Need some 904 trans help

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Thanos

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When I bought this car it had a problem shifting from 2nd to 3rd. I had to rev it high to get it to shift. I figured it was the kickdown as I had had this problem on another Mopar and sure enough there was no spring attached to the kickdown. Somebody in the past had put an Edelbrock 1406 on and didn't attach a return spring. I rigged a clip and spring to the kickdown lever and the car would now shift but it shifted within a few seconds from 2nd to 3rd. I thought I’d get to it later, added a bottle of Lucas as it was low and tore into the front to rebuild the suspension and brakes.

After the rebuild I had the car out and at a red light I lost all gears. I had to rev it high to get it going. Luckily I wasn’t far from home. I checked the fluid, not burned and at full. I knew this was a good sign that I didn’t have a burned up trans. Dropped the pan and found a thin layer of sludge. Ran a magnet thru and didn’t pick up much metal, no big pieces, but the filter had a sticky sludge layer at the bottom. Removing the filter I found a hard dry layer of sludge at the top. I’ve seen this before on cars that have sat a long time, condensation will build up on the filter and the sludge hardens when dry. I dropped the valve body and tore it down to clean, carefully laying all parts out so I could reassemble in reverse. I learned from the trans numbers that it was out of a 1978 Volare and had lock up converter. It wasn’t too bad, some crap caught in the strainer. With everything clean and new shift and kickdown gaskets (as one or both were leaking) I adjusted the front and rear bands. Front tightened to 72in then backed off 2 turns, rear 4 turns. New filter, gasket, cooling lines, neutral switch and since I had it up added new u-joints.

I knew I had drained over 5qt from the trans (at least that’s what I caught) an picked up a bottle of Lucas and 6qts of ATF+4 just to be sure. I added 3qts in to start with then started and put into neutral. I felt it shift into reverse so I knew things were much better and added the bottle of Lucas. It took 2qts more before it was in the full zone.

It shifted into reverse as soon I hit it and backed out of the garage. Put into drive and took off normally. 1st to 2nd was good but when it shifted to 3rd it instantly dropped back to 2nd and then back to 3rd. It did this every time I stopped and started going or slowing and dropping back to second then accelerating to 3rd. Where do I need to look here? Kickdown? I’m thinking I need to back off the kickdown but the adjuster threads are frozen and I soaked it in PB anti-seize but I still can’t get it to turn. Could the spring be too tight? I’m entertaining all replies.
 
What are you doing with the gas pedal during this up and down shifting?
Are you pushing the gas even a little bit more right after it goes into third?

AND there are two springs that look a lot alike but they have different tensions, but I don't remember which ones they are.
(the 1-2 shift valve and the shuttle valve I was thinking?)
 
I think you got some springs mixed up in the VB?
Ima guessing
Believe me the thought has crossed my mind but like I said I laid it all out in sections and snapped a few pics and I had pics of what I should see and find the way. There were only 3 springs that I had removed. I only separated the two valve body halves so I only had 3 springs to deal with the 2 near the shift and one in the VB under the steel separator, some kind of spring/ check valve. It was really obvious where they went.
 
What are you doing with the gas pedal during this up and down shifting?
Are you pushing the gas even a little bit more right after it goes into third?

AND there are two springs that look a lot alike but they have different tensions, but I don't remember which ones they are.
(the 1-2 shift valve and the shuttle valve I was thinking?)
The two springs I found at the shift are totally different, size wise and tension. I'm only holding down the accel enough to gain speed and not even half peddle. I guess I should have put in there that when it does the 1-2-3-2-3 shift it then stays in 3rd unless I floor it and it downshifts but then after letting off it shifts to 3rd normally. But from a full stop this happens.
 
There is a fight going on in the VB. The governor is calling for a shift into 3rd. The valve responds. and the 2-3 shift is completed. Immediately the throttle pressure is sufficient to command a downshift, and the 3-2complies.The problem is the 2-3 shift valve is not supposed to do that. When it drops into drive, throttle pressure that was relayed around to the other end of the plug is supposed to be dropped out. For some reason this is not happening. Either the valve is sticking, is slow to move or perhaps the PT kickdown valve is interfering. In any case the problem is in the VB and I see it as the 2-3shift valve or the PTKD valve.
Stick around a bit. I'm not the brightest bulb in the economy pack when it comes to diagnosing Tfs. Hopefully someone brighter will chime in shortly.

