Transfer case input shaft seal orientation (2 Viewers)

[lkortbeek]

Which way does the spring go for the input shaft seal on my one piece transfer case?
I was taught that the spring should face the fluid and the seal is usually driven from the non spring side against the lip of the seal opening. That would mean the seal should be installed with the spring facing the inside of the t-case. When I looked at a spare t-case I was using for parts the spring was facing out towards the transmission. It was also suggested by another 40 owner that the spring out configuration is correct to stop oil migrating from the transmission to the transfer case.
Does anyone know for sure? My Toyota manual doesn’t say and I can’t find the correct search terms to find it here or on YouTube.
I’ve included a couple of pics. Both are from outside the case. One if the reference case with the seal spring out and the other is the new case with the seal spring in but not installed.
Help.

 

[65swb45]

Spring faces trans.

 

[Downey]

I believe originally the spring (open side of the seal) faced the transfer-case oil. When guys were running an automatic transmission up against the Landcruiser transfer-case, they would sometimes get auto tranny fluid seeping back into the transfer-case. Part of the remedy was to turn the oil seal around, open spring side now facing the auto tranny fluid. I think I also recall transfer-case oil being thicker that transmission fluid, sooooo the thicker oil does not want to travel up hill to the seal, then forward through the seal, it's harder for the thinner tranny fluid to remain forward than the thicker transfer oil to remain rearward.

 

[lkortbeek]

Thanks guys. Glad I asked.

 

[SC Forester]

I believe originally the spring (open side of the seal) faced the transfer-case oil. When guys were running an automatic transmission up against the Landcruiser transfer-case, they would sometimes get auto tranny fluid seeping back into the transfer-case. Part of the remedy was to turn the oil seal around, open spring side now facing the auto tranny fluid. I think I also recall transfer-case oil being thicker that transmission fluid, sooooo the thicker oil does not want to travel up hill to the seal, then forward through the seal, it's harder for the thinner tranny fluid to remain forward than the thicker transfer oil to remain rearward.

Do you know if it would matter which way it goes if you are using an SM465 with the old style AA adapter with the spud shaft in the Toyota transfer case? It was leaking on mine and I got a replacement seal. The way it was in there had the spring facing the transfer case and the flat side underneath the bearing for the AA spud shaft facing the transmission. My replacement seal has no spring either. Can you just order a spring?