My Th400 transmission failed on me. Rebuilt it found really bad frictions and a blown seal on my direct drive. Went through it and took my time to clean everything and keep it that way. When I bought the Jeep the PO told me everything in the drive train was stock. As I disassembled the valve body on the tranny I noticed that a couple of springs were different from factory and one was relocated to the other side of the spool. I reassembled as removed. I have it all reassembled and installed and when I test drove it, at first, it seemed to shift ok, possible adjustments to modulator needed. As it reached temp I lost 3rd gear and couldn't feel the shift from 1-2. Down shifting manually verified that I was in 2nd and 1st is working. Let it cool overnight and tried again. Same as listed. I believe I may have a Shift or Reprogramming kit installed and I replaced the modified gasket with a stock one and this is causing my issues. I have been through the valve body again to verify that all spools move freely, checked vacuum to modulator while idling and driving,(ran vacuum line and teed into modulator through rusty floor panel), removed and inspected governor to ensure smooth movement. My next step I was thinking of replacing the valve body with a stock one, or buying a shift kit to install. Any suggestions would be truly appreciated. Sorry for the long post.
Took off the valve body and inspected everything, cannot find evidence of a shift kit other than the one spring reversed. Did find that I assembled the low 2/front band servo incorrectly. I was curious if this could cause my issue? I had the retainer on the wrong side of the spring and when I pulled it out the washer came out. What is the function of the low2 front band servo? Have not had a chance to reassemble and test drive. Hopefully get to it tomorrow.
I'm assuming you have reverse just no 2-3 shift? Check your vacuum hose again just because it's easy. Then I'd look to the 2-3 valve being stuck. Make sure the valve body gasket is right for your trans also. The 400's had a couple different ones if i recall. Just a couple of my cents, good luck.
I'm assuming you have reverse just no 2-3 shift? Check your vacuum hose again just because it's easy. Then I'd look to the 2-3 valve being stuck. Make sure the valve body gasket is right for your trans also. The 400's had a couple different ones if i recall. Just a couple of my cents, good luck.
Rechecked everything, all is good with the vac and 2-3 valve. pulled the governor again and double checked. Reassembled everything and topped off the fluids. Drove around town for a while with no issues. Shut it down to run into the store and on the drive home... No 3rd gear. will shift sometimes now when I put it into neutral and back into drive.
I really don't know what to tell you, that was the extent of my TH knowledge from my old trans am days. You checked modulator vacuum and have been into the valves enough that any sticking should have been evident. That's really all i know to tell you to check that would stop a 2-3 shift. Idk, check the detent solenoid? Good luck, and let me know if you get this sorted. Might help someone else.
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