For General Motors 700-R4 & 4L60E Transmissions/h4>
The 2-4 band in GM's 4L60 platform requires the servo pin to seal in two different positions, in two different gears. First, when the transmission shifts into third gear, it releases the servo using 3-4 clutch oil. Thus a leaking servo bore can cause a loss of pressure to the 3-4 clutch, and drag the band. Second, when the transmission applies the band in fourth gear, oil comes up through the hollow pin and applies a separate piston. This second piston allows the pin to travel through the second gear piston, which is still being held in place by 3-4 clutch oil. Thus not only does a leaky bore create a leak in third gear, it also creates a leak to the case of fourth gear oil, AND a cross leak of third and fourth gear oil.
The 4L60 kit contains tooling necessary to repair the 2-4 servo pin bore. The 4L60 kit is a GOLD series kit and is currently only available as a Master kit (pictured).