W204 (2008 C-Class) Parking Brake MOT Fail

[MBnewbie123]

Hi,

My car just went through the vehicle test (MOT test) and it failed due to the parking brake not working well enough. When I depress the pedal to engage the brake - all feels fine. I should say, recently, I had a wheel-bearing replaced at the rear on the left hand-side (UK car) and the mechanic said he replaced and fixed the parking brake. Is that where the parking brake is? Also, I presume the brake shoes that are used for the ordinary braking (while the car is in motion) are the same used for the parking brake? If so, I presume they are okay as the mechanic would have said otherwise (although I am not sure if I can trust them anymore). They hold themselves out to be Mercedes-Benz specialists, but seemed to have failed to ensure that my parking brake was working sufficiently before I left the garage. Presuming it is the fault of the mechanic, how do you think I should approach them about it? I think they should look at it for free and fix it for free.

The braking system passed, by the way.

On the way home, I parked the car on a steep hill, I engaged the parking brake, put the gearbox into neutral, let my foot off the foot brake and sure enough the car rolled backwards... slowly - so I presume there brake is working to some extent, otherwise it would have rolled back at a quicker rate.

The figures that came from the brake efficiency test are:-

Service Brake - 72%

Parking Brake - 5%.

Kind regards.

Thanks in advance.

 

[Blobcat]

Parking brakes are separate system. Inside the rear disks are a drum brake setup for the parking brake. Sounds like it needs adjustment- covered quiet a few times on here please have a search.

 

[EmilysDad]

Parking brakes are separate system. Inside the rear disks are a drum brake setup for the parking brake. ...

It's not on my ML

 

[Blobcat]

It's not on my ML

Yours uses the disc callipers? Those Americans will do anything to be different…

 

[EmilysDad]

Yours uses the disc callipers? Those Americans will do anything to be different…

It does .... it's a new fangled leccy 'handbrake' acting on the discs. The R Class before it had a top hat disc/drum set up.

 

[Gazwould]

This is of interest to me as I've never had a foot parking brake effort yet I've had it MOT tested in 3 different parts of the country !

Last year it did get two new cables but still wont hold on a slight slope so still needs adjustment .

 

[Droverunner]

I end up posting pretty much the same in all the handbrake threads...

Need to have the discs off to check the handbrake shoes (for example friction linings can detach with age)... clean all the pivot points and check friction surface is reasonable. Assemble and set up by the book (many places are not nearly as good as they should doing this) with the cables backed off initially to set shoe to drum relationship and then set up the cables. Quite likely the mechanism under the rear seat has seized too so free and lubricate. Final check is lubrication at the pedal end.

 

[MBnewbie123]

Thanks for all the replies.

 

[MBnewbie123]

I end up posting pretty much the same in all the handbrake threads...

Need to have the discs off to check the handbrake shoes (for example friction linings can detach with age)... clean all the pivot points and check friction surface is reasonable. Assemble and set up by the book (many places are not nearly as good as they should doing this) with the cables backed off initially to set shoe to drum relationship and then set up the cables. Quite likely the mechanism under the rear seat has seized too so free and lubricate. Final check is lubrication at the pedal end.

By any chance, is what is shown in this video of any use to me?

 

[Blobcat]

By any chance, is what is shown in this video of any use to me?

Yes

 

[Droverunner]

I would add a couple of things to that...

With a 14yr old car and such a low parking brake effort I'd want to take a look inside the disc. Also make sure someone hasn't previously tried to increase the effort by the cables alone and over-tightened them so make sure they are "loose" and applying no effort before adjusting the shoe click wheel.

 

[MBnewbie123]

Thanks to everyone for the replies. Much appreciated.