What It Is And How To Prove It To Yourself
Mine is doing it too and I know EXACTLY WHERE it's coming from.
I just lowered mine. (Eibach Pro/Ford Racing Dampers) and I made one mistake which MAY or MAY NOT have contributed to the CAUSE. when I was putting in the front (assembled) spring/strut, I was on the bottom pusing it up throught the 3 (tri-pattern) bolt-holes, and a buddy was on the top spinning on the nuts for me. At some point lost when all was said and done, was torqueing down those nuts and I drove home (some 10 miles) with the those top, 6 nuts, only finger tight. I realized it after I got home and did get them tightened down good in the morning before moving the car again. BUT almost rightaway I noticed a soft grinding/creeking noise coming from the right front wheel/suspencion. First thing I did was tighten those same 3 bolds more. nada. BACK-2-THE-RACK ! Here's what I did to find it.
Put back up on the lift. (must be a wheels-hang-free-type)
Put a tall jack-stand under the lower ball-joint. The one I used had a foot-pump on it to push(nudge) the top up and down. (not actually a "pump-up" height adjusted by a spin-nut at the top-side)
Let the car down just enough to take the weight off the wheel, compress the spring just a smidge
(steering should be unlocked)
now the person wanting to know where the rub is coming from reach up and put their hand on the spring, as close the top as they can get.
NOW have a buddy grab the tire and turn it slightly, like maybe an inch or so, and gently push-pull it back forth (turning left/right-in/out). Repeatedly. At which point it should be crystal clear to the person who has his hand on the spring, where it's coming from. IN MY CASE the "grind-creek-rubbing" sound was coming from where the top of the spring meets the metal of damper-housing it sits in. BECAUSE apparently the bottom of the strut mount moves slightly and the SPRING WITH IT, WHILE the TOP side, tightly secured by 3 bolts DOES NOT move, (poducing the grinding you hear between the SPRING and top of the strut-mount the spring in mounted inside of.) So I took a cheap rubber-cement type brush and slathered and stuffed everywhere I could reach, with BEARING GREASE. This got me about 50% reduction in the rub/grind/noise. I'm told by one of "my guys",
1. It's nothing, it's safe to ignor, if you want, turn up the stereo and try to ignor it, it's not a situation that's going to deteriorate. Over time it MIGHT even FADE away.
2. If making it STOP NOW is all you're willing to accept, the only way is to REMOVE the sping/damper from the car, return to the spring-press, disassemble it, and lube up real good the offending-zone, then put it back together, which is likely to be an even bigger bitch than it was the first time with the spring now greased, since you're pressing it "into/on-to" the UNEVEN, slanted base. If you assembled your own, (or just watched it being done) you know what I mean. I'm currently in a holding pattern, waiting to see if the grease I already put up there ( I also blasted it with aerosol White-lithium) works in and makes for further silencing. If I end-up pulling it appart again I'm putting some-sort of rubber pad in there and if I can find it, wrap the end of the spring with plumbers teflon.