904 trans won't UPshift to 3rd gear

[Kern Dog]

I have a 67 Dart with a 360 and a 904. That 904 was in my red Charger when I bought the car in 2000.
The 904 currently won't upshift to 3rd but is otherwise just fine. It goes into gear fine, reverse works as always too. I've had Chrysler automatics that lost 3rd and reverse at the same time, I've had them lose all gears at once but I don't recall ever losing just 3rd/drive.
I've messed with the throttle pressure linkage (kickdown) but it doesn't seem to make a difference. It has been awhile since I changed the ATF and the filter so I'm going to try that. The fluid level is on the mark.
Is there anything else to look at? Be warned, I know a little about the guts of a transmission but I am no expert!

 

[451Mopar]

I had that happen once, one of the fluid channel walls in the valve body cracked and I lost 3rd gear. I was at a friends house 200 miles from home, and repaired with JB weld epoxy and it worked to get me home, and then some before I replaced the valve body.
My problem might not be the same as yours.
With the valve body removed, pressure check the front clutch, and front servo

 

[Kern Dog]

Thanks!
As I mentioned, I know a little but not a lot. I've replaced valve bodies, turned up the line pressure, done fluid and filter changes to transmissions but not much else.

 

[dvw]

Does it just stay in 2nd? Or act like its in neutral when it tries to make the 2/3 shift. I'd get some pressure readings before changing the fluid. Very doubtful a fluid change will help. In 3rd gear you should see line pressure (50-90 depending on how much throttle) on the KD servo pressure tap (very front tap). This port reads forward clutch pressure. This pressure pushes on the KD servos release side while apllying pressure to the forward clutch. Also check governor pressure (tap is in the tail housing). It should be roughly 1 psi/mph. I have also seen cracked valve bodies. But not for this issue. In the 45 years I've been doing Torqueflites ther have been 2 with cracks.
Doug

 

[vance.dykes]

Doug is correct and you could remove the valve body and do an air test this is in the factory service manual.

 

[493 Mike]

I think you will find the front clutch piston seals worn out.
Mike

 

[Kern Dog]

Does it just stay in 2nd? Or act like its in neutral when it tries to make the 2/3 shift.

It just hangs in second gear as if I have the shift lever stuck in place.
I drove it today and it did the same thing. Imagine the revs at 55 with a 4.10 diff and no third gear.
I drove maybe a mile and a half and came back home. Now with it warmed up, I checked the fluid again.
ADD one quart.
Okay, I did. Out for a test drive and…..
It did finally kick into 3rd. I drove around a bit and it seems to be fine now. I don’t recall another car that was so sensitive to one quart of ATF. Maybe the dipstick tube is too short, giving me the false impression that I’m okay on fluid level when I am actually low?
It could happen. I’ve traded parts around for years and sometimes a combination of slight errors leads to this. The dipstick reads above FULL now but the transmission is shifting.
Another thing… I just remembered today that THIS was the first transmission that I worked on after reading a Mopar Action article entitled “Get your *** in gear” written in the early 2000s.
In the article, it showed how you can improve shift firmness by removing the accumulator spring and turning UP the line pressure. I also did this to other Torqueflites that I’ve had and one side effect I’ve noticed is delayed upshifts. Jigsaw has the 727 from the red car and it performs the same despite a 100 cubic inch difference.

 

[dadsbee]

Sounds like the '76 Volare the Wife and I bought off her Mom in '84. Had sat for probably 4 years and it took 15 miles before it came out of second and never skipped a beat there after...

 

[Kern Dog]

I was all ready to pull the pan.

 

[Geoff 2]

The front clutch is engaged for Reverse & Drive. So if you are getting 1 & 2 when in D, & also getting Rev, rules out the front clutch.