Vibration

[FourEyes]

Im having vibrations at speeds about 40mph. The vibrations are very harmonic. they pulse. I have a C4 transmission with a big stall convertor and a FMS aluminum driveshaft. I think that its a u-joint. Is there an easy way to tell which one it is. am i wrong in my assumption?

 

[white99gt]

Im having vibrations at speeds about 40mph. The vibrations are very harmonic. they pulse. I have a C4 transmission with a big stall convertor and a FMS aluminum driveshaft. I think that its a u-joint. Is there an easy way to tell which one it is. am i wrong in my assumption?

Did you have to change the yoke on the d/s when you installed the c4?
If so did you have it rebalanced? FOrd d/s are balanced OK but they really need a good rebalance to get them perfectly smooth.

 

[FourEyes]

no. the yoke was not changed. The vibration isnt constant. its like something is out of balance and ginding.