Odd transmission problem

[fury fan]

It's really hard to explain this.

I agree, it's hard to follow it. (but that's not your fault)

FWIW, most of us already know that 65 is 1 year only due to NOT being a pushbutton.
The thing that isn't widely mentioned is that this trans still uses 2 cables, 1 cable does the park pawl.
So the console shifter has 2 cables going into it.

So in this situation, possibly 1 cable has somethign amiss at the shifter, or an adjustment at the trans? Something that is affected when the trans is pressurized (when engine is running and/or rear pump is pressurizing the trans.

 

[3175375]

I agree, it's hard to follow it. (but that's not your fault)

FWIW, most of us already know that 65 is 1 year only due to NOT being a pushbutton.
The thing that isn't widely mentioned is that this trans still uses 2 cables, 1 cable does the park pawl.
So the console shifter has 2 cables going into it.

So in this situation, possibly 1 cable has somethign amiss at the shifter, or an adjustment at the trans? Something that is affected when the trans is pressurized (when engine is running and/or rear pump is pressurizing the trans.

I still think that the kickdown linkage is partially suspect. Combined with a cable misalignment and possibly some sticky valve body components. But what do I know.

 

[Big_John]

my first thought, it sat a lot. now needs to be driven a lot. stop and go with as much manual shifting as possible. all just seems to random to be any one thing.

That is a good point. The car has "loosened" up a lot since I've been driving it.

With it being random, it's harder to diagnose, that's for sure. At least the car is drivable the way it is. It's a little bit of a pain in the neck not to be able to downshift for the hills though. Lot's of hills around here...

I agree, it's hard to follow it. (but that's not your fault)

FWIW, most of us already know that 65 is 1 year only due to NOT being a pushbutton.
The thing that isn't widely mentioned is that this trans still uses 2 cables, 1 cable does the park pawl.
So the console shifter has 2 cables going into it.

So in this situation, possibly 1 cable has somethign amiss at the shifter, or an adjustment at the trans? Something that is affected when the trans is pressurized (when engine is running and/or rear pump is pressurizing the trans.

The '65 is a one year trans because of the cable shift and the tailshaft has a sliding yoke. Many years ago... I sold a '65 small block 727 to a guy that used it in a '34 Plymouth and he fitted a pushbutton shifter and it worked great.

I haven't double checked it yet, but I think the valve body is interchangable with at least '64, possibly '63.

The cable seems to be in adjustment... I screwed around with adjusting it in my '65 Barracuda and this one seems right. If it's not right, it won't go into gear.

I do think it's something that changes under pressure.

I still think that the kickdown linkage is partially suspect. Combined with a cable misalignment and possibly some sticky valve body components. But what do I know.

I did adjust the linkage (Dammit, it's not a kickdown!) because it was a little tight at full throttle. I haven't driven after that, but I don't think that's it. Sticky valve body bits really might be the issue though.

 

[3175375]

That is a good point. The car has "loosened" up a lot since I've been driving it.

With it being random, it's harder to diagnose, that's for sure. At least the car is drivable the way it is. It's a little bit of a pain in the neck not to be able to downshift for the hills though. Lot's of hills around here...



The '65 is a one year trans because of the cable shift and the tailshaft has a sliding yoke. Many years ago... I sold a '65 small block 727 to a guy that used it in a '34 Plymouth and he fitted a pushbutton shifter and it worked great.

I haven't double checked it yet, but I think the valve body is interchangable with at least '64, possibly '63.

The cable seems to be in adjustment... I screwed around with adjusting it in my '65 Barracuda and this one seems right. If it's not right, it won't go into gear.

I do think it's something that changes under pressure.


I did adjust the linkage (Dammit, it's not a kickdown!) because it was a little tight at full throttle. I haven't driven after that, but I don't think that's it. Sticky valve body bits really might be the issue though.

Sorry, I come from the land of Fords.

 

[rags]

went through post 19 line by line. seems like there are separate problems with the shifter mechanism itself and another problem internal to the transmission. governor? shifter always goes into first with the vehicle stopped. sometimes goes in with the vehicle moving:

The shifter was now stuck in drive, but car was in second gear. I could move the shifter to drive, first and second, but no change in gears....

