727 Wont go on to second or third

[BayArea67GTX]

Hello Mopar community, I am putting this out there to see if the forum universe can help.
I have a 727 transmission (67 GTX, 440) that won't shift up to second/third. First and reverse run great. My fear is that there is an issue with the valve body. I have another period correct valve body but seems to be missing a Throttle Valve (part number 1636 423). Any recommended transmission gurus in the Bay Area? Any recommended aftermarket plug and play valve bodies? Any recommended full valve body rebuild kits?
Thanks for reading.

 

[Fran Blacker]

A service manual in the trans section has trouble shooting and what's engage or disengage for gears. Service Manuals – MyMopar

 

[Fran Blacker]

From 67 Service manual

 

[Rebelrouser]

You need to put a pressure gauge on it to see what's up. If pressure is getting to the friction elements, then it is a mechanical problem. When you test drive it, run it up in D and when it does not shift let off the gas quick, if it does not pull the engine down, engine will drop to idle speed, most likely it is a governor issue. again, there is a port for checking governor pressure. Harbor freight has reasonable gauge sets. Torqueflites are probably the easiest trans to diagnose mainly because they have so many pressure ports. Governor pressure as you accelerate equals speed until about 65 lbs as I remember. Shift valves are balanced between throttle pressure and governor pressure, governor pressure has to overcome throttle pressure to get the shift valve to move.

 

[Rishi]

Hello Mopar community, I am putting this out there to see if the forum universe can help.
I have a 727 transmission (67 GTX, 440) that won't shift up to second/third. First and reverse run great. My fear is that there is an issue with the valve body. I have another period correct valve body but seems to be missing a Throttle Valve (part number 1636 423). Any recommended transmission gurus in the Bay Area? Any recommended aftermarket plug and play valve bodies? Any recommended full valve body rebuild kits?
Thanks for reading.

For full transmission rebuild, with new clutch disc, band, and so forth. I like the B&M Trans Kit #10229. It's pricey at $500 but a complete rebuild with the kit would fix your problem or diagnose it, and give you nice hard shifts to boot. If you decide to go this way, let me know. I live nearby and may have some tools you'll need.

B&M 10229 B&M Transkit - Mopar A727 Automatic Transmissions

 

[Rishi]

I'm curious if the transmission has a history of shifting correctly? If the tranny has not shifted correctly for a new owner, there may be some things we can look at.

If so, I recommend we start with making sure the throttle pressure linkage is functioning and correctly adjusted.

 

[Cranky]

Had a newly rebuilt trans where the governor stuck....I had just bought the car with the newly rebuilt trans and the shop that did it said to bring it back in and said that's what was wrong. It did fine when I first got it until a few days later when it did the same thing yours is doing. Has the trans been running fine up until now or has it been running fine for a good while?

 

[Tinker67]

I had this very same thing happen to mine last year. Upon pulling the pan, found end of the lever for kickdown band laying in the pan. Freak thing but it does happen. Funny thing was I drove the car in the morning. 4hrs later got in hit the street and no shift.

 

[Dave6T4]

I am voting for situation "l" on post #3. Broken seal ring on the output shaft. This allows fluid pressure to bypass the governor circuit. I have seen this personally, and the result is the transmission will not shift out of first gear.

 

[Wietse]

For all you know it's a manual valve body..?

 

[dvw]

Easy way to tell. Screw an oil pressure gauge into the governor pressure port in the tail shaft. Run the car in gear (can be on stands). If you see little or no pressure you have a governor/governor seal ring issue. Pressure will roughly mimic vehicle speed with a 3.23. More gear ratio will lower readings slightly.
Doug

 

[BSB67]

When did you start having the problem? Was it auto shift before the problem or was it a manual shift?