The Stovebolt Site Forums The Parking Lot Big Bolts Still shakes like paint mixer between 30-40 then smooth as glass 40+

just to share one of my experiences... I had a 79 C70 twin screw that was similar. Around 30'ish it would begin shaking. The faster I went, the worse it got. Not a vibration... but SHAKING! The hood was bouncing around and you could not keep anything laying on the dash or it would come off. After 40-45'ish... it would smooth out and be smooth as glass at any speed above 45-----
Really thought it was tires, but after new tires installed - same issue.
The truck was un-usable because of this shaking.
Found the problem when I went to a wheel upgrade on the rears.
This truck had 20 inch daytons installed and when I changed over to 22.5's - it all stopped.
I could see a "slight" movement or "wobble" in a pair of the old wheels on the back, but never thought it would cause that.
I am thinking I was incorrect on my thoughts.

Good luck.