904 "sometimes" shifts into drive

[Rusty 72]

Hello all,

I have a 68 904 that I rebuilt and put in a 1972 Charger. I replaced all the seals, bands, and clutches. I pressure checked everything after rebuilding and all seemed good. Now I am having an issue where it will shift 1-2 perfect, but only 2-3 sometimes? It'll shift 2-3 in the morning when its cold but once it warms up it doesn't want to shift 2-3. The original KD linkage is gone and I am using a cable set-up. I checked the governor pressure and it was 0psi at idle, approx 30psi at 30mph, and 50psi at 45mph. I didn't go over 45mph because the rpms were getting up there. It's shifting 1-2 around 15mph, and when it does shift 2-3, it's about 30mph.

The fluid looks nice and clean still. Could it just be under filled? I am following the dipstick and was worried too much fluid would aerate like the book says.

Thanks in advance! Jeanette

 

[1 Wild R/T]

Did you adjust the pressure regulator setting on the valve body? If the pressure regulator is high the governor pressure will have a hard time overcoming it... even if the throttle pressure is low....
As far as not going over 45 unless you have low gears like 3.91 or numerically higher when you hit the throttle & the trans downshifts it will typically hold second gear to 70+ MPH.. I'd go drive it & confirm 3rd gear does kick in before 60 under light throttle...

 

[Rusty 72]

I just have highway gears. Okay I will test it out up to 60mph.

I did attempt to adjust the line pressure/throttle pressure. The book I used for the rebuild got a little wordy with those adjustments. It read that the throttle pressure should be adjusted before the line pressure. Is there a more simplified description for those adjustments?
Thanks for the help!

 

[1 Wild R/T]

The three pressures all work together/in opposition of each other....

The line pressure doesn't have an external adjustment so suggesting it should be adjusted after the throttle pressure is weird...

I have seen people add a small hole through the case in line with the line pressure adjustment but thats typically for fine tuning a shift kit...

On a stock overhaul you normally set the pressure based on a measurement..

A sticky 2-3 shift valve or a sticky governor could cause your issue too....

Again take it out & drive it, also sometimes manually shifting the trans sometimes will free a sticky valve/governor..

 

[Dave6T4]

Is it just me, or does it seem that a lot of the threads where OP has shifting problems with a Torqueflight they also have cable kick down conversion?

 

[multimopes]

I have a reverse manual valve body with the B&M cable setup & indeed, my trans went south as well. I am in the process of procuring a replacement tranny right now!

 

[Dave6T4]

I have a reverse manual valve body with the B&M cable setup & indeed, my trans went south as well. I am in the process of procuring a replacement tranny right now!

Usually a manual shift valve body does not need a kick down cable. The governor circuit is bypassed. Or, are you talking about B&M shifter cable?

 

[multimopes]

talking about B&M shifter cable?

Yes, I have no other kick down rod or cable. Trans was built for racing.

 

[Rusty 72]

Okay I'm back, I had to find a free day to take it out on the highway. At 60mph it's at 3,000 RPM. If I let off the throttle it goes down as it should but if I give it more throttle it goes right back to 3,000 at 60mph.
I'm pretty sure that's not direct drive.
I'm thinking the 2-3 shift valve isn't stuck because it does go into drive when it's cold. The other morning it was cool out and it shifted normally, went into 2nd, then drive as it should. It's only once it warms up that it "slips" out of drive.
So maybe I wasn't as precise with the initial throttle/line pressure adjustment when I rebuilt it. I'm using Type F trans fluid also.

P.S.
The kick down linkage was gone when I got this car. I had it towed to my house. (Probably why the trans was smoked when I got it). So I'm not using a cable set up by choice. Just FYI. I'm just trying to get this clunker back on the road for a reasonable price. It's not in my budget to buy a repop KD set-up at this time.

Thanks Jeanette