4L80E help, has reverse, acts like transbrake in foward gears
07-04-2014, 11:19 AM
#1
4L80E help, has reverse, acts like transbrake in foward gears
I just finished installing a 4l80e I rebuilt myself, last night it drove forward roughly 150ft down the road, it was acting like it was low on fluid, so I reversed back up the road fine, and forward back into driveway added fluid. This morning, backed it out of the driveway fine but it acts like a trans brake in all forward gears. It'll flash up and not move, on the slight incline of my driveway, netural rolls down hill fine and in drive it feels just like going into park, creeps a hair and stops.
The trans modifications are:
-replaced case and pump bushings, all bushing looks great
-billet input
-billet forward hub,
-rollerized the rear, and forward hub
-sonnax self regulating boost valve, and line to lube kit
-sonnax tcc valve and springs
-drilled pump to give full line pressure to tcc, and enlarged pump drain back
-stock valve body plate with shift orifices enlarged to .120
-used the shift springs and some parts out of old trans-go hd2 shift kit, did not use plate, and repaired the holes for their pressure relief crap they have you drill, with set screws and epoxy
-internally dual feed, no sealing rings on second center support land, and inner seal on drum and blocked the hole in the case (which I used a small freeze plug, which I felt iffy about, should of just used a set screw)
-I bought a solenoid kit and wiring harness kit, which they seemed cheap, may put old ones back in because I know they work atleast
-all clearances are in spec
I can feel the shift into drive, hear and feel the engine load some. It don't go anywhere though. I hope it's just something in the valve body. I swear I also hear the slightest bearing noise in Park and N that goes away in R and D. ****, well I guess I'm about to go drop the pan and valve body and hope it's an easy fix and it's not something internal. Any help or insight would be so much appreciated. Thanks
The trans modifications are:
-replaced case and pump bushings, all bushing looks great
-billet input
-billet forward hub,
-rollerized the rear, and forward hub
-sonnax self regulating boost valve, and line to lube kit
-sonnax tcc valve and springs
-drilled pump to give full line pressure to tcc, and enlarged pump drain back
-stock valve body plate with shift orifices enlarged to .120
-used the shift springs and some parts out of old trans-go hd2 shift kit, did not use plate, and repaired the holes for their pressure relief crap they have you drill, with set screws and epoxy
-internally dual feed, no sealing rings on second center support land, and inner seal on drum and blocked the hole in the case (which I used a small freeze plug, which I felt iffy about, should of just used a set screw)
-I bought a solenoid kit and wiring harness kit, which they seemed cheap, may put old ones back in because I know they work atleast
-all clearances are in spec
I can feel the shift into drive, hear and feel the engine load some. It don't go anywhere though. I hope it's just something in the valve body. I swear I also hear the slightest bearing noise in Park and N that goes away in R and D. ****, well I guess I'm about to go drop the pan and valve body and hope it's an easy fix and it's not something internal. Any help or insight would be so much appreciated. Thanks
07-04-2014, 05:28 PM
#3
TECH Fanatic
iTrader: (38)
Damn I feel for you!! I have been there. Pull the valve body and double check everything...pull the tcc valve and boost valve from the pump to double check for anything backwards. Maybe the band is being applied for some reason?? I have been in my 80e 3 times and its about to come back out this weekend. I have fought low pressure issues everytime.
07-04-2014, 08:26 PM
#4
Damn I feel for you!! I have been there. Pull the valve body and double check everything...pull the tcc valve and boost valve from the pump to double check for anything backwards. Maybe the band is being applied for some reason?? I have been in my 80e 3 times and its about to come back out this weekend. I have fought low pressure issues everytime.
I will try to keep the thread updated thanks guys
07-05-2014, 11:47 AM
#5
Any thing is possible.
I was thinking something internal along the lines of a bearing backwards, the wrong clutch steel orientation, or possibly something wrong with the modification you did.
Its also possible something in the valve body is not set up correctly and is blocking fluid flow.
I was thinking something internal along the lines of a bearing backwards, the wrong clutch steel orientation, or possibly something wrong with the modification you did.
Its also possible something in the valve body is not set up correctly and is blocking fluid flow.
07-05-2014, 04:34 PM
#6
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Join Date: Apr 2014
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Look up ATSG, (automatic tranmission service guide) technical service information it has a great troubble shooting guide, follow it to the T its verry accuret to narrow down the poblem.
