gman4dx266

Well I had the 4L80e installed at my buddies trans shop today, and they called me up with some bad news. They say that something is bound up inside. The shift lever pulls smooth so the manual valve is operational. It has trouble moving in reverse and trouble moving in forward gears (not due to the stall or anything, but does need a decent amount of gas to move at all and does so SLOWLY). Its almost like the parking brake is on a little bit or something, but not. The following ideas have been proposed by the shop:

Worst case scenario first: Cross-leak past 3 center support sealing rings and thus applying the intermediates.

Other theories:
-Incorrect check ball locations
-Reversed VB gaskets
-incorrectly drilled holes (transgo)

I am almost POSITIVE I have the 3 'other theories' correct, so I'm hoping i didnt bust any of those sealing rings. They looked like they were snapped together at the seams decently when i slid it down on there.

So what else could it be? I hope its in the VB, but like I said, Im almost sure everything down there is okay, so the trans may have to come back out.

venomhp

iTrader: (13)

is the torque converter all the way in?

built408

iTrader: (10)

is this a FLT trans?

Wilde Racing

iTrader: (26)

Let me get this strait.. you Rebuilt your own trans, then had some-one else install it?
Does it have reverse? line pressures are at?

FLT

iTrader: (1)

I'm pretty sure from reading what gman posted this was a home built unit. Also he has a couple threads posted for the build of the 80. If I had to guess you have a cross leak somewhere. The obvious are sealing rings and valve body gaskets or even a mismatch in parts. The first thing to do is a get a gauge on this thing to see where your pressures are at. Check for codes and the most obvious is that the trans is full of oil. From there you need to decide which direction to go. Removing the valve body is probably one of the first places you can look without pulling the trans. Also if low pressure is an issue check your pressure regulator circuit to make sure all looks correct in there. Conditions like this are usually a major leak in the transmissions circuits. Time to start digging. Let us know what you find. Vince

gman4dx266

Wilde, Yes, I had my buddies install it for me because they have a lift at the shop, and Id rather not lay on my back in my driveway and use my jackstands on the last notch lol!

Yes it DOES have reverse and it DOES go forward, but like I said its like the brakes are on, or you're towing 8000lbs. The converter is in all the way; good clearance, no whining or any noises. (restalled stock GM)

Vince, No codes on the pcm. We're going to pull the pan and VB and take a look and see. I didnt even think about the pressure guage test. Ill bring that up. I hope its not that freakin hole for the pressure popoff valve. It's in the right spot because I triple checked it, but it was on a retarded angle to keep the bit from damaging the adjacent wall of the VB. Since I legitimately believe I got the VB right, I have a good hunch the trans will have to come out. Those center support rings didnt seem as fragile as everyone says they are so I didnt pay them much attention. But who knows, maybe the little end latches where they lock together came out when I slid direct down. I guess time will tell.

EDIT: found this sheet that came with my sealing kit. 2 issues printed on each side.

First side titled "Bind in Low / 3rd Gear Starts"
says that a 4l80e with a complaint of a 3rd gear start regardless of electrical commands accompanied by a bind in low, could be caused by the dished cushion plate in the direct drum. A broken cushion plate can cause the clutch to be mechanically applied which will cause the above complaints and can give a false solenoid B code 81. --It says to eliminate it, remove the dished plate and install 2 early waved steels in the following fashion: Install 1 wave, then a friction, other wave, another friction, then stack the rest of the drum with .077 or .090 steels to adjust clearance.

Next side, makes me wonder, because of the culprit they mention:
"Selector lever moves by itself, Low or no line pressure rise, 2nd Gear starts"
Says: "All of the above complaints may be caused by a broken actuator feed screen located inside the valvebody. If the actuator screen breaks at highway speed, it can cause the manual valve and shifter to move into the reverse position at 40 to 45mph. This filter should be replaced."

...since I had trouble with that screen, could it be a leak around the top of that thing? I kinda doubt the first issue on the paper, because I would think in ANY gear it would be torn between which way to go if direct is engaged.

gman4dx266

Well the valvebody and everything under the pan checked out, so the problem lies internally. I checked all my gaps with a feeler guage and endplay guage, so really the only thing it can be (as far as i know) would be an internal leak. So, back on the bench we go!

gman4dx266

Well we took it back out, and checked inside. What my buddy said was going on is that there was originally extreme bushing wear inside the direct, which wore the area on the center support around the oil rings. He said there was tiny metal fibers around there that he had to file off. Trans was put back together and put in the truck, and it didnt have reverse! So we're about to pull it out AGAIN and look to see what else could be going on. The shop guys said everything else looked decent inside there, so we're stumped. They double checked the VB, once the first time, put it all back together, and now checked it again while it has no reverse; tip top shape. If it weren't for bad luck, I wouldnt really have any sometimes.

FLT

iTrader: (1)

Was the direct drum replaced in this trans when it was built? Also how was the condition of the forward drum where the rings ride? With worn bushings and what the symptoms are, I think your problems might be in those areas. Vince

gman4dx266

Vince, I did not replace the direct drum, or any technical hard parts actually. I did have all new bushings pressed in (11 or 12 of them). The ring area of the fwd drum was okay, but like i said it had apparently been wearing in that area because of a worn direct bushing and had tiny metal embers 'frayed' on it around the oil ring grooves, which is true as I remember constantly cussing because I kept getting them stuck in my fingers when building it but couldnt figure out where I was getting them from haha. I vaguely recall the condition of the direct drum bushing and it was a little 'toasty'. So perhaps that was what caused it.