ShawnOk

iTrader: (1)

In regards to clunks.... these....
http://us.lexusownersclub.com/forums...ront-of-sc430/
https://www.clublexus.com/forums/sc4...p-turning.html
https://www.clublexus.com/forums/sc4...illing-me.html

I suggest using an airgun/breakerbar to tighten the two bolts on the back of the all the calipers. Also make sure the shims are in place on the back of the pads. Missing shims will not allow the pads to sit against the rotors flushly and can cause a clunk when the pads move back and forth in change of direction due to decreased pressure against the rotor ("floating pads"), even if only a millimeter or two. Missing shims can also cause a "pad shutter/chatter," or even a "squeal," when braking due to the pad not sitting flush against the rotor. These specific noises will be amplified when turning, as this changes the pressure/contact point on the pads vs straight line driving, as it was explained to me.

Harold57

Yes, the brake clunk is common. There are several threads on it (Shawn listed a few). The biggest contributor is the spring in there used to return the brake pads to where they are supposed to be. Typically, there are two main contributors to the problem: weak (or missing) springs and rust or crud making pad travel difficult (it adds friction to the travel path). There is grease available to for the pad travel (used after cleaning the pathway) and you can either replace or reinforce or re-bend the springs to regain the proper pressure to move the pads. (There have been a few different methods used on the springs to rectify the problem, including placing some rubber pads either behind or in the springs, I forget the specifics though.) Note: re-bending the spring is only a temporary fix at best.

iolmaster

iTrader: (1)

You are misunderstanding what Ruger and I are talking about. We are talking about the clunk when the pedal hits the stop on the return. As in, when you release the brake pedal. Not a sound in the brakes themselves.

Bgw70

Like I said back in post 12, I have not heard the clunk since I installed new brake pads and clips.

I agree with this thread, compliments of Shawn,
https://www.clublexus.com/forums/sc4...illing-me.html

My brake pad replacement
https://www.clublexus.com/forums/sc4...rs-please.html

iolmaster

iTrader: (1)

Again, I think we are referring to two different issues.

Bgw70

Apparently there are two clunk sounds that happen with the SC430. One in the wheel brake area and one in the brake pedal. Most of us are familiar with the brake clunk but not the pedal clunk.

Do us a favor and post a video of the sound, if you do, we might be able to help more.

Harold57

I just looked at my brake pedal mechanisms to see what could "clunk". The brake light switch has a plastic interface so unless that is missing, it is unlikely that the pedal arm is hitting the metal limit that holds the switch, but it is something you could check.

There is a shaft that is attached to the pedal arm at 90° and extends through (or at least towards) the firewall. The shaft goes through a rubber bellows and it sounds like there is some sort of travel limiter inside the bellows (or beyond). You might check to make sure that there isn't a plastic or rubber piece missing inside there that normally limits the shaft travel along with dampening the sound and instead the shaft end is hitting something metallic.

JBell1

I had the same clunk sound when pressing brakes. Turns out it was the engine mounts that were weak enough to allow the engine to bump the firewall. Replaced them and clunk went away. Also much firmer feel going over speedbumps and general driving.

jimisbell

The sound at the pedal is very familiar if you are over 60 years old. It is the sound that ALL cars in the 50s and earlier made when getting older. The sound is heard with the engine off, the car stopped and stable. Without turning on the key, just press the pedal to the floor and hold it there, then slide your foot off the pedal to the side so that the pedal returns to the top by itself, freely. Voila, "Thumk". In the older cars there was a rubber bumper that the pedal hit when it came to a stop at the top. But I dont think the sc430 has such a stop at least I cant find it. Wish I could.