leak in the transfer case?

[ClaysFJ55]

I noticed that my truck was riding very rough in first and second gear last night. Once I got home I noticed a small leak in the transfer case I believe, on the drain plug and a drip spot on the seal between the rear drive shaft and the transfer case.

Any thoughts?

 

[Dizzy]

One thing that I noticed lately about one of my drive shafts is that for the splined section is that there is no outlet for extra grease. When I took off the zerk fitting, I was able to squeeze out an obscene about of grease that was preventing the spline section from being able to compress fully, put in there by an overzealous previous mechanic. I was wondering if the rough ride was just a driveshaft vibration from it lacking compression travel?

 

[MadMace]

I am currently working through the parking brake assembly and speedo-gear housing that are attached to the transfer case. The parking brake drum has a shaft that develops a groove where the seal rubs on it. Oil can get through that groove and into the parking brake assembly. The oil will then drip out the bottom of the backing plate. A Speedi-Sleeve can correct this (99177 is the specific Speedi-Sleeve). I have also heard that the splines that feed into the parking brake drum shaft need a small amount of RTV applied to them to stop some leaks.
That leak out of the speedo-cable attachment could be a deteriorated O-Ring around the speedo gear (there are 2 different o-rings, one on the outside of the housing and one on the inside of the housing that is a real PITA to get out from what I understand).

These are the speedo-gears and o-rings. You might need to take yours out and put a little RTV round that outer o-ring.

This is the brake drum shaft with a groove that oil can get past and might be causing your leak.

This is the speed-sleeve installed over the groove.

This is the speedo gear housing with the seal that the parking brake drum rides in that might also need to be replaced to stop your leak.

 

[MadMace]

It also looks like the backing plate for your parking brake assembly is upside down. That nut you see on the bottom should be on the top--or at least it is on my 1974 FJ40.

 

[3_puppies]

It also looks like the backing plate for your parking brake assembly is upside down. That nut you see on the bottom should be on the top--or at least it is on my 1974 FJ40.

not upside down, it is from a 55 series, the pull cable comes in from the other side on 55's

also the seal area can be machined out to accept 2 seals which also helps.

how is the oil level in the transfer?

 

[ClaysFJ55]

not upside down, it is from a 55 series, the pull cable comes in from the other side on 55's

also the seal area can be machined out to accept 2 seals which also helps.

how is the oil level in the transfer?

the oil level was a little low from the leak but it seems like replacing the seal and getting the drain plug flush to the case solved the leak issue.

 

[skidplate]

I am currently working through the parking brake assembly and speedo-gear housing that are attached to the transfer case. The parking brake drum has a shaft that develops a groove where the seal rubs on it. Oil can get through that groove and into the parking brake assembly. The oil will then drip out the bottom of the backing plate. A Speedi-Sleeve can correct this (99177 is the specific Speedi-Sleeve). I have also heard that the splines that feed into the parking brake drum shaft need a small amount of RTV applied to them to stop some leaks.
That leak out of the speedo-cable attachment could be a deteriorated O-Ring around the speedo gear (there are 2 different o-rings, one on the outside of the housing and one on the inside of the housing that is a real PITA to get out from what I understand).

These are the speedo-gears and o-rings. You might need to take yours out and put a little RTV round that outer o-ring.
View attachment 2168898View attachment 2168899

This is the brake drum shaft with a groove that oil can get past and might be causing your leak.
View attachment 2168900

This is the speed-sleeve installed over the groove.
View attachment 2168901

This is the speedo gear housing with the seal that the parking brake drum rides in that might also need to be replaced to stop your leak.
View attachment 2168902

Quick question, does the speedo gear assembly just pull out after that keeper is unbolted? I have a slight leak there.

 

[MadMace]

Quick question, does the speedo gear assembly just pull out after that keeper is unbolted? I have a slight leak there.

Yes, it pulls out. There are 2 different o-rings—one or both are likely no good, causing your leak. One is around the speedo gear assembly and the other is in the assembly. The one in the assembly is smaller and more difficult to get to.

Here is a picture with the o-ring around the assembly.

Picture of the o-ring inside the assembly courtesy of @Coolerman.

Coolerman has an awesome write-up here.

Hope this helps.

Happy Easter!!

 

[skidplate]

Thanks