I have a ’99 Expedition, Eddie Bauer, with 275K. It has developed a vibration in the front that grows louder with speed. I am assuming tire problem here, but I am not 100% sure. Will bearings or U-joints cause this kind of vibration?

 

Dry or worn axle bearings (front or rear) can cause a vibration. Axle cv joints that are dry or worn and driveline ujoints that are worn or dry will also cause vibration. Pinion bearings can also cause a vibration but will usually cause the seal to leak on the rear differential. Putting vehicle up on sturdy jackstands and using a stethoscope while the drivetrain is turning is one method of detecting a vibration's location or just shaking the heck out everything while the engine is off. You are right to suspect a bad tire as well. Some brands of tires have this problem more than others, but the bigger the tire, the more difficult to make up for out of round or a dynamic balance problem.

 

Ok I wasn't getting much in the way of vibration but at first when I was pulling a trailer with a bit of weight in it, as I started off from a corner while turning I was getting this grinding sound. It wasn't there on straight acceleration but over the past few months it's been getting worse so I ordered some Dana Spicer U Joints and after all the headaches I read about from others I thought I was going to be in for a nightmare. Well as usual the front 12 point bolts came out like a breeze so now the back that are hidden under the cover. I found with a 13 mm deep socket and a couple of extensions and a universal I could reach back over the crowded area to undo the two nuts holding the shield in place and push it up out of the way. It looks as if it's there in case the U Joint self destructs to prevent anything from entering the passenger compartment. I didn't bother trying to undo the drive shaft bolts in such a tight spot so just by taking out the universal I could use the same procedure to take the bolts out while they were pointing down. It took a little hammering to get the shaft out but other than this it was fairly simple. The new Spicer U-Joints went together without any headaches so greased them up and now had to re-install the front shaft. Getting it back up in place was simple and I put in a pair of bolts in the front to hold it up in place then went to the back. I was having one awful time trying to get the bolts started until I got smart. I cleaned the threads good, then ran the die over the first two threads because they seemed rounded out added some lube and they spun in slick as whiskers. After torquing I re-installed the shield then finished installing the last two bolts in the front, torqued them then took her out for testing. That rotten grinding sound was gone and now I feel at ease stepping on the gas in turns coming out from stop signs. I now have to tackle the back, just praying they are the same size.