4L80e no reverse after rebuild
01-07-2015, 04:17 PM
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4L80e no reverse after rebuild The transmission is out of a 2003 Silverado HD behind a 6.0L . It was rebuilt using Jake's stage 2 kit by a local transmission shop . The powertrain has been swapped into a 2009 Jeep wrangler . So I finally got the engine running and I tried reversing out of the shop the first time and here's what happened . I put the shifter into reverse and nothing happened , after about 5-6 secs you can feel it engage into reverse but it barely moves , when you rev it , it just slips and doesn't move much either . The forward gears work fine but that's just moving it around the shop. Haven't taken it for a proper drive yet .
So after searching around a bit , I figured it had to be the reverse/low band servo adjustment . The only problem is I moved to a different city and its like a 20 hour drive to the place where I got the transmission rebuilt from . So taking it back to that shop is out of question . I decided to drop the pan today to check rear servo clearance myself .
Drained the fluid , dropped the pan and there's a whole bunch of clutch material at the bottom of the pan
. So my question now is should I just pull the tranny out and go through everything again? Is all that material from the low reverse band? Or should I just flush the fluid install a longer pin and see if it works .
So after searching around a bit , I figured it had to be the reverse/low band servo adjustment . The only problem is I moved to a different city and its like a 20 hour drive to the place where I got the transmission rebuilt from . So taking it back to that shop is out of question . I decided to drop the pan today to check rear servo clearance myself .
Drained the fluid , dropped the pan and there's a whole bunch of clutch material at the bottom of the pan
. So my question now is should I just pull the tranny out and go through everything again? Is all that material from the low reverse band? Or should I just flush the fluid install a longer pin and see if it works . 
01-07-2015, 08:33 PM
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Thanks for the reply, so I hooked up a pressure gauge to see whats going on. At idle in park the pressure was about 40 psi , in reverse while idling the pressure is about 60-70 psi . In d,3,2,1 while idling its 40-45 psi . Now when I step on the gas pedal the pressure doesn't go up at all in reverse or D it remains steady . Is the pump no good ? Is the pressure control solenoid messed up? I was careful when installing the convertor made it sure it was seated in all the way , checked for proper clearance as well . 
01-07-2015, 08:43 PM
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Also the I was looking at the PC solenoid pids , the duty cycle would drop as soon as I stepped on the throttle and so would the volts . The trans fluid level was good as well .
01-07-2015, 09:07 PM
#5
You have zero pressure rise.
It sounds like you have a stuck pressure regulator valve or a leak in the torque signal circuit.
See if the Pressure Control Solenoid is even installed. Be sure all the solenoids are in place, and the VB is tight, etc.
With pressures like that, all the clutches and band are cooked, so it's coming out for a rebuild but you may want to figure out the root cause before attempting it again.
It sounds like you have a stuck pressure regulator valve or a leak in the torque signal circuit.
See if the Pressure Control Solenoid is even installed. Be sure all the solenoids are in place, and the VB is tight, etc.
With pressures like that, all the clutches and band are cooked, so it's coming out for a rebuild but you may want to figure out the root cause before attempting it again.