LustrousWS6

iTrader: (1)

Alright, I've always heard a slight clunk from the rear suspension when going over speed bumps but since I had SFCs welded in, it's become more pronounced and I can distinctly hear/feel it when I'm coming down from speed bumps at low speeds (each side, individually). This generally happens when coming down from typical speed bumps at around 5mph if not just under. Almost feels like there's some gap that's made up then closed between metal parts when the rear suspension is slightly unloaded then loaded again. This sound/feeling is very, very rare during normal driving but almost always present when coming down from speed bumps. Any help/ideas would be appreciated. LCA bolts were not torqued but were tightened as tight as the installer could get them. I trust him and he has done well over 40 SFC installs if not more. Thank you for any help you can provide.

Just a thought: before, when I'd hear this sound (although it wasn't nearly as pronounced as it has been since the SFCs were installed), I attributed it to the rear suspension bumping my True Duals which run under the axle. The duals have a good 2 1/2 inches of travel before hitting the duals, could the SFC's changed this in any way? I doubt the weight is enough to make a difference, especially at such a low speed coming off a speed bump.

SS1875

iTrader: (34)

Get it up in the air and check for any rub marks along the frame where the exhaust runs, also double check all of your bolts....PHB, TA to rearend, etc. Is the car lowered?? do you have an aftermarket rearend?? More info as to your setup would possibly allow someone to better help you. Any number of parts could be the issue.

LustrousWS6

iTrader: (1)

I'll try to get it in the air soon. Stock everything but what's in sig. Car's not lowered except for the fronts being on the lower perch of the shock.

fast01z28

iTrader: (6)

when the KONIs were put in, were the foam pads put back in? they werent overtightened were they? i just put my KONIs in, and i can see someone leaving the foam off and hearing a clanking sound.

LustrousWS6

iTrader: (1)

Foam? Everything that came off the car (but the stock shocks) went back on. Don't recall any foam though it has been a while. Like I said, sound/feel became 300% more pronounced after the SFC install.

JD_AMG

Probably the LCA's then.

LustrousWS6

iTrader: (1)

Anything specific to look for? I just don't see how this came about other than the bolt that came with the SFCs was too thin but I doubt it? Forgive me if I sound like an idiot - I don't know all that much about suspension, especially when it comes to LCAs.

JD_AMG

If I'm not mistaken the SFC's take up some space between the bolt and the chassis where the LCA's connect.
You can see what Im talking about in this pic:

Maybe I'm wrong but I swear I read on here that with the SFC's there is makes it hard to tighten down the LCA's all the way because of that extra space they take up.
Could also be that they are sending vibrations(or amplifying sound) through the whole chassis now since its connected to the front and rear directly by one hollow(right?) piece.

LustrousWS6

iTrader: (1)

^^^ correct - the SFCs did come with extended bolts to compensate. I'll get it up in the air some time this weekend and have a look.

Crimson

See if you can recreate the noise by grabbing the rear bumper in the center and lifting the rear up and quickly pushing it down as hard as you can. I had a similar noise and it was because the rear shock was a little loose.

motrhd

I have the same clunk on bumps and hard launchs, on bumps sounds like the springs on launch sounds like the LCA. I have BMR sub frames-welded,LCA's and bracket LCA in upper hole, Bilstein shocks, Hotchkiss springs, BMR swaybar which i have never been happy with end links don't sit vertically which i think causes the noise

UMI Performance

iTrader: (77)

Those look like yellow UMI SFC's

One thing you need to when installing SFC's that sandwich the rear control arm mount is torque those bolts! They need to be 90-100 ft lbs in order to compress the control arm bushings and prevent any noise.

LustrousWS6

iTrader: (1)

I have BMRs on there but thanks for the info as I'm sure the same applies to my setup. I tightened down the bolts on top and bottom of the shocks and now it squeeks and groans like crazy (took an impact gun to em) ... guess it's time to lube up those poly bushings again.

LustrousWS6

iTrader: (1)

Well I lubed up the poly bushings real good and tightened down the LCA bolts. ALL noises gone (execpt for the normal interior rattles, from the passenger seat no less - wierd). For once I was actually right! Thx for the help guys.