I just recently lowered my 2010 Mustang GT myself with the Eibach Sportline Springs as well as the J&M Adjustable Camber Plates. The install went fine with a friends help and heard no noise at all once I was done. A couple of days after I went to a local shop to have my alignment done and a day after I started hearing a "clunk" noise on the driver side. Every time I hit a little bump or big bump at any speed I would hear it and then I don't. It happens only when I hit a bump. I went back to my alignment shop and they checked the vehicle and made sure everything was tight and in spec. The issue was still there which is when I went to another shop to have them inspect my suspension. They told me everything was normal and they made sure everything was tighten up good. I am now still having the same issue. I called American Muscle and they were not able to help me. I am not sure what it can be. I still have the stock Shocks at 58K miles but seems odd to me that it is only the driver side. I am not sure if maybe something is defective or not. At this point I am not sure what to do and i'm helping someone here can help me out.

 

It's not odd at all. Your extra weight in the car while driving will cause it to possibly bottom out when the other side doesn't. If you put equal weight on the car on the right side... maybe a little more due to your probably being solo more than not... then it might make the same noise. You're probably hitting the jounce stops, which is why it looks ok and no problems on the rack.

The stock shocks suck at dampening lowered suspensions. They want to dampen to the original ride *height*, believe it or not, and not just cancel the bounce and jounce. The result, you bottom out, you make noises, you just wind up being unhappy with the results. Happened to me.

To fix, you need to acquire at least Koni Oranges or other, similar, aftermarket struts and shocks to get that car's bouncing under control. They don't care about the height, they only stop the bouncing around, no matter what the ride height is.

You could just get the fronts, and that would be the majority of the issue right there. The weight of the engine is going to cause the most bottoming out. And I've done that so far. But I have the rears ready to get in the car (when I have a chance) because the dang thing is still a little too bouncy in the back. I'd therefore suggest just biting the bullet and getting all four corners. I mentioned Koni, but there are plenty to choose from... Koni yellows, Bilstien HDs, Eibach, Steeda, even Ford Racing.

Hope that helps.

 

Exactly this.

Why would you install Sportlines on stock shocks and struts, let alone stock dampers with 58k miles? Typically you would replace struts and shocks at 60k miles anyways.

Also, did you replace the PHB with an adjustable? You're going to want to do an adjustable upper, relocation brackets and LCAs too. When you go to these super low springs (I'm on H&R Supersports right now), you really need to replace everything else to maintain the proper geometry.