2 speed transfer box question

[Kaiser2boy]

I replaced all 4 oil seals on the transfer case while the case was still in place. It went better than I figured it would. The only one that was a bit of a tussle was the one on the rear output shaft.
What got my attention was the slotted nuts that hold the flanges on.
All of them still had their cotter pins in place and looked like they had been there for a long time. The surprise was that all of the nuts were only finger tight. When I say finger tight I mean just that , I removed them with my fingers with not even a tiny grunt.
Looking at the book they should have been MUCH tighter.
What could cause them to be so easy to remove.
Has something worn away letting them come loose or maybe they were not done up right.
The box seems to work fine , no noise and it shifts in and out ok.

[Gordon Maney]

That transfer case had been together and in operation for many years. One, entirely theoretical, answer is simply that tapered bearing sets wear and when they do you get increased end play.

I would suggest you do your work and do all diligent, visual inspection. Assemble it correctly, and not worry about that. Move forward.

[Kaiser2boy]

I took a chance with the box seeing as how it has not given me any problems other than leaks, I torqued the nuts per spec one at a time and inbetween nuts I rotated the shafts to see if anything felt wrong or made noise or got tight.
Passing that test I took it for a short drive and it actually sounded better than before so I went for 5 mile ride and checked again for heat or leaks or noise and it seems ok.
I looked at the exploded drawing and it looks like there are shims that set the load on the bearings. The flange nut tightens up on the shims I think. If you put the 140+ pounds of torque load on the bearings they would fail in a matter of seconds,,I think.
Anyway it runs fine and sounds better so I am going to let it be .
The brake drum flange had zero wear marks on it where the seal sat and the output shaft had only a faint polished area that was hardly noticable the same for the input flange the only one that needed attention was the output to the front axle.

[Gordon Maney]

Just for the record, those transfers are not quiet nor cool when in perfect shape. They get pretty warm.

[Kaiser2boy]

Oh I hear you on that one. I have lock outs on the front hubs to reduce some of that stress and heat so mine does not get as hot as a standard one , but you are spot on about the heat and noise.
I will keep an eye on it for sure but I really think its ok. He says with his fingers crossed.

[wayneh]

So the shims set the preloads for the bearings. They are supposed to be set at about 15-20 inch pounds I think. I'm not sure how worn bearings though would make the nuts come loose, I don't think that is related. Regarding the seals, if your transfer case has some miles on it you may think about putting speedi sleeves on all the shafts that turn. Also, there are seals for the two shift rails.

Wayne

[Kaiser2boy]

After pulling all the companion flanges off there was only one that needed attention as far as a wear grove. It was the one that sends power to the front axle. All the others were OK, some slight wear but the new seals fit differently and did not sit on the slight wear area from the old ones.
I did not even think about the shifter seals as they only had a minor seepage.
The flange shaft that was groved I welded it with a wire welder and turned it down with my lathe and polished it. It came out nice. I actually set it up in the lathe and turned it at a very slow speed while wleding it like a pipe shop would do. It worked out nice.
I have driven the truck for a while now and used it to pull a friends tractor out of a mud hole and also pulled some nice sized logs up out of the creek and so far no leaks and it still sounds better than it did before doing the seals and retorque of the nuts. The truck showed 31000 miles when I got it. I dont have too much faith in that but it is an indicator. The brake drum must have been replaced at one point because it was like new, zero wear on the seal area and zero rust.

[Charles Talbert]

What I would do in this case

Hate to be a bubble popper; but based on what I've read here, you simply have no idea what may be going on inside that case. The bearing preload must be correctly set to get long, dependable bearing and gear life. You haven't the slightest idea what preload may be, too much too little, not possible to guesstimate it. There is certainly some reason why the shaft nuts were only finger tight. They should have been in the 130-150 ft. lb. range. It is highly unlikely that the nuts were left that loose when they were installed prior to you removing them, as the case internals would have failed quickly as a result. That leaves only one other option, bearing wear will allow the preload to relax, then all becomes loose, this is the most likely scenario that is in play. Like always, it will be the unknown that bites the hardest. You will do well to remember this in all situations. There is only one wise option to take, that would be pull the case apart completely for a thorough cleaning and inspection. It is impossible to tell about the amount of bearing wear from a visual inspection unless deterioration signs are obvious. Reinstalling a bearing cone and cup assembly that has significant wear back into an application under suggested preloads can cause premature failure. The worst chance you are taking is whatever else may be damaged beyond use should a bearing failure occur. Many parts in the NP200 cases are no longer easy to find and are quite expensive to obtain, so there is cause for concern much bigger than just a bearing failure.

Long story short; you are leaving the door wide open for a costly, unpleasant outcome. I would suggest some serious thought before continuing down the road you are on.

[Kaiser2boy]

Oh your not a bubble popper by any means. I had in the back of my mind that there had to be a reason for the slack nut. The amount of slack was almost non exsistant. It was not like I had to turn the nut in 3 or 4 turns.
It may have been only one full turn to get it tight.
As I did each one I rotated the shafts to see if there was any odd noise or friction or binding. failing that I went on to the next and the next .
I have driven the truck several times on short test runs of about 3 to 5 miles with no problems. Over the weekend we took it for a 40 mile ride , 20 out and back non stop, still sounds and feels good.
when I did the seals I drained all the oil and it was black but no sign of water or crud. Inside the bearing caps were very clean and the bearings were free form any signs of crud or rust or build up . That surprised me.

