Servo Apply Aea

[boostmaster]

Can someone tell me what is the actual servo apply area, I have quite a few servo's and looking at them I can't tell the difference. Even swapping the pistons tells me no difference.

 

[chris718]

servo apply area is the area between the piston and cover where a given oil volume is accumulated to apply the band ,stop the forward sun gear ,and create second gear reduction.this given volume varies between piston and cover pairs which must be used in pairs and cannot be mismatched unless used as a pair.there are 4 piston and covers available ,however i only remember 3 and they are 569 cover 6 cyl use ,692 cover v8 use ,and 694 cover turbo 6 cyl use.the more volume in the cover the more of an increase in clamping force that is generated to hold the band with a given psi .heres an example 200 psi at a 5 square ince cover will apply 1000psi.200 psi at a 10 square inch cover will apply 2000 psi.this is why the bigger servos increase firmness and reduce band burning .at www.ckperformance.com we build all our 2004r transmissions with a 112 piston from a 200 3 speed gm trans .it has a larger apply area than all the factory issue 2004r servos.