Eating 3-4 in 4l60E's like candy
11-24-2015, 10:24 PM
#1
Eating 3-4 in 4l60E's like candy
Guy's been threw three rebuilds in the last month, every time it's 3-4, the truck is a 2000 rcsb with just bolt on stuff, texas speed 228R,4.10's, and a ptc 3600, nothing special, the truck does good for a about a 150 miles then goes to ****, no hard driving or nothing on the last one, the guy before that built it the first two times gave up and said trash it, so took to another guy so he tried it and same result, the trans has all good hard parts, wide band, and z-pac clutchs, tps seems to be working fine, could it be some thing pcm wise, it shifts fine when new then just goes to ****, line pressure is good also, any ideas other than switching to a 4l80, I mean dam the truck doesn't make enough horse power to be doing this ****, ANY IDEAS, THANKS!
11-24-2015, 10:50 PM
#2
TECH Enthusiast
Need a good builder that will find why the 3/4 frictions are burning..has too have a big leakage some where..most leak from the input drum where the input shaft presses into drum..or the 3rd exhaust accumalator capsule..something else to look at is the cooler make sure its not clogged up
11-26-2015, 12:03 AM
#7
Sounds like the 3/4 clutches are dragging in first and second. This is probably making the truck feel under-powered in first and second at high throttle positions.
Check the input to forward housing o-ring seal. This seal is on the internal hub of the input drum. Leakage across that seal will bleed forward clutch fluid into the 3/4 piston. Even with that seal missing entirely the transmission will actually still work because the 3/4 bleed will exhaust enough fluid at low throttle position that it barely matters. The damage is done is at higher throttle positions and higher line pressures where that leak begins to move enough volume into the 3/4 piston to drag it, so in first the 3/4 clutch is trying to make it "third" and in second gear that leak is trying to make it "fourth".
My vote is a missing/damaged $0.19 O-Ring (#622)
Check the input to forward housing o-ring seal. This seal is on the internal hub of the input drum. Leakage across that seal will bleed forward clutch fluid into the 3/4 piston. Even with that seal missing entirely the transmission will actually still work because the 3/4 bleed will exhaust enough fluid at low throttle position that it barely matters. The damage is done is at higher throttle positions and higher line pressures where that leak begins to move enough volume into the 3/4 piston to drag it, so in first the 3/4 clutch is trying to make it "third" and in second gear that leak is trying to make it "fourth".
My vote is a missing/damaged $0.19 O-Ring (#622)
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11-26-2015, 01:08 PM
#10
Check wear in the 3-4 accumulator bore in the case.... Have seen worn accumulator piston seals burn a 3/4 clutch bad! If bore's worn it will cause same problem even with new seals!!! Also check the third accumulator check valve, its a known culprit of burnt 3/4 clutches. And have heard mixed reviews of the zpak..... Some say it great others say its junk, if youre having issues with it try another 3/4 clutch pak, alot of guys recommend the hi energy 3/4!!