Chasing vibration

[demian5]

I had like 15 year old tires that did that.

Thought it was pinion angle, nope, carrier bearing, nope.

Replaced rear tires, smooth as glass.

[Quikshft]

Originally Posted by morepwr

Check the motor and transmission mounts. I had a weird vibration in a car and it was the transmission mount. It looked fine but once I unbolted it, it was in two pieces.

Same here, 67 Dodge Dart had a rumble that cycled on & off at hi-way speeds. Figured it was something that was rotating until I discovered I could hear the rumble just sitting at the curb in neutral. The transmission mount had lost the rubber damper and there was a metal to metal contact allowed. New trans mount and quiet cruising was restored.

[67 chevelle]

The 2 that caught me by surprise were , pinion bearing , and shocks

[kazoocruiser]

https://i.imgur.com/78EkQJM.mp4

[franken]

Call me dumb but I'd ask where the op feels or hears the vibration; steering wheel, butt, whole truck? Maybe I'm oversimplifying, but the waveform interactions in the posted pic seem so show two equal bu opposite waveforms of the same frequency. The combination on of equal same frequency sine and cosine waves will canceleach other out and there will be no harmonic. The 2 frequencies have to be different for the amplitudes to add/subtract. Chances are the pic is just to give a simple illustration and not actually representative, or the frequency difference is sbtle and I missed it....

[72c20customcamper]

My 72 has the same vibe. Put all new u joints center carrier bearing and tires. Its between 55 and 65 . But if I pop it into neutral going downhill it goes away so I'm thinking it's not the shaft or tires. Thinking it's the motor or trans mount or a compo of both.