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4l80e burnt overrun clutch, roller sprang ok

BobTM

New Member
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Location
San Diego
Thread starter #1
98 gm tiltmaster/ Isuzu NPR with 5.7 and 4l80e. Everthing looks original except the transmission. Trans out of a 2007. Put about 500miles since I got it. Pulled trans because I was getting a hard shift from 3toOD and trans fluid looked like it was never changed ( not burnt). Trans is currently disassembled and mostly rebuild. Everything looks good, but overrun clutch, metals, and pressure plate are burnt and dished. Overrun sprang has burnt plastic but still looks functional.

So, my guess is overrun clutch/piston is being applied in OD? Reverse felt normal.
Best way to check? I'm a bit lost on how to troubleshoot this.
 

WarWagon

Well it hits on 7 of 8...
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Location
AZ
#2
The sprag is used for OD, period. That small clutch comes on in manual 3rd for compression braking. Not used in OD. Here is a hint: don't compression brake with a 4L80e because that clutch slips and burns up easy.

Some kits drill the valve body to bring this clutch on in OD to help the sprag hold.

Best you can do is get the best frictions available for this clutch. And the upgraded sprag. Shift Kits to bring it on in OD are your call.
 
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