4L80E & TH400 Tech.

[clinebarger]

Originally Posted by softballnrd27

Cline-
I got a 98 model with 80k on the odometer now that is in good working order. I want to just put it in for now, should I go ahead and do the AFL fix now? I want to get it up and running, and start collecting the parts for a proper rebuild. I want to overbuild the transmission to handle 800-900hp but I will probably live in the 6-700 hp area.

If it really only has 80K, You will probably be OK, You can do the AFL fix when you build it. It is usually an issue on higher mileage units, Which most 4L80E's are at this point.

Symptoms of AFL wear are....Wrong gear starts, Converter clutch slip/Fall out Hot, Codes P0757, P0894, P0730.....If it gets bad enough....Clutch Burn-Up.

Originally Posted by 1BadAction

Cline, thanks for this thread, found it google searching for a few things on my 80E valve body rebuild-mod and it's absolute gold.

I have a question re: the AFL bore wear. How can you tell if it's bad? I don't think my 91 has ever been apart other than the fluid and filter I did at 78k. it has 93 on it now.

Do you work at a local DFW transmission shop or are you "retired"?

The above applies to you aswell, But OBD 1 equivalent codes would be 39, 85, 68.

If ya'll want to check the Bore physically, Remove the AFL spring, Move the AFL valve 3/16" from the bottom of the bore & wiggle the valve, Compare that to how much wiggle it has when at the bottom. It is hard to explain "Feel" & "technique"....

I stopped working at Transmission shops long ago, I work at a specialty Performance shop here in Fort Worth, We specialize in TH400/TH350/700R4/4L60E/4L80E performance builds, Ring & Pinion installs, And LSX swaps.

PM me for contact info.