TF 727 extension housing seals

That Guy

That Guy

Member
My output seal on my transmission has failed, the atf is migrating into the transfer case, overfilling it, and puking out the vent tube.

I was reading the "guapo" and two seals were mentioned, one facing in and one facing out.

Has anyone had to replace these seals while the trans is in the vehicle? Does the extension housing have to be removed? Also do you have the seal part numbers handy?

Thanks

bart

1973 Scout II- 345 with 727 and Dana 20.
 
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Only the transfer case has to be removed for servicing the output gear and/or seals on a Scout II transmission.

Remove the bull gear and it's spacer from the transmission output shaft and set aside. Next remove the seals.

We have the replacement seals available here:

output seal set for all 72'-80' Scout II, terra, traveler w/ 4wd - International Scout parts

One seal goes into the case to keep the transmission oil inside the transmission. The other seal goes in "backward" to retain the transfer case oil inside the transfer case.

Don't forget to re-install the gear spacer after cleaning and also use a new gasket between the case adapter and the case, not any sort of liquid sealant. The gasket serves as a proper spacer between the two components.
 
I think that the shaft from the transmission is traveling forward to back about 3/8" of an inch, this is in turn throwing the transfer case in between neutral and 2h when I romp on the throttle. I have the transfer-case out of the truck now, and realized that the seals are blown too. I am at a loss of what to do, the transfer case seems like all's clean and well, so I have to think that it's either in the extentions housing, or... Please help

thank you
 
More than likely, one or both shift rail detent or poppet springs inside the case are weak and no longer able to hold proper tension. This is a fairly common occurrence with the Dana 20 t-case, which is what I'm assuming you have, although it most commonly presents itself while either 4lo or 4hi is selected. How is your function while in 4x4? If the springs are indeed weak, you May as well overhaul the t-case, especially since you already have it out of the rig.

Have you actually measured your trans output shaft end play with a dial gauge or are you just speculating about the movement? If it truly has 3/8" of free play, that would be well out of spec and r/r for inspection and overhaul May be necessary.

You don't have some ridiculous amount of suspension lift that is placing your rear prop shaft in an obnoxious bind, do you? How about your prop shaft u-joints? Are they in good shape?
 
I saw the rebuild kit for the transfer case was close to $300 by itself, does that sound right? Second question, I broke a tooth on the smaller gear that is coming out of the backside of the extension box. I couldn't get the gears to budge with a puller, is there some secret to getting the extension off and seperated from the trans?

Thank you for your help, I'm frustrated...
 
Oh, and I know the seals are blown, I can see a rubber o-ring and looks like parts of a rubber flange coming out of the extension box, behind the gears between the shaft and seal...
 
gingercowboy said:
I saw the rebuild kit for the transfer case was close to $300 by itself, does that sound right? Second question, I broke a tooth on the smaller gear that is coming out of the backside of the extension box. I couldn't get the gears to budge with a puller, is there some secret to getting the extension off and seperated from the trans?

Thank you for your help, I'm frustrated...
Click to expand...

I know these events are frustrating. Hang in there. I'll do what I can to help you work through it. Pricing for t-case master rebuild kits can vary greatly depending on the vendor. I'm assuming, with precious little vehicle data from you, that this is a d20 and not a d300 case you're dealing with. That proper determination should be made before ordering any parts. In my quick online research I saw prices range between $98 and $240. The lower-priced option looked like a quality kit with timken brand bearings, but I know nothing about the vendor "mad4wd" who sells it. The higher priced option is from novak, which is hands down the most respected name in the game when it comes to multi-speed gear boxes. I think if you spend some time shopping around, you can find what you need for a price that will agree with your budget.

Broken tooth on the auto bull gear?...awe shit. Did you find it that way or did you break it yourself during the removal attempt? Either way, it will obviously need to be replaced. You did remove the large retaining nut before attempting to remove the gear, correct? It is held on with a great deal of torque. The gear should slide off with zero effort once the nut is out of the way. Not surprisingly, that part is not included in any overhaul kit and will need to be sourced separately. I'd give the guys at IHPA a call tues am to see if they can help you there. The gear must be removed before the adapter housing can come off. The housing and much of the weight of the transmission is resting atop a cross-member that spans the frame rails. The trans will need adequate jack support placed under the pan so that the housing to x-member bolts can be removed and the x-member itself can be set aside. Then there are a series of bolts around the housing perimeter that will need to be removed. The parking pawl lever/rod will still be engaged to the housing by a spring loaded latch. Freeing it from the latch is fairly intuitive. At this point, the housing should be free to remove.
 
Tooth was broken, nut was already removed, gears will not budge, got all the bolts out of the extension, but that doesn't do me any good without the gears removed. I have a 1979 International Scout II, with yes the Dana 20. So the movement. Of the shaft, coming out of the tranny, with the gears still attached, is indeed at least 1/4". That's not normal? If I need to have thvtranny rebuilt becaus of this issue, I eill, but something just doesn't seem right because the truck shifted beautifully. And it was just throwing the transfer case in between neutral and 2h will on the highway. 4h and 4l worke beautifully....

At a loss...
 
That's way excessive. Shaft end play on these units is measured in thousandths of an inch, not hundredths. I can't think of anywhere on the rig where that much shaft play would be considered acceptable. So now I'm thinking your t-case is probably fine and the real problem is inside the trans. Sorry to say it, but I think your trans needs some quality time on the workbench. Either it was serviced at some point in the past and a critical spacer bushing was omitted, or the original clutches have surrendered enough friction material to create the additional slop...or some other less likely reason that escapes me at the moment. Regardless, the unit should be removed, torn down and inspected to determine exactly what the deal is.
 
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