I note that my 2004 CLK 240 Auto exhibits a bit of a lurch after
setting the parking brake - especially if I am on a slope.
Sequence of events would be: stop car with right foot on footbrake -
shift Auto stick into Park - tread left foot on parking brake - remove
right foot from footbrake - lurch.
Can anyone advise me what wheels the parking brake operates on, and
why there is a slight 'backlash' in the system. Anyway, it seems safe
I am not sure what you meant by lurch... a slight roll perhaps? The reason
for that is the tranny has a cam and cog for parking... so there is a wide
gap in cog to make sure you can park without excessive roll. So the car will
roll a bit until the cam and cog meet each other.
Parking brake are not a strong brake... they are only tiny brake shoes...
so car will roll if not tighened up properly... which bring us to your
case... you need to have your parking brake shoes adjusted a tad tighter.
Speaking of a slight roll, all three of my W123 and W124 cars have
had the opposite characteristic: a certain amount of slop in the
driveline that's noticeable when Drive is engaged. There's a slight
hesitation and then a bump when I press the accelerator as driveline
lash is taken up, before the gears engage and the car begins moving
forward. It's particularly noticeable in the morning, when the
transmission is cold.
This driveline lash is also noticeable when descending a grade while
running on cruise control. The cruise control will "hunt" back and
forth as it struggles to maintain a constant speed, causing the car
to jerk back and forth slightly. It's mildly annoying, but pressing
on the accelerator smooths it out. Since all three of my 5-cylinder
models have done that, I gather it's normal. (My SDL doesn't display
this behavior for some reason.)
It occurs to me that perhaps the OP simply isn't pressing on the parking
brake pedal hard enough. The parking brakes on my W124 take a lot of
pressure on the pedal to set them properly, and the pedal has more travel
than it seems like it should -- significantly more than was the case with
my W123s. It goes most of the way to the floor before I can press it no
farther and the car stops rolling.
I brought this to the attention of my mechanic, but he swore up and down
that the parking brakes were adjusted to spec. I had occasion to drive
his personal W124, and its parking brakes were adjusted the same way.
Maybe this is a characteristic of the more recent Benzes in general, not
"Admittedly, conservatives give as good as they get. The difference
between us and [leftists] is that we can argue as well as inveigh.
Yes, the car definitely seems to move just a little...
But shouldn't the brakes operate such that even though there is a bit
of movement around the tranny park cog, the wheels will be jammed from
further movement by the parking brake, if it is the last thing
applied? Otherwise, what is the point of these brakes?
It may be that I have to apply this brake more firmly. It cannot be
worn, or even need adjusting - the car has only done 3500 miles, and
has just had an A service.
(it was a Embassy car, mainly garaged for 2 years. I've rescued
Just to wrap this up... I was in my local Mercedes main dealership
today, and raised this parking brake issue of mine.
The guy in the Service Dept said that:
1. The parking brakes operate on the rear wheels only. 2. They are
separate pads that grab the regular brake discs. 3. There is a
tendency for all current MB car to 'settle' after they are applied,
especially on a slope.
I'm assured that the road wheels are not moving - it just seems that
they might be.
From my experience any vehicle that has disk brakes MUST have
expandable shoes used for the emergency brake, and there has to be a
little movement or they couldn't expand. That's why many cheaper cars
were so late in installing them for production.
The only exception I can think of is for a 1956 Dodge that tried to be
innovative by using circular shoes around the drive shaft. They
discarded that design before years end! :-P
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