For loss of drive their is literaly 35 things that can cause loss of drive
From reading you build..if YOU did your build you should have enough knowledge that i feel like eveything is good except your converter isint getting enoughf fliud. Do you have a stock converter? A higher stall converter will need more line pressure to engage the converter, especialy in a truck, i would look over the converter and pump gears, maybe hook up a line pressure guage would be the easiest quickest troubble shooting tool
I failed my tranny build the first time, instaled a broke sprag that i thought was good, no second gear, had to tear it all back apart...agin.
For loss of drive their is literaly 35 things that can cause loss of drive
From reading you build..if YOU did your build you should have enough knowledge that i feel like eveything is good except your converter isint getting enoughf fliud. Do you have a stock converter? A higher stall converter will need more line pressure to engage the converter, especialy in a truck, i would look over the converter and pump gears, maybe hook up a line pressure guage would be the easiest quickest troubble shooting tool
I failed my tranny build the first time, instaled a broke sprag that i thought was good, no second gear, had to tear it all back apart...agin.
07-06-2014, 01:45 AM
#7
The original reason for the rebuild was a burnt up intermediate clutch, and the frictions, steels, and pressure plates were all warped up some. I never determined the exact cause of the failure. It was a stock 4l80e with unknown miles, stock 80e stall, and trans-go hd2 kit. Everything else looked great, just some hot spotting on the direct steels, which I replaced during this rebuild along with clutches of course.
Ok, so I got the valve body out and gave it a good look over, and did not find anything out of the ordinary.
I then made the following changes:
- replaced all the the shift solenoids, EPC, and tcc solenoid with the originals
- replaced torlon check ***** with factory steel *****...
- replaced lo/reverse servo spring with original
- left out the sleeve trans-go puts on intermediate band to reduce servo travel
-replaced the the trans-go PR spring in pump for boost valve with original.
It drives forward now no bind up accept... In D4 range it shifts 1-2 but when shifting up to 3rd something grabs/binds, and the truck instantly engine brakes like it's in a big downshift until it gets its 3-2 shift speed where it shifts into 2nd again, and will downshift to first normally. D3 range functions the same way. Manual 2 and 1 seem to function properly.
I've been studying the heck out of the 4l80e technicians manual I downloaded. The clutches are working or at least applying that are needed (except OD clutch) to get me into third in D3. I know the direct clutches engage and disengage, and lo reverse band, because I have reverse.. forward clutch obviously working, and intermediates working... manual 2-1/intermediate band functioning can feel engine braking effect in manual 2.
Could it be a sprag causing this.. or maybe the intermediate band not releasing or applying in third? I remember when I was in school in trans class I could literally visualize the power flow pretty darn good but now I can't for the life of me get it together haha.. Must of got my brain jiggled one to many times.
On the bright side, the Circle D converter is legit, I turned my boost back down to just run off the gate (8 lbs) for the time being while sorting this out and just a quick foot stall it was screaming off the gate instantly. Cant wait to get his sorted out and enjoy this madness.. Sorry for the long post, again thanks for all the input.
Ok, so I got the valve body out and gave it a good look over, and did not find anything out of the ordinary.
I then made the following changes:
- replaced all the the shift solenoids, EPC, and tcc solenoid with the originals
- replaced torlon check ***** with factory steel *****...
- replaced lo/reverse servo spring with original
- left out the sleeve trans-go puts on intermediate band to reduce servo travel
-replaced the the trans-go PR spring in pump for boost valve with original.
It drives forward now no bind up accept... In D4 range it shifts 1-2 but when shifting up to 3rd something grabs/binds, and the truck instantly engine brakes like it's in a big downshift until it gets its 3-2 shift speed where it shifts into 2nd again, and will downshift to first normally. D3 range functions the same way. Manual 2 and 1 seem to function properly.
I've been studying the heck out of the 4l80e technicians manual I downloaded. The clutches are working or at least applying that are needed (except OD clutch) to get me into third in D3. I know the direct clutches engage and disengage, and lo reverse band, because I have reverse.. forward clutch obviously working, and intermediates working... manual 2-1/intermediate band functioning can feel engine braking effect in manual 2.
Could it be a sprag causing this.. or maybe the intermediate band not releasing or applying in third? I remember when I was in school in trans class I could literally visualize the power flow pretty darn good but now I can't for the life of me get it together haha.. Must of got my brain jiggled one to many times.
On the bright side, the Circle D converter is legit, I turned my boost back down to just run off the gate (8 lbs) for the time being while sorting this out and just a quick foot stall it was screaming off the gate instantly. Cant wait to get his sorted out and enjoy this madness.. Sorry for the long post, again thanks for all the input.
