DrX

iTrader: (7)

Finally had a couple hours to take a quick look at this 80E I've had sitting here for over a year. It had been overheating since I purchased it and I had replaced or tested everything external to the trans. Thought something broke the last time I took it out for some logging, so I pulled it and swapped in another 80E which has been running super cool with the same(new) 40k cooler and converter. As I recall, it was making an ugly noise similar to driving with the parking pawl engaged....well maybe not that loud, but a ratcheting sound like that.

So far, I have emptied the case and just had a quick look at things. Have not pulled apart the pump or VB, etc. I don't see any broken parts yet, but the sun gear appears to have been heated up. Clutches look pretty well new. Any parts that I haven't cracked open seem to spin smoothly. It took some prying to separate the center support from the reaction drum. Looks like I have a 97 up rear ring gear/shaft and sun gear, and a 91-96 sun gear shaft.

4l80e Center Gear Box Changefor 1999

http://www.transgo.org/Research/Tech...be-Changes.pdf

4L80E Service Manual

4L80E Tech Guide (from Superado's Dropbox)

DrX

iTrader: (7)

Anybody know exactly where this part fits in? I am not seeing it anywhere. If its supposed to go under the roller clutch, the roller in this trans has little supporting legs on it.
"645 Ring, Reaction Drum Spacer"

smokeshow

iTrader: (16)

Lot of pretty colors in there.

1FastBrick

iTrader: (17)

Not sure on that part, but at least you found your issue...

The mix match of parts caused your lube issue which caused the failure.

DrX

iTrader: (7)

Could be the roller design changed and the spacer is no longer required. Here's the roller...

DrX

iTrader: (7)

I really don't see any other obvious damage as to what was making the ratcheting sound after I believe the t-brake engaged via forced upshift during decel at probably 2X MPH....forced upshift cannot be disabled by HPT or EFILive. From what I can deduce, in this situation the direct clutches would apply and act as a brake on the rotating parts. This noise did not go away. The only other things I noticed were that the center support was jammed tight inside the low roller clutch but spins freely and separates easily now, and the low/reverse band looks a little chewed up.



Sprag

James B.

iTrader: (1)

Looks like the return lube from the cooler was losing pressure before entering the center support. Can you confirm that the inlet port was the type that protrudes into the case and that the center support had the seal installed...

DrX

iTrader: (7)

Yes, it was correct.

DrX

iTrader: (7)

Finally got around to putting this back together with the correct sun gear shaft and a fresh gearset. Couldn't keep it over 100*F at 55 mph on a test drive today running through the 40k cooler only(rad bypassed). Ambient was around 50*F. I got it to 108*F on some lower speed driving.

GMCtrk

iTrader: (27)

I don't see any problem with that personally.

My runs 135-142 F with regular driving in upper 90s temps. Back to back passes at the track I think it got up to 178 F. Running Walmart dex3. Trucool 40k.