smoke1425

I have an 04 FX4 and I had this very same prob 2 days ago. That wasnt the 1st time it happened but I finally figured out what it was. I had my truck at the shop getting the front end alligned after putting new BFG ATs on. It started to shutter pretty bad right when it shift into OD so I thought it was the trans since I had just had it serviced also. I got home and was cleaning the blue stuff off my tires and when I sprayed water on the left rear tire steam literally blew up in my face and scared the **** out of me. You could feel the heat about 3-4 feet from the tire/rim. I had to take the tire and rotor off and relalse the park brake. I personally do not ever use the park brake but apparently my mechanic thought it needed to be engaged. Its fixed as of now so hopefully itll be ok.

FYI the park brake was actually disengaged in the cab just the left rear did not disengage at the wheel.

mike_112

well for me it ended up being the emergency brakes.. my shoes and springs are all seized.. at least the cables good!!

i gotta order shoes and a spring kit, ill be good!!

mwelder

I have one to throw at you I have a 2009 150 with 30k miles but this started within mabe 3k miles and it is almost exactly the same vibration, its a weird feel just like the first post the dealer balanced the driveshaft rotated tires replaced tires and now have resorted to the ole well the vibration is under the allowable limit so if we do any moore checkouts it comes out of your pocket. I have noticed a drop in Gas milage and what seems to be a slight loss in power.Maybe the brake dragging could cause both MPG and a power loss? I have thought to myself that it just seems like the truck is being held back.

dbunchjr

i have a 2005 f150 xlt extended cab with 87,000 miles on it, and i bought it used and ever sence ive owned it i have had a vibration in the steering wheele at speeds between 40-50 mph when i bought it the deal was new tires so i got bfg long trail t/a and i didnt notice it on the test drive but my roters were so warped i dont know if i would have any way. took it to my mecanic and he said tires and rims are fine and he can see it in my drive shaft so i rebuilt the drive shaft and reballanced it, no change so he said it had to be my tranny so i rebuilt it, no change had rear end serviced looks good, new plugs boots and egr valve and fuil filter no change front end is tite and breaks and wheel bearings looks good im stumped. and broke now!!

primalurges

Well it really sucks that your mechanic focused on every part of your drivetrain that isn't connected to your steering wheel or your front tires. In order to rule out any engine issue at the problem speed and load put truck in neutral when experiencing the vibration, clearly if it continues keep looking. Also I would check for proper inflation of your front tires, probably should be around 35 psi cold. If properly inflate try inflating more but within the limit of the tire capacity and see if vibration worsens. If it does heck your front end components and perhaps have tires hi speed balanced at a different shop.

Rick_F150

I had some vibration too when coast and releasing the gas pedal and just lightly touch...
I thought I had LSD rear end...
It felt like the clutch trying to engage...
When I checked My Rear Shaft My Pinion bearing was lose they can be tighten But I replaced the bearing and seal all vibration stop in rear end

Bill Tarbell

I realize this is an old post, but since I was having the exact same symptoms as the OP i thought i'd post my findings.

I recently bought a 2005 fx4 4wd from a stranger. After driving it for a while i noticed the intermittent symptoms that the OP described. I found this thread (and a few others) and saw a handful of proposed problems/suggestions, but the ebrake one seemed most relevant since i noticed one of my rear tires was much more worn than the other.

I went out and engaged the brake then went to each rear wheel to check the springs (you can see them if you look stick your head above the tire and look down over the back of it). One side was fully compressed, whereas the other side hadn't moved at all. I released the brake.. the compressed side relaxed and the frozen side didn't budge. note: the good one was 3" uncompressed and roughly 1 7/8" compressed.

I took off the rotor and then the brake assembly and saw that the lever mechanism was made from 2 pieces of flat metal that acted like a pair of scissors. They were effectively rusted together, which caused the brake to stay fully engaged at all times since the spring wasn't strong enough to pull them back open.

It took some effort (and lots of pb buster) to separate the 2 pieces. Once that was done i hit them with a wire brush to get the rust off then coated them in bearing grease for good measure. It operates properly now and i haven't experienced any more vibrations.