I own an '88 Ford F-150. It's 2WD with automatic transmission, V8 302ci
engine. I've tried everything I know to reduce a slight shimmy or
shudder in the truck when it gets to around 65mph. I've replaced the
rear transmission mount (it had a small give to it), the U-joints, had
the tires replaced, balanced, and rotated. It seems that it only begins
to shudder slightly when higher speeds are attained. I'm scratching my
head on this one. The truck does have high miles (169,000) and I know
with age there comes a few tics. I had a good friend try to help me
diagnose the problem and his only idea was to change the rear
transmission mount because of the amount of play in it. There is a
bushing in the rear of the transmission too but was told there should be
some play where the spline on the end of the driveshaft fits into the
transmission. I was also told that the bushing would not need to be
changed out unless it was leaking fluid. The driveshaft looks ok. The
rear end is ok. I've jacked the truck up by the rear end and checked the
drivetrain and all seems to be nice and tight. My question would be what
else could cause a slight vibration when reaching higher speeds? Any
help will be appreciated!
Thanks
Mark

 

I had a GM vehicle that once had this problem and it was discovered that one of my wheels was slightly warped (I clipped a curb rather hard at one time). I went to a salvage yard, purchased a new wheel for $35.00, had the tire installed and balanced and the problem went away.

Good luck with this problem. I have an '88 F150 too.

 

Dean, thanks for the info. I had thought of this since I have aftermarket rims on the truck. They are about 7 years old now. One could be warped. How would I go about checking to see which one might be the culprit? Is there some way to do this without taking the tires off the rims?

Mark

 

Mark,

Like you, I had a vibration that wouldn't go away after I visited a tire shop for wheel-balancing. I insisted that their work was inferior after they stated they "balanced" the tire. They put my vehicle on a lift and physically spun the tire and had me stare at it from an angle. It was ever so subtle of a warpage, but definitely there (I still wonder why their "computer balancing" machine didn't detect it).

My guess is that those wheels are suspect. I had another car, a Camaro, with aftermarket aluminum wheels that I never could get balanced correctly. My experience is that its tough to beat the oem factory wheels for "balance life"

Good Luck!