It happened again, Trans stuck in Neutral!

[Misfit]

Hi Folks, This is the third time it's happened. This time I thought it would be cool to drive my jeep to the golf course. I had a great time. After the game, I showed my friends the jeep, started it up and then could not get it into gear. The jeep moves when pushed, the propeller shafts move fine. It just won't go in to any gear. I towed the Misfit home, got out of the pick- up and tried the shift lever again and guess what.? The trans shifts just fine. ( until the next time). So I drove it into the back yard.. and I'm not going to talk to it for a few days.
I can understand if one of the shift rails might not move, but how can both shift rails not move at the same time? It happens when I stop at an intersection, or in this case, stop at a golf course. I'll move it into neutral and then it won't move into any gear. I bought a new shift plate from Ron, but obviously that wasn't the entire solution. I checked the rivited part under the trans top and it is solid. I can't see why a new shift lever might be the solution because it is not slipping out of the shift plate or shift rail notch. Any ideas? The trans still regularly slips out of 2nd, but I don't think that that is related. There was one time when the 2nd/3rd shift rail grease cup obstrucked the rail and then popped out when forced. Other than that, who knows? Thanks for thinking it over.
Marv

[iron duck]

Marv,

I think that you have an intermittent pin problem.
The gearbox slips out of seccond gear which points to a worn gearbox.

Somehow you did not propperly shifted the jeep out of previous selected gear...which the intermittent pin doesn't like.
She can get locked between both shifter rails causing your described problem.

I think that an overhaul from your gearbox is on hands to make it reliable.

Luc

[BrianT]

Hi Marv,
I've just rectified an intermittent lockout situation which occurred when changing from 1st to 2nd. After much advice including from members of the G and having printed out John Barton's sticky I took the lid off the transmission and investigated. I photographed each gear position- meant a lot of removing and replacing the cover. What I found was that when moving from 1st to 2nd sometimes the column shift would move the shifter plate close enough to neutral to disengage 1st but it was not getting to neutral and allowing me to select 2nd. The interlocking pin was doing its correct function in preventing access to 2nd because the shifter plate had not returned to neural.The distance involved was very minor.
Anyway after checking a long list of potential linkage problems I discovered that the problem was caused by wear in 3 areas - the pivot grooves in the shift collar of the transmission top plate, the gate arms underneath the top late and rounded edges on the neck of the column shift where it comes into contact with the gate. I replaced the top plate with another used one but with virtually no wear on it and got a friend to fill the grooves in the column shift with weld and then ground them back to sharp corners.
The gear change is much more defined now and I have not s yet had a reoccurrence of the lockout.

My complete list of potential problems that I investigated in getting to this was:
1. wear on stick pivot pins
2.wear on end of stick
3.wear on pivot sockets on shift collar of top plate
4.wear on shift plate
5.wear on rail shift sockets
6.secure attachment of forks to rail
7.correct alignment of forks
8. smooth movement of rails/forks
9.secure and wear on top cover gate plate
10. spring washer above/below shifter plate.

Hope this is of value.

Cheers

[Misfit]

Luc and Brian, thank you for the suggestions. It sounds like the trouble might be on the top end, at least. So maybe I won't have to drop the trans. One question for Luc, what is the intermittent pin? This week I'll take off the top and take some detailed photos of the parts in question. It is often difficult to figure out how much wear is too much wear. I also realize that many small amounts of wear are cumulative. If this thread is off the page by then, I'll start a new thread called "How much wear is too much? Thanks again for your help. I don't know what I would do without the Gee!
Marv

[iron duck atelier]

Marv,

The intermittent pin is located between the T-case and Main case housing.
It sits between both first and reverse and seccond and direct gear shifter rail.
This intermittent pin makes sure that the gearbox can't select 2 gears at the same time.
One shifter rail must be in neutral position before the intermittent pin allows the other shifter rail to move.
If a gearbox is not completelly in neutral before a gear from the other shifter rail is selected....it can lock up the gearbox.

Maybe to much at a time, but you'll find out when dissasembling the gearbox ones up in the time.

Bottomline is : that if the gearbox is shifted to neutral decently before changing side with the shiftercane....the issue won't come up again.

Regards, Luc

[Ian Jamieson]

Guys,
Luc is referring to the INTERLOCK pin that resides in the milled groove on the front of the transfer case. When one selector rail moves either back or forward, the interlock pin moves away from that selector rail and into a detent on the other rail thus preventing the engagement if 2 gears at once (which would cause a disaster!).

