transmission help

[rkeane]

I need to know where to start looking for some transmission trouble on my 1956 flat fender PW. I backed it into the garage, pulled forward and straightened it out, then I went to back up again and it will not go into reverse. All other gears are OK. It acts as if there is no detent for reverse. It doesn't grind. It doesn't get that far. Any ideas on how to tackle this and what to check first?

Thanks

Rkeane

[Gordon Maney]

I need to know where to start looking for some transmission trouble on my 1956 flat fender PW. I backed it into the garage, pulled forward and straightened it out, then I went to back up again and it will not go into reverse. All other gears are OK. It acts as if there is no detent for reverse. It doesn't grind. It doesn't get that far. Any ideas on how to tackle this and what to check first?

Thanks

Rkeane

I would start by pulling off the tower, or top cover assembly. You can then inspect that assembly and also the interior of the transmission. At that time you can manipulate the internal parts of the transmission to see if anything does not move as it should.

Visual inspection.

[rkeane]

thanks, I'll give that a try

[MoparFreak69]

Reverse gear is not synchronized. If you are trying to shift while the gears have 2 teeth in the same position it will not go no matter how much force you put to it. Try letting the vehicle roll one direction or the other slightly while pulling gently on the shifter. If that was the problem it should fall right in.
This is all under the assumption that the shifter will not go into reverse. If it goes but feels like there is no gear then you have other problems.

[rkeane]

Thanks guys,

It feels like it won't even go into gear, like there is not a reverse gear there. It does not feel like ti went into gear and then won't move in reverse. The shift lever never goes down almost like there is a "lock" on reverse that has to be released before the lever can go. It does go into all other gears and they work fine. the clutch seems to working fine too. As I said I backed up fine, went forward and when I went to back up again I couldn't get it into reverse. The truck is in a garage 40 miles away so I have to make plans etc to work on it. I was "hoping" it was something easy.

[Charles Talbert]

Which transmission do you have? The early trucks used a totally non-synchronized trans, then came a later style, still rather crude, but was synchronized in 3rd and 4th gear only. Later came the NP420, a way better unit all around, but still only 3rd and 4th were synchronized.

From what you describe, it is a good bet that the issue may be with components that are attached to the top cover. Could be as simple as a loose set screw, maybe a broken and jambed fork, on the 2 early units it could be a shift rail issue, or the shift lever ball pin and groove worn past the point of being serviceable. Either way you can likely see the probem right away by just pulling the cover.

We have good take-out units of the first 2 types I mentioned, no 420's though as they are more in demand.

[Gordon Maney]

Which transmission do you have? The early trucks used a totally non-synchronized trans, then came a later style, still rather crude, but was synchronized in 3rd and 4th gear only. Later came the NP420, a way better unit all around, but still only 3rd and 4th were synchronized.

From what you describe, it is a good bet that the issue may be with components that are attached to the top cover. Could be as simple as a loose set screw, maybe a broken and jambed fork, on the 2 early units it could be a shift rail issue, or the shifter stub shaft pin and groove worn past the point of being serviceable. Either way you can likely see the probem right away by just pulling the cover.

We have good take-out units of the first 2 types I mentioned, no 420's though as they are more in demand.

Charles, that only applies to M-series Dodges, not Power Wagons, right? He apparently has a 1-ton Power Wagon.

[Charles Talbert]

Charles, that only applies to M-series Dodges, not Power Wagons, right? He apparently has a 1-ton Power Wagon.

I think you are right in that assumption as far as original equipment was concerned, however the unit in question that was the early style in M37's also found their way into some power wagons also, we have seen several that had that trans installed in them, so either of the 3 is possible.

[Gordon Maney]

I think you are right in that assumption as far as original equipment was concerned, however the unit in question that was the early style in M37's also found their way into some power wagons also, we have seen several that had that trans installed in them, so either of the 3 is possible.

Interesting. I did not know that. Thanks for your reply!

[rkeane]

Guys,

I am the third owner of the vehicle and it has about 52000 miles on it. I assume it has the original tranny. I know the second owner never changed it. I am reasonably sure it is a late 1956 CP3W, but not new enough to be a CP4W.

Maybe I'll be lucky enough to have the trouble be in the top.

Thanks

Rick

[Gordon Maney]

Guys,

I am the third owner of the vehicle and it has about 52000 miles on it. I assume it has the original tranny. I know the second owner never changed it. I am reasonably sure it is a late 1956 CP3W, but not new enough to be a CP4W.

Maybe I'll be lucky enough to have the trouble be in the top.

Thanks

Rick

I think that should be a 420. Someone else may comment.

[Charles Talbert]

Guys,

I am the third owner of the vehicle and it has about 52000 miles on it. I assume it has the original tranny. I know the second owner never changed it. I am reasonably sure it is a late 1956 CP3W, but not new enough to be a CP4W.

Maybe I'll be lucky enough to have the trouble be in the top.

Thanks

Rick

Most likely you have the non-synchro unit in that particular model.

[Gordon Maney]

In reviewing the Zentmyer Power Wagon owners manual it says synchromesh late 1956. Not sufficiently definitive, I guess.

You will know when you get the top off.

[Clint Dixon]

Something to look for

I had this same problem happen on a Jeep CJ with a Tremac T176 transmission, only I could shift only into reverse and none of the forward gears.

I have never had trouble with a Power-Wagon transmission, so I have never had a shift tower apart and am not sure if the design or function is even close to that of a Tremac, but for your reference, here is what happened:

I will keep the terminology generic.

One the end of the shift lever, below the ball where the shift lever rotates in the shift tower, was an extension of the shift lever about 4-inches long. On the lower end of this was a round ball about 1/2-inch in diameter with the sides milled flat and parallel to one another. This ball fit into a mating slot in each of the shift rails. One rail for 1st and 2nd gear, one rail for 3rd and 4th gear, and one rail for reverse gear.

The ball wore over time and the milled sides were no longer flat. The slots in the shift rails also wore so the sides were no longer perpendicular to the axis of the rail. This allowed the ball to slip out of the reverse shift rail and end up in between the reverse and 3rd-to-4th shift rails when getting in a hurry and failing to move the shift lever in deliberate, straight, forward and aft, and side-to-side directions. Once I learned that I could not cut corners (literally) in shifting from gear to gear, I successfully drove the Jeep for another 6 years without having to fix the problem.

I do not know if this problem is even possible in a Power-Wagon NP transmission, but it is one type of wear to look for when you get it torn apart.

[Charles Talbert]

In reviewing the Zentmyer Power Wagon owners manual it says synchromesh late 1956. Not sufficiently definitive, I guess.

You will know when you get the top off.

I think they changed to the 420 at some time during the 56 model year. We just tore down an early 56 for a restoration, it had the non-synchro. The one we have has a second series bed suggesting it to be an early 56. I think the 3rd series bed also started during 56. Many say when the 3rd series beds came along, so did the 420 trans at the same time. I haven't bothered to research this to see if it proves out. It seems your manual may suggest that also.