Transmission / Overdrive: Help me re-assemble the overdrive to my T96 transmission?

[Ted Preston]

I've just replaced the countershaft "cluster gear" in my transmission after a bearing failure. I reassembled the main case, countershaft, reverse gear, mainshaft and input shaft. At that point I tested all the functions and everything's working well. Now I'm trying to reassemble the overdrive.

I have the whole tranny sitting in a vice, with the rear of the tranny and the overdrive sticking straight up in the air, so that I can easily lower the overdrive case into place and align the overdrive switch mechanism and the spring that keeps it disengaged. Everything looks right at this point, and I can lower the case into place, get the switch shaft aligned in its place, where the spring engages like it should. I have the tapered pin removed from the switch mechanism, and the mechanism pulled back out of the way when I lower the case into place.

The problem I'm running into is when I get the overdrive case set into place loosely, everything appears to align like it should, and the whole transmission, from input shaft to output, turns freely by hand in neutral. When I snug down the four bolts that hold the overdrive to the main case, the whole shaft binds somehow, and stops turning by hand.

I've tried re-setting the case in place several times, looking for anything that would cause the binding. Each time I get the same result.

What am I overlooking?

[(S)]

Are you sure both sliders up front are 'neutral'? With the top cover removed, it can be in 2 gears at the same time and it from turning.

[RadioRoy]

You might try assembling it in the horizontal position. Maybe something is sliding/falling into a position it shouldn't be. I used rubber bands to hold the rollers in place.

Is your gasket between the two case parts too thin causing the cases to mate too closely?

[gordr]

Sounds like the tailshaft with the internal gear is not completely meshed with the planets and the sprag clutch. One of the sprag clutch rollers could have slipped out, and become wedged in such a way as to keep the tailshaft assembly from seating fully.

[rusty nut garage]

One experience I had a T86OD that someone let water get in . output shaft ring gear was ate up more then I felt comfortable reusing. I had a used one sent to me, put the trans together without issue until it got to the step of putting the tail housing on. Come to find out the output shaft ring gear was interfering with the housing. I ended up taking the ring gear to a machinest and have some material removed, less the .005 if i remember correctly. it was difficult to figure out and took several attempts at reassembly before I figured it out. If all your parts came from the same trans this is probably a mute point.........thought I'd pass it along anyway.

I've just replaced the countershaft "cluster gear" in my transmission after a bearing failure. I reassembled the main case, countershaft, reverse gear, mainshaft and input shaft. At that point I tested all the functions and everything's working well. Now I'm trying to reassemble the overdrive.

I have the whole tranny sitting in a vice, with the rear of the tranny and the overdrive sticking straight up in the air, so that I can easily lower the overdrive case into place and align the overdrive switch mechanism and the spring that keeps it disengaged. Everything looks right at this point, and I can lower the case into place, get the switch shaft aligned in its place, where the spring engages like it should. I have the tapered pin removed from the switch mechanism, and the mechanism pulled back out of the way when I lower the case into place.

The problem I'm running into is when I get the overdrive case set into place loosely, everything appears to align like it should, and the whole transmission, from input shaft to output, turns freely by hand in neutral. When I snug down the four bolts that hold the overdrive to the main case, the whole shaft binds somehow, and stops turning by hand.

I've tried re-setting the case in place several times, looking for anything that would cause the binding. Each time I get the same result.

What am I overlooking?

[Ted Preston]

Moderator: Welcome to Time-wasters' Anonymous. The coffee's in the back, and Bob's our designated butt-kicker today. If you need a swift kick, just bend over before you fill your coffee cup. We have a new timewaster in our midst today. Time for an introduction.

New Guy: Hi. My name's Ted, and I . . . I'm a time waster. I've been making good use of my time for less than a day now.

I thought I could re-assemble my Studebaker tranny with my eyes closed. I didn't read the shop manual. The tranny didn't go back together very well. (kinda like it was assembled by a guy with his eyes closed.) I even posted a thread on the Studebaker Driver's Club forum, and wasted a bunch of other peoples' time too. I should have just read the shop manual, and I wouldn't have wasted so much time.

So it turns out that T96 synchronizers are not symmetrical. You actually CAN put them on the mainshaft backward. Like that guy named Murphy likes to say, any thing that can go wrong . . . Well, you get the picture now.

Five minutes with the shop manual and I would have read those couple sentences that explain how to install the synchronizer, and what will go wrong if you install it backward. If you install the synchronizer backward, it will prevent the input shaft from seating against the synchonizer, and thus prevent the bearing that the input shaft rides on from going all the way into the transmission case, leaving the snap ring on that bearing standing away from the case by about an eighth of an inch when the case is bolted together.

In short, installing the synchronizer the wrong way 'round will result in all the problems I described in the first post in this thread. DAMHIK.

If you get the tranny installed back into the car with the synchronizer installed backward, things won't work right, and you'll get to waste a whole lot of time pulling the tranny back out to fix the problem.

[Ted Preston]

So in the end, it turns out that my problem had nothing to do with the overdrive at all, except that tightening the bolts attaching the overdrive cover to the main case has the effect of pushing the mainshaft forward. If the synchronizer is mounted backward, it makes the mainshaft slightly over-long, thus pushing the input shaft's bearing hard against the input shaft cover bolted to the front of the tranny, preventing the input shaft from turning freely. The solution was to pull the whole maincase apart again, and flip the synchro around on the mainshaft.

[RadioRoy]

What has been learned from this? If knowledge is gained, then there is no real loss. There is the actual knowledge of how to install synchronizers, plus the wisdom of knowing how to (or how not to) go about a project the next time.

Thanks for the great wrap up, Ted.

Thanks for helping make the case I keep bringing up. Studebaker technical literature is the best I have seen.

[Ted Preston]

What has been learned from this?

Thanks for helping make the case I keep bringing up. Studebaker technical literature is the best I have seen.

I have to agree that the shop manual is very well written on this point, even describing exactly the trouble you will have if you install the synchro backwards.

What I learned is to read the shop manual more carefully . . . and don't do mechanical work with my eyes closed!

And in terms of the knowledge gained, I just drove the car to work, and all the way I was envisioning what was happening inside the transmission as I shifted. I'm all in favor of gaining knowledge, even if I do it the hard way. It's much nicer learning from other peoples mistakes, though!