So here in Vermont we have to have yearly "safety" inspections done on our vehicles. Last year (beginning of November 2016 I think) I had mine done. I happened to have a bad wheel bearing, so to pass inspection it had to be replaced. I was at the local Ford dealership because they are competitively priced on inspections and wash your car for free after. So I paid them to replace the bearing. Throughout the winter, I was experiencing some sporadic and random bumping as I drove down the road. It was bad enough at times, I thought my butt might come off the seat, but then it would go away. I had just bought new winter tires and thought it might be those, but couldn't find anything wrong with them. By June 2017 I was fed up with it. I put it up on the lift at my dad's business to check things out. I found my front left wheel bearing had a lot of play in it and the caliper on the same wheel was sticking. So I replaced both of them...completely forgetting I had already replaced that wheel bearing once just 7 months prior. Fast forward to just last week and I was getting a new inspection...again at the Ford dealership. Guess what? The front left wheel bearing was bad again. This time I remembered it had been replaced, but I coudln't remember when. They looked it up and saw they had done it a year prior and covered the repair under warranty. I know the mechanic who worked on it from when he worked at a different local shop and he told me that the threads on the CV joint/half shaft were getting kind of rusty and were starting to disappear. He said everything torqued fine so not to worry about it. He also said if the bearing goes bad again to replace the CV joint.

SO, all that to ask, would a bad CV joint cause a wheel bearing to go bad so quickly? Is it just a freak thing where I happened to get two bad wheel bearings in a row (the first was aftermarket because the dealership didn't have a motorcraft in stock, the second was motorcraft from Rock Auto)? Anyone have any insight on what might be going on? I'm kind of perplexed.

 

I will take a stab at it, so it sounds like you have a 4x4 hence the reference to a front CV. A bad CV can cause some binding and this can lead to exessive vibrations on the bearing. However, you should be hearing some clicking from that side if the CV is going, especially while turning. Let us know what you find as the possibility of a bad bearing or 2 is low but also don't rule out a poor install that might of damaged the bearing during installation

 

Thanks for the reply! It is 4x4...apologies for not providing that up front. The second wheel bearing (it's really a hub assy...) I installed myself so it's always possible I overlooked something. At this point it's a waiting game to see how this bearing lasts. The only other thing I can think of (besides bad parts or bad installation) is that the threads on the shaft aren't holding the torque. But it seems unless the nut loosened right up that wouldn't necessarily cause a problem.