1991 5 speed transmission, 2wd, 2.3 L 4 cylinder standard cab

It's been a long, sordid trip to where I am now. Basically, the transmission died at about 140k, almost certainly due to "failure" of the rubber plugs - there was essentially no fluid in it when I pulled it out. No signs of leaks and I had never heard of the "rubber plug issue" prior to this.

Transmission rebuilt, and reinstalled, still leaking from somewhere - that's when I heard about the plug fixed - and they have been replaced with the Dorman freeze plugs. While doing this, I somehow got the thing "stuck" in 1st gear - it wouldn't shift when I was finished. So, out it came again. I removed the top cover to free the transmission - and it is now happily in neutral - BUT I can't get the top cover and shifting forks to go back together and close up the transmission. Obviously, something is out of whack.

So - can anyone describe the proper alignment/assembly for the top plate back onto the manual transmission, or point me to some sort of guidance? My search hasn't turned up anything useful.

 

If the collars are all in the middle of their travel, the forks must be in the middle of their travel also. I would figure out which fork and collar are mis-aligned.
The shift rails in most have interlock mechanism(ball bearings & springs for most) that will prevent the shift forks from selecting two gears at once. You should be able to move the forks from gear to gear, selecting 1, then 2, then neutral then 3, then 4, then neutral then 5 & R. One of them is likely in the wrong position, even though you can move the lever as if it is in neutral. I think I would exercise the forks a bit and see which one may be out of position.
The interlocks work by moving a ball bearing into the detent or depression in the side of the shift rails. The ball locks the rail in place, or prevents the gear lever from moving into a particular position.
The shift fork bushings can get worn and allow the forks to be out of position, and difficult to get into position and stay there. Before you did all the work, was the shift mechanism tight or sloppy? The pivot that the fork arm goes into should keep the fork at the proper angle to the collar, and position the fork in its fore and aft motion without slop. If the fork can move too much, it might not fall into place in the collar groove, making re-assembly difficult. IOW, the forks should not flop around, but be held firmly.
tom

 

The advice is appreciated!

Transmission was rebuilt by a shop, through the auspices of a friend who helped me with the project. Near as I can tell, the subsequent leak appears to have been through the top of the transmission - the cover/seal that the shifter passes through. The plugs that were in place look to be new - but I have replaced them with the Dorman plugs.

When I took the truck off the jackstands, I found it was "stuck" in 1st and simply would not shift. Getting it back out and removing the cover, the transmission was in gear - I now have it in neutral - turning the input shaft does not turn the output. The shift forks appear to be new, or at least in very good condition, but I haven't figured out how to "position" them so they will mate with the gears - I don't see how to get and keep them in any position other than where they are now. Is it simply a matter of reassembling the shifter and using that for leverage to position them?

 

