Have you ever experienced running after your car while it free-coasts down a hill? Or have you thought leaving the car in Park on your automatic was totally safe until you later find the car flipped over at the bottom of the hill? Well maybe it’s time to fix that little issue with the emergency brake! Might also come in handy if your hydraulic brakes decides to take home-office one day, better safe than I told you so!
Many cars have issues with the emergency brake simply because of too little use especially when you have an automatic. Simply leave it in park and it will not move, well that’s mostly true if on flat ground. The emergency brake is mechanically operated usually though the pulling force of wires and springs. When not in use this mechanism will inevitably rust in place. This is exacerbated on salty winter roads with and infrequent cleaning of the car. On the Mercedes W245 it uses basically the same system Mercedes have always throughout the last decades, except there is very unconventional Mercedes style of using a hand lever in the center-console instead of the usual pedal lever.
On this B-Class the emergency brake system was completely inoperable and nothing happened when pulling the lever. My initial thought was to exchange the cables, but after some thinking I decided to change both the brake shoes and the cables together. The job took a little longer than expected due to corrosion and some unforeseen stuff.
I urge you to inspect the brake shields for rust before starting on this journey, because if they are very rusted, you will not be able to secure the brake shoes inside the brake rotors. If the brake dust-shields are severely rusted, you will need to get new ones. And the job requires you to detach the rear hubs in order to install them. Changing the brake shields will not be covered here.
You should also just change the rear brake pads and rotors if necessary since you will be dealing with the same area of the car anyway.
Things you might need:
- Emergency brake cable left side
- Emergency brake cable right side (not the same as the left one)
- Emergency brake shoe repair kit, which includes new springs
- (Rear brake pads)
- (Rear brake rotors)
- (Left and rear brake dust- shield)
To support the rear end, you need medium tall adjustable jack-stands. Start by jacking up the rear end. Use wheel chucks to prevent the front wheels from rolling. Place the rear on jack-stands, there is a clever area near the back end of the car for the stands, I also use a backup jack at the jack-point for the side I’m working on. Take off the rear wheels, and before you do anything else, get a bucket with soapy dish water and a stiff brush (like an old dishwasher brush). Then brush down the entire brake assembly and surrounding area! This is to prevent harmful brake dust getting loose and into your lungs. The soapy water will bind up the harmful brake dust and road grime so be generous and thorough with the scrubbing. It also makes the job a lot less dirty and more enjoyable.
Remove the brake caliper. Use two spanners to loosen the piston assembly. Then loosen the bolts for the brake carrier attached the rear hub. These bolts are not very tight compared to the front calipers. To relieve stress from the brake hose, use some string or zip ties to hang the caliper from the spring or similar.
Now comes the tricky part. Loosen the securing nut for the rear rotor with a Torx bit. Then you need to pull outwards the rotor from the hub. It might be frozen due to rust and seized in the parking brake mechanism. Make sure you don’t have the parking brake applied. If the rotor is frozen, tap it lightly with a hammer. Too much tapping might warp the rotor and you will get vibration while braking. I used a lot of time and force in able to pull it loose from the emergency brake. The old rusted springs ended up snapping instead of the shoe giving in. There was a thick layer of rust encapsulating the brake shoe.
Since the springs broke and the brake shoes fell off I don’t have a picture of the assembly still on the hub, but the mechanism to the cable is . This was very rusted together and was the reason the mechanism didn’t work along with a very tired cable.
Use a lot of WD-40 or similar rust penetrant and let is soak before starting to loosen it. Unhook the cable from the underside of the car in order to loosen the cable mechanism.
Using a plier drag out the E-brake lever mechanism from under the hub in order to get more space.
The lever is made up from 3 parts. The outer lever, the inner lever and a pin connecting the inner lever to the cable. Use a punch to remove this pin in order to get the cable free. The repair kit for the e-brake usually does not contain the lever mechanism and the pin so make sure not to loose these parts!
There is one last step to free the cable. There is one bolt securing it on the backside of the hub. Here you will need an E-Torx bit to get it loose.
Now the cable is free and you can pull it from the backside and the cables can be removed.
