Transfer case input gear to shaft play (1 Viewer)

[miller]

Rebuilding a 78 transfer case and transmission . When I separated the two the transfer case came off the shaft easily. The tranny shaft does have some wear. I can slide the transfer case input gear on and off the shaft and it does have play both directions. Is play allowed or should it be a snug fit?

 

[reddingcruiser]

Some wear on the splines is common, but a picture of the shaft would help. Excessive backlash in this case is not good. Some of this is controlled by the torque on the output shaft bearing retaining nut. Relying on the nut over the long term is not optimal.

The fact that the Trans came off easily is probably because it's been pulled apart previously. If this is a low mileage rig and you don't mind periodically checking the torque on the nut you may be a fine. If this is a serious trail rig, and there is a lot of play on the the input gear, you might want to replace the shaft and gear. Again, pics would help.

 

[miller]

So I put the transfer input gear on the good part of the shaft and it still has radial play in both directions. It does not look like the input gear teeth are worn, but I do not have a new one to compare.

 

[Living in the Past]

That gear looks pretty worn to me. The flat on the top and bottom should be close to equal. The top looks pretty narrow. Slip it on the tailshaft where it isn't worn and there should not be any play. Thought I had a box with a couple of input gears and PTO gear to take a picture of but think I moved them to another location. The early four speed gear I have shows some wear but not as bad as yours does. I wouldn't run either that gear or tailshaft but I have other parts available.

 

[miller]

I will just go ahead and replace them both and be done with it. The gear does have slop on the good part of the shaft.

 

[emac]

I just went through this same problem, with similar wear patterns. I ended up replacing the shaft and gear, along with the bearings. I cant recall who I bought the shaft and the gear from, but the price was ok and he had them in stock. I can dig it up if you need it. A couple of other thoughts:

I found somewhere (maybe Aussie??) a gear that was longer and engaged more of the shaft. I think I found it after I had already bought a new shaft. That seemed like a great solution. A more knowledgeable Mudder probably knows more about that solution.

When I tried the new gear on the old shaft, it had very little play. I don't know if it would wear very quickly in that situation. In a thread I posted, someone made that suggestion and I really didn't think about that being a solution until after I got the parts. That poster may have been on to something with that suggestion. Buy a gear only.

All in all, I am comfortable with having replaced both the shaft and the gear and eliminated having to go back into it later.

Let me know if I can help.

 

[Living in the Past]

Would be interested in what gear gave it more area on the shaft. I know there is a gear for the split T case that uses the area for the PTO gear but but because of the one piece design it was possible to do in the earlier cases.

 

[Living in the Past]

The problem with wear is once it starts the more play the faster it wears. While your foot is on the gas the engine is driving the shaft. With your foot off the gas the wheels are now driving the gear. The more play the harder the force every time the force switches which means the faster it will wear.

 

[emac]

Would be interested in what gear gave it more area on the shaft. I know there is a gear for the split T case that uses the area for the PTO gear but but because of the one piece design it was possible to do in the earlier cases.

My 77 did not have a PTO gear, only a sleeve. I will look and see if I can locate the link again. I could be all wet about it helping in this situation. It may not have been for my year. No doubt you know way more than I on this topic. But, I recall thinking it was a great idea and that may have been an option.

Those were some dark days for me, as I ended up putting a lot of money into my tranny/TC, so I could have a clouded memory. Zero play with a new shaft and gear.

FJparts.com is where I got the shaft and gear.

 

[miller]

I am familiar with fjparts as I ordered the transfer output shaft, high speed gear and hi/low clutch sleeve for this same transfer case. Its worn out!! I will get the rest of it from him. Yes expensive I will have $1800 bucks into the transfer and transmission when they are done, but shouldn't have to do it again! I have seen some prices on rebuilt units for around $800, but that must be just bearings and everything else is probably worn, but sold as rebuilt.

 

[emac]

FWIW, I replaced the synchros (OEM) while I was doing it as recommended by others here. Make sure the thrust washer is properly seated on the "key" when reinstalling the tranny shaft back into the tranny. If it isn't then the bearing will not seat properly and things will go downhill fast from there. Trust me.

It cost me a new bearing and a ton of frustration. Put it together with some grease, to hold things inline while you wrestle in in place.

 

[Living in the Past]

My 77 did not have a PTO gear, only a sleeve. I will look and see if I can locate the link again. I could be all wet about it helping in this situation. It may not have been for my year. No doubt you know way more than I on this topic. But, I recall thinking it was a great idea and that may have been an option.

Those were some dark days for me, as I ended up putting a lot of money into my tranny/TC, so I could have a clouded memory. Zero play with a new shaft and gear.

FJparts.com is where I got the shaft and gear.

I remember someone trying to weld the input gear and PTO gear together after it was installed. I don't remember anything that could be installed that lengthened the area the splines were in connect with.

 

[tlc762]

Think I remember reading in another thread that Georg@Valley Hybriids had a jig that he used to weld two input gears together to lengthen the spline contact area... Might be worth asking him if that is an option.
HTH
Will

 

[miller]

I ordered new transfer case input gear and tranny output shaft. Thanks for all the input!

 

[reddingcruiser]

^^^ Wise choice, Grasshopper!