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Early '70's A727 valve body questions

Shade Tree Mech

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Gentlemen, experts too, This forum is the best I can do for my early 70's motorhome. It has the info I need for the Dodge running gear. The trans had fried and melted the clutches in the rear clutch pack. I have seen many causes for this condition in the forum here, the manual, and in other net postings. I will replace the pump with OEM parts to get the pressure back up. No, I didn't check before I disassembled. (First timer, learning as I go.) I have modified the valve body in accordance with instructions in the TF-1 TransGo kit. While cleaning, I found that the 'regulator valve throttle pressure plug' was sticking. It was not a contaminant. It was a fit issue. I polished the plug in the lathe with some 1500 grit paper. It took a few iterations and a couple hits with a fine Cratex wheel on a Dremel tool to bring the clearance to a sliding fit. I was not able to measure the difference with a .0001 reading micrometer. Note: The sliding valve components are deeply hardcased and extremely hard at the surface. They were easily held in the chuck jaws without any indications of marring on the surfaces of the valve bosses. Light jaw pressure, of course.
Now, the question: Is the sticky 'regulator valve throttle pressure plug' coupled with the low pump pressure the likely/obvious source for the rear clutch failure?
Next: There is an additional subassembly attached to the valve body that is not identified in the TransGo instructions. It is attached to the valve body directly above the 1-2 and 2-3 shift control valves. In it, are at throttle valve and a limit plug. In Mr. Munroe's book, it is described as "used in some V-8 models." Question: Will this additional subassembly interfere with the functional intent of absolute shift control incorporated in the TransGo TF-1 modifications?
Finally, Imagine yourself at the wheel of a 14,000 lb lumbering inverted bathtub. You are approaching a steep grade. I.E. typical white knuckle grade, say, 7% for the next five miles. The old beast is equipped with the latest early '70's vintage brakes, and as you enter the slope, everything is fine. The slope gets steeper, and you know the brakes are heating up. Thirty seconds later, they start to fade. You downshift to second. Then you realize you should have gone to second before starting the whole deal. Too late for that now. Second kicks in ok. You're fine. Thirty seconds later, brakes are fading again. Speed is fifty plus. Your only option is to drop it into first. Question is: What will happen given the instructions in the TransGo modification sheet to not modify the '1-2 shift valve governor plug' when the trans is used in heavy duty applications. I missed that part of the instructions. I did the modification. That's where I found that the valves are hardcased. According to the instructions, the transmission will shift to first no matter what the speed. Question is: Will the trans survive a 2-1 downshift at 55-60 MPH? I don't know enough about the operation of the trans to know where the greatest stress will manifest. Is the overrunning clutch involved? I've read that they will disintegrate under certain very stressful circumstances. Opinions and speculations appreciated. Trans code: PK 3410668L 2964 2655
 
Not only is it a question if the trans would hold but will the bottom end of said engine with stand the RPM and for how long ?
 
That other little assembly on your valve body is part-throttle kick-down. You don't have to stomp the gas pedal to the floor to downshift to lower gear. The TorqueFlight definitely won't take a full load dump into First at 50 mph. Sounds like time for a brake upgrade. Maybe discs off a newer Ram 3500.
 
I polished the plug in the lathe with some 1500 grit paper. It took a few iterations and a couple hits with a fine Cratex wheel on a Dremel tool to bring the clearance to a sliding fit. I was not able to measure the difference

Sorry to say, you ruined it. Get another valve body.
 
Sorry to say, you ruined it. Get another valve body.
L 71, I knew that was a possibility. I decided to take the chance. I'll get it all back together and get back to you on the "ruined" issue. What symptoms would I be looking for other than not working?
 
What symptoms would I be looking for other than not working?

They say the edges must remain very sharp... i assume the problem would be more of a timing issue, causing softer (and therefore slower) action, therefore runaway to a degree between shifts, which does cause accelerated clutch wear.
 
