Somehow I didn’t see this post, until just now.
There are a ton of possibilities as to why you have the vibration.
By far the most common (between 55-65 MPH) are tire belt separation and/or propeller shaft U-joints are loose.
Other possibilities are:
- Belt wheel (aluminum wheels can bend – but they break, more often).
- Tire balance weight(s) came off (common after a flat fix)
- Bent axle shaft (easy to do on ice or slight taps on curbs during otherwise normal driving).
- Get under car and feel for any play (up/down, side to side) on the rear differential yoke (which indicates a differential bearing problem).
- Worn suspension parts (ball joints, worn control arm bushings, worn/broken torsion bar bushings and shocks).
- Bent suspension parts, (spindles, upper and lower control arms, bent or torsion bars that have moved from original position and even bent shocks).
- Worn steering components (tie rod ends, idler arm/pittman arm and loose steering gear).
- Bent steering components.
- Steering gear mounting bolts are loose.
- Wheel bearings that are loose or out of adjustment. Also any one of the wheel bearings (front, rear, inner or outer) can develop a bad spot or can physically come apart – that feels correct when checked but when on road is a different story. Also, our front wheel bearings were meant to be removed from car, cleaned and re-packed with fresh grease every 30k miles (which is about the time to perform a brake job, anyway. Wheel bearings that has traveled over 30k miles on current grease are subject to failing at any time.
Rotate each tire (off of ground) by hand a few rotations to feel for any abnormally.
With each tire off of ground, grab tire at 3 and 9 O’clock position and feel for looseness when moving (pushing) tire left to right and back.
Grab tire at 12 and 6 O’clock position and do the same thing.
- Worn/loose U-joints. Loose bolts holding U-joints to rear differential yoke. Bent driveshaft and/or balance weights have come off. Transmission slip yoke to output housing bushing is excessively worn/loose.
- Bent transmission output shaft (hard to diagnosis).
- Warped brake rotors/out-of-round brake drums (only come in play when brakes are applied).
- Bad or bent shocks – mostly noticed after hitting a small bump in road.
When driving car, put car in neutral and see if vibration changes. If on a not so busy road, get car to 60-70 MPH and place car in neutral and turn engine off (but don’t lock the steering!) – and let car coast for a bit. Without the extra noise (engine), other noises can be more easily noticed. Keep in mind you will not have power steering (or A/C, etc.) during this process.
Bent parts (like axle shafts) and worn/loose/came apart wheel bearings are not so easy to diagnosis and are a lot more common than one knows.
About a year ago, I heard a crunch noise during a turn, just after dropping my twins off at school, in my ’77 wagon. I then had a bad vibration. What happened was a Left Front outer bearing had come apart. I was in a position to hear the noise and knew what it was when it happened
BudW