Transmission Main Shaft

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   Hello,
I've been enjoying reading the messages on the CJ2A forum for several years now as I've been trying to get more educated on my own CJ2A.  I inherited a 1948 CJ2A which appears to be pretty much original, albeit in rough shape.  My father had used it to plow out his driveway for many years and decided to retire it after the engine began smoking quite heavily.  

I now have the vehicle and have decided to get it running again.  I'm not sure how far I plan to take the rebuild, but I know I need a snow plow and this vehicle has one!  I've already pulled the motor and had the cylinders bored out.  Before reassembling the motor I thought I should pull the transmission and transfer case and clean up the 60+ years of accumulated grease.  I decided to at least clean the components and replace the seals to prevent more oil leaks on my garage floor.  The transmission looked really clean on the inside which I was happy with; I didn't feel like taking on more than the motor this year.  However, once I separated it from the transfer case, I noticed the main shaft as it exists out the back of the transmission isn't a snug fit, leaving the shaft to wobble a bit.

Here are some photos of the Jeep taken last summer.  Right now the motor's out and there are parts all over the garage.

My question is concerning the wobbly main shaft.  I read a few of the transmission rebuild manuals and they don't really specify how tight this rear seal should be.  One manual does say the shaft shouldn't wobble which makes me think I've got a problem.  See the photos below.

In the first photo, I've pushed the shaft to the right and you can see the gap between the metal collar on the shaft and the transmission casing rear plate.  On the lower photo I've pushed the shaft to the left and you can see how the gap is pretty much gone.  

My question is pretty simple.  Do I need to deal with this and if so, what needs replacing?  The metal collar around the shaft, or the larger circular plate that fits in the rear of the transmission?

I hadn't planned on doing much work on the transmission so this is just catching me off guard.  I'm hoping this isn't too much work to replace if it needs repair.

Thanks for your assistance!

Mark Mortensen

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mortensen Members Profile Send Private Message Find Members Posts Add to Buddy List Member Joined: 03 Aug. 2014 Location: Fairfax, VA Status: Offline Points: 28	Post Options Post Reply Quote mortensen Report Post Thanks(0) Quote Reply Topic: Transmission Main Shaft Posted: 29 July 2016 at 2:56am
	Hello, I've been enjoying reading the messages on the CJ2A forum for several years now as I've been trying to get more educated on my own CJ2A. I inherited a 1948 CJ2A which appears to be pretty much original, albeit in rough shape. My father had used it to plow out his driveway for many years and decided to retire it after the engine began smoking quite heavily. I now have the vehicle and have decided to get it running again. I'm not sure how far I plan to take the rebuild, but I know I need a snow plow and this vehicle has one! I've already pulled the motor and had the cylinders bored out. Before reassembling the motor I thought I should pull the transmission and transfer case and clean up the 60+ years of accumulated grease. I decided to at least clean the components and replace the seals to prevent more oil leaks on my garage floor. The transmission looked really clean on the inside which I was happy with; I didn't feel like taking on more than the motor this year. However, once I separated it from the transfer case, I noticed the main shaft as it exists out the back of the transmission isn't a snug fit, leaving the shaft to wobble a bit. Here are some photos of the Jeep taken last summer. Right now the motor's out and there are parts all over the garage. My question is concerning the wobbly main shaft. I read a few of the transmission rebuild manuals and they don't really specify how tight this rear seal should be. One manual does say the shaft shouldn't wobble which makes me think I've got a problem. See the photos below. In the first photo, I've pushed the shaft to the right and you can see the gap between the metal collar on the shaft and the transmission casing rear plate. On the lower photo I've pushed the shaft to the left and you can see how the gap is pretty much gone. My question is pretty simple. Do I need to deal with this and if so, what needs replacing? The metal collar around the shaft, or the larger circular plate that fits in the rear of the transmission? I hadn't planned on doing much work on the transmission so this is just catching me off guard. I'm hoping this isn't too much work to replace if it needs repair. Thanks for your assistance! Mark Mortensen

Joe Friday Members Profile Send Private Message Find Members Posts Add to Buddy List Moderator Group Sponsor Member x 2 Joined: 26 Dec. 2010 Location: Jeep Central Status: Offline Points: 3655	Post Options Post Reply Quote Joe Friday Report Post Thanks(0) Quote Reply Posted: 29 July 2016 at 3:48am
	You interlock plate appears to be a bit buggered, but to answer your question, that spacer controls endplay. The side to side is controlled by the bearing you took off the shaft that fits snuggly.

pjensen641 Members Profile Send Private Message Find Members Posts Add to Buddy List Member Joined: 21 June 2014 Location: United States Status: Offline Points: 690	Post Options Post Reply Quote pjensen641 Report Post Thanks(0) Quote Reply Posted: 29 July 2016 at 4:27pm
	It looks like a lot of side to side play to me. If you've got it out this far, why not do a rebuild? Is the input shaft still installed? Without that shaft, I could see it wiggling slightly since the bearings do have some radial clearance. Almost need a short video.

