Throwitup518

So I recently installed the RCX 6" lift in my 2004 F-150, as stated in the instruction you may get a vibration when the truck is in 4X4 over 40 MPH. Their reasoning is that Ford did not aligh the yokes from the factory and the heightened angle of the driveshaft from the lift makes the miss align more noticable.

So I got the vibration even when I was in 2wd and called them to see if that could happen without being in 4X4 and they said yes. So their fix is to pull the driveshaft out and groove out the master spline and turn it 90 degrees so the yokes lign up and re instal it. Did that and it still has the vibration.

I drove the truck with the front driveshaft out and that stopped the vibration so it is most likely 100% that, cause I dont think its the transfter case and I just re-geared it and after the 500 mile break in I changed the oil and everything looked good inside the pumpkin.

I just took my drive shaft to a expert in our town and he lengthened it by 3/8 of a inch and balanced it, STILL VIBRATING!!!!!

Watt-maker

Are the hubs disengaging when in 2wd? You may need to have a shaft made with double cardian joint at one end.