Hi all,

I need some help tracking down some noise from the rear suspension.

The car is an 02 WS6 T/A with very low mileage (about 8,200). I'm the original owner, so I know it's been babied and never abused. I have had SLP SFCs installed by a professional chassis building shop (welded in - they had no trouble getting them in, they went on at about 4,000 miles). Since then I have added an SLP STB, and just on Halloween this year, Koni SA's all 'round with the lower perch/heater hose mod, and some BFG g-Force Sports (stock size on stock rims), and a UMI rod ended double adjustable PHB.

The ride has gotten firmer due to the Koni's, which led me to getting tires that were softer than the stock ones (despite them having essentually full tread), and this has led to bits of the interior shaking loose and rattling in ways they never did before.

I have secured the jack (even used foam and rags to silence it), pulled the plastic jack cover entirely (the one with the instructions on how to change a flat) and made sure the spare is secure. The interior is emtpy and bone stock. The passenger side A-pillar cover is now rattling, and I think the rear driver's side hatch panel is making noise too. That will be solved with a stealthbox (as it'll have support under it), but the A-pillar cover has me stumped.

But the thing that concerns me most is the noise from the rear suspension. I've checked the body side of the LCAs and the brackets of the SFCs are smooth against the LCA mount and there is no gap or signs of movement. Looks like the chassis shop already took care of that potential problem during the install.

The PHB is torqued down to about 87ft lbs, which the dealer manual called for. The rear shocks are also torqued to spec top and bottom. There is no metal contact between the top spring coil and body.

By all rights it should be quiet. When I took the driver's side wheel off and grabbed the lower spring perch and pushed/shook the axle laterally (with the car in the air, on jackstands, supporting the rear suspension), I heard a clunk/rattle sound. The very sound that I'm hearing in the car, from what I can tell.

My first thought was the PHB. But high quality brand new rod-ends aren't supposed to make noise from what I've heard, and the PHB in particular is not supposed to be a component that creates noise problems - again, from what I've read on these forums.

I had someone get under the car while I shook the axle and they looked for the noise, but nothing was touching or banging, everything looked fine. When they grabbed the exhaust tips and pulled down on them a little (applying pressure), the noise was muted.

That's the weird thing. If it's the PHB, why would pressure on the exhaust mute the noise?

When we shook the exhaust, it did not make the noise at all. So it doesn't seem to be the exhaust either.

Anybody have any ideas?

 

Bump....

 

do you have stock rearend?? do you hear these noises when you turn to right/left??? if so, then itz normal.

i have some ideas.. turn up the radio and just drive it till something breaks or gets louder. plus i believe this is garage queen so why even worry about it?

all f-body rattles/squeaks/clunk.

 

Check the LCA bolts and the p-=hard rod bolts. They could be not tight enough to squeeze the bushing.

Yes, thats is excellent advice David! seriously. this is no cadillac!

 

I didn't actually put a wrench on the LCAs, I guess I can try that. The nature of hte rest of the SFC install was such that I assumed it wasn't loose.

It is the stock rear, and it isn't when I'm turning, it's when I'm going straight over rough pavement (which we have a LOT of around here).

Yes, it's true that this isn't a 70's Caddy or a Maybach. But that doesn't mean it should clunk and rattle. It may be an F-Body, but it's still just mechanical components, if something is making noise, once one locates it, it should be possible to silence that component. It seems kind of odd to me how F-Body owners seem to almost support the notion that these cars are cheap crap and as a result, they should rattle and that is that.

My '88 hard top GTA didn't make this kind of noise, and it had 90,000 miles on the stock suspension.

It's not quite a garage queen either. More of a weekend toy really. Originally the idea was to have fun with it on the weekends in the summer, but the warmer weather has extended so deep into winter that it's really become something of a year round weekend toy. It still never sees snow, salt, or rain though. (the last just because I don't want to track muck and grime into the interior or open the door and have the insides get rained on lol) And until I got the SFCs on, prior to learning just how solid the 4th Gens are, I was crazy paranoid about chassis flex. I've pushed it through corners having a little more fun since then, but I'm just not into burnouts, donuts or drag racing so I haven't had the desire to subject it to that.

Funny that you should mention the radio. lol Between re-torqueing the PHB and securing the jack I have quieted it up a good bit and cranking the radio can just about cover it up. lol Trouble is, I'm bound and determined to get a car that can be quiet and comfortable, as well as a barn burning performer. I'll leave the hard core, raw performance, harsh ride to the C5 I'll eventually get around to buying. I'm kinda hoping that some sound deadening can have a similar effect to the radio - mask/hide the noise. I'd be satisfied with that. As long as it's not dangerous and I can't hear it, that's all that matters. lol

One thing about the LCAs - would they be making that noise when you push on the side of the axle spring perch in a lateral direction? I could see if they were moving back and forth from wheel hop over rough pavement, but this tiny bit of movement laterally... I dunno. (but that's why I'm here )

 

Keep us posted, I think i am having the same clunking in my ride. It sounds like it is coming from the rear right. When I push against the rear fender and lean to the left (So as to moving it right to left in a rapid motion) I hear the same noise.