PaulEdm Members Profile Send Private Message Find Members Posts Add to Buddy List Member Joined: 15 Sep. 2013 Location: Edmonton Status: Offline Points: 130	Post Options Post Reply Quote PaulEdm Report Post Thanks(0) Quote Reply Posted: 29 July 2016 at 5:04pm
	I'm with Joe on this. Slide the bearing back on (it should engage a little bit with the transmission housing, and see if there's still side play. Be careful with that main shaft. It's not being held in place without the transfer case attached, and can slide out. The pilot bearings will fall out of position, and you've got some work ahead of you to put it back together. The manuals all say to run some wire from the mainshaft back to the case to hold it together while separated from the T/C. There's a hole in the end of the shaft you can use for that. -Paul

bretto Members Profile Send Private Message Find Members Posts Add to Buddy List Member Joined: 05 June 2010 Location: Orem, Ut Status: Offline Points: 1930	Post Options Post Reply Quote bretto Report Post Thanks(0) Quote Reply Posted: 29 July 2016 at 7:26pm
	Yep, there should be no contact there, that round plate is just the bearing holder. Put the bearing back on. If it has play, the bearing is worn. There could also be some play or wear on the other end where it mates with the input shaft.
	PHOTO DIARY OF MY BUILD

mortensen Members Profile Send Private Message Find Members Posts Add to Buddy List Member Joined: 03 Aug. 2014 Location: Fairfax, VA Status: Offline Points: 28	Post Options Post Reply Quote mortensen Report Post Thanks(0) Quote Reply Posted: 30 July 2016 at 12:51am
	Thanks for the replies. I'll put the bearing back on and see how much the shaft moves around. I didn't even think of that. On the down side, since I hadn't planned on doing much to the transmission when I started, I wasn't prepared for how to handle it once separated from the transfer case. Stupid me. The needle bearings fell out of the front just as you warned. Of course, I've read up a bit on it and see the recommendations for wrapping wiring around the shaft to hold it in place. A little too late for me unfortunately. It looks like I'll need to do a bit more disassembly now to put it back together again. I'll try the bearing and let you know how that changes the shaft wiggle. Of course, now that the needle bearings are out, that might allow the shaft to move around a bit more than necessary. Mark

PaulEdm Members Profile Send Private Message Find Members Posts Add to Buddy List Member Joined: 15 Sep. 2013 Location: Edmonton Status: Offline Points: 130	Post Options Post Reply Quote PaulEdm Report Post Thanks(0) Quote Reply Posted: 30 July 2016 at 4:37am
	Google the Rick Stivers rebuild guide (there's one for the T-90 and for the D-18), you're going to need it now. That's not to say you'll need to rebuild the whole thing, but there's good hints in there for getting things to go back together. If you haven't already opened the top, you're going to have to now, and once you do, you might see things that will make you want to rebuild. Or not, if you're lucky. You will need to get some transmission assembly lube. You might not find it on the shelf at the auto parts store, but a decent place should be able to get it for you in a day or two. (Same day in a larger city.) That will hold the pilot bearings in position while you install the main shaft. All the guides say not to use regular grease for this... Without the pilot bearings, the front of the shaft will have a huge amount of play, so you may not be able to judge the play at the back right now. -Paul

pjensen641 Members Profile Send Private Message Find Members Posts Add to Buddy List Member Joined: 21 June 2014 Location: United States Status: Offline Points: 690	Post Options Post Reply Quote pjensen641 Report Post Thanks(0) Quote Reply Posted: 30 July 2016 at 1:40pm
	Whoops, I missed that the rear bearing wasn't even installed.

mortensen Members Profile Send Private Message Find Members Posts Add to Buddy List Member Joined: 03 Aug. 2014 Location: Fairfax, VA Status: Offline Points: 28	Post Options Post Reply Quote mortensen Report Post Thanks(0) Quote Reply Posted: 31 July 2016 at 2:29am
	Thanks for the additional input. I was able to remove the main shaft, reinstall the needle bearings, and get the shaft reinstalled. I had already purchased some transmission goo so that simplified things quite a bit. The play on the shaft is minimal and is acceptable. The transmission overall looks really good and I don't think needs to be rebuilt at this stage. It's just a bit leaky at the normal seals which I plan to replace. I've now secured the main shaft with the obligatory piece of wire to prevent the needle bearings from falling out again. Thanks everyone. The help through this forum is awesome! Mark