My truck has around 30K miles on it, and for the past few months I have been hearing/feeling a vibration everytime I am slowing down to a stop (unloaded). It seems like it's coming from under the vehicle, I am suspecting driveshaft or axle. The sound of the vibration starts at a fast speed( around in the 35 mph) and slows down accordingly as my speed goes down. I do not hear/feel any vibration when I am accelerating or coasting.

Took it to dealer one time and it stayed with them for 3 days and they were not able to find the real source of the vibration. Here's what the rep told me that they did:

1. Rotated the tires
2. Resurfaced the rear brake rotors.
3. Swapped left and right rear brake rotors.
4. Put on "electronic ears" and they narrowed it down to the right side. Still, they don't know.

I've heard a lot about the tranny clunk on the Screw, so far I don't have that. The Screw is coming in for it's scheduled 30K maintenance and radiator upgrade, so I want them take another look at it.

I want them to check the slip-yoke, torque converter, rear-differential, tranny and possibly the chassis.

What else should I be looking for out of the obvious?

 

I just got my 99 F-150 supercab 4x4 back from the Ford shop..4.6 with the AOD, 64k miles....it took them from 26k 'til now (over a year) to find the vibration in my rig...I took it in 3 times. Turned out to be pinion bearings in the 3.55 open rearend..Ford repaired as if under warranty due to registering complaint while under warranty. My rig had the vibes at 60 to 70 mph when "coasting". (no load on driveline)..hope this helps.

 

maybe loose motor mounts?

 

Does this only happen while using the brakes?

Many of these trucks have warped brake rotors and the vibration coincides with the speed of the vehicle but only while braking.

 

Exactly! It only vibrates when I step on the brakes to a stop. The noise/vibration that I hear coincides with my speed and also slows down as I am about to stop.

Ford already resurfaced the rotors, so far no luck. Once I bring it in this week, I will make sure they cover all the basics, rotors, caliper, rotor mounts, driveshaft .. all the works.

It doesn't seem to get louder, and I don't feel anything on the brake pedal. It's more of an audible noise coming from the rear end.

Thanks guys for the respond. I will keep you posted on what my service rep finds out.

 

What is this screw you are talking about at 30,000 miles,are you suppose to change the fluid at that mileage.Thank's

 

*hammer

The 30K maintenance is just another "signature" service that my dealer does. If you are talking about the transmission fluid, I think you should not change it unless it's really discolored.

Well, I got my truck back after it spent a night at the deaership, they couldn't find the source of the noise. I will bring it again since I am close to the end of my warranty period, I'm at 30.5K.

They said that they will have to take a look at the rear-end and open it up. I've been telling them that all along!

We'll see what happens next.