[R129 SL] RE: shift knob replacement part 2

[Cliff Sadler]

OK. here goes. I'll have to post the pictures somewhere.

To replace the shift knob on a 91-93 500SL, you'll have to replace the shift
arm as well because the knob is "fused" to the original arm. To replace the
arm, you will have to loosen the locking nut at the base of the shift arm,
and then unscrew the arm from the shift lever, and boot.  Sounds easy,
except that the locking nut is 15mm, and there is virtually no way to get a
wrench into the shift gate  to loosen the nut.  If anyone comes up with a
tool that will loosen, and subsequently tighten the nut through the shift
gate, then most of the rest of this story can be ignored!

The first thing you need is a new shift arm. I have found a source that will
sell me new chrome units for around 30.00 with shipping. I can do a gang buy
if I get a lot of requests to get shift arms. What I can do is set up an
Ebay "buy it now" listing, and then let you know about it.  I'd like to get
a show of hands here for how many might be needed.

Second, you need to gain access to the locking nut on the shift arm so you
can remove the original. Here's how you do that:

You  will have to remove the console cover. That requires first removing the
radio, and the temp control unit.  THAT requires you to have the proper
radio removal keys. You can pick these up on Ebay, or you can stop by a
shop, give em a couple of bucks, and ask them to release your radio. Circuit
City is a good candidate for this.  NOTE: when you remove the radio, and
unplug it, you will have to enter the security code before it will work
again. Make sure you have the security code, and the instructions for
programming it.

The steps for removing the console cover aren't that complicated, but you do
have to be careful with the wood veneer to avoid breaking it.

I have attached 2 diagrams for removing the cover. IF this list doesn't take
attachments, then I will post the diagrams on a web site, and forward that
link. Pay special attention to the technique for releasing the aft clips.
You push from the right side of the cover, and lift up slightly on the left
back edge. Then you push from the left side, and lift up the right side.
You can't do this until all of the screws, inserts, radio, and temp unit are
removed. I went ahead and unplugged the window, top, and mirror switches in
order to get the cover all the way out of the vehicle.

Also, the harness assemblies for the temp control unit were puzzling for a
bit. There is a lever on each harness that when slid towards you, will
unlock the connector and remove it. when reinstalling, just put the
connector on the unit, and slide the lever back to its original position.

Once you have the cover off, then you can remove the shift gate cover and
slide it up the shift arm, and turn it so it's out of the way. This is
accomplished by releasing the 2 clips on the front, and left side of the
shift gate, and then the large clip on the rear. Mine was tight enough that
I had to reach under the tabs, and pull out slightly with my finger while
pulling up on the gate cover. Then, take a 15mm open end wrench, and turn
the locking nut counterclockwise. Shouldn't take much for it to get loose.
As soon as it is free, you can unscrew the existing shift arm. The threads
are about an inch long and metric, so it will take a few turns to get it
out.
When you pull the arm out, the receiver will spring to the left. Don't be
alarmed. When you screw the new shaft in, you'll have to reach into the
shift boot, and hold the receiver vertical until you get the threads started
on the new arm. BEFORE you screw in the new arm, first thread the locking
nut onto the new arm. You won't be able to just drop the nut over the new
arm. It's too thick in some spots.
Screw in the new arm, positioning the arc in the shift arm correctly, and
then using the 15mm wrench, tighten the locking nut.
It helps to use a wrench with the thinnest claw you can find.
Now, you can replace the shift gate cover, and the console in reverse steps.
With everything on, now you can put your new knob onto the shift arm. I have
found that the one from Canada takes the large bushing insert, and you
should drill out the bushing where the set screws go, and use the long set
screws in the pack. This will enable the set screws to contact the shaft,
reducing the likelyhood that the knob could turn.