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I recently purchased a 2007 997.1 C2 cab (6-spd). While I absolutely love the car, the slight 4x4 look nagged at me until I decided to undertake a father/son project over the summer and lower it using Eibach’s Pro-Kit. I read many, many, many posts before doing this and decided to go with Eibach because the drop was less aggressive than with the H&R’s. The car already scraped a little and I was fully aware that more scraping was to be expected. The new ride height is spot on visually, in my opinion, and I actually feel the ride comfort over general rough road is improved over stock. The scraping is obviously worse but I’m fine with that.
However, what I didn’t expect, are the incredible BANGS from the front of the car that occur when I hit something that’s raised more than say 3/8-1/2”+ at normal driving speeds, i.e. the backside of a deepish pothole or a milled road with a bump at the transition back to the regular road surface. I also get the bang when crossing utility trenches where the infill has sunk and created a depression. Basically anything that suddenly compresses the suspension creates a bang that is so loud and jarring that it scares the life out of everyone in the car! My feeling is it might be slightly worse on the front right but this could just be because I’ve hit more stuff on that side; it certainly occurs on both sides. No issues from the rear as far as I can tell.
The car has around 60k miles and I DID NOT change the stock struts when I replaced the springs. The bump-stops were a little perished, but looked to be essentially intact, and I also reused them; but I’m now wondering if this was a mistake. The bangs are so loud and jarring that I have to believe they are caused by the springs bottoming-out and transmitting the impact through the strut mounts. Has anyone experienced the same problem after lowering, and do you think replacing the bump-stops is the solution? I have to believe Eibach anticipated real-world driving when designing the springs and that what I’m experiencing isn’t normal. I haven’t called Eibach yet but any thoughts from you good folks would be greatly appreciated.
I also bought a 997 recently, it's also a 997.1 on lowering springs. Mine has 20" wheels, so I was thinking perhaps the wheels were way too big and was going to look into it.
I was planning on going back to stock springs, but now you have my thinking I have something else wrong...
Thanks for the feedback everyone! Definitely sounds like there's something wrong with my car, with the struts being the most likely cause.
Devioustrap - makes me feel better to hear I'm not alone. I'll let you know if the struts are the solution for me as soon as I find time to replace them!
What are the widths and offsets of your aftermarket wheels - maybe your hitting the inside of the fender or wheel liner but that would sound more like a scuff than a bang. Assuming you don't have PASM where you could try the sport setting which would increase the compression stiffness....
They're 19" Rohana RF2's and have offsets designed for the car so I don't think it's a wheel clearance issue - like you say, I'd expect a scuffing sound rather than the banging. And no PASM on this car so nothing to adjust unfortunately.
I have the same bottoming out issue with my 05, with the lowered springs. They were on the car when I bought it a couple of months ago, and it is driving me crazy. I am going back to stock.
No issues on my non-PASM Eibachs, 50k miles. Ride is slightly better than stock on the crap SF roads. I did change the bump stops when installing the springs. They were shot.
My indy said 60k miles was when the 997 struts started to fade but I haven't seen any evidence to corroborate this.
I have them on my '06 C2 non-PASM and have never had such a problem. hey've been on for 6+ years. Looking at the feedback it seems you may have a unique issue worth looking into. I have found the ride to be NO more harsh etc. relative to stock. Extremely happy with them
10-17-2017, 07:03 PM
Bottoming-out after lowering with Eibach springs?
