Transfer Case Bad Input Bearing

[Wildchild467]

I backed out of my parking spot yesterday at work and heard what seemed to be a gear grinding. A gear grinding a little like how something would sound if not engaged all the way. It did not in any way effect how the truck backed up, nothing shuttered at all and no loud crunching. I got scared and thought maybe the transfer case lever got bumped down or something. I looked and saw it was down a little bit lower, so I pulled it up and it went into its detent for the high range position. The lever some how got lowered (probably lowered itself when the bearing gave loose). When I drove it up the road after that, I could hear a bearing whining in the transfer case area. I at least knew I had a bad bearing somewhere. To troubleshoot what it could be, I put the transfer case in neutral, put the transmission in 4th gear and engine running. I climbed under the truck to listen. I could hear the noise coming from the transfer case. It sounded like a very light bearing noise mixed with a little gear clanking sound. Next I shut the truck off and removed the jack shaft. I did the same test with the engine running, transmission in 4th gear and transmission only spinning. There was no sound at all. I knew it was in the transfer case. I then spun the transfer case by hand with the transfer in neutral. I could feel a very slight binding once in a while spinning it by hand. I could also hear the sounds of what seems like a ball bearing without the bearing cage and the balls spinning on the race and then a “dropping” sound like they went over center in the bearing races and then fell down to the bottom of the race. This would make sense because when I changed my transfer case oil when I bought the truck 2 and a half years ago (15,000 miles since I bought it), I found pieces of a bearing cage then. So if sound I heard sounds like a ball bearing without the cage, I would think my diagnosis is pretty close. I also found the input shaft of the transfer case moved in and out about .020.

Now the part that could be my fault is I had a leaky input seal and the oil was exactly a quart low. I topped it off about 2 weeks ago, but it must have leaked out by then. I ordered the seal from Napa a couple days ago too. Either way, the lack of a quart of oil could have been a part in the bearing going. Then again, when I bought the truck, I found a piece of bearing cage… so who knows.

Last night I got everything disconnected from the transfer case and the only thing holding it in is the mounts. Tonight Dad and I are going to pull it out and start the process of taking it apart to see what happened.

One thing I have always noticed with the truck since I got it is that under power, the transfer case lever drops a very little bit and when I coast down a hill and let the engine hold me back, the transfer case lever comes up a little bit. Is this at all connected to the fact that there was maybe .020” play the input shaft of the transfer case had when I pulled it in and out? I am just wondering if it is at all connected to each other somehow or if it is just the case flexing in the rubber mounts.

So if I am doing a tear down, inspection and repair of the transfer case, is there anything special I should look at? What else are the transfer cases prone to wear and breaking? What else would you guys do to this transfer case if you had one apart to replace a bearing?

Attached are pictures of what i found when i drained the oil.

 

[steelandcanvas]

70Deuce, who doesn't log on very often, has firsthand knowledge of this particular transfer case problem. Ask him put his response in the thread.
Steel Soldiers::Military Vehicles Supersite - View Profile: 70deuce

 

[gringeltaube]

Usually what goes first is one of the smaller (BL210Z) bearings, inside the gears. For peace of mind I would replace all 6 bearings on the input shaft, besides the seal (Victor # 47431 or equiv.)
Also, while its open inspect the races of the tapered bearings for intermediate- and output-shafts.

Just in case, here's some info about IS bearings/ numbers: https://www.steelsoldiers.com/threads/transfer-case.66875/#post800822

Found metal in my transfer case

Well, I was changing all the fluids on my new GL purchased Deuce and had to wait/order the 9/16 pipe fitting for the transfer case drain plug. It came in last week and I proceeded to drain the case. First concern is that the case sounded pressurized when I removed the plug. I have had some...

www.steelsoldiers.com

G.