Gentlemen, experts too, This forum is the best I can do for my early 70's motorhome. It has the info I need for the Dodge running gear. The trans had fried and melted the clutches in the rear clutch pack. I have seen many causes for this condition in the forum here, the manual, and in other net postings. I will replace the pump with OEM parts to get the pressure back up. No, I didn't check before I disassembled. (First timer, learning as I go.) I have modified the valve body in accordance with instructions in the TF-1 TransGo kit. While cleaning, I found that the 'regulator valve throttle pressure plug' was sticking. It was not a contaminant. It was a fit issue. I polished the plug in the lathe with some 1500 grit paper. It took a few iterations and a couple hits with a fine Cratex wheel on a Dremel tool to bring the clearance to a sliding fit. I was not able to measure the difference with a .0001 reading micrometer. Note: The sliding valve components are deeply hardcased and extremely hard at the surface. They were easily held in the chuck jaws without any indications of marring on the surfaces of the valve bosses. Light jaw pressure, of course.
Now, the question: Is the sticky 'regulator valve throttle pressure plug' coupled with the low pump pressure the likely/obvious source for the rear clutch failure?
Next: There is an additional subassembly attached to the valve body that is not identified in the TransGo instructions. It is attached to the valve body directly above the 1-2 and 2-3 shift control valves. In it, are at throttle valve and a limit plug. In Mr. Munroe's book, it is described as "used in some V-8 models." Question: Will this additional subassembly interfere with the functional intent of absolute shift control incorporated in the TransGo TF-1 modifications?
Finally, Imagine yourself at the wheel of a 14,000 lb lumbering inverted bathtub. You are approaching a steep grade. I.E. typical white knuckle grade, say, 7% for the next five miles. The old beast is equipped with the latest early '70's vintage brakes, and as you enter the slope, everything is fine. The slope gets steeper, and you know the brakes are heating up. Thirty seconds later, they start to fade. You downshift to second. Then you realize you should have gone to second before starting the whole deal. Too late for that now. Second kicks in ok. You're fine. Thirty seconds later, brakes are fading again. Speed is fifty plus. Your only option is to drop it into first. Question is: What will happen given the instructions in the TransGo modification sheet to not modify the '1-2 shift valve governor plug' when the trans is used in heavy duty applications. I missed that part of the instructions. I did the modification. That's where I found that the valves are hardcased. According to the instructions, the transmission will shift to first no matter what the speed. Question is: Will the trans survive a 2-1 downshift at 55-60 MPH? I don't know enough about the operation of the trans to know where the greatest stress will manifest. Is the overrunning clutch involved? I've read that they will disintegrate under certain very stressful circumstances. Opinions and speculations appreciated. Trans code: PK 3410668L 2964 2655
Wow is this what I have to look foreward to have a 1972 727 from a motor home putting in a 1973 charger and doing a tf-1 shift kit cant wait. To answer one thing yes overunning clutch always involved did mine splined and through bolted.
 
You can't ruin a valve with 1500 paper unless you held the paper on the corners for a LONG time.
Doug
 
When I have a valve body apart for cleaning, I always roll the valves on a smooth white honing stone to clean imperfections.
 
Wow is this what I have to look foreward to have a 1972 727 from a motor home putting in a 1973 charger and doing a tf-1 shift kit cant wait. To answer one thing yes overunning clutch always involved did mine splined and through bolted.
440, '71 was a major transition year as the history story goes. This rebuild is my first auto trans job. If I get through it, I'll be able to put a big check mark on my bucket list. According to codes, my trans is a '70. However, I believe there are '71-on parts in it. The trans that was in it before was "toasted" somewhere in Yosemite, probably back in the '80's. The replacement trans is what I'm dealing with now. If this is your first valve body mod, be sure to read the instructions many times. They cover a multitude of trans variations. Mark as "not to do" those steps that are not applicable to your trans. I did that and still made a mistake. I will always have to keep that in mind while driving. I.E. the manual shift to first gear at any speed. One slip could kill my transmission. If you have the short stubby output shaft and housing with the parking brake attached to a splined flange with 4 bolts holding the drive shaft yoke, I would like to put dibbs on that ball bearing that sits just inside the end of the housing. That is, if it's good. Mine is rusty. Moisture tends to congregate there. That bearing might as well be made out of moon rock. They are impossible to find. No one makes a replacement that I know of.
 
When I have a valve body apart for cleaning, I always roll the valves on a smooth white honing stone to clean imperfections.
Dave, thank you for the encouragement. I can't afford a valve body anyway. I did the polish treatment to assure myself that there was no "varnish" on the valve surfaces. I was also worried that the very sharp edges of the valves would nick the edges of the aluminum holes as they were inserted. The valve body is so critical to the operation of the trans that I figured it was worth it. I do love to polish stuff.
 
Wow is this what I have to look foreward to have a 1972 727 from a motor home putting in a 1973 charger and doing a tf-1 shift kit cant wait. To answer one thing yes overunning clutch always involved did mine splined and through bolted.
440, I forgot to mention to take lots of pictures. I did the spool valves ok, but didn't do enough detail on the servos and accumulator. Then I find out that there have been many changes to those parts. The service manuals I have do not really go into enough detail on what parts go where. I'm pretty sure I got it right on all three, but it was a real challenge. The pics in the manuals don't show exactly what I have.
 
You can't ruin a valve with 1500 paper unless you held the paper on the corners for a LONG time.
Doug
Thank you, Doug. Just enough to assure myself that there was no "varnish" on the sliding surfaces, except for that one sticky throttle valve. You're right. 1500 does not remove material. I knew I removed some material on the throttle valve, but I was not able to measure it with a ten thousanths micrometer. The only way I knew I removed anything was by the feel of the fit when I put the valve back into the valve body. There was still a small amount of stick at the very bottom of the stroke, but I figured that was ok.
 
440, I forgot to mention to take lots of pictures. I did the spool valves ok, but didn't do enough detail on the servos and accumulator. Then I find out that there have been many changes to those parts. The service manuals I have do not really go into enough detail on what parts go where. I'm pretty sure I got it right on all three, but it was a real challenge. The pics in the manuals don't show exactly what I have.
Agree totally we all have cell phones that take great pics take tons of them if you get to a sticky spot and can look back on just one to get an answer it was well worth it.
 
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