Tranny/Transfer Case Lubrication

1945 - 196*, Willys CJ series, questions, discussions, regarding anything related to the post war jeep.®

Tranny/Transfer Case Lubrication

Postby Cabin Fever » Thu Apr 20, 2017 11:03 am

I have a 1955 M38A1. I believe that somewhere along the line a previous owner swapped out the original tranny/TC for a set from a CJ-5. The reason I say this is the tranny and TC in my military jeep share the same lube. According to the CJ-5 Owners Manual (see below) there can be ports (or drilled holes) between the two components in some CJ-5s. I do not see the same description in the M38A1 manual, which makes me assume this shared lube does not occur in military jeeps.

Every spring, I check the oil level in my tranny and, if necessary, I bring the level up to the bottom of the fill opening. Then, when I go over to check the level in the TC, once the plug is removed oil pours out the hole. So, I quickly reinstall the plug.

The elevation of the plug hole for the TC is slightly below the elevation of the tranny plug hole. I am guessing the TC fill hole is about 1/2" or so lower than the tranny fill hole.

My question is, which is better for my drive train:
(A) Tranny lube at correct level and TC overfilled, or
(B) Tranny lube below correct level and TC at the correct level.

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Re: Tranny/Transfer Case Lubrication

Postby sjalbert » Thu Apr 20, 2017 12:38 pm

A, X-case will pump excess fluid to X-msn, both will be happy.
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Re: Tranny/Transfer Case Lubrication

Postby Ben Dover » Thu Apr 20, 2017 3:41 pm

If your gear boxes are CJ-5, the Transfer Case Counter Shaft will be the larger 1 1/4" with the48 loose rollers. The Pivot Pin for the shift levers will not be the Screw in type of the M-38A1 and they will have swabbed out the rear bearing retainer to install the M-38A1 Parking Brake. M-38 and M-38A1 Transmission and Transfers have the drilled lube passages
If you have the Powerframe manual for the M-38a1 there are illustrations just showing the holes.
Paragraph 80, P.90 TM9 -8015-2 "Power Train, Body, and Frame" describes the drilled oil passages.
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Re: Tranny/Transfer Case Lubrication

Postby Cabin Fever » Fri Apr 21, 2017 7:10 am

Thanks, Ben, I didn't know that I'll check out the Power Train manual. I must have the original tranny and TC in my M38A1, then! That's good news.

Do you agree with sjalbert's recommendation to fill the tranny to the bottom of the fill hole (which results in overfilling the TC to a point above its fill hole)?

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Re: Tranny/Transfer Case Lubrication

Postby Ben Dover » Fri Apr 21, 2017 8:57 am

Just top it off to fill plug level and let the Jeep do the rest.
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