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TF999 Tech question

O

og48

Basic User
City
Amador City
State
Ca
I will do my best to explain my current TF999 “issue”. First off, I bought a postal a few years ago. I finally got a new to me motor in about 6 months ago. When I put the TF999 in gear ( on jack stands). The postal would go in gear both forward and reverse. I thought to myself great.
Once I got it on the ground, it would only have enough power to go in reverse. Forward gears I had to rev the motor very high to get it to move on a flat surface. No problem I thought. I have a friend who use to rebuild transmission.
So, I took it out and he rebuilt it for me. Once I got it back installed.
Same problem, reverse works very well( I have a steep driveway) Forward gears, nothing.
I consulted my friend and he suggested replacing the valve body. Since we didn’t replace it on the rebuild. It does have a new torque converter. Replaced the valve body and still has the same exact same issue.
At this point I’m wondering if the pump is not working. He suggested taking off the tranny line and see if it’s pumping fluid properly
Any advice is appreciated
 
Thinking you should be able to check the pump by the line pressure without taking it out. Suggest you get a copy of the workshop manual section 2C or a transmission book. Check out https://oljeep.com/edge_small.html - Guessing it's the rear clutch from the guide - but it could be as simple as adjusting the rear band. I had mine apart a couple times - pretty worn out after the Postal service had done with it
 
Measure line pressure, and tighten the bands.

I will see if I can locate the part of the trans used in reverse vs drive breakaway. Will post back later.
 
I would suspect the pump is okay as i believe reverse requires higher pressure than drive does.
The workshop manuals chart would indicate a problem with the rear clutch but as its new that seems a bit strange?.
Is the throttle rod that goes from the accelerator linkage to the auto box there and correctly set?,




clutches.png
 
I was going to say that maybe the seal got damaged on the rear clutch during rebuild- but if it had the issue before your friend rebuilt it that would be unlikely.

I assume you have seen Aglever's thread https://www.cj-8.com/threads/torqueflite-999-rebuild.52594/

Did the overrunning clutch get rebuilt? - Looking at the chart that Dave posted it could be a problem with first - have you ever got it in second?

​

 
Overrunning clutch is a basic item, really does not need rebuilding. Either works or does not. One of the tests is to manually shift to 1 low. “Direct Breakaway” is the “D“ position and does not use the rear band. If “1” works, then I think that means the overrunning clutch is slipping.
 
My guess, line pressure wrong, or seal leaks in the clutches.
 
Power flow in the various shift positions.

1C90986A-6340-4AEC-9B4D-182883253ECF.jpeg

783892DE-12C7-4E05-9CDC-9E87D08F386B.jpeg

D9C0250C-0794-4E5B-BE8F-A7F4111023D5.jpeg
 
I highly suggest buying Tom Hand’s book on the A-904 / A-727. It has ALL the info needed to troubleshoot these transmissions.
 
All I can say at this point is “wow”.
Thank you all for your input. I have a lot to learn about this transmission.
Where do I get the tool to measure the line pressure? I think I’m going to check the front and rear band adjustments first. Then figure out how to check the line pressure. Again, thank you everyone
 
Line pressure tool is not cheap, you might be able to borrow one from an auto parts store???

My wonderful bride gave me my line pressure gauge set.
 
I should also mention that when it shifts into reverse I can feel the transmission engage and when I shift into D, 2, 1 I get no indication that it’s in gear.
 
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