If it's just a loose nut, then you may not need to do anything other than remove the dust cap and tighten the nut. If it's related to the spring, perch, or strut in any way, you may not have any choice but to remove the strut and inspect it out of the vehicle.
First, check the strut nut and make sure it is tightened and secure. Check the 3 strut mounts up top to ensure they are not loose either.
If everything seems secure up top, then jack the vehicle off the ground and remove the wheel. Check to see if the spring is seated in the lower perch properly. It should seat securely in the notch in the lower perch. If it is not seated properly, you will need to release the spring tension enough to move the spring into its correct location. You may be able to do this without removing the strut by loosening the top nut almost all the way off and slowly lowering the spindle assembly with the jack while the vehicle is supported securely on jack stands. Move the spring into place and then increase the tension slowly by jacking the spindle assembly back up. Once the tension is increased again, you need to tighten the top nut back into position. Be sure to check the top nut again to ensure it is secure once the vehicle is back on the pavement.
If you have not found the problem after these steps, then you will need to remove the strut/spring setup from the vehicle for a closer inspection. I highly recommend that you borrow a strut spring compressor set from Auto Zone or any other local auto parts store. They will charge you $40 when you take the compressor from the store, but they will then refund the $40 back when you return it.
If it is the keyway hitting the upper spring perch, you will probably need to disassemble the strut/spring setup. More than likely, the bottom of the spring perch will have some sort of marks on it around the keyway hole if the keyway has been hitting the perch hard enough to cause audible noises.
I hope this info helps you find the problem quickly with minimal trouble. Let's just hope it isn't a damaged or failing strut.
Good luck!

 

Thanks... I adjusted the spring this morning, it wasn't properly seated. I was able to tighten the top nut down a bit more on that side... so far, so good. The strut only has 7K on it, so it shouldn't be failing yet.

Thanks for everyone's help, I'll keep you all posted.

 

Glad you found your trouble spot. Just as an FYI, I had a bit of clunking going on way back when and it was the 2 bolts that attach the front strut to the rotor. They were a bit loose from a spring install and just needed a quick tightening.

 

i plan to go threw and re-tighten all the bolts that were touched during my spring/strut install. prob in another week or so.

 

i love my torque wrench – one of the best investments (my brother) made. all my friends are constantly borrowing it now – really gives you that "peace of mind" when doing DIY stuff. your bolts were probably too loose, but i know even with a torque wrench its still a beoch to tighten that top nut

glad to hear everything is ok

[loving that DS btw]

 

I've often thought about picking one up.