 

[Wildchild467]

I would think it is the input shaft, but if you say the gears on the smaller BL210Z bearing go first, are they ball bearings that have a bearing cage also? Thinking back about the sound, I could definitely hear a whine coming from the transfer case but also the sound of a gear being driven that is loose or flopping around and making a sound similar to a bell. Almost like if somebody made wind chimes from a bunch of big hanging gears mixed with a bearing whine. I hope that describes it good. I have to look inside the TM and see what bearings are the same and what the prices are. Of course I will see the condition of everything else to see if it’s worth putting the money in it. The transfer case did not shake, jar the truck or make horrific sounds when it happened. So I think it should be decent inside as it happened at very low speed. I was able to drive it home just fine.

I will have some pictures tonight of what I find in the transfer case hopefully.

 

[gringeltaube]

See diagram, below... it shows where goes which bearing, for the input shaft.
All 6 are deep groove ball bearings, with their specific (civilian) part numbers listed.

What I meant to say is that the bearings #5 (not the gears) are the ones which usually fail first.

If the T-case wasn't jumping out of gear I would say it definitely IS worth your time and expenses to rebuild it.


G.

 

[Wildchild467]

Thanks for the good info G! I was thinking the same thing about it not popping out of gear and it might be worth rebuilding. Everything was still fully functional when this bearing went bad. I want to tear into the transfer case for the learning experience, knowing what I have when I’m done, save money and to provide good documentation to somebody else that may have the same problem.

I took a couple pictures last night showing how I lowered the transfer case down and what I found. One picture shows the my method for lowering it down.

Picture #1

Dad and I used a piece of 2.5’ square tubing (48” long) laying across the dash and back of the cab. It is longer than the distance from the back of the cab to the dash, so some hung over both ends which was good. We removed 2 bolts from the top of the transfer case to attach the lift chain to. It worked fairly well as far as that attachment point balancing the transfer case as it came down.

Picture #2

I could see some RTV sealant around the flange of the input shaft. Somebody was definitely in here before doing some work. Going back to how I found metal pieces in the transfer case when I first bought the truck and this bearing going back now, who knows how it was put back together….especially when there is some play in the bearings now that allows the shaft to go in and out about .020”. Knowing somebody else was here before makes me want to pay special attention to the TM’s and make sure all the pieces are accounted for when I put it back together. I still have to study the TM’s more, but I don’t think somebody could do a whole lot by only accessing this one flange. Maybe only a bearing change? Not sure.

Picture #3 and #4

Removing the rear cover on the input shaft I noticed the same kind of metal debris that I found on the drain plug I am not exactly sure what it is. My best guess would be pieces of a bearing cage. I also removed the top access cover to look inside. I could see part of the synchronizer, shift forks and 2 big gears on the input shaft (one toward the front of the transfer case and one to the rear). I believe these are for the high and low range as the synchronizer is on the same shaft. The gear in the front looked very nice, no missing teeth and had good polish/wear marks on the gear teeth. The gear on the back was definitely acceptable looking but not as nice looking as the gear in the front. The gear in the back did not have any missing teeth, but showed more signs of “tooling” marks or scratches on the gear teeth faces. This is also the end where I found the metal debris, so maybe it is from some of these pieces going through the gears. Again, I think the gear definitely looks acceptable and just wanted to state that as an observation. I also put my ear close up to the access cover and slowly turned the input shaft and I could hear the same sound like some ball bearings were rolling around loose within the races.

Does the synchronizer look similar to the ones in the transmission? I would like to check them out and make sure they look good before I put it back together. I know my M109 shifts real nice and I’ll have to inspect this one to see how it looks. Maybe I could find a better take out synchronizer if mine does not look that great.

I wonder if my transfer case being exactly 1 quart low on oil was the reason the bearing failed. It’s my fault it was low and I did not think it would dump that much oil in the short of time, but it did. Obviously it should not be low on oil and maybe it starved the top end from lubrication?

 

[steelandcanvas]

I understand even when the T-case is topped off, that bearing does not get lubricated properly. This is not a isolated incident, several guys I know have lost this bearing. I'll have 70Deuce join the thread and write about his experience.

