My 2004 F-150 has an intermittent shake in the rear end. It feels like I am driving over the rumble strips on the side of the road. It is rare that it happens below highway speeds. When it does happen, the only way to make it go away is to turn the truck off and let it sit for a few minutes. Then it disappears for weeks. I have tried putting it neutral but it still shakes until the truck comes to a stop. It doesn't appear to be brake related because the truck does not slow down. (and the wheel isn't hot nor is my parking brake on) It isn't tire/wheel related because it happens randomly with no obvious pattern. So I assume it is differential related but the dealer doesn't know what it is because I can never duplicate the problem.
I've read several threads but none of them seemed to describe my problem.
Can anyone help?

 

My truck did this at one time, but it was a combination of the rear e-brake and caliper locking up. How far have you drove while it was shaking? Wondering if maybe it just wasn't long enough to heat the wheel

 

I have driven a couple of miles to the next exit. I have also tried applying light braking as I apply throttle just to see if it was brake related. It still shakes when I do this. When I take my foot off the accelerator, there is no apparant force slowing the vehicle down. So it just doesn't seem brake related.
I had seen the e-brake posting so that was my first guess.
Thanks however.

 

Is it while driving straight, in corners, or both?

 

Kyle,
It is occurs while driving straight and only after a few miles; some time it has been 10 or more miles. It is different than the minor vibration that sometimes occurs when going around a corner.
Kevin

 

I was just curious because I have an FX4 with a posi rear and mine had a vibration when I turned left or right from a dead stop. We still haven't figured it out but loosed the e-brake pad and also put new gear oil in it. It helped it out a lot. Maybe if you try to put new gear oil in it and you could inspect the gear teeth as well.

 

I also had this vibration, then came the grinding noise... Turned out my rear end was trashed. Luckily I have the ESP warranty and it only cost me $100..

 

i had the same problem wiht my 2004 f-150 stx 4x4, took it in to look at it, and it was the drive axel, it was loose, they used a rebuild kit on it, and never had that vibration again!!!! i was told good thing yu brought it in, could of had the drive axel fall off while driving, not to scare you but get it in to look at, you can even check your self, go under truck and see if you can make drive shaft move back and forth, that was the first way to check it!!! hope this helps!

 

let us know what you find out

 

I could't detect any movement in my drive axle but I didn't jack it up to take weight off the wheels. I have an appointment Wed with the drivetrain mechanic at the dealership to discuss. I mention your axle experience. I will post what I find.
Thanks

 

Turns out my wheel is getting hot. So it is not the differential.
I replaced the calipers and hoses but the driverside rear hub is still getting hot. I don't know how to check the emergency brake. When I release the emergency break I can see the lever on the back side release. Could it still be sticking? I watched the left and the right side; no obvious difference.
Is there any other reason that a wheel hub would get hot.
Thanks in advance for any advice
Kevin

 

hi Kyle, i have a FX4 too, and i have the same problem. Could you tell me exactly what you did?
Thnx!

 

gueron,

I haven't fixed the problem yet. I thought my brake calipers were sticking so I replaced them and the hoses because they can calapse and prevent the caliper from releasing. That didn't help. The problem has gotten worse from when it first occurred and that has helped me figure out the wheel is getting hot. Just a short trip around the block will not make the rear end vibrate but I have now figured out that my wheel hub is hot after just going around the block. Last night I pulled the caliper off to see if I could inspect the parking brake. The caliper slides right off so I don't think that is the problem. I have yet to figure out how to get access to the guts of my emergency brake to see if that is where the problem lies. I know it is not the emergency brake cable because it is releasing. In fact I can unhook it with relative ease. I can't imagine it is a bad bearing with only 60K miles nor would I expect it to get hot just going around the block. It has got to be the emergency brake.

 

The dealership replaced my bearings when they replaced the rear end gears at about 60k.

 

Your FX4 probably has a posi-trac rear end. My truck still vibrates a lil bit but not as noticable after I loosened the e-brake and, changed the rear main seal, and new rear brake pads. If you find out what is wrong and takes away the vibration please let me know.