Replacing Transfer Case Rear Output Shaft Seal

[fatherdoug]

I am starting to leak gear lube out of the transfer case rear output shaft seal. Is this just a matter of removing the rear driveshaft, the yoke nut, the yoke, and the bearing retainer to get at the seal, or is it more involved than that?

Vehicle is a '78 F-150. Transfer case is a P/T NP 205. I just don't want 32 needle bearings to fall out onto the ground when I remove the bearing retainer.

I am assuming the yoke nut will have to come off with an impact wrench, since I remember some really high torque values on that nut?

 

[holtz]

Yes, just unbolt the drive shaft remove the yoke and unbolt the housing and you have it.

 

[m78]

I am starting to leak gear lube out of the transfer case rear output shaft seal. Is this just a matter of removing the rear driveshaft, the yoke nut, the yoke, and the bearing retainer to get at the seal, or is it more involved than that?

?

Thats all I did. But check the torque specs for the nut.

 

[fatherdoug]

Yes, just unbolt the drive shaft remove the yoke and unbolt the housing and you have it.

Thats all I did. But check the torque specs for the nut.

Thank you, both. Torque looks like 90-130 ft/lbs.

 

[fatherdoug]

Does anybody happen to know what the size of the yoke nut on the rear output shaft is. 1 1/4" is too small but close. I'm assuming it's 1 5/16" or 1 3/8"?

I'll have to buy a socket. The largest I have is 1 1/4".

 

[fatherdoug]

I installed the new seal today. The yoke nut was only about 20 - 30 ft/lbs when I removed it. It took a little bit of effort to get the bearing retainer off, since it had a layer of RTV around it. I put another thin layer of RTV around the sealing surface and around the inner lip of the retainer.

Hopefully, new U joints will arrive tomorrow for the rear driveshaft, and I can replace them.

 

[DNFXDLI]

Cool....and what size did that nut turn out to be?

 

[fatherdoug]

Cool....and what size did that nut turn out to be?

I tried to get an 1 5/16", but local supplier did not have one. I settled for a 35mm. I don't like doing that, but there was no slippage on the nut when I tightened it up to 100 ft/lbs. It was a snug fit on the nut.

 

[DNFXDLI]

That is pretty close...1-3/8.

 

[fatherdoug]

My cheap analog caliper showed the nut as 1 5/16". I guess the emphasis is on CHEAP. It actually is 1 3/8", as you so poignantly pointed out.

 

[DNFXDLI]

I keep a laminated chart down in the garage to convert from the tool of the devil system to normal measurements.

 

[fatherdoug]

 

[fatherdoug]

Big OOPS on my part, it was a 34 mm socket!, So, I guess it WAS 1 5/16".

 

[fatherdoug]

Done and Done! I'm no longer leaking gear lube out the output shaft, and replacing both U joints on the rear drive shaft solved an intermittent vibration problem. I ordered the U joints from a local parts house and I actually got Dana/Spicer. Woot, woot!

And for the record, the 34 mm socket worked just fine with no slippage.

 

[fatherdoug]

Rear Output shaft is leaking gear lube again. I think the rubber bushing holding the transfer case in place is squashed beyond its normal limit, stressing the seal. Is it possible to replace the bushing on the driver's rail without removing the front and rear driveshafts. I know I would need a way to support the transfer case, but is that all I need?

 

[DNFXDLI]

From what I can remember when I took mine apart, you should be able to do it by supporting the transfer case and dropping it a little.
The rubber bushing on mine was pretty distorted as well.

 

[fatherdoug]

Thank you, Duncan.

 

[DNFXDLI]

NP...but upon thinking about this, it shouldn't really affect the seal as the seal rides in the case and the shaft stays centered from the support bearing....so even if it (the transfer case) moves, it shouldn't affect the seal....a rear axle pinion seal would be similar and that moves quite a bit as the suspension moves.

Did the output shaft feel like it was moving at all?

 

[fatherdoug]

No, it didn't, but there was a ridge where the old seal was seated on the shaft. Maybe I need a sleeve? But if the transfer case sits lower because of the bad rubber bushing, would that stress the lower part of the seal?

 

[DNFXDLI]

No, it didn't, but there was a ridge where the old seal was seated on the shaft. Maybe I need a sleeve? But if the transfer case sits lower because of the bad rubber bushing, would that stress the lower part of the seal?

You might need a Speedisleeve if there is a groove.....but if it sits lower, the change would be absorbed through the u-joint...it shouldn't affect the seal...the shaft that the yoke mounts to that the seal goes around should stay straight.