1964 Dodge Dart 904 transmission stopped working

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oneaveragejohn

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Ok sounds have a 64 dart 225 slant six with i believe a 904 transmission. Motor has been rebuilt and is running great. We drive it about one a month between 1-2 hour drives. I moved the other day and drove it to our new house 1.5 hr away mostly 55mph. No issues there. The next weekend i noticed it was have trouble getting into gear. I let it warm up a little longer and didn’t have anymore issues. So the next time i took it out the only way to get it into any gear was high revs, 3-4K. Drove it around town and somehow made it into my garage by high reving it into gear. Now nothing! Can’t get any gear at all. Things i have checked:

Throttling cable- no issues
Push button gear selector- no issues up top or on tans
Drained and removed filter and replaced- no big metal chunks. Just usual soot. But clean
Put everything back and filled and turned car on, warmed up and had to add more fluid to get to level while warm which i assume means pump is working.

Please help! I don’t have much knowledge on transmission like i have on engine as we always stayed away from them
 
Does reverse work? I'm no expert by any means but when I was in high school I rebuilt 12 727's-904's in the vocational auto mechanics class I took in my senior year. In fact my first car was a 71 Demon with a bad 727 and the teacher had me rebuilding it the 2nd week of class. Great teacher cause he had no lesson plans...just bring it in and tear it down. EVERY single one of them had the same problem which was the piston seal for 1st/reverse had failed. Over the years people rebuild these with all kinds of non-OEM parts including throttle kick-down cables instead of the stock linkages so who knows what the problem could be but just my 2 cents.
 
ACME SS said:
Does reverse work? I'm no expert by any means but when I was in high school I rebuilt 12 727's-904's in the vocational auto mechanics class I took in my senior year. In fact my first car was a 71 Demon with a bad 727 and the teacher had me rebuilding it the 2nd week of class. Great teacher cause he had no lesson plans...just bring it in and tear it down. EVERY single one of them had the same problem which was the piston seal for 1st/reverse had failed. Over the years people rebuild these with all kinds of non-OEM parts including throttle kick-down cables instead of the stock linkages so who knows what the problem could be but just my 2 cents.
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It sounds to me like the lip seals have reached their end and would need to be replaced. I'm no builder but have been around enough good builders to pickup the odd piece of advise. A slipping transmission is indicative of lip seals going away. If the transmission has a lot of miles on it, probably a good time to get it rebuilt.
 
Sounds like maybe it got low on fluid and you continued to drive it. I would guess the transmission is done. You know that high revving it was doing? Yup, they cannot take that kind of abuse long, much less "driving around town". Your transmission was telling you something was wrong. You didn't listen.
 
Just had my 904 rebuilt in my 64 Valiant. Similar symptoms after a drain and filter replacement to replace a leaking park cable. Slow degradation of responsiveness until no drive at all.

Pictures of the clutches that were removed are attached here. There was also some unexplained damage inside the tail housing. There was minimal metal in the pan when I pulled it.

There are a number of checks you can do with a pressure gauge externally (the test points are on the passenger side of the case) but it does sound like the transmission is just tired and needs a rebuild. There are some "cheat codes" to get a few more miles out of it but not sure that's what you want to do. There are tech manuals that provide a matrix of symptoms and probably causes. IF the transmission is truly a 64 (check the stamp on the side of the oil pan) then a front or rear pump can contribute as well.

Good luck to you.

clutch pack 1.jpg


clutch pack 2.jpg


Tail housing.jpg


Screenshot_20230119_154951~2.jpg
 
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Buy this book written by @VOETOM. https://www.abebooks.com/servlet/BookDetailsPL?bi=30284411690&cm_sp=snippet-_-srp1-_-tile4&searchurl=ds=10&kn=904+transmission&sortby=17
Read it twice cover to cover. It is indispensable and worth every penny. Buy the parts and take advice from A and A Transmission. Overhaul it yourself. You CAN do it. On zero experience, I just did mine for less than $500 before buying a torque converter. I installed a mild shift kit and replaced both the kickdown and reverse bands.
 
Ok to answer a few questions from your guys comments,

-No gears at all

- fluid level perfect on warmup in neutral

- i did also have a leaking gasket on parking cable but i made sure to always check levels before driving

- the tranny has been rebuild once so it makes me think the clutch plates should be fine as it ran maybe 15k miles since the rebuild

Also what is this lip seal your talking about?
 
get some fluid off the dip stick and see if it smells burnt. Has the transmission ever been rebuilt??? They can last a long, long time, but not forever...
 
Even if you got lucky and it's a lip seal, the transmission still has to come out. I think you're gonna find out it's done and over with.
 
oneaveragejohn said:
Ok to answer a few questions from your guys comments,

-No gears at all

- fluid level perfect on warmup in neutral

- i did also have a leaking gasket on parking cable but i made sure to always check levels before driving

- the tranny has been rebuild once so it makes me think the clutch plates should be fine as it ran maybe 15k miles since the rebuild

Also what is this lip seal your talking about?
Click to expand...
I believe the lip seals they refer to are on the pistons inside the clutch retainers. You really should get this book. It will help you understand the advice you get on this forum. It has in-vehicle tests you can do with compressed air and a troubleshooting section. Based on your symptoms, it could be a ton of things. This book will be the single best investment you make into your transmission at $28.00 https://www.summitracing.com/parts/sad-sa394

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He's described what happened perfectly, but he doesn't want to hear what it is. It went out a little at a time. It started slipping. He should have shut it down then and there but continued driving until it will not move at all. That spells fried forward clutches any way you slice it. Even if by some miracle it is a leaking lip seal, the transmission still has to come out and completely apart......but that's not what it is. The transmission is burned up.
 
I wouldn't call them lip seals, although technically they are a lip seal. The pistons for the clutches have a rubber seal (lip) that when not torn or brittle will engage the piston and squeeze the paper and steel plates together. Yes, those red coated round dohokies in the picture above a ways are made from paper. When the seal is torn, worn, burnt, whatever, the plates slip and the car goes nowhere. Reverse and first are both actuated by the same piston, depending on if a band is holding the outer carrier or not (planetary gears). That is why I asked if reverse is working. Tear it down and put a full kit in it with new bands, etc. It is beyond mechanic in a can.
 
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