If you regularly dropping out of 2nd gear, check that the nut that holds the out put gear onto the main shaft (actually in the transfer case)is still tight. I have known this to come loose (some folks forget the split pin) and cause all sorts of gear selection issues, and dropping out of 2nd.

Ian

[Misfit]

Thanks Luc, Now I know what you mean. I have one of those three-in-one manuals for reference, and on page 174, it describes this pin as the Gearshift Interlock Plunger. I remember this pin when putting the T case back on the trans. If I remember correctly, it can only be installed when shiftrails are in the correct position. So, if both shift rails are in the neutral position, the intermitent pin would be free to move side to side, waiting for one of the shift rails to be moved and push the pin into the notch of the other rail. Is that correct? Now, if this pin fails to fuction properly, and the transmission finds itself in two gears at once, then when I let out the clutch, the engine would stall. Worse would happen if the jeep was moving at the time. That is not my problem right now, but if the pin is not lubricated enough and gets stuck in the slot in the between the T case and trans, neither shift rail may have enough leverage to push the pin to one side or the other, thereby keeping me in neutral. I think this is correct. Thank you for explaining to me what is going on here. I'll have to try other options first before pulling the trans again, but I would not have thought of that as the possible problem. Thanks.
Marv

[BrianT]

Marv, one peice of advice that I missed from my last reply - in addition to photographing the various gear positions I forced the lockout to occur and then examined the shifter plate and gear positions. It was from this that I was able to deduce that the problem was with the column shift/gates and their incorrect alignment. Also with the lid off you can move the two rails back and forth using a screwdriver in the shifter recess on each rail to see if the interlocking pin is functioning correctly as stated in the previous replies. I also thoroughly recommend printing off John Barton's series of posts at the top of this forum on the transmission. They really helped me get an understanding of the transmission, its parts and the potential wear problems.

Luc and Mike Walford, I I have only just got around to taking a deep breath and plunging in to find the problem in my transmission. Thank you for your input some time ago - much appreciated.

All the best Marv - it really isn't as daunting as it first seems!

Cheers

[Misfit]

Brian, As I mentioned in the first post, after towing the vehicle home, the trans shifted normally, so the interlock pin functions normally 99% of the time. Darn that one percent!
Marv

[iron duck]

Marv, that interlock pin is surelly involved.
The reason why it is there is to make sure one shifter gear is completelly in neutral before the other rail can be moved just as you explained.
When the shifter plate riveted to the top cover and the shiftercane starts to get wear, the driver can change side before the rail is at neutral.
Than the interlock pin finish the job as soon as the driver select a gear with the other rail as the pin push into the rounded notch.
But if wear starts to appear....it wedge up between both rails causing a locked up in neutral transmission.

When rebuilding the gearbox one should replace the rails if wear in the interlock pin notches is visible.
Also the fork should be a tight fit on the rail.

Regards, Luc

[Misfit]

OK, it would seem, as you are explaining, the ONLY way to lock up in neutral, is if I move one of the shift rails far enough to overrun the interock pin (thinking I am in neutral) and then moving the other shift rail out of neutral. The whole thing would then bind up. The interlock pin would then be out of both notches on the rails, or nearly so.
Now, see if this makes sense. If the rails and pin are worn, but you have a perfect shift gate and shift cane, then the 2nd/3rd shift rail would be protected from overruning the worn interlock pin. As for the 1st/rev shift rail, there does not seem to be a similar protection, but even though the shift plate is a rather sloppy way to move its rail, maybe the protective stop is the other gears on the shaft itself. If the interlock pin and both the shafts are in perfect condition, then a worn shift cane or shift gate, or even a worn shift plate will not be able to overrun the interlock pin. Only in the case of a very severely worn shift gate would the shift rail be able to be pushed into two gears at once and even that, only when the interlock pin is also badly worn.
Bottom line is, if I would replace the shift rails, the interlock pin, the shift cane, and the shift gate, and maybe check the slots in the shift tower to make sure they are not overly warn; then there is little chance of any more lockout problems. Replacing only a coulple of these components will only delay replacing all of them later. I will post some pictures. soon.
Marv

[Misfit]

Here are some pictures, see if you detect undo wear.



In this picture the cane is in the extreme left position riding against the shift gate underneath.

In this picture the cane is in the same position as before, but taken from the other side.



Notice that the shift plate does not have the usual metal piece welded to the bottom on the plate. That's how it came from Ron.

