4l80E shudders at low rpm

[pitsingerk]

I have the 6.5L w/ 4l80 transmission, 4x4, w/ 4:10 gears. When travelling down the road at approx. 40-45 mph, with the engine rpm low, the tranny begins to shudder like the convertor is trying to lock up. My buddy told me to just change the fluid to a synthetic and it should cure the problem. This is my first automatic in 15-16 years, need some help here.

 

[ak diesel driver]

sounds to me like the torque convertor is failing

 

[pitsingerk]

I was told the transmission was rebuilt at approx. 175k-180k. I would hope that at those miles he would have not reused the convertor. I was talking with with a guy last night that said it may be the convertor lockup solenoid hanging up, any thoughts on that?

 

[THEFERMANATOR]

The shudder is normally a converter, but it could be the PWM solonoid for the TCC acting up. At 40-45 though you shouldn't be locked up yet as IIRC it is 47 for lock-up with 4.10 gears(at least that is when mine would lock-up).

 

[pitsingerk]

it may be closer to 47 mph, never really staring at the speedo to make sure, 40-45 was a guess. I do know it only happens at this speed at low rpm's. Never happens going down the highway at 55-75 mph. How hard is it to change this solenoid? Is it external or do I have to drop the pan? If it is the convertor, what is recommended for a replacement. I plan on towing with this truck, upwards of 10-15k.

 

[THEFERMANATOR]

The solonoids are all internal inside the pan. If your converter is bad, I would pull it down completely as normally a failed comverter will send clutch material through the whole tranny it it will fail shortly after you replace the converter, then you have to do it twice with ANOTHER new converter. PRECISON INDUSTRIES of TN carries a good HD converter that a 6.5 probably could never tear up. TRANSTAR also builds some nice HD converters for reasoneable money, and most tranny shops carry TRANSTAR products.