I've had some work done lately... had someone do pinion and wheel bearings/seals in my '01 5.4L (2WD). He made the mistake of not replacing the crush sleeve in between the two pinion bearings, so I had to get that replaced. That took care of the noises, but the guy that fixed it today (after also doing u-joints) said "I think its vibrating. You tell me if its worse than when you brought it in". It wasn't any worse under 40 mph (I expect some vibration at 210,000 miles) but once I hit 55, its SHAKING.

He said he thought the driveshaft needed balancing. To me, sounds like some BS. He also said I was missing a balance ring... wtf?! Any insight here would be greatly apprecaited.

 

Sounds like the guy was being honest with you. To balance a drive shaft they weld what looks like coins to an end of it. If there is a spot that looks like a coin was once there but now is gone and clean metal is in its place then you have your answer. If you doubt his work then take it to someone else, or take the shaft out bring it to a driveline shop and ask them to balance it. Other things that could cause a vibration include but are not limited to. Wheel bearing, tires/wheel balance/pressure, bent rim, cv joints, worn differential bearings, out of sync front u joints(if applicable), loose lug nuts, poor alignment/failed steering components.

 

Can I blame it on him then? There was little to no vibration when I took it in, now its nuts. Could he have done something wrong when installing new u joints?

 

I suppose he could have caused a weight to fall off but if he did he probably did not do this intentionally. Last thing a tech wants is to redo a job he just did. Take it back to him tell him there is an issue with vibration at highway speeds you believe to be drive-line related. Have him deal with it. I think for the shaft to be pulled balanced and reinstalled it will be 2-300.