Nauticalx

Bump.

I responded to this thread earlier and just noticed that I have the same problem. It seems to be coming from the right front wheel on my vehicle. Has anyone here resolved this issue on theirs?

I suspect loose hub bolt(s) could also cause this. I don't like hearing noises from brakes, it makes me suspect their ability to stop the vehicle in an emergency.

Has anyone contacted Lexus to see if they can chime in since this is possibly a safety issue?

ancdmd

This noise is the ABS system going through a quick systems check. It is normal.

ancdmd

If you changed the pads and removed the calipers, you need to replace the caliper bolts at the same time. You also may want to have a mechanic check the camber bushings.

Nauticalx

Can you please explain how the abs self check works and why there is a knock?

If this were the case, wouldn't it be a much more commonplace and noticed characteristic of the vehicle as well as noticed by drivers ever since these vehicles were new?

ancdmd

Just going by what I was told by a Lexus/Toyota mechanic. Makes sense that the system does some kinda check, but I can't explain why its more pronounced on some cars. Honestly I find it annoying and am surprised that its noticeable on a car that prides itself on being noise/rattle/vibration/funny-sounds-etc-free.

Nauticalx

Any toy/lex techs here who can chime in on this abs system check explanation? It doesn't make sense to me.

Upon driving the vehicle, I suspect the suspension may be a cause of these knocks. If you think of it, the greatest force is placed on the front wheels the moment before the car hits a stop since the mass of the car swings forward while braking. As soon as it stops the mass swings back towards the rear wheels again and to level.

I'm going to get the entire suspension (linkages and all) inspected. Anyone thought of the possibility of the air ride shocks causing this? Are there any of you out there with the knock on a non-air ride LS?

daddykay24

Non air ride and I have it too.

Peter_95

iTrader: (2)

so pretty much, i just removed the brakes, checked, and put them back together, now the noise is gone... but i have another problem now....
the brake light came on, but pads are still practically new. I changed it like 7 months ago and there isn't any air in the lines, car still brakes and functions as it should, besides the noise it had and now the brake light... ERGHH>!

Nauticalx

is the light more of a message that says "brake wear?" If so, the sensor right there by the pads is probably not connected properly.

Are you sure the noise is gone? What do you think you did differently this time to get it to stop?

Peter_95

iTrader: (2)

honestly, im not too sure exactly what i did different.... well i do remember bending that top metal piece a little more to create more resistance agains the 2 pins that go all the way through... im guessing that's where the sound was coming from.

yes, it says brake wear now, but i checked all brakes, they looked fine and connection seemed ok.

Nauticalx

Then if you pull out the sensor you will see that it is worn down and the two leads no longer connect. You can either replace the sensor or get something to connect the two leads again.

campisi

Sounds like the pad is shifting slightly at the end of the braking cycle. Is anyone who is experiencing this 'knock' using OEM pads? My first thoughts are non-OEM pads (the locating 'ears' may not be quite the same dimension as OEM allowing some movement) and next would be the shims. Might want to get some new shims if you didn't when you replaced the pads.

a13n0rma1

The OEM pads may be the answer. The calipers are of a one piece, "fixed" design. The pads slide one the two pins that go through the caliper, and if the hole is either too small or the pin is not smooth the pads will have trouble moving along them.

Another possible cause for the knock (happens in 2004 STIs with a similar brake caliper design) is the fixed location of the caliper. What happens is the mounting location of the caliper (suspension upright, knuckle, etc etc) is different than the mounting location of the rotor (hub), any play in the wheel bearing causes the rotor to move inside of the caliper, between the pads, causing the "knock" noise you hear.

Complicated explanation but it's what happens with the Subarus! A stronger wheel bearing design fixed the issue with the later model cars.


I'm not TOO familiar with the LS430s, but this is one of the problems with having a single piece fixed caliper as opposed to a two piece bracket/caliper design. Some have tried to fix it with springs inside the caliper pistons, as well as greasing the caliper's sliding pins.

RyanV

iTrader: (9)

Make sure those 2 big bolts that hold the caliper bracket on are TIGHT and with BLUE LOCTITE, just in case.

I've had both back out now, on two seperate occasions. I replaced both of them with new ones and torqued them both too so Im loctiting these MFers now!

curiousB

I had a problem with a Lincoln Aviator that may be similar. The noise was only just before you stop. A clicking noise. Turned out to be the parking brake shoes in the rear rotor. The parking brake lining had sheared off from the shoe and was getting throw around inside the drum. At higher speeds the centrifugal force threw it tight to the drum but as you slowed down it started to dance around inside. I'd pull the rear rotors and take a look inside.