"stuck in drive" meaning it wouldn't move to neutral? because it "could move to drive, first and second". "but no change in gears" due to vehicle speed? because when:

I put it in first and when I got down to ~25MPH, the car downshifted to first.

shows at least that the shifter can move into first under various conditions but there was this:

(stop sign) and just for laughs, I tried pulling it down to first and the shifter would not move to first. Stopped and I could shift to first again, so I tried it again and shifted it and this time

it seems that at first the shifter had some difficulty moving into first but as you were driving it the shifter action improved. oops, not so fast:

Around the corner and the shifter freed up to shift to neutral, but not to first. The trans also shifted normal at that point.

now it goes into neutral, but not first and now the transmission shifts normal. sometimes it's neutral and sometimes it's first. is there a connection between the transmission shifting normal when it can be shifted into neutral, but not shifting normal when it can be shifted into first? trying to find something consistent here. something going on in that spool valve bore? valve bore worn slightly causing the the valve to hang up but when it goes there's a pressure loss?

 

[fury fan]

The '65 is a one year trans because of the cable shift and the tailshaft has a sliding yoke. Many years ago... I sold a '65 small block 727 to a guy that used it in a '34 Plymouth and he fitted a pushbutton shifter and it worked great.

Dammit, yes. Forgot about the slipyoke being the main reason. Thanks for reminding me.

FWIW, many years ago I reviewed the 300L shifter and it looked like using only 1 cable could allow it to control a 66-up trans.

 

[fury fan]

The '65 is a one year trans because of the cable shift and the tailshaft has a sliding yoke. Many years ago... I sold a '65 small block 727 to a guy that used it in a '34 Plymouth and he fitted a pushbutton shifter and it worked great.

Dammit, yes. Forgot about hte B&T being the main reason. Thanks for the reminder.

 

[Big_John]

I had a talk with the previous owner this morning.

This problem has been going on for a while, even before he owned it (he bought in 2000) and going back to the owner before him, who bought it in 1993. His description of the issue matched mine.

He said he has talked to a bunch of folks that know these transmissions and none had any idea what's going on.

He did say "it has a 1976 pan on it".... and with that, we figure someone else has had their hands in it before anyone we know owned it. I'm wondering if there was either a rebuild gone wrong, or even a shift kit installed incorrectly. There's also the possiblity that it's been this way since day one and quite frankly, if you don't downshift (I do for the long hills I live by) you'd never notice it.

This is a little frustrating, but at least it's usable as it sits.

I think I'm going to video this as it's getting harder to explain and it may even help me out to understand what it's doing.

 

[3175375]

I had a talk with the previous owner this morning.

This problem has been going on for a while, even before he owned it (he bought in 2000) and going back to the owner before him, who bought it in 1993. His description of the issue matched mine.

He said he has talked to a bunch of folks that know these transmissions and none had any idea what's going on.

He did say "it has a 1976 pan on it".... and with that, we figure someone else has had their hands in it before anyone we know owned it. I'm wondering if there was either a rebuild gone wrong, or even a shift kit installed incorrectly. There's also the possiblity that it's been this way since day one and quite frankly, if you don't downshift (I do for the long hills I live by) you'd never notice it.

This is a little frustrating, but at least it's usable as it sits.

I think I'm going to video this as it's getting harder to explain and it may even help me out to understand what it's doing.

The fact that the pan is known to have been changed, leads me to believe that something else has changed - I am thinking valve body or as you mentioned, an incorrectly installed or applied shift kit.
Can you verify that the transmission valve body is indeed the year of manufacture?

 

[rkrochen]

Something to consider is maybe the original pan was damaged and had to be replaced. If this was the case there could be other components that were changed or should be. I still think I would pull the pan and check inside. At worst it gives you a chance to service the tranny.

 

[Big_John]

The fact that the pan is known to have been changed, leads me to believe that something else has changed - I am thinking valve body or as you mentioned, an incorrectly installed or applied shift kit.
Can you verify that the transmission valve body is indeed the year of manufacture?

Not without pulling it apart.

