Steering and what is not a box of bowling balls.

[megaladon6]

if you've never done a u-joint before find a friend who has and/or a basic repair manual. haynes is a decent manual. it's easy if you've done it before and you're accurate with a hammer. they're easy to check, try to wiggle the drive shaft around and watch the joint--you will see and probably feel any excesive movement.
shocks won't cause this noise, they can clunk but thats on vertical movement.

 

[85 Cutlass Brougham]

I would also consider the possibility that the torque converter clutch is not disengaging when you hit the brakes or that it is doing so abruptly. If you have the ECU controlling the clutch engagement, check the brake light switch as it controls disengagement under braking, and the TPS sensor on a feedback Q-jet also controls the engagement and disengagement point. It could also be any number of bad bushings or U joints or even loose shocks. Iwould get under there and check things out before it becomes a real issue.

I will also add that when checking U joints, be sure the rear wheels are off the ground. Otherwise, the way the car is parked in combination with the parking pawl in the trans can effectively lock the joints and they will seem solid.

 

[Derision]

I now present myself for the "Bonehead of the Month" award:

Well, I checked the bushings. Everything looks fine; the body bushings are (almost) just as perfect as the day they were new (surprisingly, they're barely even cracked slightly). Control arm bushings are a little more worn, but still perfectly serviceable.

I didn't get a chance to jack the car up and check the U-joints... but when I did open my trunk to get my hydraulic jack, I discovered that my full size spare, sitting in "The Pit" (where the spare tire is supposed to go) was standing up straight. I could roll it forward and back with my pinkie. Which, at least, explains the thump and gets me my newest bonehead award: when I hit the brakes, the spare rolls forward as much as it can in "the pit". Once I've come to a stop, its forward momentum stops and it plops back, hitting the rear wall of "the pit" and causing a thump.

Crisis averted.

I also checked the steering as per the instructions of 85 Cutlass Brougham. There is a little bit of play, but not more than I would expect. I'm going to replace the rag joint as soon as I get a nice day to play around on.

Thanks for the help, guys!

AJ

 

[megaladon6]

murphy's law of combat #2: the simple thigs are always hard and the hard things are always simple.