SS728

iTrader: (15)

Ever since I put on these coilovers, they have been nothing but trouble. I am not complaining about the actual coilover and quality but what trouble it is making my rear suspension have.
After I put them on, I noticed a rear thumping sound, it varies on the loudness scale, but usually when I go over a bump in a road, a sound is made.
The front's endlinks make noises, but that does not bother me, because it's mostly when I turn going over a bump, that I can live with, but these rears are annoying.

*Shocks are pictured with some space still on the shocks, currently they are set all the way down.
I have the rears set all the way down, spring is all the down and so is the shock, and dampening is set at 15/30.
I ruled out the shock being dead, because I have rebounce and it goes back to the same height. (When I pushed down on the fender)
The shock is fine, so it has to be the rear spring, seat and bottom mounting part.

I think the mount (bottom gold piece that the spring sits on), along with the spring is moving in the spring seat when I drive over bumps. When I have the car in the air, under no load, the spring cannot be moved so it is not preload.
But when the car is in the air, I can slightly move the spring along with the bottom mount side to side, so it moves.
But what could be the problem?
Here is a video, pay attention to the sound at 8 ,2, and 1 seconds. It is very noticeable towards the end.


Any other BC, or other coilover people, have this problem?
*Every bolt is torqued down, nothing is loose whatsoever.

tnk210

iTrader: (23)

It's the sound that pillow-ball mounts make. Mine do the same thing and I've been told it's normal.

SS728

iTrader: (15)

Yes, I have been told that, but this sound is very obnoxious and weirdly enough, it only makes them on certain bumps. But what is causing the sound? I mean the mount itself it flush with the inner fender and the nuts are torqued down.
I am an amateur when it comes to suspension, but I just do not know what exactly is causing the sound.
The only way I can describe is like there are 2x4's being thrown underneath my car.

Gsedan35

iTrader: (10)

Never the less I'm impressed that you managed to post a video that pretty clearly let's us hear what the problem is. Not a lot of people bother with that let alone pull it off like you did.

IMO, you have a adjusting collar on the damper or rear spring assemblies that is loose. I would check the dampers first, especially the one's that tighten where you adjust the damper longer or shorter. If that's not it move to the other parts like the collars on the front springs and then the rear springs.

red350track

iTrader: (7)

idk dude mine dont do that at all i hope you get it figured out bro

SS728

iTrader: (15)

The adjusting collars, front and rear, are very tight, but having loosened them before, I know the sound they make and there is no way I would be able to hear it if I was inside the car, so it is not them.

But on the rear springs, the "coilover" part that adjust the spring, the two spring collars, are all the down and tightened, so they would not make any noises regardless.
It has to be either the upper top mount that the collars screw on or the bottom mount that the spring sits on.

*red350track, does your rear suspension look like mine in the picture?
For the rear suspension, there are 4 parts total correct?
The shock, spring, upper mount (where the threads and collars are) and the lower mount (where the spring sits on).

Diesel350

iTrader: (6)

Hope this helps, This is directly from Pete@BC Racing

Hey fellas,

This is something I just posted over on the g37 board.

Hey everyone,

After my last update I was getting everything ready to ship out those items that made way here. I got a call from a fellow board member with the rattle/knock noise. He's not to far away and we arranged to bring him in on friday late afternoon. I appreciate Dan for coming down to have a ride around and see if we can't finally take care of this. On the first drive out, it was noticeable on low speeds as he said. I tore down the back, checked the shocks, preloads and spring assembly. After 3 attempts and it getting a bit late, we decided we'd work on getting the car back here. I just made contact with Dan today and we are providing him with a rental and we'll have a week with his car to look over and trouble shoot it.

Some of the things we did:

Preload did not make a change

Changed to the older style design, no change.

Changed spring rate.

Took the upper ***** off just incase the extenders were making them pop

Dissassembled the rear shock and tested for any problems, nothing found

Checked the pillowball casing for any signs of it hitting. Found no signs

I did take the top plate off and checked the upper mounting position and found that the bolts are a bit smaller than the ones on our plates. The slop could allow for some play. I thought maybe this could cause the noise shifting. So I looked around the shop and found a perfect spacer. After finishing up, we thought this would have fixed it. It seems to have helped, but the sound is still there. To make sure we are all on the same field here. Dan's noise is generating up high, which leads me to believe it has to do with the top mount. Atleast this is where I will start concentrating trouble shooting first. One thing I want to verify is the 2 upper bolts for the rear top mount of the shock. This is just a thought, most of you having this issue was not immediately. Atleast that's what I've understood. What if using too much preload, or even a combination of preload, extra weight of larger wheels and tires are pulling down on those 2 studs and causing a uneven contact patch for the top plates. Minimal enough to cause it to seesaw and cause a rattle. Strut towers are known to mushroom on certain vehicles, so it is possible but needed to be verified. If any of you that have this rattle issue have a chance, take a look or shoot a pic of how the rear top plate is sitting on the car. I know Dan's had a slight gap.

Well, we'll have the car on thursday evening. So we'll keep everyone updated to the progress. Let me know if there is any questions I can help with.

Check out this thread for more reading:

http://g35driver.com/forums/brakes-s...need-help.html

red350track

iTrader: (7)

yea man mine looks identical did you buy them new?

SS728

iTrader: (15)

No they were used, but only like 3-4k miles, and never abused. I know the owner.

sflg35

iTrader: (8)

hey guys

the car that pete worked on was mine.
your noise sounds pretty similar to mine.

we finally solved the problem in my car by getting rid of the pillow ball mounts and going with rubber mounts in the rear.

SS728

iTrader: (15)

^Really?!
How a tutorial on it?

r0csfinest

iTrader: (12)

mine makes that sound too. i noticed it after talking to ss728 lol. i thought it was normal at first

SS728

iTrader: (15)

Added more sound clips if necessary,
19-18secs, 8-7secs


4-2secs,

darklocust

iTrader: (19)

Are these only happening on the old versions? The new one's have a fatter coil at the bottom. How exactly did you get it fixed? Did you use stock parts?

SS728

iTrader: (15)

Nothing fixed yet. I'm awaiting more post over at g35driver to see solutions.
If you look at my first pic in this thread, you can see the spring is the same width all the way around.