Keeper - Lock Link Repair. (LONG)

["Al Powell" <APOWELL@agcom.tamu.edu>]

AWRIGHT!!

I went back in today and fixed the alarm-crazed driver's side door on 
my 1990 200.  In doing so, I discovered some important things about 
the way the lock link replacement must be done.

Comments:

First, roll the window fully UP.  This keeps it out of the way later.

Remove the inner door armrest and trim panel, then pull six bolts 
(one each on the front and rear door edges, one each at the lower 
corners of door (count number of spacers used on these so you can 
replace them) and two small bolts at the center top.   This lets you 
separate the black inner panel of the door from the main door shell.  

Lift upwards on the inner panel and you will be able to separate it 
slightly.  If you're working by yourself, free the manual door lock 
rod so you won't bend it, then lean the inner panel outwards and 
run tape from the door over the top of the window to keep it from 
falling outwards.  You need about a three-inch gap between the inner 
and main panels to work through at the end of the door where the 
handle is.

The faulty lock part which breaks is the link which comes off the 
rear end of the key cylinder, connecting it to the rod which 
activates the locking mechanism.  Disconnect the locking rod before 
messing with this....

The replacement kit usually includes both a stronger link AND a 
replacement key cylinder.  Both must be used.

To replace the faulty link, you must remove the circlip which is on 
the back of the key cylinder.  This may require circlip pliers with 
VERY small tips, or it may be a small conventional circlip which can 
be pried off with a screwdriver tip.  Don't lose it!

When you pull the key cylinder out, NOTE its orientation.  It 
can be inserted 180 degrees off, making the door impossible to lock. 
You won't discover this until it's all back together....

When you replace the key cylinder, the tumblers from your old 
cylinder can be removed individually and inserted into the 
replacement cylinder.  DO NOT forget about the little tiny springs 
which are under the shoulder of each tumbler.  Transfer both springs 
and tumblers, using a bit of grease to retain them in the new 
cylinder.  Then insert the key to keep the tumblers safely in place.

IMPORTANT STUFF:

Two things are NOT obvious but make this repair work or not.

1)  There is a circular spring which goes under the new lock link,
between it and the cylinder.  I found it easiest to install this 
spring first, hooking one end over the small protrusion on the 
cylinder, then using needle nose pliers to stretch the spring and 
hook the other end over the protrusion.  Check your Bentley on this; 
the view is not perfect, but it does help. The lock link sits OVER 
this spring, retaining it.  The spring interlocks with a protrusion 
on the replacement lock link, providing a spring-load against moving 
the lock either direction.

2)  ***Believe it or not, the small teeth on the white alarm-
activation mechanism on top of the cylinder are INDEXED.***

If you look at the replacement lock link, you will find it has teeth 
across its top.  *ONE of these teeth is only half as wide as the 
others.*  If you look carefully at the teeth in the alarm-activating 
mechanism, you will find that ONE of them is only half as wide as the 
others.  These two teeth should be MATED when assembling!  If you 
take your time, this can be done.

NOTE:  I dissected one of the alarm mechanisms on top of the key 
cylinder.  The toothed mechanism is actually a wheel with one flat 
side; when the wheel is turned far enough, this flat side rocks and 
triggers a switch which activates the alarm circuit.  This is the 
reason that indexing the teeth is important; if you get it wrong, the 
alarm will arm at the wrong point as the key is turned.  (This 
happened to me.)  This little wheel with teeth can actually be turned 
360 degrees, but it is only aligned correctly when the single half-
width tooth on the wheel is aligned with the half-width tooth on the 
lock link.

When the teeth are interlocked, the new link must be held in 
place and the retaining circlip must be installed while holding the 
link, spring, etc. in place.  It is easy to push the key cylinder 
back out of reach, so have an assistant handy to help hold the key 
cylinder in place.

When it's together, you can reverse the order of disassembly.  One 
caution: on the forward side of the inner door panel, the electrical 
wire harness for the power window can come loose and get pinched 
while re-installing the door.  Make sure it doesn't get loose. Mine 
got loose and I caught it with the side of the bolt on the front edge 
of the door, requiring some wiring repairs.

But now, instead of having the alarm go off about one time in three 
when I unlock the door, it works correctly!

Hope this helps someone else.

.......................................................
Al Powell, Ph.D.                 Voice:  409/845-2807
107 Reed McDonald Bldg.          Fax:    409/862-1202
College Station, TX 77843      
Http://agcomwww.tamu.edu/agcom/satellit/alpage.htm

"Some people can tell what time it is by looking at the
sun...but I have never been able to see the numbers."
             [From 5th/6th grade essays....]