Joined: Apr 25, 2024 Posts: 54 Location: Eastern WA State
Posted: Sun Dec 29, 2024 8:35 pm Post subject:
wesk wrote:
Using a hammer on alternating sides of the bearing shell can and often does result in uneccessary wear on the opening. Much better to drive the bearing race squarely with a round adapter or even a piece of pipe or large socket.
Agreed. This fit is a fairly "loose" fit and was easy to work into place by carefully going back and forth. I do usually use a pipe for this application and agree it's the better meathod. Thanks Wes.
Joined: Apr 25, 2024 Posts: 54 Location: Eastern WA State
Posted: Sun Dec 29, 2024 8:35 pm Post subject:
Back at it....
Time to seat the front bearing race and mount the front bearing housing.
Adding some engine assembly lube to the pilot bearing so it won't start dry.
Just in case I ran into any unforeseen complications I decided to assemble the bearing housing onto the case with a dry gasket to set the depth of the outer bearing race then pop the housing back off to apply sealant to the gasket once the bearing race is set into position. The depth of the bearing race is set by the protruding lip on the front bearing retainer. You want to tap the retainer with a mallet and slowly tighten the bolts of the retainer back and forth to work the housing all the way down against the case, don't just try tightening the bolts to pull the bearing retainer down as you run the risk of breaking an ear off the retainer casting.
Bearing race seated and front bearing retainer removed once again. Be really careful pulling the shift rails through the seals since they are already installed.
Prepping the gasket with Aviation Permatex. I've used this sealant for years with great success, it can be messy but it just plain works.
Slowly working the cover back on for the last time, taking care to make sure the lip seals don't get cut or folded during assembly.
Permatex #2 on the bolt threads. I'm using copper washers under the bolt heads for extra sealing protection, with Permatex #2 under the copper washer as well.
Torquing the bolts to 30 ft/lbs
I decided to leave the interlock pill out of the shift rails, this will allow us to run low range while in 2wd....great for creeping along slowly in parades ect without having to ride the clutch.
Dropping in the shift rail indent balls and springs. I added some gear oil to the spring/ball before installing the cap but I did have a suggestion to add some grease to these parts so I may pull them back apart and add some grease before installing them back in the jeep.
With the front bearing housing complete it's time to turn my attention to the rear output shaft
To start I checked out the original bolts I had removed from the rear bearing housing and the threads were in poor cond. I ran a die over them to clean up the threads but they had a loose fit when threaded into the case so it's time for new bolts. I had some grade 8 bolts so I drilled some safety wire holes in the bolt heads and now had nice snug fitting bolts for assembly.
When I took the transfer case apart I found .182" worth of shims and an end play of .0365".....waaaaay out of spec! Since I'm starting with new bearings I wanted to get an approximate idea of where to start on the shim pack. I tapped the bearing race into place (was a little on the loose side so I will add some Loctite 640 to the race upon final assembly) and got it to about .010" end play, I then used feeler gauges to measure the gap where the shims go with the bearing cap held lightly in position against the bearing race. This was a start...then I would adjust from there.
Each time the shim pack was adjusted I would install the new shims, torque up the rear bearing housing to 30 ft/lbs, tap on the front and rear housings several times with a mallet to seat the bearings then measure the end play with a dial indicator. If the play was to large then it was off with the assembly, adjust the shim pack and repeat the process. These steps were repeated several times.
Factory specs for end play is .004" - .008". Sal from Vintage Jeeper prefers a tighter setup and Novak recommends tighter clearances as well...002" - .006". Playing with a combination of my new and old shims I was able to get the end play set at .0027". Perfect.
Happy with my end play I started prepping everything for final installation. I'll be using copper washers under the bolt heads for added sealing benefits. Ignore the star washer on the short bolt, it gets a copper washer as well.
Pay attention to the three sizes of bolts and where they go into the bearing housing. One bolt is 1/4" shorter than the others, this is necessary to clear the shift fork, if a long bolt is installed in this position it will limit the throw of the shift fork.
Adding Permatex #2 to the bearing housing to prevent any oil from seeping out between the bearing cap and emergency brake backing plate, if any oil ever gets by the threads. I also mounted the emergency brake arm before I added the backing plate with the sealant on it.
Since I didn't feel like the race was a tight enough fit in the case I carefully worked the race back out of the case and applied Loctite 640, this will retain the bearing in the case firmly once installed. If your using this be very careful not to get any on the inner race.
Copper Spray a Gasket applied to the flange surfaces and both sides of the shims. NOTE: This is the point you want to install your speedometer drive gear onto the rear output shaft.....before you install the rear bearing cap. Notice mine isn't installed here? More to come on that below lol.
Applying Permatex #2 to the bolt threads and under the copper washers.
Back on the case and torquing to 30 ft/lbs for the final time.
Verifying final end play clearance after everything is assembled.
Added safety wire to the bolt heads.
And that is that.....or is it? I hit the bed for the night, woke up at 4am this morning...went to roll over and within 30 seconds of waking up thought..."Dang! I didn't install the speedometer drive gear!". By 4:10am I was back out in the shop taking the assembly back apart to install the gear. I had thought about this set several times during assembly, but never took the time to take the parts out of my parts bin and place them up on the table with the other parts so I wouldn't forget them. Totally my fault on this one and lesson learned.
The Copper Spray a Gasket had set up very well! Brake clean on a rag did a great job of cleaning up the shims and mating surfaces once again.
Installing the speedo drive bits into the rear bearing retainer.
Ahhh....the step I missed that let me do all of this again lol.
Assembled once again, bearing retainer torqued to specs, new copper washers installed on the bolts, fresh Permatex #2 on the threads and under the copper washers and end play clearance verified once again. Right on the money.
