Joined: Apr 25, 2024 Posts: 76 Location: Eastern WA State
Posted: Wed Nov 27, 2024 7:15 pm Post subject:
Winter is here...time for some M38 maint! Although the Jeep has been running great it has a couple issues that need to be dealt with. First and foremost is oil leaks, the jeep is hemorrhaging oil from the transmission and transfer case leaving a lake of oil on the garage floor. Oil needs to be topped off often when driving the Jeep and it's making a huge mess under the Jeep and everywhere it parks. The trans also suffers from the common T90 popping out of second gear syndrome on Deceleration.
Time to pull the transfer case and transmission and get these issues fixed so it's ready for fun next summer.
Oil filling the drip pan and soaking up towels....
Getting a bit more working room under the Jeep. I used my spare set of Honda Civic wheels to jack up the jeep. The wheels work great as they are dished in the middle and lock the tires in place nicely.
Pulling the skid plate
Draining oil on the transfer case and transmission.
Joined: Apr 25, 2024 Posts: 76 Location: Eastern WA State
Posted: Wed Nov 27, 2024 7:17 pm Post subject:
Made a bit more progress today.
Pulling the transfer case shift lever pin and removing the shift levers. The M38 has a nice removable cover that makes this task easy.
Draining the fuel tank for removal. The fuel tank needs to be completely cleaned out so I'll be removing the tank and cleaning it thoroughly before re-assembly. I keep a siphon setup on hand that works great, it's a air nozzle stuck into the end of a piece of fuel line, the air creates a vacuum that pulls the fuel through the hose nicely and starts the siphon. The tank does have a drain plug on the bottom of the tank but it's stuck pretty firm so I used the hose.
Removing the vent line, clutch clevis and engine stay.
Using a Harbor Freight transmission jack to lower the transmission/transfer case. I kept the cross member attached and used two ratchet straps to secure the units to the jack. It worked like a charm.
Separating the transmission from the transfer case. The previous owner used silicone on everything, making disassembly a bear. I ended up having to use a thin paint scraper and heat to separate the trans/transfer case.
Removing the nut inside the transfer case in preparation to separate the two. Once the cotter pin was removed the nut was already loose, easily spinning off by hand.
Placed a piece of wire on the cluster to keep everything forward during disassembly.
Cross member removed.
Dealing with more silicone.
The rear plate and bearing stayed on the transfer case during separation due to large amounts of silicone used.
Disassembling.
No metal bits in the bottom of the case.
Lots-O-Parts
Lots of wear on the gear teeth.
I'll be completing a more thorough inspection soon so I can get replacement parts on order, along with completing the tear down of the transfer case.
Joined: May 30, 2014 Posts: 3474 Location: Texas Hill Country
Posted: Thu Nov 28, 2024 9:39 am Post subject:
Somebody really worked over the trans.
What kind of shape is the clutch and throw out bearing? Might change the bearing anyway since you have access.
Since everything is out check your pedal shaft for wear also. The pedals wear on the inside where they ride on the shaft and they get play in them. They should move straight forward and back with no slip side to side.
Joined: Apr 25, 2024 Posts: 76 Location: Eastern WA State
Posted: Fri Nov 29, 2024 8:22 am Post subject:
4x4M38 wrote:
Somebody really worked over the trans.
What kind of shape is the clutch and throw out bearing? Might change the bearing anyway since you have access.
Since everything is out check your pedal shaft for wear also. The pedals wear on the inside where they ride on the shaft and they get play in them. They should move straight forward and back with no slip side to side.
I’m guessing all the silicone was to keep it from leaking, lol.
I'll defiantly be checking the clutch and installing a new throw out bearing. I'll also check the pedals, thanks.
I hate silicone! Only thing it did was make disassembly a pain lol.
Joined: May 30, 2014 Posts: 3474 Location: Texas Hill Country
Posted: Fri Nov 29, 2024 8:52 am Post subject:
Did you find any safety wires when you were disassembling?
I sourced all US or Japan bearings when I rebuilt mine. It took some doing.
Also had to shop several of the MV suppliers to get all my rebuild parts. No one had them all, and there were a couple with slight differences in pricing.
Joined: Apr 25, 2024 Posts: 76 Location: Eastern WA State
Posted: Sat Nov 30, 2024 7:26 am Post subject:
4x4M38 wrote:
Did you find any safety wires when you were disassembling?
I sourced all US or Japan bearings when I rebuilt mine. It took some doing.
Also had to shop several of the MV suppliers to get all my rebuild parts. No one had them all, and there were a couple with slight differences in pricing.
All good reliable parts.
There was safety wire on the shift forks only. I'm doing the same as like you said not one place has everything, but trying to stick with US NOS parts as much as possible.
