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Dynaflow Guts

Bill Stoneberg

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A trusted source once told me to inspect the shaft that the torque converter rides on. Can't remember the official name of that shaft . Anyway, He claimed many times he welded it up where it was worn down,turned it to size

, and cured vibration complaints

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  • 3 weeks later...

Great idea and photos Bill.  Looks like photo 6 n 7 are showing some out of spec wear possibly ? It would be neat to see the transmission spread out buffet style from end to end with all components located in the exact position they were taken out kinda like in the shop manual diagrams.  In the past I have heard a lot tales regarding transmission shops that folks have taken their dynaflow to for a rebuild only to find the trans was just cleaned and new gaskets installed.   Can't really blame these what I call gasket n gooey shops for doing that because there are but few folks around today that really know how to inspect the various parts for " In Spec " run out and wear.  So not knowing what is spec or an in-depth knowledge of how the dynaflow functions and the various normal wear suspects, they just clean it up and install new gaskets and apply gooey sealer.  No test bench fluid psi test work before or after R & R etc.  

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Neat pictures!  "Wear" is "wear" whether it's in a DynaFlow or a THM400.  Just have to know what moves, what doesn't need to move, and what does what with the friction elements.  The main calibration areas would be inside the valve body and on the end of the band that wraps around the drum.  Plus the piston that applies the clutch pack inside the drum.  AND any fixed bushings or replaceable bearings (as pictured in one shot). 


One possibly critical area would be the build thickness of "the frictions and steels" in the clutch pack.  ANY total build thickness "out of spec" can relate to ultimate "apply time" of the clutch pack once fluid is supplied behind its actuating piston.  Similar might be true with the band and the drum diameter, I suspect.


Inside the valve body, that's where the "pressure-bias" springs and shuttle valves reside, which change the fluid circuits to make things happen as desired.  AND where some unseen wear can also happen.  I believe there has become a small industry of rebuilding/resurfacing the shuttle valve contact areas in the valve body?  Even replacing the shuttle valve springs, too?


Also be cognizant of any lip seal/shaft wear points, usually shallow a groove in the shaft at that sealing point.  AND any shaft/bushing/seal wear points, too.  Not unlike the resulting groove in a harmonic balancer/hub from the related crankshaft front oil seal.


As always getting at least "OEM Quality" seals, frictions, and such is important for long-term durability.  But for many owners, even that is "too good" for what is actually needed, I suspect.  End result, a quality rebuild with quality parts and today's better fluids could well make for a very long-term smoooooth-operating automatic transmission, I suspect.


Y'all have fun!



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