Hi, I'm brand new to this forum, but have been reading lots of posts. I have a vibration on my 99f150 5.4l. It starts coming on at about 62mph and is worst at 65mph and seems to calm a bit after that, but doesn't go away. It is related to wheel speed not rpm because it is the same on acceleration or deceleration. I just got new tires (goodrich long trail at samsclub) had them rebalanced twice... i can't say whether it was there before the tires or not, but i don't remember it . The tire shop (samsclub) said i have some play in left front wheel bearing, i jacked it up and it isn't bad. I seem to feel it in the seat more. I haven't jacked up the rear end. I was just wondering what you guys could suggest for possiblities. I'd like to take care of this myself instead of going to ford... because I've read lots of threads on here where even ford couldn't figure out vibrations. I also noticed today that I drove the truck cold on the freeway for about 15 minutes and it was not as bad, then i stopped at the store for 5 min, got back on the freeway and headed home and it was much worse. Don't know why hot or cold would make a difference.... any suggestions would be greatly helpful... btw the truck has 67000 miles on it has really been taken care of, I'm the second owner and just got it a couple months ago. I think i'm going to try checking the passenger spindle nut for looseness today and then got to samsclub and have the tires rotated to see if that changes the vibration at all. Thanks so much.

 

I would say samsclub cant balance tires... most of the time when a wheel is unbalanced its worst around 65. I worked at discount tire...

 

Thanks for the reply... well it turns out that the bearing wasn't good on that wheel. I changed it out today and my brakes feel better now and there is no play in the wheel at all. Took it to samsclub before I did it and they said that that tire was the only one that was showing bad wear... but not so bad to ruin since they've only been driving a few hundred miles... UNFORTUNATELY, the bearing didn't fix my vibration at 65... I worked on it today with my dad and he suggested u joints... he's been driving f150's for about 45 years and says he hasn't had one that hasn't had a u joint go on him... what do you guys think? I drove the truck around a bit after fixing the bearing and crawled under to feel the joint... i've been told if you feel heat in the joint it can be bad. The front was was hot not burning but very warm... the rear was less hot but still warm. I figure the front is just hot from the tranny the rear should be cool though right? There isn't any play... i'm thinking if there is a problem it would be seized... not loose with play... any suggestions are really appreciated...Anything else you could think of would be great... oh by the way... the truck was previously owned by someone who didn't drive it much at all... after all its a 99 with 67k on it. Would lack of use maybe cause the bearings in the u joint start to rust and seize? Thanks in advance

 

If the bearings in the u joint go ungreased moisture and such will build and cause them to rust, they will wear the part of the joint that goes into the cup down and cause it to gain slack inside the cup, thus causing vibration.

 

Yea, I wouldn't trust Samsclub / walmart for anything but buying 5lb containers of sour cream. I've been dealing with the exact same issues on my truck, I just replaced the front left bearing, from what I've heard ANY play in the bearing is too much play, after hitting a crater in the road. I would take it to an actual tire shop (I usually use discount tire without problems) to see what they think they see. My truck does the same thing yours does but around 50-55, sometimes the vibration is worse or better, so we are going to look into the ball joints / u joints once it warms up a bit.

 

where do you live? im only asking b/c i wouldn't mind helping you pinpoint your vibration.

 

Change the diff fluid + modifier, that's what happens once it breaks down. She begins to shake at those speeds.

Once changed, the vibration will totally quit within 75 miles if not right away.

New tires just changed things up enough to where spent fluid can't handle. That's my opinion anyway.

 

Ok... first thanks for everyones imput... well maybe I have a new piece of the puzzle... I drove the truck today after work and I am feeling/hearing a very similar (if not the same) noise at around30-35mph... just not quite as loud. If I recall correctly I think i read some threads that said that vibrations at these speeds usually point to u joints? am I correct? Does this extra info point to one part more than another? Thanks again.

If It turns out to be u joints... any idea what a reasonable shop price is? I know they are dead cheap to do yourself, just don't have the time or ambition for now...maybe afte the shop gives me a price I will!!!

 

one of my local shops told me 20 a joint, i done it myself for 10 each. I guess it depends on how tight you are, and i also live in a very small town so prices may vary. Personally i dont know whats cheap and expensive because i usually try to do stuff myself.
edit: that 20 a joint is for labor, tack on whatever the cost of your joint would be

 

I was just under the truck again looking around, and saw a rubber ring set into the metal at the front of the drive shaft. Its one a round (bracket, i think) that connects the u joint to the spline shaft... the rubber in mine looks old and there is a couple places where it is coming off... is this a problem... what is it?

 

You've already been told what the problem is.

 

as jbrew stated change your diff fluid that can cause the problem it did it to me and jbrew.....with 65000 miles it wouldn't hurt to change it anyways it doesn't cost too much and you can do it yourself in a hour or so.

 

I have been reading around on a few different threads here and on some other sites and alot of people said that ford doesn't recommend changing the differential fluid. That doesn't seem right to me... I would assume that the diff fluid would be the same as any type of oil... it will eventually break down like you guys said. Any recommendations on type of fluid to use on the change? Anybody have a link to any "how to's" for it? I'd like to look the job over first and see if its within my capabilities... or if I'd be better off to take it to a shop... like I said before... I'm a bit short of time lately.
As far as my other question.... about the rubber bushing... that was just out of curiosity. Sorry if I offended you jbrew, I wasn't dismissing your advice.

 

No one really knows why ford recommends that because with the limited slip as the fluid breaks down the clutch packs are not kept well lubricated. I personally change my differential fluid every 20,000 to 30,000 miles of course I am lifted with 37's and tow a lot. Just pick up the fluid at the local ford dealer with a bottle of friction modifier. Its pretty easy just jack up the truck put it on jack stands and remove the differential cover. Scrape of the old rtv silicon from the pumpkin and cover, put new sealant on and put the cover back on the truck. Then fill the differential back up

 

Thanks for the quick reply Nick,
So will the dealer know how much fluid/modifier I will need? Will I also need to buy a replacement gasket? or I will just use the silicone sealant? When I use that I have to wait for it to set up right? And as for putting the truck on jack stands, I don't have any...is it necessary, or does it just make the job easier? If I can borrow some I will, do they just go under the rear axle? where should I jack the truck up? I really hate to ask all these stupid questions, but this is my first truck... still trying to figure everything out...sorry if I sound like a moron. Also what kind of cost am I looking at for all the stuff needed for the change? Thanks again to everyone who has replied.