EDIT
I was just checking out the FSM, and it occurred to me that the shuttle valve might be stuck. I think it is supposed to momentarily dump governor pressure during the shift. Hmmmmmmmmmmmmmmmm, I wonder.I have taken apart quite a few VBs with stuck shuttle valves.
 
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Stick around a bit. I'm not the brightest bulb in the economy pack when it comes to diagnosing Tfs. Hopefully someone brighter will chime in shortly.

Or with a better memory in my case.
It's been almost 30 years after all. :D

Your take on it sounds about right to me though.
I would feel a lot better if it was nice and rinsed out and all the valves checked for free movement.
After what he found in it, it's possible some piece of junk came loose and is hanging things up.
 
There is a fight going on in the VB. The governor is calling for a shift into 3rd. The valve responds. and the 2-3 shift is completed. Immediately the throttle pressure is sufficient to command a downshift, and the 3-2complies.The problem is the 2-3 shift valve is not supposed to do that. When it drops into drive, throttle pressure that was relayed around to the other end of the plug is supposed to be dropped out. For some reason this is not happening. Either the valve is sticking, is slow to move or perhaps the PT kickdown valve is interfering. In any case the problem is in the VB and I see it as the 2-3shift valve or the PTKD valve.
Stick around a bit. I'm not the brightest bulb in the economy pack when it comes to diagnosing Tfs. Hopefully someone brighter will chime in shortly.

EDIT
I was just checking out the FSM, and it occurred to me that the shuttle valve might be stuck. I think it is supposed to momentarily dump governor pressure during the shift. Hmmmmmmmmmmmmmmmm, I wonder.I have taken apart quite a few VBs with stuck shuttle valves.
I was thinking something along those lines. Since I didn't disassemble the rear tail where the governor is something may have made its way there and is causing a problem. I have only driven the car once after completing this and I may need to drive it a few more times under different conditions to see what happens. Just want to make sure I'm not gonna tear something up with it in this condition and be too far from home to push. If I need a new trans so be it. Its obvious that it was not serviced for a long tome. I just really hate dropping transmissions and its really hot this summer here in Florida....
 
Well I'll be durned... I went home for lunch and started up the Demon, letting it run for a few mins. Put it in neutral and checked the fluid. Its half way down the add pint mark. Added 2 pints to get it to full zone and drove back to work. Guess what...its fine now. Thanks for all the input guys, I was really sweating it. :thankyou:
 
Yeah, I guess that shoulda been question #1
Glad it worked out for ya. I woulda been real embarrassed if you woulda dropped it and found nothing wrong
SoI am double glad

Most people tell us it's full of fluid anyway, even if they didn't make sure.
 
Yup its embarrassing. But in my defense I did let the car run for about 20 mins in neutral while I added the fluid in and I was under the assumption that I would only need what I took out since it had been full (another mistake) and not wanting to overfill when added in the 6th qt and it said full I really thought that was it. I also didn't take into account the fluid in the lines or the radiator that I blew out before putting in the new lines. I guess it took awhile to get the fluid to all the places it needed to be. I happily take this humiliation over dropping that transmission.
 
Yup its embarrassing. But in my defense I did let the car run for about 20 mins in neutral while I added the fluid in and I was under the assumption that I would only need what I took out since it had been full (another mistake) and not wanting to overfill when added in the 6th qt and it said full I really thought that was it. I also didn't take into account the fluid in the lines or the radiator that I blew out before putting in the new lines. I guess it took awhile to get the fluid to all the places it needed to be. I happily take this humiliation over dropping that transmission.

Happens to the best of us. :D
One thing about checking trans fluid is that it gets fluid on the stick just from it going down the tube when fluid has been added and can trick ya.
I always dip it three times in a row very quickly in and back out, as well as check both sides of the stick.
Then I'm pretty sure it's accurate if it reads the same all three times.

One thing that helped was I twisted the very tip of the dipstick so it doesn't slide a flat side down the inside of the tube when it goes in and pick up a bunch of fluid on it.

This isn't my trans stick but it shows the twist idea over a flat stick.

stick.jpg
 
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