I have the transgo kit installed in my 4l80 for my gbody cutlass. This will be behind a stock lq4. Leaving it all stock for now until I work out the bugs in the swap, then it will eventually have a cam and maybe head work.

Does anyone have any suggestions or feedback for what hole sizes to drill for a stock converter setup 4l80? I want firm, not harsh. I'm just nervous because once you drill too big, you can't drill it smaller

Thanks fellas

 

With a stock torque converter & all 3 accumulators active, I would drill 2nd, 3rd, & 4th feed orifices to .093"

 

Did you run your car with that setup?

 

Not exactly. I'm running a 245mm converter, 3rd & 4th accumulator delete, 3 Raybestos face grooved Intermediate frictions with a TH400 Wave & Piston, 5 Raybestos face grooved Direct frictions with a TH400 Wave & Piston, Stock Borg Warner O/D frictions, Internally dual fed, Sonnax 4L80E-LB1.
Hole sizes..... .086" 2nd, .093" 3rd, & .093" 4th

 

Dang. I'll try the .093.

Also I already drilled my valvebody for the pressure relief valve that comes in the kit. Now I'm reading reviews that say it shouldn't be done. Would it be ok to tap threads into that hole and plug it with a set screw?

 

You can, Just don't tap it all the way, The set screw needs a surface to seal to, Use red loctite & let it sit over night. You don't have to worry about the wall you drilled through.

 

What year is the computer that is being used here? Somewhere in the late 1990's the pressure "runaway" seem to be solved by GM. The early computers had a "glitch" that caused the high pressure problem. This is the same for the 4L60E, that is why the introduction of the forward steel apply piston, instead of the aluminum piston that would occasionally crack. I do not know when the problem was solved, as GM tells you nothing, and we're very slow about fixing this computer glitch. With late 4L80E transmissions, this modification is not necessary from what I have seen.

 

What year do you consider late? Anything with the center lube?