4l80e drilled

[caseysaysthis]

I have a 4l80e that I just had rebuilt upon taking it apart these spots were drilled by a pervious owner, the guy rebuilding says he can't seem to figure out why they were done. 1 is in the housing of the trans the other in half the pump. Any input would be greatly appreciated

 

[denata]

Cavity 14 is connected through a throttling hole (14a 14b) on a metal gasket. increased throughput.
How deep is the drill in the pump body? in that place there is a channel for lubrication, (channel 49)
Is a counter hole also drilled in the box body?

 

[caseysaysthis]

The hole goes to the channel on the pump cover case side and is plugged on the end. What would be tje reason for adding these holes is what my transmission giy cant figure out. And what would be the reason for wanting increased throughput from 14 a to 14 b and why would the housing be tapped like that. Thabks for the response btw

 

[denata]

49 line serves to lubricate the bushing, why the additional hole was made is not clear. Each master considers it his duty to make some change to the 4L80E hydraulic circuit. Not all changes are equally beneficial.

Removal of the throttle hole 14a, possibly compensates for wear, increased clearance in the piston boost pres.reg.. By increasing the volume and speed of fluid supply to the control piston, it compensates for losses through the worn gap.

 

[MrMarty51]

The rebuilder of the 4L60E in my 93 K1500, he drilled a bore larger to feed more lube to the OD planetaries. That was where the transmission failed. He explained that it is a GM approved fix.

 

[denata]

If they wanted to increase the flow to grease, they drilled in the wrong place.