Just picked up a '99 K2500 4L80E, and transfercase with 45k miles on it for $250. I drove the truck before they pulled it and it shifted fine and felt strong. It has a transgo shift kit (not the HD but the SK4l80e one, small blue box).

Truck frame was cracked so truck was being scrapped. Figured before I put it in my truck I would rebuild it. I have high energy clutches and a full rebuild kit for it already. I have been reading a lot of threads and will be doing the internal dual feed mod.

I noticed couple threads said to drill a bleed hole in the direct drum, is that required or just extra security ? Also anything else recommended to hold around 600-700hp? Also, I read some people leave certain check ***** out depending on application. Going into a DD truck, some towing but not a lot.

I will start the tear down tomorrow with lots of pictures.

 

looking forward on your rebuilt !!!

 

So I completely dropped the ball on the taking a lot of pictures while tearing it down. I did happen to get a few at the end of tearing it apart....























Isn't the snap ring supposed to be at 9 o'clock according to manual ?











how do these clutches look? fluid was still nice and red, didn't smell burnt at all. New wiring harness for the solenoids too.





Sprayed down with brake clean





cleaned inside with brake clean

I have a complete rebuild it for it, high energy clutches, new bands, solenoids, .500 boost valve, 3000stall torque converter. I already did the mods for the dual feed mod (removed the seals and put 3/8" cup plug in place with locktight).

What is the easiest way for cleaning the outside of the case - wire brush, sandblast ? If sandblasting what media is recommended ? Id like to paint the case black and clear coat it. Also I know to check line pressure you go in the port on the drivers side above the shift lever, is there any reason I could put a barb in that port and run a small length of hose to put my electric sending unit in for my pressure gauge, or would hard pipe be the way to go? Im worried about space, its a tight spot. Its a 400psi gauge in the cab. Id like to run it to keep an eye on pressures.

 

before cleaning





some dirt from sitting outside.











cup plug in place for the dual feed mod. Also left the second seal ring off the center support, and the lip on the inside of the drum





Freshly painted, want to do a couple more coats then clear it.

 

Looks really good! Interesting idea on hooking it up to a pressure gauge full time. I know on mine there is hardly any room so I have to take off the NSS to get the hose on the port. A low profile fitting will probably work, but you may want to use a hardline with an electrical sender. I doubt you want 200psi fluid having the possibility of bursting in the cab. Trans fluid is flammable also.

 

And you would NEVER get that smell out.

 

Got it installed, fluid is up to level. I had to shim the new converter, installed it and it was not in the pump all the ways, shimmed it now its engaging the pump fine. Goes into D and pulls itself forward, but when trying reverse nothing. It doesn't even put a load on the engine, no rpm fluctuation or drop at all. What could be the problem?

I did the direct feed mod, and a .500 sonnax boost valve. All new seals, pistons, servo seals, bands, clutches, steels, electronics, wire harness, force motor. I drilled the separator plate for firmer shifts, and left the 3rd check ball out.

Some quick Tranny pressures from my gauge. I can't take it out for a drive without reverse, blocked in place at the moment so just tests in P, R, N. I believe D pressure is ok since it engages fast and pulls forwards in all forward gears (D, 3, 2, 1).
Idle ---- 1000rpms
P - 100psi ---- did not take a reading
R - 100psi ---- 300psi
N - 100psi ---- 300psi

 

as I am reading I realize the only thing I did not check was the servo pin travel to make sure its engaging the rear band. Would a new band and the stock servo pin cause an issue? You would think just replacing the band it would still be ok.

 

Kent Moore makes a tool for checking to ensure you have the proper length pin. There are numerous pins.

 

I didn't get a chance to test drive it to see if it brakes in 1st, plan on doing that tomorrow. Then I should be able to figure out if it's an internal problem.
With the tranny pressures, does that indicate any internal problems ?