My 2002 IS300 sc front suspension 'knocks' badly on uneven road surfaces. Even a small ripple across the road makes it knock.
I've done a search here and although this seems to be a common problem, there doesn't appear to be a definitive cause- rather it could be anything or a mixture of faults!
My mechanic has given it a quick look over but can't find anything obviously wrong.
The steering feels fine, very accurate with no play. Also the ride feels good, well damped with no play. The front pads and discs were replaced when I bought the car, just a month (1000 miles) ago. I have read that if the pad retaining springs are missing then the pads can rattle, but the springs are in place.
I read that the caliper slider pins can wear causing the caliper to knock when the car is driven over bumps. To test this I drove the car over a road that always causes the knock, but rested my left foot on the brake pedal to slightly apply the brakes.- Instantly the knocking stopped! I've since noticed that under braking there is no knocking noise,
So, does this mean that the slider pins and caliper bushes need replacing (I have seen an overhaul kit with all the parts needed) or has pre-loading the suspension by lightly applying the brakes stopping whatever is causing the noise to stop ?
What a dilemma- I don't want to start diagnosing the fault by systemically replacing components until the cure is found!
Sorry for the long rambling post- but can anyone help?