A Frustrating Shake

DCAspen

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I'll agree on the bad K-frame bushing,Tranny mount?
 

MiradaMegacab

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Hmm, many different people posting with different vibration issues. Perhaps "clock" the driveshaft. Unbolt the U Joints straps , pull the shaft out of the trans, rotate 180* and reinstall into the trans and bolt the assembly back in. 180* off of what it was......
check yoke engagement too.
 

Justwondering

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Thank you AJ.
My vibration problem was handled by replacing the likely culprits -- tie rods, idler arm, etc. and a front end alignment.

JW
 

BudW

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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
 

89.Fifth

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SOLVED! (for me at least)

I changed the rear springs (every hard part including front spring hangers) and replaced with 5 Leaf spring with 1" extra arch. The ride quality difference is night and day!

But what I think took care of the vibration was the alignment that was done afterward. More specifically the change in caster angle as a result of the back end of the car not dragging on the ground. Obviously changing ride height front to back will require an alignment so getting all numbers back to factory spec is important.

Right now I get a very MILD vibration at 70-75 and that's it. Smooth right up to 90mph. Or at least as smooth as you're gonna get in a 30 year old car blasting down the highway.
 

JLN5thAve

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Good to hear!! I would at time experienced different vibrations from 70 MPH and up... but the ideal gas mileage cruise speed was around 62-65 - so that’s where I would top out unless in a hurry.
 

4speedjim

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I had the mystery vibration too. Came and went. Different speeds, I Could not duplicate. Motor mounts? Trans mount? K member? Then driving to an apt on the interstate, it went from smooth to violently shaking 1/2 turn per stroke. Thought maybe Id hit something in the road. Ripped or bent something? Nope, it was a piece of tread! Them nice deep treaded like new 215 white walls it came with threw a chunk of tread on pass front.
Id inspected everything, checked fluids, air pressures etc prior to the trip. I had to pull it out early (3/31) after step daughter totaled wives van. From earlier exams there was No rim or tire run out, wheels balanced, bearings snug and greased, tow was good. Suspensions acceptably worn, nothing loose. I cant explain why the vibration came and went or what caused it. Or how you would ever see the problem until it separated. It threw some tread. About 3"x9" patch. Thankfully It didn't hurt the car. And It Still held air.
I had no spare, no jack, no $300 to be towed off the Thruway. AAA was looking good! Wished Id sent in the check. I limped it down the shoulder 15 miles to the nearest exit and found a shop that threw a junk tire on for me. $20 for the tire, disposal, balance, time. They loved my 'Doba! True Mopar men. Never made my Dr. appt. Came straight home and changed all 4 tires. I had planned on putting them on my van. The 3 good ones are going to the dump, or maybe the ex wants them? heh heh heh
 
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