I replaced the servo in my 84, with a larger one out of the Vette's
(Well, It's actually two pistons and some seals.) It directs more pressure to the valve body and adds more forceful shifts. It is actually better for the trans. I, so far, am quite impressed.
Be careful though, my buddy did it on his truck and pinched one o' the O rings and destroyed his trans.
I also did a trans flush,(got all the fluid out of the torque convertor) as well as a filter and gasket.
Did a rear axle service with new conditioner, amazed at the response from the rear end as well. My bone-stock 305 actually kicked sideways from a dead stop...
Never underestimate the importance of limited slip conditioner!!!

 

The servo doesn't direct more pressure anywhere, all it does is increase the apply force on the 2nd gear clutch.

 

I stand corrected, thanks!
I'm not a mechanic, just an old body guy, that's how it was explained to me.

 

Yep, increases the apply force on the 2-4 band. Gonna get one myself, if I ever get around to it.

 

here is why that principle is true.the piston is bigger in area.how does it work if we are still using the same apply pressure.100 psi applied to 1 inch is 100 psi apply force.100 psi applied to five inches is 500psi apply force.this is why the fat guy always has to jump in the dumpster to compress the garbage

 

LMFAO!!!!!!!

 

Yes, it does increase the 2nd gear apply servo pressure, but its main design was to increase the amount of oil to the 3-4 clutches. It did this by using the Corvette servo, the band releases slower, the 3-4 clutches come on quicker, by forcing more oil to the 3-4 clutches. The main reason for doing this, was to prevent the 2-3 spinup (flare) on the 2-3 WOT shift. It works in almost every case, as long as the 3-4 clutches are in good shape.

 

respectfully,id have to disagree with you dana.the third clutches will be in trouble if they apply before the band lets go of the drum and allows the drum ,shell and sun gear run up with the turbine shaft.that is why i mentioned the heavier band return spring.the bigger servo is harder to knock off and can cause a tie up which you may never feel but will eat up the third gear clutches.you also must enlarge the feed hole that sends this band knock off or as we call it the third accumulator oil to the release side of the servo to eliminate this from happening.and the ball in the case at this location is also sent to restrict this oil as it tries to enter the third accumulator circuit because it is fed thru 2 holes in most applications,although some have just the big hole.it doesnt do this at the seperator plate but in the case .a bizarre reality for me when i first saw how it worked because of the footprint it leaves in the case due to its cycling.i remove the ball and dont plug the hole in the plate and it works fine when used with our other mods