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!

 

The torque converter is between the engine and the trans. It's pretty easy to do. Remove the drivershaft, unbolt the trans from the mounts and engine, slide it back pull the old one out, put the new one in, and reverse the rest of the process. Top off the fluid and go on.

 

my knowledge of trans is limited also, but i know you "MUST" fill the torque converter with fluid before installation or it'll burn up!

 

You must know more about torque converters that I do, or for that matter, Ford Motor Company. I've NEVER filled a torque converter before installing. Every automatic transmission that is built at Ford has a DRY torque converter installed. It is filled from the pump in the transmission when the input shaft is first turned.

 

I've had several people tell me (on other forums) that a faulty throttle position sensor could cause the intermittent vibration that I feel. Any ideas on what symptoms a faulty TPS could cause?

 

A bad TPS would also cause engine running problems, poor idle and/or stumble while accelerating. However a TPS is easy to test and so eliminate as a possibility.
Go to fordfuelinjection.com and click on TPS for test how to. All you need is a volt meter. Good luck.

 

a friend of mine had the same problem with the tps. real bad shudder when you first put it in gear and it was slamming gears while shifting also.

 

This does sound like a failing torque converter clutch. The shudder is the converter's clutch slipping. The lining is burnt and shudders when it slips.

Change the converter as soon as possible. If you let it go, the clutch will eventually burn up completely and overheat the transmission.

Changing the converter isn't hard. Its about the equal of changing a clutch in a manual transmission. You only have to pull the transmission and swap the converter which is located in the transmission's bellhousing.

 

I changed the TPS, and no difference. Did a smoke test on the motor, and discovered a bad EGR. I'll be changing it tomorrow, and will post the results.