Sorry for the lack of updates. Tightening the top nut did nothing. Pulled the coilover back out and found nothing out of the ordinary and no marks anywhere. Inspected the entire rear suspension yet again. Found nothing here either.

This morning, took the car in for an alignment and asked them to look for the source of the noise. This was Jack at Motorsport Techniques in Hayward btw. He said that this noise does sound normal for coilovers with pillowball mounts (i.e. all metal, no rubber). He looked everything over just to be sure and said everything looked fine.

To me, that is good and bad news. I don't drive the car on the street too much anymore, but I would still prefer this particular noise to go away. I don't mind some additional noise, but trust me when I say that this sounds like something has broken loose and is slamming around in the right rear. When driving hard, it is enough to divert my attention. On the other hand, if it indeed is normal and I'm not hurting anything, then I can live with it. I bought them to improve the handling. Period. Any side-effects are ones I will just live with.

All that said, FS sent me a link to this lengthy discussion on NASIOC:

http://forums.nasioc.com/forums/show...0&pagenumber=1

I found the Porsche link near the end very interesting. When I was trunkmonkey'ing it, I would say the noise was coming from the middle to lower part of the shock. It is just my estimation, but my boss drove me around for like 10 minutes and I heard it repeatedly. My ear was right near the upper mount and I also placed my hand on the pillowmount and felt nothing. It wasn't moving and I didn't feel any vibration there. It definitely seemed like it was coming from down lower in the suspension.

So possibly the spring and shock are coming into contact? I'm going to look into that in the near future. I would think that if the spring is binding up and popping like on the Porsche video, then that noise is easily amplified by transmitting directly through the pillowmounts into the rear body. The trunk is all metal with very little insulation or sound deadening. It would amplify any noise transmitted to it.

Why the right rear though??? I did a quick search on the net and the RR is the culprit in seemingly a majority of cases. I'm wondering if it has something to do with the coil windings. Total SWAG thinking here, but why would the right side be louder than the left? I can understand why the rear would be louder than the front, as any sound transmitted into the front unibody would be better absorbed by all the drivetrain, engine components, firewall sound deadening, etc. But I would think both the LR and RR would be equally bad as compared to the both fronts. Could the fact that both the LR and RR coils are wound in the same direction, but mounted on opposite sides, have any factor? Again, I have no idea at the moment. Just thinking out loud.

Anyone else have additional input on this one? I know a lot of you are JIC coilover owners. Clunk? No clunk? Please share.

Thanks,
Joe
www.joe250.com

 

this may be a long shot but what about the lower bushing where the shock mounts to the car? Mayve you just over torqued at that location and there is metal to metal contact under movement? worth a look anyway i guess.


PS that picture is priceless, i love your research techniques

 

What is the torque spec for all the suspension pieces involved? I didn't think about that. I torqued those down pretty hard. When I have time, I'm going to try a number of things and report back. Keep the ideas coming!

Science is my master!



Joe
www.joe250.com

 

hi joe,

if you got the chance, you should go to the norcal evo meet at gb motorsports in hayward tomorrow (actually this afternoon). unfortunately, i won't be able to make it, but you should get a ride in gino's evo shop car that has the cusco zero2r on it. it make no noise last time i drove it. as for the noise on the RR, i was thinking that it might be coming from the top plate hitting the tower. so i put in a thin piece of rubber between the plate and the tower while i am putting in new springs. right now i am experimenting with some softer spring setup, 7.5k(f)/6.5k(r) hopefully it would help soften up the ride a little. i have also added an extra 1/2 a turn of preload on both front and rear to see if it will stop the noise too. i will find out how it ride tomorrow after i put the wheels back on the car, right now the car is on jack stands.

the torque spec for the rear top is 33lb+/-3 so i torque them down to 36lb. the torque specs for rear lower bolts are both 65lb+/-7 so i torque them down to 70lb. hope this help.

-ob4

 

Just for completness of information, I will add the torque specs for the front bolts as they are different than the rear:

Lower bolts: 123+/- 7 ft-lb
Top bolts (3 on top of the strut tower): same as the rears 33+/-3

Make sure you don't overtorque them as I did and ended up stripping the thread on one of them

 

Have you checked to see if the spring is rubbing the shock. I had rub on my old set of coilocers on my Mustang it sounded about the same. Easy to miss. Look above the adjusting coller.
http://68.58.185.21/Tri-BarMotorspor...htCoilover.jpg

 

One more suggestion from JIC: put just a tiny bit oil around the pillow ball.

I'll see if I can do that tomorrow, but I am so sick, I am not so sure that I will have the energy to get out of the bed. But then again, we've got to corner balance Wojo's car

 

some feedback on the changes that I made to the springs.

With 7.6k(425lb) for the front and 6.7k(375lb) for the rear. The car is much more comfortable in the initial testing. I didn't notice to much change in the body roll with the softer springs, and the car still feels very neutral. I will let you guys know if there is anything new after a few more days of testing.

As for the clunking noise from the rear, it's gone! at least i did not hear it for the initial test drive. The following are some of the things I did:

1. Oiled the pillow ball as suggested by FSelekler (thanks!)
2. 1.5 turn of preload(with the car on jack stand, so no issues with the sway bar), i had almost no preload when I first install them.
3. (Most likely the fix for the problem)installed a small piece of rubber between the top of the plates and the inside of the strut tower. My theory is that since the rear tops has only 2 bolts for mounting and the under side of the strut tower is not perfectly flat, the top plate can still rock a little even when the top bolts are tight and there might be some metal to metal contact with the top plates hiting the strut tower.
4. Softer springs. Stiffer springs may amplifies the clucking problem.

-ob4

 

Tried the oil. No difference. At this point, I'm just going to live with it. If someone has a relatively easy solution, I'll try it, but I won't be driving this car on the street too much.

In other news, I did 2 autocrosses with AAS in Atwater over the weekend. I was able to get 20 laps in total. This gave me lots of chances to try different damper settings, play with tire pressures and with my driving lines. The car is in much better shape than before. Less lean, more grip and better feedback.

One thing I'm going to change is the springs. Does anyone know what the standard spring height is on the JIC's?

Thanks,
Joe
www.joe250.com

 

The standard jic spring height is 200mm (~8in) the id is 62mm (~2.5in). the front rate is 10kg/mm (~560lb/in) and the rear rate is 9kg/mm (~504lb/in)

-ob4

 

Did you guys figure out what the clunking noise was yet? I am going through with a similar thing right now, but in the front left coilover. I almost am positive that its the spring itself binding a little where it meets the perch...i'm not positive though....is it possible to get a spring that is wound wrong alittle?

 

I am still curious what could cause this......

 

I have the same clunking noise on the right rear with omni power coilovers. I put a piece of rubber on top of the mount and it seemed to help,a little, but the spring rate is real jouncy for a street spring.

 

i also have this problem with the right rear on omnipower coilovers. I also noticed that the RR bounces a lot more than the LR while both springs have the same preload. Several people have told me they think it's a blown strut. Any thoughts on that?

 

3 in a row..

omnipower= noises RR strut. I'm not too worried about it.. but i'm getting the car corner balanced today. i'll have the shop see if they notice anything ..