. What is .010 misalignment up and down compared to the misalignment from driving around a corner? Preload is important, yes.
We all want our jeeps to last. Sometimes we have different methods. Sometimes we agree with the book, other times a better way has been found over the years. In any case, we are aiming for the same goal,keeping these fun little beasts running for another day in the woods. Life is too short to waste on name calling, endless arguing, and constant harangueing over pet peeves. If it keeps up I will have to put on my moderator hat, and ya don't want that, do ya?? :o
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"Of course there is a lot of leeway in these axles so it probably won't matter much either way."
Yes Bob, These axles could be taken apart and repaired in the middle of nowhere with a hammer Rock and a screw driver, and maybee a set of vise grips, in a mud puddle,
Filled with just about anything that resembles a lubricant and get you where you need to go,
They also can be carefully cleaned and set up with new components , knuckle housings centered, pre load set, �filled with a correct lubricant, and get you where you need to go for 30 plus years without ever messing with it,
The question is how much improvement is there going to be when you center the knuckle housing over the factory method....will it be noticeable, all other things equal? After all ...when you turn the wheels, the knuckle is no longer aligned perfectly and the joint takes care of it. What is .010 misalignment up and down compared to the misalignment from driving around a corner? Preload is important, yes.
We all want our jeeps to last. Sometimes we have different methods. Sometimes we agree with the book, other times a better way has been found over the years. In any case, we are aiming for the same goal,keeping these fun little beasts running for another day in the woods. Life is too short to waste on name calling, endless arguing, and constant harangueing over pet peeves. If it keeps up I will have to put on my moderator hat, and ya don't want that, do ya?? :o
No need for the mod hat,
I will be good, Now your turning the wheel taking things out of alignment, No the axle is still straight, and yes the joint allows it to transfer power @ a angle, but is still straight
These U joints and cv joints can handle one load, only, and one angle,
In my process of researching this subject I read up on "Thompson Couplings" these could handle both, axial and lateral,
With only one joint in the shaft like these axles only one angle , (steering), if you had 2 joints in the power transfer shaft, then okay, �I discovered this trying to run a hydralic pump off only one u joint, could not make the shaft true enough , needed 2
Also Bill,
"The question is how much improvement is there going to be when you center the knuckle housing over the factory method.."
What I am trying to point out is that what is written in the book is not the factory method, not @ all, There is no way that Old Man Willies would have had Rosie the Riveter fiddling around with taking shims on and off, dialing in the knuckle,
Waste of time, Some sort of tool or fixture installed in the housing, lower gap measured and proper selective shim installed,
Also simply installing all the thickness of shims and then taking them out to set pre load, only and no thought to centering, No I really dont think so,
What really sells if for me is years later the world renowned Japanese machinists, centered up this axle housing very much the same way with selective shims, a very critical aspect in the replicated axle because of the location of the axle seal, off just a fuzz there and the seal leaks,
These shims take up machining irregularitys, By following the book word for word, basically states that Old man Willys had the knuckle perfectly centered something the Japanese could not do some 10 years later,
Maybee,
Preload is important, yes.
"Also, in case the main purpose is to prevent false
brinelling, the exact amount of preload needs be
calculated just enough to prohibit the creation of
clearance by vibration load, so as to prevent rolling
element from being vibrated by outside vibration
when shaft is not rotating."
And Yes bearing preloading is a rather exacting, in my humble opinion the ranges given in the books are rather broad, not exacting @ all,
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Okay,
I was wondering what this core axle would be good for,
(http://i739.photobucket.com/albums/xx39/backwoodsgoop/PICT0838.jpg)
When I have time I will get this cleaned up and set up and start playing around with king pin bearing pre load, It would seem that with such a large spread in pre load, it should be narrowed down,
The reason I think 16 lbs of pre load is a bit to much is the happiest trunnion bearings I have seen the knuckle had very little pre load, and reading up on bearing pre load they tell me it is exacting,
I dont think anyone would argue the fact that a 3- 16lb range is not exacting, as mentioned earlier a excess pre load adds to the potential of brinnelling,
Now there is no difference in the bearings of the older axles vrs this newer one, None, same exact thing, �Jeep or Toyota, Timken or Toyo yoyo,
However in the most recent design of the axle of this type, they went with altogether the wrong bearing, entirely the wrong thrust angle for this application,
(http://i739.photobucket.com/albums/xx39/backwoodsgoop/Screenshot2011-06-25at52246PM.png)
This bearing with the steeper thrust angle is correct, easy to see,
(http://i739.photobucket.com/albums/xx39/backwoodsgoop/PICT0831.jpg)
Now the greatest bearing pre load that I ever seen or worked with is .008 in a transmission with a aluminum case, this tight pre load is ( I think) required because the aluminum will expand quicker and more then the steel,
When setting the shafts up this tight you cannot turn them by hand, very tight, So What I want to do is get a idea between actual thickness of pre load and lb of pull,