[Charles Talbert]

Oh your not a bubble popper by any means. I had in the back of my mind that there had to be a reason for the slack nut. The amount of slack was almost non exsistant. It was not like I had to turn the nut in 3 or 4 turns.
It may have been only one full turn to get it tight.
As I did each one I rotated the shafts to see if there was any odd noise or friction or binding. failing that I went on to the next and the next .
I have driven the truck several times on short test runs of about 3 to 5 miles with no problems. Over the weekend we took it for a 40 mile ride , 20 out and back non stop, still sounds and feels good.
when I did the seals I drained all the oil and it was black but no sign of water or crud. Inside the bearing caps were very clean and the bearings were free form any signs of crud or rust or build up . That surprised me.

Assuming the correct shim packs were installed at build up, significant loosening has occured over time to get to the point of looseness that you found; likely due to relaxation at the bearings. Of course my diagnosis is using the assumption that it was built up and adjusted correctly at the onset, again that is another unknown. Did you actually remove any bearing cones for a close visual? If not then we are still in the absolute realm of the unknown. Even if you did, there is little to be seen unless they are to the point of roller or race metal deterioration. Here's the deal, once a bearing has been run outside of a correct set up; which obviously yours have, and who knows how long. Bearings develop wear patterns; once they have run in that pattern for some time, then a sudden change takes place, break down starts to happen because it is now in a totally new and different wear pattern after the original pattern is already set. You changed that already established pattern in a significant way when you put preload (or not) back into the set up where there was none before by tightening the nuts to specified torque.

This is your call; I'm just making you aware of issues that can happen. I've seen some pretty nasty and costly ends in similar situations. Most likely you will not see, feel, or hear anything you deam out of the ordinary before a problem occured. You could be the lucky one, again no way to know; however that door will always be open.

[Kaiser2boy]

Yes I slid the bearings out and looked at them to see if I could see and problems. I could not see and scored rollers or tarnished or any odd wear patterens on the rollers. I tried to see the cones but I could not get a very good look but I did the not very scientific fingernail test on the cone to see if I could feel a ridge and could not. There was no solids or build up on them at all and they all seemed almost new looking. I forgot to mention that all of the bolts that held the bearing retainers on were also not tight at all nor were any of the nuts on the -U- joints. All of them came off with little effort. Two or three had the lock washers missing and some of the bolts that should have been pressed into the U joint plate had the knerling filled off so they were a slide fit. So some one was in there at some time.

[Charles Talbert]

Yes I slid the bearings out and looked at them to see if I could see and problems. I could not see and scored rollers or tarnished or any odd wear patterens on the rollers. I tried to see the cones but I could not get a very good look but I did the not very scientific fingernail test on the cone to see if I could feel a ridge and could not. There was no solids or build up on them at all and they all seemed almost new looking. I forgot to mention that all of the bolts that held the bearing retainers on were also not tight at all nor were any of the nuts on the -U- joints. All of them came off with little effort. Two or three had the lock washers missing and some of the bolts that should have been pressed into the U joint plate had the knerling filled off so they were a slide fit. So some one was in there at some time.

The best thing to use on companion flange bolts are the crush type self locking nuts. They will work loose otherwise, that is common. The specific bolts for the flanges have fine splines on them so they press in tight. What you saw was not likely due to filing off the splines, but came from the bolts being run loose is what we typically see. These were ungraded bolts as were most in the entire truck; thus my personal preference is grade 8 bolts with grade 8 approriate type self locking nuts so they can be torqued properly without stipping or breaking. Our rule is also to use red lock-tite on the threads.

As to my other comments concerning this; I say what I do because if it were us taking this chance with a t/case and it failed; we would be liable for that failure and resulting necessary repair. We try to cover all our bases when it comes to doing repairs correctly. If a customer told us to just put it back together and go for it like you have; we would require them to sign a waiver relieving us from liability if a problem with the case occured later. I would offer a full explanation as to the reasoning behind that just as I have for you before asking them to sign the waiver.

[wayneh]

I'm still scratching my head how the front spline showed a wear groove? I can understand the input shaft from the transmission since that always has to spin, and maybe the brake and one that goes to the rear, but the front axle one has me wondering. Just trying to apply some logic as I learn!

Wayne

[Charles Talbert]

I'm still scratching my head how the front spline showed a wear grove? I can understand the input shaft from the transmission since that always has to spin, and maybe the brake and one that goes to the rear, but the front axle one has me wondering. Just trying to apply some logic as I learn!

Wayne

The front drive shaft yoke is usually the one that typically shows the most wear. It tends to vibrate some at road speed, anytime vibration is going on, wear isn't far behind. This is why front wheel lock-out hubs are one of the best additions you can add to your truck, really it's a no brainer. A modestly priced pair of hubs will do, and really nice repro WARN hubs are out there also, but at a lot higher cost.

[wayneh]

The front drive shaft yoke is usually the one that typically shows the most wear. It tends to vibrate some at road speed, anytime vibration is going on, wear isn't far behind. This is why front wheel lock-out hubs are one of the best additions you can add to your truck, really it's a no brainer. A modestly priced pair of hubs will do, and really nice repro WARN hubs are out there also, but at a lot higher cost.

Charles: Ahh... good point! My truck has lockouts, so I was thinking the shaft that goes to the front is along for the ride since it is not in 4WD most of the time. Only if you have lockouts!

Wayne