It has to be between 1962 and 1965 as those were the only cable shift transmissions. What I need to do is compare part numbers in the parts book and see if that leads me anywhere.

 

[fury fan]

I think I'm going to video this as it's getting harder to explain and it may even help me out to understand what it's doing.

And/or make a chart of all the conditions?

engine running yes/no
car moving/stationary
shifter moves into 1, yes/no
etc, etc, etc...

 

[D Cluley]

I think fury fan is right, time to start a spreadsheet.

The next thing I would do is jack up the rear end and see how it behaves while "driving" without going anywhere and check the pump pressure & governor pressure in different gears and speeds.

Don't know if it helps, but here are some photos of mine when we had it apart last year.

 

[rags]

time to start a spreadsheet.

what do you think the chances are that there's a problem related to the manual shift spool valve. if the shifter stays in the range between park and second the the transmission will shift automatically with no problems. once the shifter is moved past second into low it gets stuck in a range between drive and low and the transmission will not shift correctly. that spool valve is one thing that could cause both issues. shifter hanging up then not shifting automatically after the shifter is moved in to a certain range.

 

[Big_John]

what do you think the chances are that there's a problem related to the manual shift spool valve. if the shifter stays in the range between park and second the the transmission will shift automatically with no problems. once the shifter is moved past second into low it gets stuck in a range between drive and low and the transmission will not shift correctly. that spool valve is one thing that could cause both issues. shifter hanging up then not shifting automatically after the shifter is moved in to a certain range.

This makes a lot of sense.

 

[C-440-300]

Hello, Big John, Did it work out?

 

[Big_John]

Hello, Big John, Did it work out?

The plan is to change the valve body and see what happens. I haven't had a chance to do that yet. I had hoped to do it this week, but the heat hasn't done much to motivate me.

 

[fury fan]

Using this pic from @D Cluley, I would recommend checking this first, as you need do all of this to change the VB anyway.

Disconnect the shift cable (lime color) and rotate the lever arms out of the way. See if the shift valve moves freely, you should feel some spring pressure behind it, too.
Presumably the pivot shaft for the levers is removable in order to remove the VB, if you can remove it, the shift valve might clear the panrail with the VB in place.
The valves in the pic above look to be steel, so any scoring might only be in the VB bore?

Also verify that all of the circular edges on the valve are fairly sharp. It's counter-intuitive for sharp edges, as we usually like nice soft chamfers.
But sharp edges prevent a spec of debris from lodging in a chamfer. (I learned this from some experts on a modern AT trans, but I presume sharp edges are a universal rule?)

So if this problem that occurred in the past was determined to be shift-valve related, and fixed by a well-meaning 'blueprinter', who saw fit to remove those sharp edges to fix the problem - there might be the same problem but for a different root cause. Especially if there's scoring in the bores, which gives a larger debris-trap if the valve edges have been softened. (but if so - VERIFY if sharp edges were in use 50+ years ago!)


As @Davea Lux said:

there is a test port on the tail shaft housing to check governor pressure. At idle it should read about 2psi. With the rear wheels off the ground, the pressure should increase about 10psi for each 10 mph.

The fact that you cannot shift the lever into 1st above a certain road speed makes me wonder if there's some excessive pressure (or cross-talk) somehow blocking the valve until that pressure drops below a threshold. You should be able to shift the lever into 1 at any speed, but the trans will not perform the shift until it's possible.

And it's entirely possible you have 2 problems here. If the trans was rebuilt at a 'service' shop as you mentioned - maybe they weren't savvy to find all the problems.
As economist Thomas Sowell once said - 'They found what they were looking for, why would they look any deeper?'

 

[fury fan]

@D Cluley
This pic seems not correct for a 65 trans, it shows a rooster comb, which would be used in a 66-up unit.
1965 has the detents in the shifter mechanism.
But thanks for the effort of finding and posting the pics, they are surely helpful to whomever reads this.

 

[D Cluley]

Those pics are of my actual transmission, so I hope it's right for a '65.

Looking at this 3 pin reverse / neutral safety switch into a 1965 727 push button transmission the earlier 727 combs are shaped a little differently, but still have teeth.