Another "no shift" 727

[Martin Shows]

Ive searched the forum and have found a lot of useful info, but I thought I'd run my problem by you guys again. My 727 (TCI, est. 10k miles since new) will not upshift at all, manually or in "D". It did this a few weeks back, after turning back to head home it finally made the shift and was fine for the rest of the day. All shifter linkage is adjusted perfectly,shifter works great. I've readjusted the kick down "throttle pressure" linkage (aftermarket cable type) in every imaginable adjustment, still no upshift. I have disconnected the throttle pressure cable completely, still no upshift. Fluid level is fine and fluid appears clean. I have the car on jack stands and have pulled 3500-4000 rpm trying to shift manually and in D, still no upshift. From what I'm reading, the most likely suspect would be a sticking valve in the tail housing or possible a valve body issue. I'm no transmission guy, what would be the first thing that you would check to diagnose the issue? I'm hoping that the fix would be as simple as dropping the pan and unsticking a piston or something of that order, suggestions for a transmission novice? Thanks

 

[Fran Blacker]

I assume you have low and reverse? The post is out of the service manual. It's a process of elimination. See if DVW chimes in he is very knowledgeable.

 

[Martin Shows]

Yes, low and reverse are good with no issues. Thanks for the check list, but I'm looking for the "most probable" cause of the problem, excluding those that I've already checked as mentioned in my OP. Thanks again for the input!

 

[Fran Blacker]

I had the same problem it was h on the list. Go My Mopar and down a service manual. There is an air test if you remove the valve body. It works some of the internals. The h is down on the list. dvw should have some input on this. 2/3 clutch pack seal small crack in it. Could hear it leaking when I did air test, see service manual.

 

[RT K_line]

I learned a little trick from a builder when I was doing transmissions back In the day. Don't know if you want to try it. It frees up a sticking governor valve and I've done it and know it works if it's a little hung up. Take the car out on an open road above 30 mph then throw it in park for a split second. Just up and back down that quick, now it will make a racket but won't hurt anything if your quick and deliberate. If the problem is in the governor valve it will usually start working again.

 

[Yatzee]

Ive searched the forum and have found a lot of useful info, but I thought I'd run my problem by you guys again. My 727 (TCI, est. 10k miles since new) will not upshift at all, manually or in "D". It did this a few weeks back, after turning back to head home it finally made the shift and was fine for the rest of the day. All shifter linkage is adjusted perfectly,shifter works great. I've readjusted the kick down "throttle pressure" linkage (aftermarket cable type) in every imaginable adjustment, still no upshift. I have disconnected the throttle pressure cable completely, still no upshift. Fluid level is fine and fluid appears clean. I have the car on jack stands and have pulled 3500-4000 rpm trying to shift manually and in D, still no upshift. From what I'm reading, the most likely suspect would be a sticking valve in the tail housing or possible a valve body issue. I'm no transmission guy, what would be the first thing that you would check to diagnose the issue? I'm hoping that the fix would be as simple as dropping the pan and unsticking a piston or something of that order, suggestions for a transmission novice? Thanks

Drop the pan and check that the retaining clip for one of the servo pistons has not poped out of it's groove or the piston has not tilted. If this is the case, there will be no pressure on the arm that engages the band, and no shift. The TCI shift body applies a lot of pressure really quick ( for quick shifts ) and the cir-clip for the servo cannot handle the piston when it moves that fast. If this is the case, there is a fix available which includes a new thicker piston that can't tilt in it's bore. Never reuse an old cir-clip. View the downloaded instructions for you shifter body and ensure the one port in the case below the shifter body has been plugged or restricted per instructions for you shifter body. If none of the above is the problem, check your pressures as per the transmission manual and/or consider the pumps pressure and volume output.

 

[miller]

Thanks for the check list, but I'm looking for the "most probable" cause of the problem

Probable cause could be anything on that list. Could be something simple, or not, but it will take pulling the pan...and look.

 

[hangn0ut]

I learned a little trick from a builder when I was doing transmissions back In the day. Don't know if you want to try it. It frees up a sticking governor valve and I've done it and know it works if it's a little hung up. Take the car out on an open road above 30 mph then throw it in park for a split second. Just up and back down that quick, now it will make a racket but won't hurt anything if your quick and deliberate. If the problem is in the governor valve it will usually start working again.

Now thats down and dirty!!!

 

[khryslerkid]

I learned a little trick from a builder when I was doing transmissions back In the day. Don't know if you want to try it. It frees up a sticking governor valve and I've done it and know it works if it's a little hung up. Take the car out on an open road above 30 mph then throw it in park for a split second. Just up and back down that quick, now it will make a racket but won't hurt anything if your quick and deliberate. If the problem is in the governor valve it will usually start working again.

 

[dvw]

If it doesn't upshift governor pressure is not overcoming throttle pressure. The is a governor pressure tap to see if you have enough, or any governor pressure. pull the plug and screw a gauge in. If it has correct governor pressure I see a valve body issue. Band, clutches, rings oil pump etc would not in my opinion lose 2nd and 3rd gear. The governor valve is in the tail shaft., not in the pan.
Doug

 

[Fran Blacker]

dvw isn't the rear clutch engaged in 2nd and 3rd gear. I'm not disagreeing with what you said what you mention is the best place to start. I've posts you put and there spot on.

 

[Martin Shows]

Sounds as though governor pressure may be the first thing that I should check. Any idea what pressures I should be looking for at idle, xxxx RPM, what gear to check pressure in, etc.?? Thanks to all for the info.

 

[dvw]

dvw isn't the rear clutch engaged in 2nd and 3rd gear. I'm not disagreeing with what you said what you mention is the best place to start. I've posts you put and there spot on.

Yes, but also in 1st gear. 2nd requires the KD band and rear clutch, 3rd requires both clutches. neither 2nd or 3rd function. Highly unlikley that both a clutch and band failed together at the same time.
Doug

 

[Martin Shows]

I learned a little trick from a builder when I was doing transmissions back In the day. Don't know if you want to try it. It frees up a sticking governor valve and I've done it and know it works if it's a little hung up. Take the car out on an open road above 30 mph then throw it in park for a split second. Just up and back down that quick, now it will make a racket but won't hurt anything if your quick and deliberate. If the problem is in the governor valve it will usually start working again.

That did it, light bump into Park at idle on jack stands, back to Drive, shifts perfectly! Stuck governor I guess, thanks!

 

[RT K_line]

That did it, light bump into Park at idle on jack stands, back to Drive, shifts perfectly! Stuck governor I guess, thanks!

I'm glad it helped you in this case. I know that it's a little unorthodox but works in some cases. I would still drop the pan to check for excesive material in the pan and change filter to the fiber type if your using a screen type.