M809 series 5 ton transfer case issues

[tobyS]

Drain the gear oil. fill it to the fill line with diesel. Drive it for about 50 miles, drain it and refill it with gear oil. Simple as that.

His comment that the rear output shaft can be moved around by hand and that the seal has given up, means the flush is not going to do it. flushing is something that I would do after knowing weather the bearing can be tightened or if it is toast. If there are parts of that bearing in the TC bottom, they could get moved into the gears or splines in the "flush" and do much more damage than only a failed bearing. That bearing is probably only about $60 and I doubt if the shaft or gear is even hurt. Don't forget the shaft at Eastern has used bearings and probably does not include the race they ran in.

Take it apart (after trying to tighten the bearings) and see what is wrong before you throw money at it.

 

[simp5782]

His comment that the rear output shaft can be moved around by hand and that the seal has given up, means the flush is not going to do it. flushing is something that I would do after knowing weather the bearing can be tightened or if it is toast. If there are parts of that bearing in the TC bottom, they could get moved into the gears or splines in the "flush" and do much more damage than only a failed bearing. That bearing is probably only about $60 and I doubt if the shaft or gear is even hurt. Don't forget the shaft at Eastern has used bearings and probably does not include the race they ran in.

Take it apart (after trying to tighten the bearings) and see what is wrong before you throw money at it.

That was to 319ssg or whoever who was referring to the flushing. Not the output bearing

 

[319cssb]

That was to 319ssg or whoever who was referring to the flushing. Not the output bearing

Thats correct.

 

[Ajax MD]

His comment that the rear output shaft can be moved around by hand and that the seal has given up, means the flush is not going to do it. flushing is something that I would do after knowing weather the bearing can be tightened or if it is toast. If there are parts of that bearing in the TC bottom, they could get moved into the gears or splines in the "flush" and do much more damage than only a failed bearing. That bearing is probably only about $60 and I doubt if the shaft or gear is even hurt. Don't forget the shaft at Eastern has used bearings and probably does not include the race they ran in.

Take it apart (after trying to tighten the bearings) and see what is wrong before you throw money at it.

Toby,

I've always been decent with engines but not so great with transmissions and transfer cases. The last transmission I had apart, was a 3 speed for an old Ford F-100. But, I digress.

I think the bearing is blown. I can't see how the bearing could just fall so grossly out of adjustment after so many years but I'm willing to see if it can be adjusted. I'm looking at TM 34-1, pages 9-50-9-52, section 9-4, paragraph 91: "Set rear output shaft free play" Is this correct?

The procedure indicates that I should use a special "adjusting fixture" for this, which I don't have. I'm betting you don't have it either, but can suggest a work around?
Basically, you stack these special washers, put the adjusting fixture on top of that, and use a micrometer and a dial indicator to set the free play. This tells you how many shims you need in your shim pack, to get the proper free play.

Line "n", para 91 states that acceptable rear output shaft free play is .005 inches. With the parking brake off, I can grab the drum and move it around a lot more than .005 inches.

The next thing I'm going to do, is drain the transfer case and see if any metal falls out of it. I'll run the gear oil through a mesh filter.

The prices I'm seeing for a replacement transfer case are ugly. ($1,000 - $3500)
I think there's no harm in snapping up this $500 take-out that I've located. ****, Eastern Surplus wants $200 just for an output shaft w/bearing.
I can run the take-out while carefully dissecting my original t-case and seeing if it can be salvaged.

 

[US6x4]

Line "n", para 91 states that acceptable rear output shaft free play is .005 inches. With the parking brake off, I can grab the drum and move it around a lot more than .005 inches.

Is the TM talking about end play (fore and aft) or about runout (up and down or side-to-side). Both can be considered "play" but both are in different directions and possibly impacted by different components...

 

[tobyS]

Yes, sudden major looseness seems really unlikely with a properly functioning bearing. And sure, $500 seems like good insurance if it's not in the same condition. It's not too high stakes of gamble. feel the output and input for play and rotate it feeling for "smoothness" (no grinding or hang-ups).

Too many years have passed, I don't recall specifics, but it was a trial and error process. The .005" would be end play like the TM alternative 2 describes, not up and down. I think they are referring to end play at the shim location, pushing on the race.

When I split the case and clean off the gasket, it brings both sides together closer when reassembled. That frees up some of the bearing shims while doing it in the truck, you would add more to push the race further in. I'm not sure where you would come up with them, probably have to make them from shim stock or a suitable metal. (These adjustments are made after the case is re-assembled and tight). Also I has the drive shaft flanges (splined) off so they did not hang on the seals. I used them for turning the shafts, but not installed, just locked by the spline. Hope that makes sense.

I did one at a time after making sure all were loose and turn free. Beginning at the input shaft I tapped with a piece of brass until the race started to be tight, working my way around to keep it square. I rotate the input shaft and keep working the bearing in until it starts to have some resistance. Then measured the distance from the face minus the distance on the flange to come up with an approximate distance (shim thickness). Then I put the shims chosen and the flange on. If rotation was dragging, I knew it was too tight. Once I knew it was tight, lightly dragging, I removed about .005 of shim. I think I loosened the shaft race by tapping the other end of the shaft, so each time I drew the flange in, it was seated. Torque before going to the next shaft. This is what I called a "light preload" where some metal heating would not make it bind, nor be too loose cold. Must work, I had no heating nor movement or growling.

I did the intermediate shaft and drive shaft using the same "feel" method. Of course since I had the entire thing apart and was reassembling with light red grease, the rotation by hand was free and obvious when going too tight. In the truck, that same level of "feel" may be much more difficult.

Oh yea, the sprag...take it off but don't get in a hurry to take it apart unless cleaning is not enough. There are a lot of small parts that make this job more complicated when it doesn't have to.

 

[Ajax MD]

US6x4/Toby,

Yeah, the manual is talking more about "in/out" not "up/down" but that was the closest information I could find. I have up/down/all-around movement, plus leakage. I didn't check in/out movement.
Toby, you did an incredible job considering that you were working by feel, without the specific tools that the manual calls for.

Winter is having its last hurrah down here, temps are in the low 20's so I'm going to wait a few days before I drain the transfer case.
If there's no metal in the oil, I'm going to try to have it repaired or rebuilt and I'll keep it as a spare. The 809's are getting old and I worry about parts availability.

 

[Ajax MD]

Finally a couple of warm days.

I tinkered with the truck for a bit today.

For a few moments, I was genuinely concerned that I was making an expensive diagnostic mistake. I think I exaggerated the amount of play the rear output shaft has. The truck wasn't making the noise at first, but then it started up. It sounds like a box full of marbles or gravel. I was able to make it happen in low and high range. I think something is literally swimming around loose in there. When the noise happens, it doesn't stop until the truck completely stops, even if I coast with the transmission in neutral. That means the output shafts of the T-case also stop, so it's related to wheel rotation.

I also put the transfer case in neutral and ran through all 5 gears and rev the engine a bit, there is no gravel noise.

Finally, I crawled underneath the truck when I got back into the driveway. The t-case is just puking gear oil from the rear output seal. It's flinging it all over the rear of the transfer case and undercarriage.

I was actually hoping for a mis-diagnosis and finding a less expensive problem, but I don't think so. I admit, I have not drained the transfer case to look for metal bits yet. I might do that tomorrow. I think I'll buy a cheap, plastic colander to filter the gear oil as it drains, to help check for metal. Any better ideas for a filter?

I've got a NOS T138 transfer case lined up for a good price. The freight cost was a kick in the junk but I think it's worth it to eliminate the wildcard of a takeout. This thing is massive and will be a PITA to swap out. Grrrr....