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Opened up the door card to a few surprises

Started by BigGreenMachine, 26 December 2022, 02:55 PM


Was able to carve out a sliver of free time today and got the passenger front door opened up so I can lubricate the window mechanisms.

I found a few things. Fortunately they mostly appear to be minor:
1) It's definitely bone dry in there. It's sure to appreciate a full lubrication treatment.
2) There were a few loose / broken parts in the bottom of the door I can't identify.
3) I bought the wrong plastic clip! I bought a replacement clip for the vertical bar, but once I got inside it turns out the broken clip I've got is from the diagonal bar.
4) Rust!

Here's the photo evidence.
Photo 1:
-At left are the broken white clip, and the incorrect replacement I ordered. Back to eBay to get the right one. Any leads on a part number to help the search along?
-In the middle is a tall barrel type screw I found loose in the bottom of the door. This looks like it's intended to limit a component's travel in some way - to stop some piece from moving too far, but I'm not sure which. Any ideas?
-At right is another broken piece that was also loose in the bottom of the door cavity. Any idea what this piece is or how critical it is? If it's critical and identifiable, I can work on finding another one of these. 

Photo 2&3 of rust by the rear corner. How bad does this look? Do I need to take immediate action, either by myself here at home or at a body shop? 

What kind of glue have people used successfully to stick the plastic sheet back in place when I'm all done and putting it back together?

Thanks for any advice you may have here.


For openers you will have to remove the door seal.  It's toasty for sure and there will be more rust underneath. That rust looks pretty bad unfortunately. It's always worse than it looks.
Best to remove the rubber door seal and give the area a good poking to see if the rust went through but from here it looks for sure that there will be a big old tin worm surprise lurking :'(
1977 450 SEL 6.9 - Astralsilber


Thanks for the hard truth, Daniel - I'll start scraping and sanding to see how deep it goes, and get some Miracle Paint on order. And I guess a new door seal now too!

I'd say the most pressing issue I face at the moment is identifying the correct replacement / part number for the broken white plastic clip I've got so I can eventually get the door put back together. It's alarming how much unwanted forward-backward travel is introduced to the glass by that piece missing.

Thanks for the help!


Confirming my suspicions, I just ran across this quote in a BenzWorld thread that breaks the bad news I'd been avoiding: "Mid-sized white plastic piece with large central hole - not availble as a repair piece - part of the front window regulator arm - available new only as part of the whole front window regulator. You might get lucky and find a usable one on a junkyard W116 front window regulator."

Sadly, the eBay auctions I see for window regulators all seem to be already missing this little plastic piece when I zoom in on the pics.

So, this won't be an easy find unless there's anybody here who hasn't yet got around to throwing out their old bent/broken regulators after replacement. I'd happily make it more than worth your while if you did.

Otherwise it looks like an eBay/salvage yard journey is ahead.


Even if you find the white piece with large hole you wont be able to attach it because of how it was assembled in factory. The regulator will actually work fine without it.

The round pin looks like from door handle, and maybe the other part look maybe from the door latch,

Though not ideal you can repair the rust holes in bottom of door with fiberglass laid inside the door. First remove just loose rust. Then treat remaining with a rust converter. You need to leave enough rust still on piece so it can work. Then do fiberglass reoair and then topcoat with paint.

The bottom of doors are too complicated to cut out metal and replace.

3m spray adhesive for plastic sheet.
'68 250S
'77 6.9 Euro
'91 300SE,
'98 SL500
'14 CLS550,


The plastic (Delrin?) glide gets pushed out of the pivoting guide for the reulator arm due to lack of lubrication, and eventually breaks when is gets jammed.

You can see the wear marks on the arms of both spare left front window regulators.

Fortunately the dislodged glide is still intact...and it is soon to be yours.
Send me a PM to set up a meet. I work in Oakland on weekays.

78 W116 300SD 'Desert Rose' new as of 01/26/2014
79 W116 300SD 'Stormcloud' RIP 04/11/2022
91 W126 300SE 'Kjetteri' new as of 02/19/2022


Thanks for this info rumb - extremely helpful!!

And Alec, thank you very very much for your generosity. PM is on the way...


Please report back if you are able to get the plastic piece in place and stay there. IMHO you will be unable to so. Good luck anyway!
'68 250S
'77 6.9 Euro
'91 300SE,
'98 SL500
'14 CLS550,


The 2 pieces centre and right in your first pic are from the door handle.  The small cylinder in the middle is the adjustable latch inside the door handle that when pulling the handle opens the door.  The pieces on the right are part of the door handle assembly as well. on YouTube has a really good video on how to remove and repair the assembly as well as explaining all the components.
Never stop loving
1980 280SEL


You can still buy the front right regulator new from Mercedes. Retail is around $290, and wholesale is around $220.  Part number 116-720-12-46.
1966 250se coupe`,black/dark green leather
1970 600 midnight blue/parchment leather
1971 300sel 6.3,papyrus white/dark red leather
1975 450se, pine green metallic/green leather
1973 300sel 4.5,silver blue metallic/blue leather
1979 450sel 516 red/bamboo


Thanks for the tip on the MSource video Gpapaniko - I'll check it out.

Good intel on the nuclear option too, UTn_boy. I'll hope it doesn't come to replacing the whole regulator, but the deeper I get the more limited my options are appearing.

I'll share whether I'm able to fix things with the clip provided by Alec300SD.

rumb - you say the regulator works fine without that plastic piece, but I assume that means you're OK with the window glass moving laterally as it's being rolled up all the way closed and seated in the felt channels? I'm surprised how much movement there is in mine when I reach the top.


Look at job 72-195 - Adjustment of Window.  The vertical guide bar and associated parts should control any side to side movements.

The missing piece on the regulator has mostly up and down forces working on it.
'68 250S
'77 6.9 Euro
'91 300SE,
'98 SL500
'14 CLS550,