The e-brake lever mechanism is probably rusted like mine and needs a thorough clean and lubrication. I applied some rust stabilising paint in order for the repair to last longer, but this is totally up to you. The E-brake mechanism also contains a cylinder with a small cog over it. These are neither included in the e-brake service kit and you need to reuse these in a non-rusted fashion.
I decided to clean and repaint the rear calipers as well since they were really ugly. This is totally optional and of course the whole ordeal will take longer.
Lubricate the e-brake lever mechanism with heat resistant lubrication, such as aluminium paste or copper paste. This will make it not seize up as fast. Also lubricate the adjusting wheel on the cylinder screw.
After you are satisfied with the restoration work you can start assembling the stuff.
Reverse from removal…. Just kidding! This might take longer than you expect, since working with the springs of the E-brake is very fiddly. There might be some tools that might make this job easier, but you still need some brute force. So take a sip of the patience tea (or hibiscus) and get going!
Start with attaching the new cable in place and attach the lever mechanism. Make sure to drag the lever all the way in so it takes up as little space as possible. This is the easy part.
Now for the hard part. Check out the picture for reference on how the emergency brake is assembled around the hub. Make sure the adjstment screw is all the way in so it’s at its shortest length
This is a bit trial and error since I might not have the best method here, but I found out that you need to keep the top spring in place on both sides and the adjusting cog in place. Keep the lower thicker spring in place on only one side and slide it beneath the lever mechanism. Use a flat headed screwdriver which is at the same width as the two outer springs which will need to fit into the slots in the brake dust-shield. They have to go in vertically then use the screwdriver to turn the spring 90 degrees to secure the spring. Start by doing one end then the other. Now the e-brake shoes are under quite a lot of tension and they are totally out of place. Try forcing one side into its natural place while using a strong hook to grab the loose end of the lower spring and try reaching the other shoe. This is more tricky than it seems and it’s possible to get it all fit up and still the whole assembly to be out of alignment. Trust me you will know if it’s not aligned properly. You will not be able to use it or get the brake disk rotor on.
I must have used a couple of hours to get both side on and was quite tired after it. Drink a lot of hibiscus to not loose nerves!
A trick is to use gloves while working to spare your hands, try to avoid impaling yourself on sharp hooks, spring and your tools. Also try not to use too much force on the smaller spring since it will break easily. If you break some of the springs you will need to get new ones otherwise the wheel might get stuck while driving. This is critical and must be sorted.
Now that the E-brake assembly is in place, put back the brake disk rotor, this should pop right on now that the E-brake is adjusted all the way in. Make sure there is no tension in the cable, adjust the cable at the cable clip under the car if necessary. When the rotor is back on. It is time to fit the rear calipers back on. The bolts require some thread lock and only tighten them to 35Nm.
If you are putting on new brake pads, remember to coat the mechanical moving parts with some brake pad grease to avoid friction. Use lightly and never coat the disk surface or the brake pad material itself.
So you thought you were done? Time to adjust the E-brakes now!
Start with tightening the cable mechanism under the car. When it’s tight enough so the wheels will spin with a slight resistance when the E-brake is off the cables are good. Now fine adjustment is needed with the cogs. Put on the wheels, but leave one bolt off on each wheel. Spin the wheel again with the E-brake off. If it’s freely spinning, then tighten the E-brake with spinning the adjustment cog with a long flat headed screw driver through the wheel lug hole. Tightening is done when the screw is going outwards. Use a small torch to see what you are doing. When there is a small resistance. You should be good. Now pull on the E-brake on hard. Remember the cables will stretch and settle a bit. Now with the E-brake off again, repeat the same procedure. The wheels should be not able to spin after just one click with the E-brake on when the shoes are new.
The next step is to find an incline to test with. Here usually you will find that more adjustment is needed. I really like when there only needs on or two clicks for the car to stand still when there is an incline. I had to go back and adjust a couple of times before I could find the right adjustment with the cogs. If the cogs will need a large adjustment, then rather adjust the cable under the car. Because when next E-brake adjustment is needed, it is more easy to just have the extra available adjustment for the cogs with a screw driver, for example at the next wheel change. Instead of crawling under the car and doing the cables.
Hope it was helpful. This job really sucks and in order to avoid it more times, better use the E-brake frequently so they do not rust. I have never seen worn out E-brake shoes rather than rusted out mechanism. Cables also wear out or stretch faster than the brake shoes gets worn.