96 f150 4x4, vibration coming from the front right, intermittently. Random speeds, random roads, random times, wont do it for days or weeks, then will do it out of no where. Typically at slower speeds i believe (its a friends truck). Pads and rotors were done less than littlr over a year ago, i did follow procedure and even used a torque wrench when putting everything back together because there was a slight vibration putting it back together the first time, the axle nut was a little loose, was only for a couple weeks and not driven very much, has been fine since, over a year ago but that was the driver side. I just replaced the caliper and brake hose. He says its still doing it, but not as bad.

First time it happened we were driving it around the block after adding trans fluid to get it to temp. It started like 5-7mins into the drive, but wasnt very noticeable. I noticed, he didn't. Fluid was low, added it, this time i drove it. Starting off, wasnt doing it, got to the exact same spot in the ride, this time it was bad. So bad i almost didnt want to finish the 1mile back to his house. Basically had to ride the brake, lightly, and it would stop. Jacking it up and shaking the wheel down, everything left solid and looked good. I took the caliper off and it was a bear to compress, but once it moved it moved free, this caliper isnt even that old, maybe 3 yrs. Stopped doing it for a couple weeks, then started again, once in a while. Replaced the caliper, still doing it, but not as bad.

Rotors, pads, and bearings less than a year old, caliper brand new. Im thinking possibly ujoint on the half shaft. I did the ujoints on the driver side half shaft a couple years ago, but that was a different type of vibration. Really stumped on this one, and that doesnt happen often.

 

What could cause an intermittent vibration on the passenger side that only happens once in awhile? sometimes severe, other times barely noticeable, sometimes wont happen at all. Everytime it happens, lightly applying the brakes it goes away. Pretty much everything brake related has been replaced, especially specific to that side, and this just randomly started. It does have autolocking hubs, those were gone through a year or two ago when replacing rotors.

 

I would suspect the passenger u joints.

 

Thats pretty much what i expected. I just didnt want to tear everything apart, have him spending money on seals and stuff if it was likely to be something else. When it first started happening, i told him i believe its the ujoints. The more he drove it and the more we talked about it, i was thinking it could be the caliper, especially since it was such a bear to get it to collapse, but once it broke free it continued to collapse easily, then it didnt happen for awhile, and when it did happen, it wasnt as bad. He also stated the more he drove it, the better it got, making me think it was a sticking caliper that was sticking less often the more he drove it. But the new caliper says, yea, thats not the case haha

 

So he got a new caliper and hose, didnt solve the issue. i took the passenger axle out, the u joints are good. I dont see anything noticeably wrong on the passenger side, where the vibration is coming from. Possibly the hub engaging and disengaging? Its the 3 bolt/screw auto locking hubs, and i believe they are original. 140-160k i believe. Is there any way i can put this back together wo assembling the whole hub to see if it goes away? Like just installing/torquing the axle/hub nut? Also the outside of the hub that the locking ring holds in so i can put the cover w the 3 screws back in to keep debris from getting in, but leave out the shims/washers and the other piece with the spring that engages with the rest of the hub?

 

They are mechanically engaged hubs, make sure they are clean with fresh grease (not too much) and they shouldn't engage. If you want, you can take the front driveshaft off as well, to ensure zero power is being transmitted.

 

I thought about disconnected the front driveshaft, that would certainly stop 4x4, just wasnt sure if the vibration was coming from the hubs in any otherway/aside from 4x4 engaging and disengaging, if it would still stop it. Not sure a vibration from the hubs could be caused from anything else, just wanted to eliminate as many possibilities as possible.

Hubs were cleaned and greased probably less than 2 yrs ago when pads and rotors were replaced, so i dont imagine that being an issue, unless possibly too much grease. But since this started about a month or so ago, well after everything was installed, its probably not very likely.

 

It sounds kinda like a weed whacker when one hub tries to engage, you can hear the teeth grind. I'm not convinced the hubs are the issue. They cannot disengage under load.

Just to rule it out, are your tires balanced? Maybe try rotating the tires to see if anything changes.

 

Tires were replaced not all that long ago. Its a friends truck, he came to pick it up yesterday, when he got here, we were going over a few things, when he asked me, "if this doesnt fix it, where do we go from here"?
-idk, i guess we pull the front driveshaft, or dive a little deeper
"what are the chances its coming from the rear"?
-i highly doubt it. When you were driving it, it sounded like the front passenger side, like it was right under me. Then i drove it, i didnt hear it on the driverside, sounded like the front right. When we got back, i had you drive up and down the street while i listened as you drove passed, and walked/jogged next to it, definitely was coming from the front right.
"hmmm, cause i thought i was hearing something from the rear"
-well i wish you told me that sooner! After i got the caliper to break free, you said it didnt do it for a little while, then started again, then got more consistent. We replaced the caliper, you said it was still doing it. That tells me its still doing the samething/coming from the same spot. You never told me it was making a different noise, and it sounded like it was coming from the rear, so obviously i never looked at the rear. You should have told me it was a different noise, asked me to drive it, or at least taken me for a ride. Saying its still doing it makes me think we're looking for the same issue.

After that bit of new information, i go to the back wheels, shake it, its squeaking like crazy, both sides. He says, yup thats the noise!
"Well wth!! Thats not the noise it was making before"!!
I go to the driverside, samething. Jack up the rear, shake it down like checking the front end, its got side to side/holding the wheel at 9 & 3 its got a little play like a front would with a bad tire rod end or bad wheel bearing, samething holding it and 12 & 6. Also, in and out play when push and pull with both hands at the same time, but i imagine thats just from the axle until it hits the c clip in the dif. Driver side does the samething as the right side.
Also, when i spin the wheel forward check it, then backward, check it, it only has the side to to side play at certain spots. Like it will have play, spin the wheel, no play, spin it a little more, no play, spin it a little more, now there's play again. Little strange. So hes dropping it back off tomorrow, and ill be pulling the drums and checking out whats going on.

 

After checking everything else
Check the front axle u joints
The ones out by the wheels
If those u joints start to seize up, you get the problem you have (shimmy / death wobble)

 

Driverside front axle u joints ive already done. I pulled the passengerside axle and checked those, those are good