I think that your selector mechanism (lever position & interlocks) are in first gear position. If the rearmost fork won't drop into the collar, it is the one that does not drop in place, it is likely 1st gear. It is difficult to move the fork and associated mechanism because you have to overcome the 'detent' and 'interlock' spring pressure and move the ball out of the detent and up the ramp to allow the shift rod to move.
I have used crescent (adjustable) wrenches on the shift arms that carry and move the fork 'swivel'. I don't know the names. In your case you have two choices. Move the collar to engage 1st gear, or move the fork for 1st/2nd into neutral.
I would lay the cover over/near the top of the transmission and determine which fork is not aligned with which collar. I think you'll find the first fork does not align with the 1-2 collar.
I think I read the lever seems to be in neutral. If that is the case, it may be possible that the end of the lever is not really 'caught' by the mechanism(shift rods & u-shaped aperatures) but is outside of its normal spot. You should be able to move the lever and watch the shift fork levers move forward and back as each gear is selected. Moving the gizzards without the normal shift lever length(for leverage) will be hard, so the lever must be attached, or something similar, to gain enough leverage to cycle through the gear selections.
You should be able to select each gear and see the forks move. If the linkage is out of synch, one or more of the forks will be out of position. If there is missing interlock bits, you could end up having two gears selected, which is not good, and would lock the transmission. If the 'rebuilder' got the shift linkage wrong, it won't operate properly.
If the transmission was 'locked' in 1st gear, then the linkage is/was messed up. The interlock is set up, I think, but putting all the rods in 'neutral', with the detent springs/***** installed to keep them aligned. As the shift rods move into a gear select position, they force the other two selecting rods to be 'locked' into place by pushing ***** into place that interfere with the rod moving. When the gear is de-selected, the rod moves, and then the interlock ***** are allowed to move out of the way of the other shift rods. If you were locked in gear, then one or more of the interlocks ***** were out of place, preventing the rod from moving. You just have to get them all in place, neutral, and see that they can move to and fro properly before installation. They should be movable, with sufficient force, and will resist to where you may think them locked, but if you use a gentle persuader, such as a hammer handle while you hold the hammer head, to push, you can apply more force without the possibility of damaging things which would occur using the OTHER end of the hammer. IOW, use the hammer as leverage to be able to supply more force BY HAND, than you can normally do, but not as much as you could apply with a hammer. The detents WANT to stay in place, and need a good 'thunk' to get freed and move the lever & fork. Get 'em all in 'neutral' and work from there.
tom

add: If I didn't mention it, I would think that there might have been an assembly problem if the transmission was stuck in 1st after the work was done. If bits were left out of the interlock, or spring/ball or ball/spring/ball assembly were flip-flopped or spring left out, or ball left out, you can get a jammed linkage. Spring-ball-spring would force one or the other of the ***** into a detent in one or the other of two shift rods. Spring-ball would force a ball into one detent in one rod. Get them crossed, and the rod might get stuck. I would NOT put it back in place until I had checked that the linkage worked properly. You could take the linkage(or the whole thing) to your transmission shop and tell them it was stuck in 1st... and let them check it for you. tom

 

Again, thanks for the input/guidance/suggestions.

I will take another look tonight when I get home and try this. If I understand your suggestion correctly, you are recommending assembling the shifter mechanism to gain the needed leverage and then just working to get all of the pieces lined up. Makes sense, and is essentially what i was trying to do - just not successfully.

Let's see if the "extra" leverage and a little perseverance can get the shifter to match where the transmission is!

 

TomW,

I see in rereading that I didn't make it clear that the truck ran well for about 2 weeks - albeit with a fluid leak. Researching that led me to the "rubber plug" issue. I attempted to address this with the transmission in place, prying the plugs out through the limited shifter access - I didn't learn about the removable plate under the carpet till later. After putting the freeze plugs in I found it locked in 1st - hence my effort to get it sorted rather than just dumping it back to the shop - figured I had done something to it in my efforts.

With your input I got the shift rods/forks to position where the top plate would drop into place!! With the shift lever attached, I can move the selector and feel some "selection" happening. It feels a LOT different - but then I also installed one of the shifter "rebuild" kits - and found there were NO bushings left in the transmission when I started, so not sure how it should feel now. I am assuming that I should be able to feel 5 distinct gears and a clear neutral, even with no engine input. I need to look into that further before it goes back in.

Thanks for the guidance.

 

GeoP: I am assuming that I should be able to feel 5 distinct gears and a clear neutral, even with no engine input.

Yes. Every available gear should be selectable and felt. The shift lever should swing from right to left, and have some resistance(a little bit more) going to the 5/R selection area. The lever should 'want' to go to the left when taken out of 5 or R, towards the 1-2 and 3-4 area.
You can or should be able to run the engine and select each gear with the clutch pedal depressed. You might have to ease up the pedal just a slight amount to get the gears to spin a bit, so the synchros/blocking rings can align the splines, not enough to move the truck, to get the gears to engage.
tom