Transmission shaft question

[Fitz98]

I have taken out the transfer case from my 98 Expedition 5.4 4x4. I am doing a rebuild to chase an intermittent grinding noise coming from the transfer case.
While it is out, I was looking at the transmission shaft on my 4R100 transmission. There is about 1/8" of vertical play, and some front to back play as well.
Does this seem like a normal tolerance and is held in place with the transfer case shaft bearings when the transfer case is bolted to the transmission, or does this sound like bearing failure in the transmission itself?

 

[Kuato]

Not an expert by any means, but IMHO 1/8" sounds like too much pay. I think your Ex uses the same transmission for both 4x4 and 4x2 versions, so supporting that shaft with the TC isn't the design. Your TC might be ok.

 

[Fitz98]

There are definately a couple issues with the transfer case that need to be addressed, the most recent finding is that the housing that holds the front bearing has some defects causing some bearing play, but if I need to address transmission bearings, now is the time I guess, since I am already half way there.
If it is normal to have that shaft play in the transmission though, I don't want to tear it out in vain.

 

[MolaKule]

Quote:
but if I need to address transmission bearings, now is the time I guess, since I am already half way there.


Yep, since you're already there replace any suspected bearings.

 

[Fitz98]

I have been looking all over the web and I don't see anything about the transmission having bearings on the output shaft. Is it possible that the input bearing on the transfer case is the bearing for the output shaft of the transmission, once it all gets bolted together?
I don't know much about transmissions, but just wanted to verify if some play in that output shaft is normal before reassembling the transfer case assembly.

 

[SteveSRT8]

Originally Posted By: Fitz98
I have taken out the transfer case from my 98 Expedition 5.4 4x4. I am doing a rebuild to chase an intermittent grinding noise coming from the transfer case.
While it is out, I was looking at the transmission shaft on my 4R100 transmission. There is about 1/8" of vertical play, and some front to back play as well.
Does this seem like a normal tolerance and is held in place with the transfer case shaft bearings when the transfer case is bolted to the transmission, or does this sound like bearing failure in the transmission itself?


While I am not personally familiar with that platform the amount of play you are describing sounds extremely large. I wouldn't want to drive it that way!

 

[OVERKILL]

Originally Posted By: Fitz98
I have been looking all over the web and I don't see anything about the transmission having bearings on the output shaft. Is it possible that the input bearing on the transfer case is the bearing for the output shaft of the transmission, once it all gets bolted together?
I don't know much about transmissions, but just wanted to verify if some play in that output shaft is normal before reassembling the transfer case assembly.


Yes, this is probably the case.

Here's a 2WD 4R100:

Here's a 4WD 4R100:

You'll notice the 4WD version has a completely different tail stock than the 2WD version, which has the proper supporting components for the output shaft because the drive shaft goes right into the back of it. That's not the case for the 4WD version, as the shaft is supported by the transfer case.

 

[Fitz98]

That was kind of what I was thinking as well. It is a little un-nerving when there is that much play in a component, but it does make sense, that the play would be supported, once it becomes a complete assembly.