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2004 CLK 240 Coupe
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Discussion Starter #1
My parking brake has just stopped clicking if I tread on it when stationary.

The brake still seems to work, and the parking brake light comes on. The brake release handle/cable still has tension, and will release the brake. But the clicks that normally come from the pedal ratchet when depressed are there no longer. I wonder what is going on down there?

Of course I will have to remove the cover below the instrument panel to inspect the pedal assembly - lying on my back to work down there...:(

Anyone else had this problem before? What can I expect is the cause?
 

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2004 CLK 240 Coupe
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Discussion Starter #3
Thanks, I've been studying that drawing.

Funny thing is - the parking brake and the release handle both seem to work just the same without the ratchet being involved. Perhaps it is there just to count the clicks to judge when a cable adjustment is required...:confused:

It's too cold to work outside on the car right now. Unfortunately my garage is only wide enough to park the car. Not to work on it.

Next time I go into my local MB dealership, I'll have a word with the service adviser, and see what he thinks about it.
 

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I think you are correct - if you look at that photo, there doesn't seem to be any sort of release mechanism for that part 2a/2b. The release cable seems to be connected to another tensioning lever that sits against the large disc around the pivot point.
 

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2004 CLK 240 Coupe
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Discussion Starter #5
My parking brake issue has now developed a further malfunction, which is probably not connected with the pedal click problem above, and I'm thinking about the solution.

Over the past few weeks a further two faults have shown themselves.

1. The parking brake is not working effectively. I had not been aware of this, as I have always parked on a level surface and put the transmission into P. However, recently when checking that a new reverse bulb in the rear light assembly was OK, I put the tranny into R and set the parking brake on. The pedal went down firm and stayed locked down. The parking brake light came on at the cluster. But the parking brake did hold and the car moved with the brake on. I suspect that one side only is working correctly, which is not enough to hold the car.

The car must pass it's annual MOT (roadworthy) test in a couple of months, and this fault would ensure a failure.

2. When the car moves backwards with the parking brake set, it makes a scratching noise, which is definitely wrong.

My first thoughts are to investigate:

a) the rear brake drums - to see that is going on inside there. I cannot believe that the shoes have worn out as they are only used for a static friction grip. Maybe a spring has broken? I'm not looking forward to getting the rear disc/drums off to examine the shoes, as I've read that this can be a struggle.

b) the 'cable equalizer arm' - which has a cable tension adjusting nut. This is shown in the WIS under the rear seats, quite close to the fuel tank. Not immediately visible, I guess I have to remove the floor covering to see it?

As usual, the WIS drawings for the parking brake design apply to both W203 & W209, so many models have the same design here.

This all new territory for me. Has anyone here been along this track?
 

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Keyhole, have you worked with drum brakes before? If so, then this parking brake setup will be familiar territory. It's just a matter of removing the rotor - the drum is built into it. If the rotor does not come off easily, then you will need to loosen the tension on the shoes. Note that the proper procedure for adjusting the parking brake is to first use the star wheel adjuster on the wheel to tighten the shoes against the drum just so they barely drag when the wheel is rotated. Then, if the parking brake cable is loose and rattling, you adjust the slack it under the rear seat.
 

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2004 CLK 240 Coupe
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Discussion Starter #7
Keyhole, have you worked with drum brakes before? If so, then this parking brake setup will be familiar territory.
Yes - all my life!

It's just a matter of removing the rotor - the drum is built into it. If the rotor does not come off easily, then you will need to loosen the tension on the shoes.
OK, I'm sure that the shoes are not binding at the moment. But I've seen pictures of guys using a 14 pound hammer to drive the rotor off the hub!

Note that the proper procedure for adjusting the parking brake is to first use the star wheel adjuster on the wheel to tighten the shoes against the drum just so they barely drag when the wheel is rotated. Then, if the parking brake cable is loose and rattling, you adjust the slack it under the rear seat.
Right - I've got that. It seems that the best idea is to lift the entire rear axle to adjust both rear drums correctly. Is it OK to put a 'trolley jack' (2 tonnes max) under the rear diff. Is that place strong enough?
 

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There is no reason to lift the entire axle - you can life one wheel at a time. You have an open rear differential.

EDIT: And unless you intend to replace the rotor and the entire parking brake assembly, don't use a hammer!!! :)
 

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2004 CLK 240 Coupe
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Discussion Starter #9
I took a quick peek at one rear wheel today to see the hole where the screwdriver goes to adjust the notched adjusting wheel on the parking brake. It is shown on the WIS drawing below.

Is this the same hole that the Torx screw uses to hold the brake drum/rotor in place? I can see no other hole there....
 

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No - it's on the back of the hub. There will (or should!) be an oblong rubber dust plug in it.

