Parking brake inefficiency was one of the things my W124 got an advisory on it’s last MOT last August and I’ve only just got around to adjusting it!
The parking brakes on a W124, W201 and W126 are apparently all adjusted in the same way so hopefully this guide will be helpful to you too. If you are unsure if your parking brake needs adjusting you can tell by how many clicks the pedal goes down will you apply the parking brake. If it is between 4-11 your parking break should be ok. Any more or any less and it will need adjusting.
The first point of adjustment is on the brake shoe itself. This can be done with the rest of the brake assembly in place. With the parking brake off and the car in neutral turn the brake disc so two of the bolt holes are at 10 o’clock and 2 o’clock like so:
Now take a torch and have a look into the hole at 2 o’clock if the passenger side and the 10 o’clock hole if the drivers side. You should see a spring with a thin sprocket gear just above it. To tighten it put a flat head screwdriver through the hole and push against one of the teeth on the gear to turn it and tighten it.
If you can’t turn it anymore then you will have to adjust it on this thingy (technical term) under the car.
It is located above the propshaft at the differential end. To tighten it simply take a 13mm spanner and turn it clockwise which will pull that hook forward and tighten the cable.
Hopefully now you have a nice tight handbrake cable which stop your car from running away!
Thanks for reading