Ins & Outs of Transfer Case Rebuilds

[ashyers]

So far this is how the gears look. The brown you see is congealed assembly grease. The actual gear lube looks normal.

NOSIdler.JPG (140.74 KiB) Viewed 2623 times

[Cal_Gary]

I've been following this thread from the beginning. I can only imagine what my original transfer case looks like inside after the roller bearings fell out when I drained the oil a few years back! I replaced that case with a rebuilt one but still have the original and hope to go to school on it some day.

Great work Andy, and great advice from you subject matter experts out there!
Gary

[06boblee]

Another rebuild related question, I got a new set of gaskets and seals. The new seals are 1/2" thick, the seals I removed are 3/4" thick. Is this the correct size for replacement seals?

[Elwood]

Another rebuild related question, I got a new set of gaskets and seals. The new seals are 1/2" thick, the seals I removed are 3/4" thick. Is this the correct size for replacement seals?

Mine have all been like that. The newer seal technology must not require as much depth for the seal housing. I just install them flush to the outer edge of the casting, with some sealant around the outside circumference of the seal housing before pressing them in place.

[06boblee]

Another rebuild related question, I got a new set of gaskets and seals. The new seals are 1/2" thick, the seals I removed are 3/4" thick. Is this the correct size for replacement seals?

Mine have all been like that. The newer seal technology must not require as much depth for the seal housing. I just install them flush to the outer edge of the casting, with some sealant around the outside circumference of the seal housing before pressing them in place.

Thanks, answered two of my questions- are they ok, and how deep to install.

[MSeriesRebuild]

Original seals had the felt dust seal around the outside, you know the moisture attractant that rust flanges to oblivion over time, thus the additional .250" case thickness. If you have what is proclaimed to be an NOS case, it will have that type of seal installed unless someone has changed them out, which won't be likely.

If you are installing redi-sleeves on the yokes, which is the best idea for a leak free case, pressing the seals inward past flush to the bottom of the bore will allow the installation of the sleeve without a necessity to trim off the press flange. We never trim off the flange of a redi-sleeve unless it is absolutely necessary, as this can end up causing a distorted sleeve which will prevent the seal from making a proper seal.

Smarter seal choice is VITON seal material. With the tendency these cases have to operate on the warm side unless you have an oil cooling system installed, VITON has a significantly higher temperature range than ordinary BUNA-N is capable of offering. VITON will last much longer than BUNA-N.

[06boblee]

Ashyers, this has been a great thread- I'm in the middle of my transfer case and this has helped a lot.
A question to all, does anyone know a source for a new overhaul plate for the transfer case? mine has one (overhauled 1976) and I would like to put a new one on with my overhaul data!

[ashyers]

Spent some time cleaning and inspecting the "new" transfer case today. It's best to do this without the "help" of my students. It is actually NOS and in excellent shape .

With the wonder preservative, notice the date, 11-16-71!

CoatedDrum.JPG (151.34 KiB) Viewed 2556 times

After a trip through the jet wash, sure is pretty, as least for a brake drum.

CleanDrum.JPG (103.83 KiB) Viewed 2556 times

The date on the case is seen in the attached photos, 11-16-1971. I spoke with the vendor today and found out the story behind the case. It was in Dubai of all places. It was intended for use as spare parts for an oil drilling operation. I guess he picked up a few of them. Looks like the desert climate treated the case well. The case had Power Wagon/M715 style flanges and rubber lip seals which is interesting. I pulled the guts out and the only issues seem to be from the grease used for the needle bearings. It had turned to a tar like substance and stained the shafts and bores of the gears. Fortunately it polished out with some 000 steel wool. I'm going to replace the rollers. All of the ball and tapered roller bearings looked new. As far as set up the end play in the idler is .002". When I set up the rear drive gear with the original shims and no seal the torque to turn the gear was 25 in-lbs, nicely between the 15-35 in-lbs listed in the manual.

Needless to say I'm happy so far. Hopefully we'll get it buttoned up this week and in the truck for a test run. I will say I believe this was by far the most cost effective way to deal with this and the advice I've received here is invaluable.

Andy

[MSeriesRebuild]

M715 trucks were only built 2 years, '67 and '68. If your case was built in '71, it was likely one of the last ones furnished as M715 replacements parts. Sounds like you did indeed end up with a new one, it is all in how these components were stored. Bad storage has been the demise of many components.

[ashyers]

Charles,
I've never visited, but I suspect the humidity in Dubai is rather low! I bet that helped considerably. If I had run the case w/o tear down I think I would have risked needle bearing failure due to the grease (?) that they were packed with. It was LONG past its shelf life. It had formed tar.


I came across this manual that may be helpful to those of you who don't have a copy of the TM.
http://imageevent.com/moosecreekmaple/np200

Andy

[06boblee]

Ashyers, what year PowerWagon service manual was that from?

[ashyers]

I'm not sure, but it sure looks familiar!!

[MSeriesRebuild]

Ashyers, what year PowerWagon service manual was that from?

Vintage Power Wagons has this manual for sale, or one that is very similar. It appears to be a reprint of the original WM300 rebuild manual.

[ashyers]

Here it is ready to be loaded into the truck.

Front.JPG (108.71 KiB) Viewed 2497 times

Left.JPG (107.82 KiB) Viewed 2497 times

This worked great! I didn't spill a drop :) .

EZFill.JPG (125.63 KiB) Viewed 2497 times

We completed the install today and I drove the truck home via city streets to give things a chance to break in. The T-case is quieter, but it's still a NP200! I think it's going to take some time to loosen up, it was nowhere near as "free" as the old T-case. Of course it now has some bearing preload and actual seals! I figure I'll stick with some city driving on my 10mi. commute to work for a few days. It will get things warm and have a bunch of on/off throttle. I'm going to break it in like a diff.

Improvements at this point are: no leaks, no more buzz in low range, no more mystery clunk, much less backlash in the driveline, quieter operation.

I'm waiting to see how it reacts to extended 55mph cruise. I hope that it frees up a bit and does not run hot on the highway.

Thanks to all for the help and encouragement! This site sure adds to the enjoyment of owning an M37 .

Andy

[T. Highway]

Andy,

It is looking good and glad to hear it solved some issues, did the kids understand why you opened the case up for further inspection even though the part was NOS?

Bert