 

[Wildchild467]

After looking at G's drawings of the T-case, it makes sense that the front gear of the input shaft is more smooth. It is the high range gear and used the most. I can also understand why bearing #5 on the low range gear would fail first. Bearing #5 supports the low range gear on the input shaft. When driving down the road in high range, the bearings on the low range gear are spinning about twice as fast as the input shaft. The bearings on the high range gear (#5) are not moving at all when driving down the road in high range. The opposite happens when the truck is in low range. The bearings (#5) on the high range gear spin about half the speed of the input shaft when driving in low range. If I do have a bad bearing (#5) on my low range gear (which would makes sense from the noises I heard), maybe I could get bearings for my low range gear from a parts transfer case high range gear. They would be probably in better shape than a low range gear and have less wear. Somebody correct me if I am wrong.

Now it makes me wonder…. How does the top end bearings get lubed if the truck transfer case is in neutral and the truck is in gear, just spinning the transfer case? I don’t think they would, right? This must be why the transfer case PTO has an oil line going to it. If the truck was being towed with a tow bar and transfer in neutral, that might be ok because ALL the gears are spinning and lubricating the bearings, right?

The only thing I am need are gaskets. I can’t seem to find them. Does anybody have a source?

 

[Wildchild467]

Well Dad and I pulled the transfer case apart last night. Everything went smooth with no unexpected finds. As Gringltaube predicted, the bearings on the low range rear bit the dust. I am sure they were already on their way out from before, but they definitely need changing now. What I don’t understand is why bearings on the low and high range gear have the shields around them. They are not a sealed bearing, but they do have a metal part that covers up the bearings. It seems like if they were open, oil would be allowed to splash in the bearings better. The one picture below shows the metal piece I am talking about. I believe the bearing part number that Gringltaube pointed out is an open design. I am going to research part numbers today and see about getting prices for all new bearings.

I also attached a picture of the shift fork. It shows some wear. The TM specs out that the wear limits for the width of the groove should be between .712” and .720”. I did not measure it last night so I don’t know if that is out of spec. I doubt it would matter that much if it was worn a little more.

So far, the part numbers I have for the Bearings are:

Input Shaft:

(QTY 1) Rear Bearing: 6309 LU (civilian number)
(QTY 1) Front Bearing: 6310 NR (civilian number)
(QTY 4) High/Low Range Gear Bearings: BL210Z (civilian number)

Counter Shaft:

(QTY 2) NSN: 3110-00-013-7743
P/N: 10948082

Output Shaft:

(QTY 1) Rear Bearing: NSN: 3110-00-165-6329
P/N: 10948080

(QTY 1) Front Bearing: NSN: 3110-00-101-6480
P/N: 712662

Front Output Drive Shaft Bearing:

(QTY 1) NSN: 3110-00-516-5491
P/N: ST202

I do not yet have the civilian numbers for anything other than the input shaft (thanks to Gringltaube). When I get them, I will add them to the list. If anybody else has them, let me know too.

 

[gringeltaube]

I'm out for lunch. Will give you all the other bearing numbers in a while.
FWIW: the rear, LARGE gear (#4) on the input shaft is HIGH range...!


G.

 

[Wildchild467]

Thanks a lot for getting me the numbers! Are any of the numbers you have for the input shaft bearings better than what were came in the transfer case originally? I would think an open designed bearing would be better, but then again, I didn’t design the transfer case. I am just wondering if there is a better bearing to put in there that stock.

I also felt the bearings on the high range gear and they did not feel that great either. They had a very little binding in them also.

Here is a picture from a different thread where Gringeltaube shows the cross section of the transfer case. It is a good visual to show how the thing works.

 

[gringeltaube]

Are any of the numbers you have for the input shaft bearings better than what were came in the transfer case originally? I would think an open designed bearing would be better.....

No, except that you could use high-load type ball bearings (BL) everywhere, instead of just inside the gears. (Their cost usually is x2 to x4, compared to std.)
Otherwise put in there what was listed.
Just avoid any other than good known US-made bearings!!

