Popping Out Of Reverse

Hi Everyone—just picked up a decent shape ‘72 cj5 with a 304/3 speed. Original engine and transmission I believe. Going through several repairs right now—rebuilding steering shaft, replacing incorrect water pump and fixing some body mounts.

The transmission seems to work ok with the exception of popping out of reverse. I have to hold the stick to keep it in.

Anyone know the cause and remedy?

 

Worn idler gear? Loose bearings or worn sliding gear? How is the oil looking?

 

No sliding gear in a T-15, only synchro hubs.

Where the clutch hub slides over the teeth on the gear could be worn. Reverse is not synchromesh, so that gear has no blocking ring. There is a brass bushing inside reverse gear, that could be worn. This allows the gear to skew and push the clutch hub away from the gear, and it comes out of gear.

Pretty much all you can do with the transmission in the Jeep is change the oil and work on the shift top. There are poppet balls in the shift top that hold the transmission in gear - I would take the shift top apart, inspect and repair any broken poppet springs. I don't think that's going to be the problem though.

On the bench, the usual rebuild targets are the main bearings and the blocking rings. You would inspect everything for wear. Since the reverse gear is closest to the rear main bearing, you would suspect that, but they don't wear much and aren't typically a problem.

This is one case where the TSM for your year does not help you much. I suggest you instead download the '77, '78 or '79 TSM from the Tom Collins site and refer to the section on the T-15 in there. Much better than the earlier books. The '72 TSM covers the T-15 but the later books have more detail; the T-15 was used in Jeep trucks in all those years. You should also purchase the TSM for 1972.

Presume you found the shorter '71-72 water pump.

First post! Welcome from eastern Massachusetts.

 

Oooh. Also -

If the nut on the output gear were coming loose, that might add lengthwise slop to the main shaft and allow reverse gear and the clutch hub to pull apart. Might not be evident in forward gears, where I expect the helix on the gears tends to push the gears and clutch hubs together.

 

Thanks Tim—I’ll look at inspecting the top to see what I can see this week.

on your last post, checking the nut on the output gear, was that something than can be checked in the jeep or only on the bench? I’ll download the TSM.

I was able to find a short water pump with Barney. Sounds like I was lucky to find one. Ordered that, hoses, rad cap, and about 6 different items he recommended for rebuilding the entire steering shaft. Previous owner said he changed WP, but it doesn’t appear to be recent as it’s already weeping, that’s when I noticed the misaligned pulleys.

 

NP! Glad to help.

Transfer case has to come off to see the nut. Dunno, you might be able to pull the extension housing from the transfer case and see it, but I'm not convinced it's that much less work.

The AMC specialists sell the water pump, and it's been available through them for years. The regular (RockAuto, parts stores) sellers will give you the wrong part. Just an aside - the newer pump is obviously wrong, and I don't know how the sellers can continue to offer it as a replacement for the earlier pump. Somehow that wrong equivalence got into their data and none have had the presence of mind and/or the moral inclination to fix it.

 

Mainshaft slack can be checked with the lid off. Carefully pry back and forth on the mainshaft to see if it moves.
Do you have a body lift? It is a common issue for the shifter to hit the floor or the boot bunching up when the shift cane is put into gear, keeping the detent from fully engaging.
Check the lid to see if the rail detents when R. If not, you may have a detent spring issue.
Inspect the shift fork face for wear. Worn fork will not allow the collar/gear to fully engage (usually an issue in 3rd with the driver riding his hand on the shift cane while driving).
Engage R and remove the lid. Is the gear fully engaging the spur gear? If not, inspect the fork to insure the roll pin hasn't sheared and the fork is moving on the rail.

 

Thanks—I’ll do those checks as well. No body lift, stock height with the exception of about 3/8” rubber between the body mounts and frame.

 

Hi Guys—working on removing lid. The rear is hitting the sheet metal. Do I just bend this out of the way and pull lid and stick out all at once, or is there a trick to pulling the lid and leaving the stick?

 

Remove the rest of the floor pan and you can easily remove the transmission shift top. Make sure it is in neutral with wheels chocked before you do.

 

Mine is not popping out of gear but the stick jumps a bit when I start moving in reverse or first gear. Does that sound like poppet springs? I am thinking about dropping the T15 out and rebuild but parts are scarce (bearings etc) I think Herm has them in stock but trying to figure out if I should also get new syncros? Might go through the Dana 20 xfer case as well. Just wanted to get some feedback on the stick jumping but does not pop out of gear. Thanks

 

Synchros or blocking rings? The synchro hub is not really a normal-wear part, but the blocking rings are. If the transmission is out, and it's been in service a long time, I would replace the blocking rings. I would buy front and rear main bearings, blocking rings, and a small parts kit, without even opening the transmission. Last I looked (when I fixed my T-18) only the Crown import is available for the front main bearing. This part is the same for the T-15 and Jeep T-18. Maybe Herm has a better source for these. If you go with a Crown bearing, feel the motion and reject any that have noticeable roughness. Look here - https://www.fsjnetwork.com/forum/viewtopic.php?f=10&t=10473&start=20#p119366

 

Hi Guys—
Got the lid off. Hopefully my pic shows up well. Detent system seems ok I believe. The sychro rings (I believe) seem very worn. Hopefully the pic shows it well. The shift forks also seem very worn. Is there like a plastic coating on the end of the shift forks? Mine seems to be coming apart. I tried to see how much play I have in the main shaft. It seems like a lot. I’ll try and quantify that.

 

Hi Guys—where do I purchase a ‘72 TSM?

 

RockAuto is probably cheapest. Faxon Auto Literature has original copies, last I looked.

http://www.earlycj5.com/xf_cj5/index.php?threads/123064/

 

Hi Guys—have the front end sorted now and turning my attention back to this issue with the transmission.

As I mentioned in my original post, it pops out of reverse, and I think I’m feeling and hearing some bad bearings in the transmission.

Anyone have any experience with the Novak kit below? Looks to be pretty complete, aside from anything I find once I have it apart.

Also—does anyone have any more information about the difference between T15 and T15a?

When I read articles about T15 transmissions, the picture they show of the shift shaft/top cover look different than mine. I’ll try and get the numbers off of the side.

Kit T15MR-J, master rebuild
https://www.novak-adapt.com/catalog/transmission/transmission-parts/t15-parts/