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Transmission/Transfer case seals

Anewway

Newbie
Joined
Aug 8, 2019
Messages
35
Getting ready to install the stock 3 speed manual and dana 20 transfer case in my 68. These have all the original seals/gaskets and have not been run in 30+ years.
Any advice as to which seals/gaskets to replace as preventative maintenance would be appreciated.
 
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DirtDonk

Contributor
Bronco Guru
Joined
Nov 3, 2003
Messages
43,139
Are they still attached to each other?
I would at replace the “snout seal” in the three speed. That would be the input shaft seal inside the front bearing retainer/throwout bearing sleeve.

If they are still connected I would separate them and replace the thin paper gasket that if I remember is between the intermediate housing and transfer case. Also a thicker gasket between the intermediate and transmission.
It’s been so long I really can’t remember all the details, but a seal and gasket kit would be a good idea. For both.

Do you know the mileage on them?
A quick inspection will tell you if the gears are good but with anything more than say about 75,000 miles, or if you suspect that the lubricant had never been changed its life, or if anything feels suspect, forget just the seals and replace the main bearings now too, while it’s apart.
 
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Anewway

Anewway

Newbie
Joined
Aug 8, 2019
Messages
35
They are still attached.
I spent a couple of days scraping 50+ years of grease and oil so there were leaks but hard to tell from where.
Mileage is around 75k miles. I removed the top cover of the transmission and had a look at the gears and everything looked clean like it has had regular service.
 
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Broncobowsher

Total hack
Joined
Jun 4, 2002
Messages
33,184
The 2 shift shaft seals are probably the hardest ones to change. If they look bad (judging from the drool you scraped off), now may be the time to replace them. And get to know the inside of the transmission as well.
 

sprdv1

Contributor
REBEL
Joined
Mar 8, 2007
Messages
79,319
They are still attached.
I spent a couple of days scraping 50+ years of grease and oil so there were leaks but hard to tell from where.
Mileage is around 75k miles. I removed the top cover of the transmission and had a look at the gears and everything looked clean like it has had regular service.

getting rid of all the old stuff can be a pita for sure
 
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Anewway

Anewway

Newbie
Joined
Aug 8, 2019
Messages
35
This got more interesting than anticipated. Upon removing the transmission from the intermediate housing the needle bearings inside the input shaft fell out and prevented the gear assembly from meshing correctly. I fished the needle bearings out and removed the input shaft to put the needle bearings back in. New seals and everything came together smoothly.
 

DirtDonk

Contributor
Bronco Guru
Joined
Nov 3, 2003
Messages
43,139
I guess it’s been so long since we’ve had this discussion we forgot to issue the standard warning about that. By locking the manual transmission in first gear you avoid the Output Shaft being pulled out far enough for the roller bearings to drop.
This is done by shifting it into first and then tying the two levers together so that it can’t shift itself out of gear when pulling on the output.

It can be done without that step of course, but it’s not guaranteed to work and more often than not it doesn’t.

Glad you got it apart and all back together.
 

sprdv1

Contributor
REBEL
Joined
Mar 8, 2007
Messages
79,319
This got more interesting than anticipated. Upon removing the transmission from the intermediate housing the needle bearings inside the input shaft fell out and prevented the gear assembly from meshing correctly. I fished the needle bearings out and removed the input shaft to put the needle bearings back in. New seals and everything came together smoothly.

sounds about right :)
 
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