BTW, a shielded (NOT sealed!) bearing - in our case two BL210Z facing each other, 1-side-shielded, to the outside - means better protection against foreign particles while they still get enough oil to work properly.


Here's the rest of all bearing #s:

Counter shaft: 2x, cone #49585/ cup #49522
Rear output shaft: at the front: cone#3984/ cup#3925; at the rear: cone#3783/ cup#3732
Front output shaft: #6209

G.

 

[Wildchild467]

Well I ordered bearings today from NAPA (SKF Bearings) for the output shaft and counter shaft bearings from Memphis. I got a take-out input shaft assembly (gears, bearings, synchro the whole thing) from a sprag transfer case at Kublos. All the bearings feel good in it and I think I will give it a try. the only reason he pulled it out is because it was a sprag case. The bearings for the input shaft were all pretty expensive. These spin real nice, so I think I will give it a try. I did not get any gaskets, I think they ones I have will be fine. I priced out a new shift fork at Memphis and it was about $120, so i think mine will be fine for now. I did not measure it to see if it is within specs, but it should be ok. That is all the updates I have right now. Maybe I will work on getting the heater installed before the parts come. It is getting that time of year.

 

[PsycoBob]

/edit- deleted.

 

[PsycoBob]

/edit- deleted.

 

[PsycoBob]

Now it makes me wonder…. How does the top end bearings get lubed if the truck transfer case is in neutral and the truck is in gear, just spinning the transfer case? I don’t think they would, right? This must be why the transfer case PTO has an oil line going to it. If the truck was being towed with a tow bar and transfer in neutral, that might be ok because ALL the gears are spinning and lubricating the bearings, right?

They don't get lubed well in neutral & you're right about the oil line. Somewhere in one of the manuals regarding PTO's, I remember the oil line mentioned. There's a check valve top & bottom & a little shaft-drive pump to oil the PTO & drool on the other gears up top. Keeps wreckers form blowing up T-cases.

Modern transfer cases & transmissions often use full-pressure lube systems or pressurised sprayer lube systems to make sure nothing starves. Spicer mentions it allows both smaller/lighter units & reduced oil temps with remote coolers. Meritor lists 300F+ temps as 'normal' on modern variants of our t-cases.

Those chunky bits from the penny picture in post #6 make me cringe. Hopefully everything gets reassembled in time for Rausch Creek- shipping always gets me.

 

[VP17IFT]

I may have to do this soon onmy duece as the transfer case hasthe same problem just not quite as much play only at .250 total end play, so I'm hanging on the edge of my lazyboy.

 

[Wildchild467]

I am still waiting for my bearings to come in from Memphis. Meanwhile, I’m looking things over, particularly the shift fork. The TM says the width of the shift fork (where it grabs the synchro) should be between .712” and .720” My fork now is .760”. I know the TM is good and all, but how far should I go with that? Do shift forks last a while or do they all seem to be a high wear item in the transfer case? Should I replace it or do you think it is still good to go for a long time? The side that is worn the most is the side to shift it into high range I believe.

 

[gringeltaube]

Tom, I have seen the shot you took of the fork. Looks to be ready for retirement, IMHO.
Now, wear is never on one part alone, except for someone having installed a new syncro and left the old, worn fork...???
So how much is missing already from the syncro's shift collar - or disk in this case-? (original thickness is 0.709")

Think about this: combined wear could mean over 3mm required shift shaft travel, on that side, before the syncro even starts to slide. And... end with the little dogs only halfways engaged... and easily jumping back out of gear.....!

I recon that a new fork is another high cost item but is it sooo difficult to find someone with a donor T-case in your area, for a good used takeout part?


G.

 

[PsycoBob]

Fork's definitely a wear item. I had one bend on a just-swapped airshift tcase, jamming the gears. Had to disconnect & tie up the rear driveshaft to towbar the truck home. Thankfully just a few miles, and it happened in the parking lot at work.