I serviced the Vic's tranny over the weekend. Not my favorite task but it needed to be done because it had developed the dreaded torque converter shudder endemic to the 4R70W. (For reference, torque converter shudder is a feeling like running over the "Hey, wake up!" stutter strips on the side of the road as the tranny shifts into third or OD). A complete flush with fresh fluid and a bottle of LubeGuard fixed that. Thank goodness, too. If the flush and friction modifier hadn't done the trick would have been a new torque converter. Joy.
One saving grace was a suggestion by the folks over at CrownVic.net to use the tranny cooler lines as a way to drain the pan. Worked like a champ. Rig up the catch system (a 3" piece of 3/8 copper tubing, a few feet of 3/8" hose, and a five gallon bucket), start the car, and twenty or thirty seconds later most all of the fluid that was in the pan is now in the drain bucket. Now you can drop the pan without taking an ATF shower. Yay!
But I can't leave well enough alone. There's also a popular mod for the 4R70W called the Jerry mod (so named because it was developed by a guy named... Jerry).
The 4R70W is electronically controlled, up to and including line pressure. Some adventurous souls will dial up the line pressure by adjusting the internal regular. DO NOT DO THIS. Guys who run these trannies hard, and who actually know what they're doing, say that jacking up the line pressure is one of the best ways to kill one. The 4R70W is very sensitive to overpressure and will die in short order. Jerry, adventurous soul that he is, and tranny guy extraordinaire, figures, “Hey, I can’t change pressure, but what about volume?”. Turns out he was on to something. By enlarging certain holes in the valve body separator plate and changing accumulator piston dynamics (i.e. removing springs) you can safely dial in better shifts.
I did the mod last night. Glad I did. The Vic no longer granny shifts, slooping and slurping into gear in an attempt to be velvety-smooth. Now it shifts like it should. The beauty part? Being electronically controlled the line pressure varies with throttle. Part throttle shifts are just firm enough to notice while full throttle shifting is nice and positive. The part throttle shift, while definitely more firm, is only enough for me to know there’s a different from before. Someone who’d never driven the car would probably not even notice. Full throttle shifts are firm without being hard or harsh. Just a nice, fast, firm ‘bump’ in the backside to let you know that, yes, you are in another gear. Hopefully the reduced slippage will also result in a few extra thou of clutch life. The further I can stave off a $1800 tranny rebuild, the better.
I’ve heard about the mod for years, wanting to do it but never being real jazzed about tearing into the tranny (especially the valve body). My concerns were unfounded. Couldn’t have been easier. A few basic tools, some good jackstands, and plenty of patience are all that’s needed. Wish I’d done it the moment the warranty expired.
Brad
