4R70W INTERNAL INSPECTION

This video shows the failure of a 4r70 W transmission that was brought in with a no reverse condition. The transmission was rebuilt about four years ago. The failure that occurred was with the reverse band. The damage to the reverse band damaged the surface of the planet carrier which is where the band rides. The likely cause for the failure was a servo that did not appear to be replaced when the transmission was rebuilt. Since this Servo was not replaced it was hard as a rock creating a hydraulic sealing issue not giving Proper apply pressure to the apply side of the Servo thus wearing and damaging the band and subsequent components. This transmission on top of that normal soft part items is also going to need some hard parts including the center support the sunshell and the planet carrier assembly for a proper operation.