Joined: May 30, 2014 Posts: 3472 Location: Texas Hill Country
Posted: Sun Dec 29, 2024 9:36 pm Post subject:
No way this is intended as criticism. This article is gold.
I have read several places that to clean threads you should use a thread chaser and not a die. The chaser has more clearance than a die, and won’t necessarily cut new metal like a die can. The die could remove enough metal to cause a looser fit like you experienced.
Joined: Apr 25, 2024 Posts: 54 Location: Eastern WA State
Posted: Sun Dec 29, 2024 10:12 pm Post subject:
4x4M38 wrote:
No way this is intended as criticism. This article is gold.
I have read several places that to clean threads you should use a thread chaser and not a die. The chaser has more clearance than a die, and won’t necessarily cut new metal like a die can. The die could remove enough metal to cause a looser fit like you experienced.
Just my two cents.
Keep it coming please!!
Thanks Mate. Your right about the thread chaser vs tap, I had used a tap when a thread chaser would have been a better option in this situation. I have a full set of chasers on hand now. That said the new bolts are a nice snug fit in the case, the threads on the old bolts were definatly past their prime. Glad your enjoying the thread and thanks for chiming in...sharing info and ideas is what makes these forums great.
Joined: Oct 02, 2014 Posts: 2024 Location: South Carolina, Dorchester County
Posted: Mon Dec 30, 2024 11:30 am Post subject:
Not stock, but I'm using magnetic drain plugs on the T90 and D18 (also on the L134 oil pan).
While there's some debate about it being "correct", I painted my drain plugs red --- although paragraph 67.d. (2) on page 50 of the January 1956 TM9-8012 says just the refill plugs get that "bling".
Joined: Apr 25, 2024 Posts: 54 Location: Eastern WA State
Posted: Mon Dec 30, 2024 5:44 pm Post subject:
RonD2 wrote:
Not stock, but I'm using magnetic drain plugs on the T90 and D18 (also on the L134 oil pan).
While there's some debate about it being "correct", I painted my drain plugs red --- although paragraph 67.d. (2) on page 50 of the January 1956 TM9-8012 says just the refill plugs get that "bling".
Joined: Apr 25, 2024 Posts: 54 Location: Eastern WA State
Posted: Sun Jan 05, 2025 8:05 pm Post subject:
Well...waiting on a few parts to finish up the transfer case so let's check out the clutch and install a fresh pilot bushing.
Bell housing removed.
Pressure plate and clutch disk removed
Pilot bushing visually looks ok...but I'm here and have a new one on hand so its time to yank the old one and install a new unit.
Using a blind puller to remove the old pilot bushing.
And installing the new bushing.
The clutch assembly and flywheel have little time on them and the old unit was working nice and smooth....butttttt....it's all apart so I think I will install a fresh clutch and pressure plate while it's all opened up. New Parts on order from Sal at Vintage Jeeper....back to waiting.
What else can I do today....ah yes, magnetic drain plugs.
Magnetic drain plugs are available for the transmission & transfer case but they have the civilian square heads on the plugs. I'd like to keep the correct round headed drain plugs for the M38 so figured I would just make my own. Magnetic drain plugs are a great addition, if you can trap any little metal bits on the drain plug and keep them from circulating through the bearings and bushings that's a huge win.
New drain plug and 1/4" rare earth magnets. Rare earth magnets are very resistant to losing their magnetism when stuck to metal over long periods of time... Perfect for this application.
Drilling a 1/4" hole in the bottom of the plug to accept the magnet.
Test fitting the magnet in the hole. Nice snug fit and the magnet holds itself there nice and tight.
Cleaning the plug and magnet of any oil and dirt.
Using Loctite 660 quick steel to secure the magnet in the plug. Magnet was twisted 1/4 turn while inserting. Once seated the excess was wiped off and part was left to cure.
Self etching primer & paint applied. Ready for service.
Notice these magnets are mounted flush inside the plug body.
While Tom does superb work, I'd offer that I heard these rare earth magnets can be fragile --- if you accidentally drop the plug and it lands on the magnet it could break or chip?
Just a thought. _________________ Ron D.
1951 M38 Unknown Serial Number
1951 M100 Dunbar Kapple 01169903 dod 5-51
“The only good sports car that America ever made was the Jeep."
--- Enzo Ferrari
Last edited by RonD2 on Mon Jan 06, 2025 11:13 am; edited 1 time in total
Nice, thanks for the link! Those look great, For that price I would have just purchased those instead of messing with it if I had known they were availabe.
Notice these magnets are mounted flush inside the plug body.
While Tom does superb work, I'd offer that I heard these rare earth magnets can be fragile --- if you accidentally drop the plug and it lands on the magnet it could break or chip?
Just a thought.
Sorry! I should have included the link up front.
Not sure they're still available. _________________ Ron D.
1951 M38 Unknown Serial Number
1951 M100 Dunbar Kapple 01169903 dod 5-51
“The only good sports car that America ever made was the Jeep."
--- Enzo Ferrari
"Neodymium magnets are formed by powder metallurgical methods. Their mechanical properties more closely resemble a ceramic, rather than a metal.
They are not easily machined, and we don't recommend trying to machine them.
Neodymium magnets are very hard and brittle. Despite the metallic appearance of their nickel plating, they are not strong as steel. If subjected to sharp impacts, such as allowing them to slam into one another, they can easily crack or break. Care and proper handling are important.
We don't recommend press-fitting neodymium magnets. Magnets are often glued into a pocket that is slightly larger than the magnet, rather than press-fitting." _________________ Ron D.
1951 M38 Unknown Serial Number
1951 M100 Dunbar Kapple 01169903 dod 5-51
“The only good sports car that America ever made was the Jeep."
--- Enzo Ferrari
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