Pontiac Grand Prix - Wheel Bearings or Struts?

2004 Pontiac Grand Prix GT1, with about 102,000 miles. Problems started with a vibration while braking, which got progressivly worse. I also noticed a vibration while driving (not braking) that started around 65MPH, and then expanded to slower speeds (40-65MPH). Also then started hearing a clunking sound from the rear passenger side, when going over bumps that was louder than I would expect.

So - have had the tires balanced/rotated and an alignment done, which seems to have taken care of most of the vibration while driving. The rear brakes were in bad shape with warped rotors, so I replaced those and that smoothed out that problem somewhat. When the tires were dealt with, I was told that the CV joints/tie rod ends were ok - but they reccommended replacing all four struts. This reccommendation though was based purely on their age (they are original - ie, 100K miles on them), and the shop just happened to be running a special on struts at the time, so I took that advice with a grain of salt.

So, while the vibration issues seem to be better (although not gone- still some vibration while braking and very slightly around 65MPH again), the clunking sound is still there.

My next thought was wheel bearings, so I jacked up the back and tried to wiggle the wheels, but they don’t budge side to side. Not the most scientific test, I know…but it was worth a shot. I have heard that wheel bearings on this era of GM products have a propensity for going bad…

I’ve also ‘bounced’ the car to test the struts and they bring the car back to rest after one bounce. I also checked for fluid leaking from the struts and didn’t see anything.

So - question is, what is the most likely culprit, and what is the best way to test it to figure it out? Or are there any other possibilities that I haven’t thought of? Thanks in advance.

there are travel stops made of rubber, kind of triangular in cross section that limit the travel of the rear axle/wheel. They are located on the body. (this is generic not vehicle specific information). Bearings give a kind of crackling sound when they go bad, not a clunking on rough roads. With this many miles, you might want to see if those struts are still on sale, it could be a problem that is indicated by noise and excess wheel travel, but without other symptoms. (this is shade tree advice I am not a pro.)

Thanks - i figured I’d try the struts, as they were old anyways. Didn’t make a difference in the sound (although it does feel better…). A mechanic suggested to check out the trailing arm bushings - they were shot. So, two new trailing arms later and…still have the sound. Checked the sway bar (disconnected the links and drove it) and still had the sound.

The only lead I have is the parking brake cable - it is loose and has play, and can make some noise/squeaks back there. But I had someone else sit in the car while I played with that cable and they didn’t think it was the same sound as what I get when driving. I tried taking some of the slack out of that cable and it didn’t change anything.

Anyone know what else to check?

Found it today…apparently the alignment shop left an adjustment rod loose, and that was what was clunking. It was probably a little loose before the alignment, and the alignment adjustments made it worse. Easy fix once it was found…tighten it up. Brakes are their own problem. Just in case someone else has a similar problem, that’s something to look for.

Howdy Prix owners. Got a sorry for disturbing you and this thread from its silence. Just have a problem with my auto and i badly need your helping hand. got a 2001 Pontiac Grand Prix GT from a guy in orlando yet i have a problem with a wheel bearing. There are 2 models at GM auto parts, they just don?t know what is the difference between both. There is one with a plastic bracket that holds the wire for ABS and the other one is stainless steel.Im still wondering if I can use either one because the one with the plastic bracket is about $200 less than others.Im planning to do Pontiac Grand Prix repair on my own to save money as well.Thanks in advance I’m gonna wait for your responses.