How much noise should the brakes make on a new LS 430? When I back out
of the garage, I hear a dragging sound. When I apply them at high speed
there is a very clear rapid bumping sound, louder and faster with
increasing speed. As I slow down to a stop, there is a kind of rumble
and at the last the car sort of lurches before it stops. Is this
normal? I do not think it is. The dealer says it is normal.
Is there a national place outside the dealer where I can get my brake
shoes and rotors replaced without violating the warranty?
When the car has been sitting overnight, it is not unusual to hear some
noise on the first and/or second brake application, especially in a wet or
humid environment. This is because some surface rust will form on the
rotor, and the pads are rubbing the rust off.
The rapid bumping/rumbling sound upon high speed brake application is often
accompanied by a corresponding rapid pulsation in the brake pedal and is the
anti lock brake system activating. In addition to antilock brakes (ABS),
the LS has brake assist. Here is an explanation from the Toyota web site:
"In emergencies, some drivers, especially inexperienced ones, often panic
and do not apply sufficient pressure on the brake pedal. Brake Assist
measures the speed and force with which the brake pedal is pushed to
determine whether the driver is attempting an emergency stop. If the system
determines that is the case, it applies additional brake pressure to allow
the driver to take full advantage of the ABS brake system. When the driver
intentionally eases up on the brake pedal, the system reduces the amount of
assistance it provides. This feature comes with VSC."
As far as whether the condition you are experiencing is normal or not, I
would ask the dealership if you can go on a road test in another car so they
can demonstrate whether it operates the same way or not.
Problem is that the old Mercedes I just got out of had the same things
on it and it did not make any such noises at any speeds. In fact, this
is the first car I have noticed the "dragging noise while backing up in
the morning" coming from. I like the idea of testing a similar car,
except that they have no more LS430s in stock. This one was the last
one in the US with any colors other than Black or Silver with Black
interiors and those were scattered around from Texas to California.
Also I got the PCS and Radar Cruise control and evidently they do not
have many of those made for the US at all! But I am going to try this
test driving thing. The one the dealer had for test driving definately
did not have this noise, but it was a base model. I have held off
asking some of my friends about this since it will require me
explaining the situation and that will hurt the local dealer by
creating talk and gossip.
I do not know how old your Mercedes was, but while ABS has been around for
20 years or so, electronic brake assist is a much newer system and has not
been around nearly as long, perhaps 7 or 8 years. What I think may be
happening is that the brake assist is activating the ABS, and the ABS is
what you are hearing. I've noticed that when I nail the brakes at highway
speeds, the ABS kicks in more often in our 2 vehicles with brake assist than
in all of our previous vehicles with ABS.
I am pretty sure that ABS and electronic brake assist are standard in the LS
430 so as long as your test vehicle has the same tires, you should get the
same results if the condition you are experiencing is normal.
The noise comes before activation of the brake assist function. Faster
the car is moving, the louder it is. And at slow speed, coming up to a
stop sign in the neighborhood, it is also noticable, and just before it
stops, it grabs and then releases. Yes, the antique Mercedes did have
ABS and the high intensity brake mode, whatever you want to call it.
Motorsforum.com is a website by car enthusiasts for car enthusiasts. It is not affiliated with any of the car or spare part manufacturers or car dealers discussed here.
All logos and trade names are the property of their respective owners.