Back Back 2CV Restoration - Repairs - Engine compartment - Brakes

Front Disc Brakes

First a word of warning: When you work on the brakes you MUST know what you are doing. Accurate, reliable and quality work is required. Your or somebody else's life may depend on your work.

Beware: The 2CVs with disc brake system need only the green LHM as brake fluid. If only a little quantity of the standard DOT brake fluid is added to the system, the entire brake system is ruined - a partial or a total failure of the brakes is then only a matter of time. Even experienced mechanics don't know about this. Read the article about LHM vs. DOT and let your mechanic know!

When you work on a 2CV with disc brakes, always check for the presence of DOT. It is easy to determine if there is DOT in the system. LHM and DOT don't mix, like oil and water. If you can see a separation line between two fluids in the reservoir, chances are very high that you look into a costly replacement of the entire brake system. When you drain the fluid from the system you will see the two separate fluids. The dirty brown fluid is the old DOT, the dirty green stuff is the old LHM. The black particles floating between the LHM and DOT are dissolved rubber from the O-rings and seals of the brake system.

If you have only one brownish fluid in the system, take a sample and mix it with fresh LHM. If it separates after some seconds - bad luck, if it remains mixed you have very old and dirty LHM.

Before you can start the work you have to perform certain checks:

The brake pads need replacement when the gap between the backing plate of the brake pads and the rotor is less than 3mm (0.1181 inch)

Check if the rotors and calipers are not oily. If you discover oil, you must find and fix the oil leak first. Once the brake pads are oily they must be replaced. Even if the pads appear to be dry again, the oil still sits soaked in the pad material, only waiting to steam out between the rotor and the pad once it gets really hot.

Also the rotors need to be in a decent shape. The disc must have at least 5mm (0.1969 inch) at the thinnest spot.

If you discover that the brake pads are worn uneven and there was no oil on the rotors, calipers or immediate surroundings, double check if there was DOT in the brake fluid. Dig into the mechanical history of this car. Which repairs were done over the past years, who did it, was the brake system involved anyhow? Sometimes the owner is not even aware that work was done on the brakes. I had a few cases where i.e. the transmission was replaced. The mechanic mounted the original front brakes onto the new transmission, bled the brakes - and of course filled up with DOT!

Check if the emergency brake pads are worn. You can't see them but it is simple to determine if the pads need to be replaced. When you adjust the emergency brake and the cam can be turned in a full circle, the pads need to be replaced.

How to replace the brake pads

This job is very easy if you do only one pad at a time. Use a big screwdriver and lever the rear end of the brake pad base away from the rotor. Use caution not to damage the rotor with the tool. Once the brake pad is pushed away from the disc, use the screwdriver in the opening of the caliper. Right in the middle of the caliper you can see the rotor and the brake pads. Carefully push the brake pad away from the rotor using the screwdriver as a lever. The brake pad must push the piston in the caliper all the way back. This must work nice and smoothly. If you discover problems pushing the piston back, you need a pair of rebuilt calipers. There are usually two reasons for the pistons to seize in. One possible reason is the wrong brake fluid. DOT works dissolving the on O-rings. In this case you can still operate the brakes, the immense pressure from the master brake cylinder pushes the pistons out, but when you try to push them back - no way. Anyway, like mentioned earlier, in this case you need a complete new brake system.
If you are lucky only the calipers are worn.
But now back to the replacement of the brake pad. Once the piston was pushed back completely, you can take out the brake pad. Use the big screwdriver to push back the wire that holds the pad in place, but don't bend the wire! To pull the wire back, you need to push the top part of the wire down to release it from the caliper.
Once the wire is out of the way the brake pad will mostly already fall out of the caliper. Catch the pad before it falls into the cooling shroud around the bottom of the rotor. Then insert the new brake pad. Push the front end into the caliper in a 45° angle. Once the pad engages into the front attachment, just lift the pad up until it engages into the rear-locking bolt. Hold the pad in this position and snap the wire back in the rear end of the pad to hold it in place. Easy - wasn't it?

How to insert the new brake pad
How to insert the new brake pad

Brake pad in the engaged position
Brake pad in the engaged position

Now you repeat this procedure on the remaining three pads. When you are done replacing the pads, don't forget to pump a few strokes on the brake pedal. The pistons need to be pushed out onto the new pads. If you forget to do this and drive the car right away, you may experience a nasty surprise! (I know what I'm talking about; 've been there - done that).

Replacing the emergency brake pads

Undo all 9mm bolts holding the 4 brake levers. Pull the handbrake cables with the levers out of the way. Watch out on the passenger side - avoid the lever and cable touching the live wire on the starter motor right above. Now comes the tricky part: Get the old pads out of the caliper. I use an old kitchen knife. The blade is slim enough to go between the caliper and the rotor. It is flexible enough to be bent onto the emergency brake pad. With this it is easy to push the pads out of the caliper. When you insert the new pads make sure that the metal base faces away from the rotor! (No kidding - I know a guy who did this wrong!) Watch out for the little steel spring in the caliper. It has to hold the pad in position and keep it from vibrating. If you push the pad in wrong, this spring may be pushed onto the rotor. When all four pads were put in place, check if they sit parallel to the rotor. If they toe out to the back, very likely the spring isn't in place.

