Moby

iTrader: (6)

I just installed fat cat coilovers that I bought off a forum member. When driving, even the smallest bump shakes the car and a weird noise is present. It sounds like something is shaking. I think it's either sway bars or how I assembled the coilovers. Is it bad if my helper springs are full compressed?

paimon.soror

iTrader: (15)

If by helper springs (unfortunately each damn manufacturer calls it something different) you mean the small, low/no rate springs that sit above/below the actual springs, then yes, they should be fully compressed when the car is sitting on the ground

if by helper springs you mean the actual coil on the coilover, then no, they should absolutely not be compressed near full.

If the car is shaking hard it sounds like you are riding bump stops.

Moby

iTrader: (6)

Yeah its the smaller spring the rated-springs are fine. Are you supposed to preload with coilovers? How do I not ride on the bumpstops?

paimon.soror

iTrader: (15)

then yea the small spring should be compressed. Most have no spring rate therefore their only job is to expand when the shock body expands. It helps keep the springs in place when the suspension fully expands.

The easiest way to see if you are riding on bump stops is to do the following:

1. Grab yourself a zip tie
2. Does the coilover have dust boots? if so, lift them up so you can actually see the shaft.
3. Put a zip tie on the shaft, tighten, and trim the tie so that it doesn't snag on anything.
4. Slide the zip tie down so that it is touching the shock body. Slide the bump stop all the way up.
5. Go for a ride
6. Come back, check zip tie. Is it touching the bump stop? Then that gives it away

Not only the most common way to test, but this is the recommended method per FCM.

Btw as far as preloading the springs go, generally you do not preload linear rate springs on coilovers that have separate height / spring seat adjustments. I would assume that the FCM are the same, but someone else would have to chime in on that one.

Lastly, if you put on the swaybars incorrectly, or if there is endlink binding, the noise would be most prevelant at low speeds on bumpy roads. It would make a loud knocking noise. Easiest way to test this is to disconnect one end link and go for a (slow) drive around and see if the noise is still there.

poacherinthezoo

When the end links were loose on my car it caused an odd "shaky" type noise, like you are describing, but it did not effect the ride quality.

Moby

iTrader: (6)

Ok so I disassembled my car and put it back together. There still is a jittering noise/feel. I put on these metal spacers on the piston of the shock from the stock shock and it still makes the noise. What should I do? I don't think its the bump stops as the suspension is no where near bottoming out.

paimon.soror

iTrader: (15)

metal spacers?

Have you considered contacting Shaikh over at FCM? He is a really cool guy and would probably help you find the issue rather quickly.

poacherinthezoo

Are the springs seated on their perch in the proper orientation?



^^^ Is probably your best bet. He is very friendly, extremely helpful and obviously knows his stuff inside and out.