I have been fighting this annoying clunk in the front end of my 2000 FRC for a few weeks now and am looking for some input from you fine folks.

Some background: When I bought the car with 104K back in January, it steered nicely and was silent going over bumps, turns, etc. There was a slight dead spot on-center in the steering, but I chalked it up to age and mileage on the steering rack.

Fast forward to today, at 110K, I have developed a clunk when the suspension is loaded/unloaded, in the front end. The noise seems to be coming from the front-right wheel. My driveway has an incline to it, and a small raised lip where it meets the street - this means that when I back the car out, the wheels are turned approximately at 45 degrees, and loaded/unloaded sharply as they hit that lip. I'm able to recreate the noise over this bump.

If I sit with the engine running, car on the ground, and turn the wheel sharply side to side, no noise. With the car on the lift, steering unlocked and turned side to side through its' travel, no noise. The noise only occurs with the suspension loaded, when the car is moving. If the car is sitting, and I push sharply on the front passenger fender up and down a few times, no noise.

Parts replaced/checked:
The sway bar end links were replaced front and rear with high quality steel Moog units and torqued to spec. Noise still there

Front sway bar bracket bushings were replaced with Energy Suspension units and installed with the supplied grease, along with multiple layers of Teflon tape at the mounting point on the bar. Noise still there

I removed the front lowering bolts when I bought the car and drove the car that way with no issues for a few months before the noise started - but thinking that the spring may have possibly been binding on the control arm, I cut out pieces of rubber to install between the spring end and control arm - noise still there.

Checked torque on the fasteners for the front engine cradle (4x) and all lower control arms (2x per side). All needed a bit of snugging to come up to the recommended torque value, but it didn't solve the noise.

I also removed the passenger front tie rod boot to inspect the inner tie rod end - it looked and felt tight with my wife wiggling the wheel back and forth. In fact all ball joints on the passenger side felt tight when checked.

Given the mileage on the chassis I chose to replace the shocks as well - I am in the process of installing new AC Delco C6Z06 shocks (not quite finished yet, so don't know if the old upper shock mounts were causing the noise). Will report back tonight on this one.

Any other ideas?

 

Check where your leaf springs attach to the frame. IIRC people that had similar issues stated it's the rubber insulator/bushing that is glued to the leaf spring. I can't remember if they said the rubber deteriorated or the glue no longer held the rubber to the leaf spring. Someone else may remember a little better than me.

 

Ironically enough, when I bought the car, the front spring had developed a hairline crack along the long side of the spring - just past the driver's side rubber mount - so I bought a low mileage replacement (literally looked new) and installed that. No noises before or after replacement - it was strictly preventative to make sure I didn't have a premature failure of the spring that would leave me stranded.

 

Also, I took a video of the innards of the steering rack after moving the tie rod boot out of the way - is that inner aluminum sleeve supposed to be moving like that?

https://www.youtube.com/watch?v=-Rse...ature=youtu.be

 

Do your front calipers have anti rattle springs? My springs were missing. I installed them and the clunk was gone.

 

It would be odd but, what about one of the engine mounts? They are not solid, but like shocks in these.

 

I am not familiar with the springs. Will do some research to find out where they should be, and check if they're on my car. I don't recall seeing any off the top of my head.

I visually inspected and didn't find any cracks or damage in the rubber. When I installed the longtubes, I had the loosen the driver's mount to move the engine a bit, and made sure it was tight afterwards. Have not ever loosened or tightened the passenger side, but I can check. You'd think that would cause clunking when getting on and off the throttle, but I have none of that...

So I installed the C6 Z06 shocks last night and took it for a ride. While the ride quality and handling is greatly improved I still have the clunk coming into and out of my driveway.


I did some more homework and found that, of the folks that remove the front spring bolts to lower the car, some never have noise, and others get a ton of noise. It's possible that the noise is unrelated, but from a problem solving standpoint I have to look at it from the perspective that the noise never started until I removed the front bolts.

I have some old junk tires that I'm going to cut a scrap out of tonight, to put between the spring and the control arm. There is always the option of reinstalling my mint condition stock spring bolts, but I really don't want to have to raise the car back up. I really like how it looks now.

More to come later!

 

I finally tested out a theory - that the fiberglass front spring was binding on the aluminum control arm after the front leaf spring bolts had been removed. An old tire sacrificed its life and offered some insulating material. Cutoff wheel + tire means ultimate smokeshow!

_DSC5194 by Norbert Ogiba, on Flickr

So I compressed the spring on each side, greased up the side that contacted the spring, and slid it in. SUCCESS! Noise fixed. The spring now moves freely with no binding against the control arms.