1987 Brake Booster Removal

I suspect that the procedure is pretty much the same for other early C4's, but I don't know for sure.

 As I recall, I needed a 12mm deep-well socket, a 13mm deep-well socket, a pair of needle-nosed pliers, a couple of ratchet extensions including a flexible one, a ratchet, a long skinny screwdriver, and a broad flat-blade screwdriver.

Remove the two nuts holding the master cylinder to the booster. Note that once you do this, you can see two more nuts behind where the first two were. Don't remove these. They hold the two halves of the booster together.

Pull the vacuum line off at the top of the booster.

Remove the dash panel above the driver's feet - take loose a couple of screws, wiggle the panel around until it's down on the floor, disconnect the light connector, and place the dash panel in the passenger seat or somewhere else out of the way.

Get down on your knees and look up at the brake pedal. There is a plate bolted to the pedal arm. If you move the pedal up and down, you will see that this plate opens and closes the brake light switch. Remove the plate.

You should be able to see the shaft coming out of the booster, through the firewall, and attaching to a stud on the brake pedal arm. There is a pin that keeps the shaft from coming off of the stud. Between the shaft and the pin is a washer. Pull the pin out and remove the washer.

You should now be able to slide the booster shaft off of the stud. If you can't quite get it, use the long skinny screwdriver to pry it off. It doesn't take much.

Here comes the hard part. Crawl into your car upside down. Your head should be down below the pedals looking up and your feet up in the air.

Make sure you have a light, a ratchet, your extensions, and your sockets.

You don't want to have to get back out. You'll see a nut on either side of where the booster shaft comes through the firewall. Remove these. One side is not too bad, but the other side is a real bitch. I'm not looking forward to getting that one back on.

Now get yourself out of the car. It's harder and more painful than it sounds. <grin>

The booster will now come right out.

Now remove the vacuum fitting from the front of the booster. In the diagram it looks like this thing screws in, but as I found, it doesn't. It stays in by friction. Pry it out with a screwdriver or two.

Loosen the two nuts holding the halves of the booster together. Back them off about 1/4". The spring inside may push the two halves apart. If it doesn't, you need to pry them apart. The manual says to pry around the seam between the two with a small flat-blade. That didn't work for me. I took a broad flat-blade and pushed it through the hole where the vacuum fitting was, against the back half of the booster while pulling on the front half. That got it started and separating them was then easy.

Once they're apart, you can remove the nuts and cone washers completely and remove that half of the booster.

I hope someone finds this information useful.