I have a '94 F150, 6 cylinder, 2wd. I just replaced the ball joints, tie rods, and wheel bearings (front end). After taking it in for an alignment, I have only driven it a couple times and there are some pretty bad vibrations that didn't exist before. The first time I drove it (other than the short trip home) I noticed a little shake on the on-ramp, but nothing much and I haven't felt that again. The major vibrations started, and are repeatable, when coasting on the highway and they get really bad when I start pushing on the brake. I don't feel anything at high speeds like I would suspect with tires out of true. Nothing was changed on the brakes, so if warped rotors was the issue I would expect to have felt that before doing the work, too. It didn't vibrate at all before doing the front end and alignment.

I've seen a lot of pages mention u-joints. But again, why would it only happen right after doing this work?

Could this be a case of a poor alignment job? Or are there other (un)likely culprits?

 

A bad alignment can cause tire scrubbing. Which will be felt as you described. However, before going after that guy/gal. One possibility to consider specific to the brakes. When you did all the work mentioned the brake had to come off then go back on. Question is did you clean and service the brakes, specifically the callipers and pins, before putting them back on. Because what you describe is also exactly what a stuck caliber will do. A very very likely culprit. Perhaps go back and check your work, particularly with attention to a proper brake inspect, clean, and lubricate while you were in there.

Did you drive it at between the repair work and the alignment? Was the vibration before / after / nodiff ?

 

The first thing to do is take it back to the shop and ask their opinion. Maybe they'll identify the cause, and maybe even fix it free, if it was their fault. But always start with the last person you paid.

Yes, brake rotors CAN be warped instantly - either due to you or anyone else mounting a wheel improperly. It's VERY easy to screw them up on these old trucks - so easy that Ford published this TSB:

(phone app link)


Follow the relevant links in the caption, especially the one about cleaning the WMSs.

 

Thanks for the link on torques. I'll check where they're at when I get home tonight.