Freddie's Back on the Road!

[MacDee]

Same U-joints? Maybe all this new "Saturn 5" launch torque has made one of them fail? They would vary with load as well.

What's the frequency?

I carefully read your posts again and can't see the specifics...

Do you FEEL anything or is it strictly "noise". I know it's hard to tell the difference sometimes.

It is definitely FELT, but it acts like an acoustic dissonance.

While cruising along at about 50 mph, there is a vibration that sort of grows and subsides, grows and subsides, over and over, continuously, at about 1 cycle per second. If I feed a little more throttle, as when going up a slight grade, the frequency of the vibration rise-and-fall cycle will increase to... I dunno... 3 or 4 cycles per second without any significant change in road speed.

This is why I'm suspecting it has something to do with the torque converter. The torque converter has within it a Stator and a Turbine which spin on a common axis, one driving the other. Because of slippage, their relative speeds will always be slightly different. However, the more load you have, the more speed difference there will be between the Turbine and the Stator. I'm not sure, exactly, how this relates to the vibration, but it's the only thing I can think of that would have two components spinning out-of-synch. Maybe the converter isn't quite centered on the flex plate so the turbine is slightly off-center?

Or am I just over-thinking this...?

I'm going to take Randy Long for a ride. It will be up to him to fix it!