Thursday, October 22, 2009

BMW E34 525i Door Brake repair

Back in the earlier part of the summer this year, I noticed that the 93 525i that my son drives had this annoying cracking sound every time the drivers door was opened. I went out and checked and found that the mounting area for the door brake was all cracked. It mounts inside of the door with the arm of it attaching to the door jam. The door brake is what keeps the door from opening to far and keeps it from closing on its own if you want it to stay open. The sheet metal was tearing and deformed. I didn't take any pictures at the time, but the brake was trying to pull its way through the sheet metal. I didn't have time to mess with it, so I took a ball peen hammer and bent the sheet metal back to near its original position. It still made noise, but at least it wasn't going to pull itself out.

For the next few months, I was kept pretty busy at work and didn't have the time to fix this problem. I thought about it a few times when I heard the pop and crack when the door was opened. I started thinking about ways that I could fix it. Most of them included some kind of welding, but I don't weld.

A couple of days ago, I finally found the time to tackle the job. I came up with a repair that only cost me six dollars and I didn't have to weld anything.

Here is a picture of the problem before I started working on it:
Here is what it looked like once I took off the door panel and could get to the door brake and remove it:
Picture of the removed door brake:
My idea for the repair was to get some metal and make a mounting plate for the door brake and then pop rivet it to the outside of the door to make the area stronger. I decided to get a piece of flat plate metal that was 1 1/2" wide and 1/8" thick. I had to buy a 36” long piece, but it only cost six dollars. After looking at what I needed to cover, I cut the metal 7” long. I took my time and laid it out the best I could and cut it and drilled it. I know it doesn't look very professional, but it works, here is a picture:
Here is a picture of the door brake mounted to the plate I made before I installed it, just to see if it fit properly:
I didn't have any special tools other than my cordless drill and a jig saw with a metal cutting blade to do the drilling and cutting. I do have an old bench grinder that I used to smooth all the rough edges.

To be able to mount the door brake back on the door, I needed to remove most of the cracked and torn metal. Here is what it looked like once I did that:
To get the metal out of the way, I used one of those hand held air operated cut off wheels. I initially tried using some tin snips, but the cut off wheel worked much faster. I left as much metal on the door as I could and still be able to get the door brake mounted. I wanted to leave the metal there to add some backing to the plate I made.

I did most of the work with the door still on the car. I figured out though that I wouldn't be able to drill the door jam for the pop rivets if I didn't remove the door. It only took me about 10 minutes to remove the door, I should have done that before I started this whole project and would suggest if you're planning on doing this to take the door off first. It makes everything much easier.

I ended up having to modify the shape of the plate to get it to lay flat and to avoid sharp corners. I rounded off all four corners. The upper corner towards the outside of the door I took more off so it would fit better. Once I was happy with the way it fit, I decided where I would drill the holes for the pop rivets. I put three on the top and four on the bottom mainly due to the shape of the door. I filed and ground down the remaining rough spots, sanded the plate and painted it to protect against rust.

Once the paint was dry, I went to install it. This is where having the door off of the car really helped. I positioned the door brake where I needed it to be and found that some of the rubber weather stripping on the door was in the way. I used a utility knife to trim away just a bit of the weather stripping and then the plate laid perfectly flat. With it in the correct position, I then drilled all the pop rivet holes and installed them.

Here is a picture of the plate riveted in place with the door brake installed:
This last picture shows everything installed with the rubber boot in place:
That's it! I used the Bentley Manual for instructions on how to remove the door panel, how to remove the door brake and how to remove the door. While I was in the door, I lubed all of the door parts and the moving window parts that needed it. Done!