M-45 intermittent high speed vibration

[casparis]

157,000 miles, new brakes all around by dealership, new front tires. I get a high speed vibration (70+mph) occasionally on a long trip (8 hrs). Slowing down to <30mph and/or stopping stops the vibration. Usually doesn't show up for the remainder of the day. Any ideas? My dad suggested u-joints...

[DeanM45]

Can you feel the vibration through the steering wheel?

[wingFeather]

If at the start of the drive, it could be flat spots in the tires from sitting. Some tires seem to need a few miles to round out in the morning.

[casparis]

Nothing through the steering save indirect. Steering is tight. Tires and wheels are tight, no sway.

[casparis]

High speed vibration after several hours of driving so I don't think it's tires.

[DeanM45]

You said slowing down makes it stop--have you tried weight transfer? Meaning, slight turns to shift weight to one side or the other. See if that makes a difference once the vibration starts. I experienced this in a different car and it turned out that the tire was slightly out of balance (during the days of stationary balance when dynamic balancing machines were rare). It would set up an oscillation in the suspension (spring) that the strut could not handle.

[casparis]

Interesting since two of the three times it happened was on the same stretch of highway and appeared to grow over time like the buildup of an oscillation...

[kermit the guy]

maybe its the stretch of highway that you drive on? happened to me i was like man it only happens on the freeway , i took a different route one day and i said yaye the vibration is gone , when i went to work it was there again , damn that 10 minute stretch of highway in the fast lane was the culprit , but yah it could be alot of things , like balancing, alignment , tires ? hope you get it fixed !!!

[Double E]

I wonder if at the speed youre traveling, the pressure builds up to the point that there may be a belt in the tire that has seperated and shows up only when the pressure increases beyond x pounds.

I would drop the air pressure in the tires by a pound, maybe 2? and see if it made a difference. Maybe rotate tires also?

Otherwise, I know several folks have replaced the front struts by your mileage and that might be one more contributor along with the condition of lower ball joints & TREs.