Occam’s razor (Front door inside latch)

Today I finally faced the prospect of disemboweling the driver side front door, a task I kept postponing because this would be the third time in as many years.  Not that the door is usually difficult to work on mind you, but I just did not relish the idea of taking it apart one more time.  State law, however, forced my hand this past week as I prepared to pass the annual safety inspection, a venture sure to fail without two functioning front doors.

Ironically, this story has its beginnings with last year’s inspection, when on the way home, the driver door window lift channel broke.  Upon fixing that issue, I found the inner door handle no longer opened the front door which compelled me to spend most of last year rolling down the window to open the door with the outside handle.  This worked just fine, but state laws require the inner handle to work as intended.

I assumed that I knocked something out of place or bent the connecting rod during the lift channel project, but was not entirely sure of what I might discover with the door card removed. I readied myself for a rain of broken parts as I peered into the door yet again, but could not find anything out of place, bent, broken or otherwise. Scratching my head a bit, I closed the door and tested the inside latch handle – pop, the door opened.  After repeating and getting the same results several times, I thought that perhaps the issue lay in the plastic trim cover that fits around the handle; perhaps this part was interfering with handle operation for some weird reason.  I put the plastic trim back in place and the door stopped opening.  OK, I thought, lets try again.  With no trim the door opened from the inside just fine, when the trim was returned handle function ceased.  The latch handle moved, but stopped at what seemed like a fraction short of opening the door.  I could see no interference between the handle and trim, but to be sure, I loosed the screw that holds the trim so I could wiggle the plastic around.  Wouldn’t you know it, the door opened again!

At this point, because I could see absolutely nothing wrong with the trim, I took off the trim and just inserted the screw.  The screw goes into the handle latch fixture at a point that might block the movement of the handle lever as it pulls the connecting rod towards the front of the bus.  Sure enough, with the screw tightly fastened, the door would not open  However, if I loosened the screw three or so turns, the handle would function again.

While I seemed to have found the issue, I could not figure out why the screw would have suddenly become a problem last fall and, therefore, was not solving the problem at hand.  I looked in the Bentley manual, just to be sure that all the door linkage was indeed aligned and oriented correctly; it was of course.  As a test, I tried installing the screw from the window crank and found that it also would stop the door handle from working.  Both screws needed to be around an 1/8 of an inch shorter.  In a final effort to discover why the driver side door handle was having a fit, I took the screw out of the passenger side door handle trim and screwed into the driver side.  Surprisingly, the handle worked and the door opened from the inside.  Out the screw came, and sure enough, the passenger side screw was a tad shorter than the driver side.  After a quick search through the parts stash, I dug out another screw that belonged to a door handle and fixed my door with the correct short screw.

While I have no idea how the longer screw wound up in the door, I am very happy that Occam was on to something; the simplest explanation is usually correct (and  that I did not need to disembowel the entire door again!).

Rear view of the door latch handle and the rod that connects the handle lever to the door catch. When pulled, the handle engaged the rod and door catch, but did not pull far enough to open the door.

Rear view of the door latch handle and the rod that connects the handle lever to the door latch. When pulled, the handle engaged the rod and door latch, but did not pull far enough to open the door.

Front side of the door latch handle showing the hole for the trim retaining screw.

Front side of the door latch handle showing the hole for the trim retaining screw.

When the door latch handle is pulled to open the door, it moves a lever and the attached connecting rod towards the front of the bus and closer to the plastic trim retaining screw.

When the door latch handle is pulled to open the door, it moves a lever and the attached connecting rod towards the front of the bus and closer to the plastic trim retaining screw.

With the handle pulled too open the door, I could see the lever move up behind the screw hole where it could hit the back of the screw.

With the handle pulled to open the door, I could see the lever move up behind the screw hole where it could hit the back of the screw.

Correct, short inside door handle trim screw on the right.

Correct, short door handle trim screw on the right.

New, shorter screw installed.

New, shorter screw installed.

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