theraptur

New guy here, I have been reading this thread for a few days. I just bought a cherry 2015 with 27k and after a long highway drive I was like WTF. My console going crazy, SHAKING the hell out of the drinks and keys and what not. It starts about 68mph and gets worse to a peak of 75mph and reduces till about 83mph. Even coasting in neutral from 80 down to 70 it still shook so it appears to be in the rear end/driveline. I would also come and go a bit. Hit a bump and shake away. Well after reading I tried the simple solutions in this order and experienced a large reduction in the shake. 1. Road forced balanced the tires, I had just put new tires on it as well. 2. Leaf spring clamps from Autozone. With the truck on lift, I placed the clamps behind the rear axle just at the point where the leafs started to gap a few millimeters. Tightened them down and then lowered truck to ground. Since the spring gap was slightly compressed now, I tightened the clamps a few more turns, effectively locking all three springs together. You do not want to go too far back because then you will run into binding as the suspension compresses and then rebounds. Went driving....by my "seat of the pants" measuring tool, you can feel the reduction in the shake, and my drinks, while still exhibiting ripples, are MUCH better. It is bearable now for a very modest effort. I definitely feel the issue is a resonance - the system of rotating parts working together at that range of speeds and allowing the frequency to transfer to the cab/etc. The springs themselves have a resonant frequency and by clamping them you are changing that frequency in the same way that a guitar string when fingered shorter now plays a higher note. Plus the added stability of a second clamp point and less wiggle between the springs. I may consider shocks although that seems weird to me in this particular situation.