AODE Transmission Shudder

I’ve a 97 Mercury Grand Marquis, 80,000 easy miles, all driven by my 82 year old Mother. From other posts I gather it’s an AODE transmission. It seems to generate this shuddering feeling about 40-45 mph under easy acceleration. That’s where it starts. It also does it at expressway speeds up to about 70, always under easy acceleration. Hard acceleration, no shudder. Coasting, no shudder. If the OD is turned off, it seems to alleviate the problem somewhat, although it doesn’t cure it completely. If you accelerate really easy, it may shudder for several seconds. If you go a little harder, it may only bump two or three times, in a second or so. I’ve seen other posts recommend flush and clean, one other mentioned a speed control, but it kind of sounds like low line pressure to me. Any thoughts?

If the transmission fluid has't been changed for a while get that done. If you notice no differance with that done, have a look at your spark plugs and wires.


I’ve a 97 Mercury Grand Marquis, 80,000 easy miles, all driven by my 82 year old Mother. From other posts I gather it’s an AODE transmission. It seems to generate this shuddering feeling about 40-45 mph under easy acceleration. That’s where it starts. It also does it at expressway speeds up to about 70, always under easy acceleration. Hard acceleration, no shudder. Coasting, no shudder. If the OD is turned off, it seems to alleviate the problem somewhat, although it doesn’t cure it completely. If you accelerate really easy, it may shudder for several seconds. If you go a little harder, it may only bump two or three times, in a second or so. I’ve seen other posts recommend flush and clean, one other mentioned a speed control, but it kind of sounds like low line pressure to me. Any thoughts?

After 1996 this transmission's name changed to 4R70W. Which is "basically" an AODE. :)

This syptom is common, as the fluid ages you can get a shudder while the torque converter clutch is modulated on/off. Basically, the clutch is made to slip on/off. So fluid integrity is important.

As already posted:
I would recommend: pand drop, filter change and drain the torque converter. That shoud take care of it. If all thats been done already... Then maybe, the torque converter is defective or the engine is misfiring. It usaully takes a few miles after the fluid exchange to know if it helped or not.

Thanks gentlemen for your observations. It sounds like you've hit it right on the nose. I'll let you know, following change. Thanks again.

I had the same problem with my 97, it was a common problem: The dealer replaced the transmission fluid and installed a transmission cooler: no charge