torque converter shudder during lockup

[Master ACiD]

my dodge stratus started shuddering when thetorqwue converter locked up in 4th gear. i checked the oil and saw mlky fluid on the dipstick. i found out my radiator was leaking coolant into the transmission fluid, and transmission fluid into the radiator!
after fixing the problem and flushing the cooling system out with freash fluid, as well as flushing the transmission out with fresh fluid, everything appears to work normally except this pesky torque converter shudder when the converter locks up in 4th gear. it feels like i hit some speed bumps every time it locks up. the shifting action from 1 to 4 is perfect.
like i said i flushed the trans fluid, and replaced the filter. what else can i do?

my car originally came with atf+3, i flushed it with atf+4. i dont know what else to do. ithere wasnt much water in the transmission when i dropped the pan. only a few ounces.

 

[unDummy]

2 easy choices:
1. toss in a bottle of Lubegard Platinum or Smartblend Titanium. If it helps, great. If not, flush again.
2. toss in a bottle of Seafoam Transtune. Drive a week and flush again.

When water/coolant end up in the transmission, you know what freezes over. If you are lucky and no damage is there, then it'll take several flushes to clean out the transmission.
LC20, Neutra, and Autorx are also options prior to your next flush.

 

[PT1]

I would do the seafoam & reflush.

 

[Gary Allan]

You're very lucky. Coolant degrades friction surfaces real quick. When you flush, make sure that you use 10 quarts. Even with 15 you won't get 100% of the old stuff out.

You may have to flush a couple of times.

Unfortunately, you're OBDII. I'd normally say just unhook the wire to the converter clutch, but that will result in a CEL condition.

Good luck!

 

[bmwtechguy]

Get a small tube of "Shudderfix" which is made by the Lubeguard people, I believe. They also make a solvent-free transmission flush that I have used, too. I would have flushed with the cheapest Dex III type stuff I could find, drive a few miles then flush in the ATF+4, plus the Shudderfix or Platinum/Titanium, and see how that goes to work to stop that shudder. I use the cooler line flush method with really good success. You may have to disconnect the batttery or pull a certain fuse to get the transmission computer to re-learn the friction characteristics of the new fluid.