Neutral with out shift plate, you may notice a very small worn area on the left edge of the 1st/rev shift rail notch.

I also took pictures of the transmission in all four gears, but didn't think that they would be very helpful, so I didn't post them. Thanks again for all your help.
Marv

[Ian Jamieson]

Ahhhhhhhhh! I see the problem NO WAVY WASHER

Seriously Marv, I have seen gear box's in a whole lot worse condition than this, and they work fine! Mine used to be way worse that what I see in the pix and it selected ok. I do admit that the shifter cane used to slip between the shifter plate and 2/3 selecter rail, but judicious giggling would bring it back into line.

When the problem occured at the golf course, did the gears grate when trying to select 1st/rev?, or does the shifter cane (lever) simply sieze up? Is it possible that the spring on the top of the shifter cane is allowing the shifter cane to rise up too far and yhus allowing the cane to come out of the shifter plate?

Frankly I dont see enough wear to give the problem, and as you have said, its unlikely that the interlock plunger can stop both shift rails at the same time.

My advice, put the top back on with only 2 bolts, leave the floor plate off, go for a drive somewhere quiet and safe, stopping and starting often. When she plays up, pull the top of and have a look around. Even just remove the shifter cane and using a torch (ok flash light) look down the shifter tower and see if you can select the gears with a long screw driver.

Ian

[iron duck]

Marv, Your gearbox looks good, but no one can tell from the pictures if it really is.
What I noticed is as follows :

-the rust pitting on the shifter rails.
This indicates that they are bussy with their seccond life...or with other words, they have been reused during an overhaul.
These rails are often overlooked as not much people are aware from the interlocking pin problem.
What you have is not the only problem one can experience with it.
Sometimes it makes shifting hard when changing from shifter rail.( out of first going to seccond or visa versa )

-The shifter cane has some play between the "neutral position" fork from the shifter plate riveted on the top cover.
Nothing really abnormal,but many small bits make a big one.

-The shifter plate ( that is the relay between shifter cane and first and reverse shifter rail ) is the early type without reinforcement.
These plates tend to bend and alow more play.

If the interlock pin and rails are both in perfect condition, a lock up would not appear as than the pin will finish the job by pushing the not in neutral rail a bit further 'till it is.
When it starts to wear, the pin doesn't slide in the notch anymore but starts to hook in it causing the shifter cane to lock up in neutral.

The shifter rails can work independatly...the interlocking pin is the only part that makes them work together.
If the interlocking pin would be removed from the gearbox, it is possible to select 2 gears at the same time, at least if one would take the top cover of and do the selection with a screw driver.

Than the gearbox will be dead frozen...the input shaft as well as the output shaft.
If that would happen while running the gearbox will split the countershaft or even crack the housing.

With the pin removed the problem you have would disappear, and the gearbox would work perfectly.......untill it happens that one gear is not fully out and another is selected.
Than it would severelly grind or lock up and ruin the gearbox.

and as you have said, its unlikely that the interlock plunger can stop both shift rails at the same time.

Ian, you know I have a high head on with you, but this statement put's is the world on it's head.
Actually...the interlock pin is the ONLY part in the gearbox that is able to lock up both shifter rails at the same time.

Regards, Luc

[BrianT]

Marv, I agree with Ian and Luc, the wear on those components is not an issue - mine was much worse. I did however get a mate to fill the grooves in the neck of the shift where it comes into contact with the gate, and had it ground back to have sharp edges.

My understanding of the role of the interlocking pin, operating correctly, is to ensure that one of the shift rails is in neutral at all times. The problem I faced was that sloppy linkage enabled the column to move through the 2nd/3rd gate before the shifter plate had been fully returned to neutral. Whilst I was through the gate I could not access 2nd or 3rd because the Rev/1st rail had not been correctly aligned in neutral to release the interlocking pin to permit the gear change.

I know this is a pain, but I must say that actually being able to view the lockout as per your tranny photos got me on the trail of resolving my situation. I must have done over 100 gear changes sitting in the garage without the engine running to replicate the situation. Once it occured, off came the lid and a couple of photos before a good deal of analysis. Very tiring on the legs with the clutch depression!

Whilst your issue may not be with gear linkages a little more diagnosis might avoid having to pull the tranny out. If of course the issue is with the interlocking pin, the rails or the gears then that is of course what will have to happen.

I did try to post the pictures of my lockout for you to compare with your photos but I ran into difficulties - something else I have yet to master!

All the best!