EDIT: Actually, I looked at your WIS document and now I'm not sure about this. I've never used that to access the adjuster - I've always used the one on the back of the hub. I guess if you can get to it through that hole after removing the bolt, then that's great, but it sure seems like a tight spot. The access on the rear of the hub is probably half an inch high and over an inch wide.
 

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2004 CLK 240 Coupe
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Discussion Starter #11
I dropped by my local Inde today to discuss my parking brake problem. He advised me that they get to the adjuster via the lugnut holes with the help of a good flashlight. I never thought to look in there!

He also said that the adjuster was held firm by a spring laying over it, and is therefore quite hard to rotate. I asked about removing the entire drum to inspect the shoes, and he showed me an old MB drum from his trash bin. There was a ridge of rust on the outer edge which he told me can prevent the drum coming off easily, and sometimes dislodging springs when it does.

I've half a mind to give it to the guy to do a brake clean-up and adjustment, as he reckoned it would only take him half an hour or so. It's 8 years since the factory built this car, so it's probably time that these two rear drums were looked at. And it might be good for my back to dodge this one:)
 

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Unless you just don't want to take the time to DIY, it's really not that hard. It's actually going to be much more difficult to loosen the adjuster from the front of the drum, and not just because of the size fo the hole. The self-adjuster that has to be release in order to rotate the star wheel is on the front. So to release it fromt he front, you have to pull on it. If you use the access port on the back of the hub, there are two things - one, you can often get enough leverage to get the star wheel to click past the adjuster, and two, if not, you just need to use a small screwdriver to gently push the adjuster out of the way. I know this photo isn't the same system, and it's upside down from the W209's drum system, but if you'll look at the mechanic's fingers, you'll see the self-adjuster that has to be pushed away to allow the star wheel to be turned in the "loosen" direction.

 

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2004 CLK 240 Coupe
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Discussion Starter #13
Hi - thanks for that photo.

However, that looks to me like the full-sized brake drum of cars from yesteryear. And is that also a 'self-adjusting' ratchet mechanism that I recall from those days? They worked well until the brake dust clogged up the works...:)

I'll investigate the rear access facility you mentioned earlier. :thumbsup:
 

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Believe it or not, the CLK's drum parking break system is identical, just smaller.
 

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Discussion Starter #15
OK folks, my parking brake adjustment task is now done, and I have a new insight on how it works to share here. I have also nailed a few uncertainties about the task.

1. There is no rear access for adjustment via a removable plug on this particular model CLK - if there is, I couldn't see it. Maybe this facility exists on other models.

2. There is also no 'self-adjustment' mechanism, as shown on the picture of the brake in post #12 above. The way it is done here is via a lug bolt hole using a small screwdriver.

Having given it some thought, I decided it was much better done at eye level on a lift, with both wheels off the ground. However, it's clear that it can be done one wheel at a time, and next time I have to get to this place I will certainly DIY.

As I had no idea what the state of the drum internals would be, (the parking brakes were not holding) or if any springs might fall off (or break) during the removal, I decided to give this task to my local Inde.

He did the job today. He agreed to remove both rear drums, inspect and fully clean up. Also to use brake cleaner to remove all the internal dust and then lubricate where necessary. Finally to adjust the brake correctly, so that it can pass the annual inspection (in his shop) in April.

Describing one side, after removing the road wheel, the brake caliper was unbolted and swung out of the way. The single retaining screw was removed, and then the drum was pulled off. It did take a few sharp smacks with a hammer to free it up, but it was not a serious problem.

The first picture shows one drum after removal. There was a thin line of rust on the edge, which was then removed, and the drum was cleaned up OK.

The second picture shows the brake assembly with the drum removed. It can be seen how a screwdriver can pass through a lug bolt hole to access the adjuster. This is rotated either clockwise/anticlockwise depending on which side the wheel is located. The large holes on the hub flange are covered by the drum, of course, so cannot be used during adjustment.

The third picture shows how a spring is used to hold the adjuster in place. There is clearly no wear on the shoes.

The last picture shows the assembly from the other side, where the cable enters to operate the shoe mechanism.

The shop charged me for 45 minutes labor. The parking brake now works much better than it did in 2006 when the car was 'new' to me, so I'm very happy with the work today.
 

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Nice pics. I assumed it would be the same as on the W203 (which does have the self-adjuster and the rear access port). Sorry to lead you down the wrong path!
 

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To adjust the parking brake turn the rotor to align a lug nut hole with the star wheel adjuster.
Turn the star wheel adjuster using a screwdriver until the rotor cannot be rotated.
Then reverse the adjuster eight notches. Do the same on both rear wheels.
Note. Turning the adjuster from the bottom to the top on the right rear wheel,and from the top to the bottom on the left rear wheel,will spread the shoes and cause the rotor to not rotate.
If more adjustment is needed then it is done by adjusting the brake cable assembly adjusting nut after removal of a panel located under the rear seat.
Ideally the parking brake pedal should click five times when being applied.
I hope this helps everyone doing this job in the future.
 
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