Note the little spring
Note the little spring

Correct placed emergency brake pad
Correct placed emergency brake pad

Before you mount the lever assembly, take the cams out of the leavers and clean the surfaces between the lever and the cam. Brake cleaner is great to do this. To mount the levers, it is easier to do it with the cams still out of the leavers. Just put both levers of one caliper back in place. Then screw the bolt with the cam in but don't pull it tight, you need some play to insert the cam into the lever. Attention: Don't tighten the bolt to push the cam into the lever as this may destroy cam and/or lever when they are not proper aligned. Push the cam in only by hand. Once the cam is all the way in its position you may tighten the bolt. When the bolt is tight the cam and the lever are in the right position for the adjustment. Open the bolt enough that you can turn the cam by hand. Repeat this procedure on all four cams.

To adjust the emergency brakes you need to lift both front wheels off the ground. (Adjusting one side at a time is possible but it takes longer and the result is less accurate).
Now turn all cams in the direction that the lever pushes onto the brake pads when the cam is turned downward. Every lever should now push onto its pad. Pull the handbrake handle a few times firmly to make sure that the brake pads are pushed all the way in onto the rotor. Open the 7mm nuts on the adjustment rods on the top of the levers check if the handbrake handle is released and adjust the rod into a position where both levers almost touch the limiters on the caliper. This way you have later the maximal possible movement for the levers. Now the whole assembly is ready for the adjustment.
Turn the cams a little bit away from the rotor to release the pads. Start adjusting on the inside cam. Turn the cam with a fat 24mm ring spanner downwards until the brake pad starts pushing onto the rotor. You can feel this easily when you turn the corresponding wheel. Now tighten the 14mm bolt. Just before the bolt is tight, open the cam just enough to make sure that the brake pad doesn't wear on the rotor anymore. When the inside cam is adjusted satisfactory, continue on the outside cam.
The next step is to synchronize both sides to retard even. Pull the handbrake out three notches. Both front wheels should turn significantly harder but still can be moved by hand. If you feel that the wheels are retarded different, adjust the rods between the levers to a position where both wheels retard even. Release the handle again to check if both front wheels can be turned again without the brakes still rubbing on the rotors.
When the brakes work even, pull the handle out 5 notches. At this position it should not be possible to turn the front wheels by hand anymore.
Finally tighten the two 7mm nuts on the adjustment rods and lower the front of the car down onto the ground.

Replacing worn out rotors without replacing the calipers

If the rotors need to be replaced it is also necessary to install new brake pads and emergency brake pads, since the old pads match the worn out surface of the rotor. Using the old rounded pads on a new and flat rotor will result in uneven retarding!
To get the rotors out you have to take off the calipers first. If you like to avoid bleeding the brakes after finishing the job, you can try to keep the caliper parts tight together at all time. First take out the old brake pads and handbrake pads. Open the rear main bolt that hold the caliper a little and tighten it again but less than it was before. The bolt must be tight enough to hold both parts of the caliper firmly together but loose enough to allow you to tilt the whole caliper upwards. Now undo the front bolt and pull it just out of the transmission. The tip of the bolt should still be in the steel spacer between the caliper and the transmission. Now lift the front of the caliper high enough that the bolt comes high enough to put a 10mm nut onto the bolt. Pull the front bolt tight against the nut and undo the rear bolt. Pull the caliper away from the rotor and secure the rear bolt with another nut. Pulling the caliper away make sure not to bend or damage the brake line.
As the next step you have to undo the drive shaft. Use a slim 14mm socket to undo the nuts and bolts holding the drive shaft. Open the front holder of the air duct on the bottom of the rotor. Now pull the old rotor out and install the new rotor. Make sure that the new rotor was thoroughly cleaned with brake cleaner since the new parts wear oil or wax rust protection.

When the new rotor is in place, mount the drive shaft again. Make sure all nuts and bolts are really tight. Don't forget to remount the air duct. To install the caliper, start with the rear bolt. Undo the nut and mount the rear bolt back into the transmission, have the steel spacer in place. Tighten the bolt only enough that you can still tilt the caliper assembly down. Now undo the nut from the front bolt and push the whole caliper down. While pushing the caliper down, hold the spacer in place with the tip of the bolt. When the caliper, the spacer and the transmission are proper aligned, tighten the bolt. Don't forget to tighten the rear bolt when finished on the front one. If you did it right, not a drop of LHM leaked out and no air entered the system. If air managed to get in, you have to bleed the brakes the old fashioned way.
Finally install the new brake pads and adjust the emergency brake.

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