My 2000 F150 Supercab (5.4L, 3.30 rear gears, 8300 miles) has exhibited a 38 - 42mph vibration while at 1,100rpm since new. It feels like an out of round tire or torque shudder. Well, I think I may have found the problem. This weekend, I had a 250lb load in the bed and the vibration got much worse at the 38 - 42 mph speed. I believe it is a bad pinion angle.

I will take to the dealer next week to have it checked. Anyone else with the same vibration? What was done to remedy the situation? Let me know.

Thanks, Jeff

 

does your vibration feel like its coming from the front or rear? does your steering wheel wobble in your hands? if its coming from rear or vice versa try swapping the front tires with the rear? or vice versa? you may have a tire out of balance or round?i had the same problem with my 97 f-150 it had a vibration in the front end around 50 to 55 mph my tire was out of balance i confirmed this by putting the front tires on the rear and the rear on front my steering wheel quite wobbling and the vibes moved to the rear end of the truck

 

Well I've eliminated driveshaft, tires, wheels, u-joints, transmission, and engine as far as where the vibration is located. After shifting a 200lb load in bed, the following conclusions can be stated:

1) 200lb load over axle = vibration got worse;

2) 200lb load placed at tailgate = NO VIBRATION AND NO WHEEL HOP.

The rear shackles/springs appear to be the cause of my 40 mph shutter and my low and moderate speed wheel hop. I will take to the dealer next week. Coincidentally, I have rear spring assembly on back order due to sprung spring causing truck to lean.

Also, if you look at these shackles, they are not "fixed" to the leaf spring like former trucks; the ones on my 2000 have a shackle extender from the eye bolt to the leaf. I believe this is the cause of the wheel hop and vibration. I will see if the dealer can leave off the extenders to see if it is the problem.

I'll post a followup soon.
Jeff