Hi again, im still having problems with my 4l60E not shifting up from 1st gear, anways i pulled out the 4th apply piston and another part of my servo, thats all i got out and cleaned it and put it all back together, took it for a ride, after a little bit of driving it shifted to 2nd, then to 3rd, then when i slowed back down and got back in 1st it stayed there. does this sound like the servo passages have sludge in them? or something in the servo? or does it sound more like the band is toast? it was rebuilt 600 miles ago and there was a light 1/16 sludge on the bottom and a tiny bit of buildup on the magnet. i was also thinking the filter could have sludged up and maybe there really isnt enough pressure to apply that band? if so does anyone know of a good way to "clean" the transmission of the sludge? thanks!

 

First, sludge (from oil breakdown in transmissions) is a thing of the past. If you found a layer of clutch/band material (black suit) on the bottom of the pan away from the magnet, it could mean the 2-4 band and or 3-4 clutches are going or gone. The 4L60E has a very good filtering system, but if some material gets by it can clog/restrict the tiny filters inside the valve body. This can create codes, no line (pressure) rise, no shift conditions, burnup the clutches/band, etc. You will need to address this problem when the transmission is torn down for repairs. Trans-Go offers a "fix" for this in their Shift kits, that will "prevent" the filter from collapsing on itself.