Joined: Apr 25, 2024 Posts: 76 Location: Eastern WA State
Posted: Sun Dec 01, 2024 7:37 pm Post subject:
More disassembly and inspection on the transfer case.
Main shaft gear shows some wear on the inner splines, as well as some isolated pitting on the main teeth.
Shift fork bolts wired in place
At first glance the output shaft gear and sliding gear look in pretty decent shape. A close inspection of the teeth show pitting deep enough to go through the hardened metal.
Minor pitting on both output yokes.
Pulling the seals out of the front output shaft housing.
Shift Rails show pitting where the seal rides. These will be replaced.
Shift forks
Checking clearance between the case and the shift rails. There is some slop here, although it shouldn't affect anything in operation. No allowable clearance is given for this clearance in the Army repair manual.
Lot's of parts on order. Now to get everything cleaned up and prepped for re-assembly.
Joined: Apr 25, 2024 Posts: 76 Location: Eastern WA State
Posted: Fri Dec 06, 2024 5:34 pm Post subject:
Some NOS parts showed up today for the transmission and transfer case....lots more to come! There is something oddly satisfying about opening brand new 1950's parts....love it!
Lot's of gooey grease, did it's job well....part is like new inside.
NOS Shift Shafts
More parts to come still. Can't wait to start on re-assembly.
Joined: Apr 25, 2024 Posts: 76 Location: Eastern WA State
Posted: Thu Dec 19, 2024 5:24 pm Post subject:
Time to get some cleaning done!
Media blasting the E-brake backing cover and drum.
All clean.
Two coats of self etching primer
And 3 coats of the final OD grean
Lots of parts waiting to go to their new home. Time to get these all cleaned up.
Cosmoline is good stuff. Parts are brand new underneath. Crazy to think these parts have been wrapped up since the 50's so they could finally find their way to my garage.
I saved the cosmoline off the parts in a small container in case I want to preserve something for long-term storage in the future.
Using brake clean to get the majority of the cosmoline removed.
Then a trip through the ultrasonic cleaner, it does a great job at removing all the cosmoline from the nooks and crannies.
More parts being cleaned.
Time to assemble the shift tower.
Installing the shift indent ball and spring on the first gear shift rail. The spring goes into the hole then the ball bearing. the ball sits into the indents machined into the shift rail.
Here I'm using a punch to compress the ball/spring so I can slide the shift rail into the shift tower.
First gear shift rail & shift fork installed.
Ran into a problem here, I tried to order as many NOS parts as possible but somehow ordered a "new" 2nd/3rd shift fork instead of NOS. Apparently this unit is a Made in India unit and the hole is drilled off center, it's also under sized so it wont even slide onto the shaft. This part is heading back and a NOS unit is now on order. No more work on the shift tower today, time to put all this in a bag and move on to another project while I wait for parts.
Original shift fork.
And the crappy "new" part.
Next up was installing the new double lip seal in the speedometer drive housing.
I use a bit of Aviation Permatex around the inner bore where the outer seal will mate up with the housing. The sealant fills any defects/scratches and helps to prevent leaks around the seal.
Stripping the old paint off the trans and transfer case housings, getting ready for fresh primer and paint.
Joined: Apr 25, 2024 Posts: 76 Location: Eastern WA State
Posted: Thu Dec 19, 2024 7:06 pm Post subject:
Let's get these parts looking good again!
After the paint stripper the parts went into a heated parts washer. The parts washer did a great job of removing any paint, grease, dirt etc. Once out of the washer it was straight into the standard parts washer to let the parts cool down and wash off any of the wash cabinet solution, this keeps the parts from flash rusting.
Out of the wash cabinet and into the standard parts washer.
The T-case output shaft bearing housing getting ready to be prepped for primer and paint....before and after.
Transmission and Transfer Case out of the wash cabinet.
Lot's of prep work getting ready for paint. Wax/De-greaser followed by masking.
Two light coats of automotive self etching primer.
And two coats of Rapco 23070 Paint....good stuff!
Next up I used a lapping block to take down high spots off the Transmission and Shift Tower gasket surfaces. I was careful not to take much off here as I didn't want to potentially change any clearances in the process. Hopefully this step will help ensure a better leak free seal.
Then back in the wash cabinet & parts washer once again to remove all leftover traces of lapping compound.
Now to repeat the de-greasing/primer/masking/painting process for the rest of the parts.
I ordered a Shift Tower rebuild kit that comes with the required small parts, except it's for the civilian model and doesn't include the gasket that goes on top of the M38 shift tower (specific to the M38). I used the gasket cutter to cut out a couple gaskets, I'll leave a couple extra in the parts drawer in case they are ever needed in the future.
And bam.....a gasket.
And installed on the Shift Tower to test the fit.
Paint Curing.
Freshly painted parts....going to look good assembled!
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