First let me say that these coil springs are great. The car handles like its on rails; it launches better, all while not beating you to death. The installation was easy and all the adjustments are very nice.

SO, I bought a set of 4 coilovers new (they do have the new style mounts) and they have been installed for a little more than a year. The car is only driven on nice weekends, probably only have 5-6k miles on them (if that). Since day one I have had problems with the coil springs making noise while going over bumps/breaks in road and this has progressively gotten worse. Ive read all the forums, talked to Pfadt, etc but could not get them quite. In the beginning the noise was not that loud so I just let it go. As the car has sat OR the bushings have gotten more worn in the noise has gotten a lot worse. I am 100% sure the top nut is tight, all suspension bolts are tight, the spring itself is tight. Yet I get this horrible clanking noise. I knew the coilovers were installed properly as I have looked at this 100 times before, so I assumed it was something else on the car. I went over every bolt, checked every single rattle, but I still could not find the source of the noise. In desperation I threw the stock shocks on and went around the block……the noise was gone. So I knew it was the coilovers. I called Pfadt again two months ago. They sent me out the new style bushings, I replaced, used loctite just as before. I did notice the small style bushings I removed were quite mashed down and not in the best shape. I thought this odd as they were brand new.

With new style bushings the noise seemed to be gone. I have driven the car a handful of times since then and haven’t given it much thought. This weekend I noticed the noise back as loud as ever. It literally sounds like they are about to come off the car. You would think they are extremely loose, but they just aren’t. I live in Houston, and yes the roads are bad. Im sure this doesn’t help but I don’t hit pot holes or speed bumps fast. The car has 19s all the way around and I am very very careful when I drive.

My question: (yes there is a question) has anyone else had this experience? I have spent hours and hours trying to figure this out. Ive had several friends over to get a second opinion, but no one can figure it out either. Do you guys think that because the car sits up so much it is somehow causing this?

Any help would be very much appreciated. I have done everything to this car (SC, motor, system, interior, wheels, tires, brakes etc), and consider it done. However it sounds like a piece of $hit when I roll over uneven surfaces.

Lastly Pfadt makes great products; I am in no way bashing them. I am just at my wits end and desperately need help. I am so close to putting the stock system back on with a set of aftermarket shocks its not even funny. I really like this product, and know others are very pleased. I don’t want to take them off, but Im running out of options.

Thanks everyone, sorry for the long post

Brian

 

Could it be teh springs comming into contact with the swaybars?

 

I also have the Pfadt C/O's on my 02 vert, which is also a fair weather driver. 18's all around. I have not noticed the problem you mentioned. Mine is very quiet. No issues at all. Sorry you are having this kind of mess.

 

haydensha...not sure who/what question you are trying to answer

SDZ06Driver, they are not hitting sway bar

Any other ideas?

 

Are you lowered? What sway bar are you using (30mm and up do hit or rest against the cradle)? What end links do you have? (adjustables can clank)

LG has a helper spring, seen it on other c/o's where it keeps the spring up when lifting the car (with a jack)- if you're not lowered and at stock height, when you hit a bump the shock could be opening up leaving the spring to flop around for a split second, then 'clank' back down. The helper spring just keeps the main spring in place when lifting. Maybe you also need to crank the spring a bit tighter? I'm not real up on these, but maybe you can get some more info here. He's got the helper springs with pics

http://forums.corvetteforum.com/c5-t...procedure.html

 

The car is a 03 Z06, has stock sway bars, and stock end links. I have CCWs all the way around. The car is "lower" than stock but by no means is it slammed. I have 2-2.5 in of light between fender and tire, car does not rub at all.

thoughts?

 

Just a thought, but could the noise be coming from the sways/end links? Have you looked into those at all?

When my end link bushings started to go they made lots of noise like what you're describing. I replaced/upgraded my sways/links and the noise went away. Since you have the stock set you might have that same issue.

 

Ok, no sway bar issue. Not being lowered makes me think my first comment may be it even more. Can the spring be compresses a bit more? Did you look at the thread I referred to about the helper spring?
Also, endlinks like dangerz suggests below, or tie rod, tie rod bushing. I'm still leaning towards that helper spring or not enough crank down on the spring allowing slop when the rear end drops over a bump,

 

The pfadts dont have "helper springs" I have the lower threaded ring the spring sits on tight, and the lock washer tight. With the car in the air and suspension fullly down the spring is still sitting in there tight.

 

also, its not like I am hitting speed bumps fast which is making the car jump and relax the suspension letting the coilover move around. I can be going 15-20 mph and just hit uneven sections in the road and it makes the sound.

 

Look at your endlinks. For a car as old as yours, the rubber grommets could be worn through.

 

I will look at end links, but car only has 35k miles on it. The noise is mostly coming from the rear of the car

 

? Exhaust hangers?

 

Just trying to throw ideas at ya. Sounds like my car with leaf. I wasn't referring to the nuts being tight, but the spring being tensioned more, cranked up a bit more to get rid of slop when you do hit a small bump. Stupid question, but shot in the dark- you removed the leaf spring and bolts, right?

 

I have a new corsa cat back, hangers are solid.

As for the springs I have increased spring tension a few times, and it doesnt make a difference

yes I removed the spring and the bolts

 

How did you "throw the stock shocks on" and drive around the block? Can you do this without your factory mono springs? Or did you install the springs back on for this test. Either way you have put a lot a labor in an attempt to diagnose your problem.

 

I took the coilsprings off, put rear factory shocks in without mono spring. Car was basically bottomed out in the rear. Tire was about 1/2in from fender drove just fast enough to try to reproduce sound but it was silent.

By no means what this the ideal thing to do, like I said im at my wits end here.

 

Try running this by the folks in the Autocrossing/Roadracing section- lots more suspension guru's there. Keep us aprised when you find the issue/fix

 

I had two versions of this problem and the roads are bad here too. The nylon insert nuts at the top of the shocks loosened up at the rear, one was off the shock and bouncing around in that cavity. That caused loud knocking at the back of the car. The other problem was not enough preload on the top rubber bushings which was corrected by tightening the top nut more. I used two nuts per shock so that they lock to each other and not loosen up but excessive force wasn't applied so as not to stress the hollow shock shaft. I also went back to the original design upper mount that seemed to control downward travel better due to the thick rubber top bushing; the newer Delrin conical design used a light rubber tube at the top that didn't seem to prevent downward travel as well as the older design. The Pfadt web site now shows yet another design for the top. Pfadt will tell you that unless the car is launched off the ground that there shouldn't be any knocking because the spring is always in tension but large bumps and potholes caused knocking in my car. If the upper mount isn't tight enough due to a loose fit or weak bushings it will allow the shock shaft assembly to hammer the frame. After changing the top nuts, top mounts and adding more preload the knocking stopped. Hope this helps some.

 

Thank you Fast One. Is there any way you can measure one of your rear springs? I am curious to see how much you had to compress it. Mine is tight, but I really dont have anything to compare it too.

I just changed the bushings to their new style thick ones and I have a ton of loctite on that top nut. Im sure it did not loosen up. I think you are on to something with the mount.