Well, if you're lucky, the inner fender liner has come partially loose and the wheel is hitting it at extreme lock. How many miles on it? I bought a 98 Z28 new when they first came out with the LS1 and 3 years ago, with 177,000 miles on it, it was starting to show signs of need in the front suspension. I put shocks on it all the way around, but the front end needed more.
About this time I discovered that the body had rust issues that were way worse than what was worth messing with so I started looking for one with a solid body. I found a 2000 SS that was all metal with less than 90,000 on it.
It must have sat for quite a while (or seen some really hard driving) because virtually every bushing in the front end was shot. I ended up replacing shocks, springs, upper arm and bushings, lower arm bushings, bar end links/bushings, every ball joint and upper shock mounts.
I picked up a couple hundred worth of parts each month until I had the all the parts and then dove in. The one item that surprised me was the upper shock mount. It is like an upside down bowl made of some rubber-like material that the shock bolts to then you you bolt the assembly into the inside of the fender. I had never been into a front end that deep on a Camaro before and had never seen anything like it. At this age they are a must replace item. GM wants $65 for one but you can find them everywhere for $35 or so. Rockauto is your friend for all of these except maybe the springs. I may have purchased those from Summit. I didn't want it lower so went with the MOOG springs in stock lb/ rates. The front end seems to sit higher than stock but I'm ok with it. I've been told they will settle some, we'll see.
I went with the KYB AGX shocks. I wanted gas adjustable shocks for fine tuning and these fit the bill, very happy with them.
I had kind of planned on replacing everything in the front end from the beginning so I wasn't totally taken by surprise by this. I wanted a like new feel and performance.
Someone had already put a full BMR suspension kit in the rear with the poly bushings and they were in great shape. To my surprise I can't feel any any kind of harshness penalty at all in the rear end.
Take it to a mechanic that is reputable, maybe he can pinpoint it for an easy fix. But be prepared to replace all the bushings, ball joints and the upper shock mounts at the very least. These are the wear points and let's face it, 21 year old rubber is not going to be in good shape. I actually had one of the front shocks break free from the upper mount. The rubber right around where the shock bolts in just gave way.
Buy the parts as you can afford them and put them all in at the same time and be done with it. Major job, but well worth it, it drives like new!