My truck has an automatic transmission (5R55E), that has given me some trouble. The truck has 88,xxx miles on it, an the fluid has been flushed (by Ford dealer) every 30,000 miles using Motorcraft Mercon V.

Some time ago, I started noticing poor shifting (sometimes no O/D downshift), a vibration/shudder under my feet (my assumption is the torque converter) and an occasional failure to shift into neutral when braking.

After describing the symptoms to my mechanic, he called his transmission specialist and we went to work. We flushed/replace the fluid with Mobil 1 ATF, cleaned the pan/magnet (both were very clean), replaced the filter (again very clean), added 2 ounces of Lube Guard shudder guard, and replaced solenoid #1 (shift) and solenoid #3 (can't remember the name).

The transmission shifts very smoothly now, and feels as good or better than it ever has. All symptoms have disappeared, except the shudder. The shudder is greatly reduced (from a "10" to a "3-4"), and really seems to mostly occur when it is cold and right before a shift. I was told that the torque converter may just be beginning to fail. Since the Lube Guard had a noticeable affect, I was wondering if I should add another tube.

If the torque converter is failing, it will need to be replaced. I suppose that that would be "major surgery", and wonder what it would cost. My knowledge of transmissions is obviously limited, so any knowledge/information/insight would be greatly appreciated. Oh, and Merry Christmas!

 

Hmm ever thought the shudder could be in the drivelines?? Front or rear.. being its under your feet thats likely where your T-case is.

I only say this cause my truck is at 94xxx and I have replaced my rear drive and it really effected the ride..

And im getting a shudder under feet and i know its my front drive thats need new u-joint or a new cv. But its always possible. Just a thought.

I get the shudder when i let on and off the gas at certain points. but i have the standard tranny.