Mystery "Clunk" Upfront - Hypothesis: ???

[helliott]

I've got a 2002 WRX with about 105k miles so I expect some issues, but this seems somewhat ominous. I'll do my best to describe the issue and I'd love it if you have any ideas or tests I could perform with the car. The noise sounds like a large glass of water dropped on a wood table - I would characterize it as a "clunk" or a "pop" while braking/accelerating. It's already been to two local shops and the dealer to no avail. There are no wear marks, no loose bolts, nothing that moves when you get it on a lift and start knocking on things. No one seems to have any idea what's causing it...

Still, it's loud enough you might think the wheel is about to fall off or the engine is trying to tear it's way out of the bay. When it's loud, you can also feel a pretty serious knock while driving. Maybe a pull to the steering when you accelerate. I can't make it happen all the time, but it's something that happens with a pretty high frequency and sometimes it's worse than others. If you hit a pot hole then brake lightly - you're probably going to feel it. If you brake hard, you might feel it. Once you feel it while braking, you should expect to feel a more muted "clunk" as soon as you accelerate. Potholes alone wont do it, corning wont do it. Only braking and then the subsequent acceleration. Braking then braking, nada. Go then go, nada. It's only when you change direction. Backing up from a parking spot you pulled straight in to, you bet!

Other possible symptoms:
1. Occasional shimmy in transmission on takeoff. It's like the clutch is catching/realeasing/catching/releasing. Fairly uncommon, may be related to the weather.
2. Sometimes there will be a slight vibration in the steering wheel at expressway speeds.
3. Excessive wear on front tires.

History:
Hit a deer on front right, some body damage. Shop had to drill out spot welds and replace front right wheel well. The repair still looks good and firm - can't make it move. Front right cradle bolt stripped nut in front subframe - cut out and repaired by shop - seems good. It didn't make the noise immediately after the accident. It has upper and lower strut braces. Shocks/springs and brake rotors have recently been replaced - since deer and clunk. I thought it might be the sway bar, but it doesn't seem to make any noise with potholes alone or just moving it up/down. Everything I can find down there has been lubed and all the bolts have been retorqued.

Hypothesis:
Engine mounts?
Driveshaft?
???
Any other ideas?

[Mikie13]

definitely check out all the mounts. Possible you could have a lot of bushings starting to wear down at that age and mileage.

I'm in the process of replacing my tranny mount and differential bushings due to all the clunk I've developed on my 2005 STI with 117k miles.

[Dvold]

Sounds like a front lower control arm bushing. Most commonly the rear one. That is why you only hear it going back then forward. If you load it up while backing up and then back up again it is already loaded that way so it won't clunk. If you back up it loads one way until you go forward then the worn out part loads the other way and you get a clunk. Hope this helps.