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Another driver's seat repair thread

Started by raueda1, 17 April 2022, 01:14 PM

raueda1

This season I'm gearing up to fix the well know sagging seat issue.  In many ways the seat sag places a real limit on car handling since I'm hanging onto the steering wheel when cornering. There hasn't been much on this topic recently so I figured I'd poll you folks for updated info.  Here are a few questions based on some preliminary searching:

  • Let's assume I have some broken springs.  Anybody got any experience with  theMercedesSource repair kit
  • Let's also assume that my pads are shot.  What's the best solution?  I found these.  Not cheap but maybe worthwhile if they really improve matters.  Good alternatives?
    pads
  • Finally, there's the pool noodle upgrade.  It seems like many have done variations of this and made substantial improvements.

I've had the seats in and out, no problems there.  I'd be reusing the existing seat covers (MB-Tex, heresy and damnation!!!).  Might upgrade the covers in the future, but not ready to do that yet.  Any comments, suggestions, experiences or recommended suppliers would be great. Thanks and cheers!
-Dave
Now:  1976 6.9 Euro, 2015 GL550
Before that:  1966 230S, 1964 220SE coupe, 1977 Carrera 3.0

Alec300SD

Grab the PS spring boxes from 2 separate 2nd generation W126's at the local JY, change the seat skins over to your MB-tex covers, and install them place of your original spring boxes.

They offer superior support and are backwards compatible to the W123 and W116 seats.

http://www.peachparts.com/shopforum/diesel-discussion/352422-diy-%96-pictorial-w126-front-seat-cushions-w116.html
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

raueda1

Quote from: Alec300SD on 17 April 2022, 01:50 PMGrab the PS spring boxes from 2 separate 2nd generation W126's at the local JY, change the seat skins over to your MB-tex covers, and install them place of your original spring boxes.

They offer superior support and are backwards compatible to the W123 and W116 seats.

http://www.peachparts.com/shopforum/diesel-discussion/352422-diy-%96-pictorial-w126-front-seat-cushions-w116.html

Fabulous writeup!  It will take several re-reads, but very comprehensive, solid work!  So now the search for 126 seats begins. 

Any thoughts on simply installing the 126 seats?  If the 126 box installs onto the 116 rails it seems like it might be feasable.  You mention that there are electrical complexities.  Can you elaborate?  Thanks and cheers,
-Dave
Now:  1976 6.9 Euro, 2015 GL550
Before that:  1966 230S, 1964 220SE coupe, 1977 Carrera 3.0

raueda1

Alec300SD, found lots more info on 126 -> 116 seat swap.  Doesn't look worth it IMO given the control challenge as you posted elsewhere.  Anyway, then I'd lose the OE look of the old seats.  But I found a few junkyard W126's.  The journey continues.  Thanks again,
-Dave
Now:  1976 6.9 Euro, 2015 GL550
Before that:  1966 230S, 1964 220SE coupe, 1977 Carrera 3.0

Alec300SD

The spring box fits into the seat bottom frame which attaches to the seat rails.
The W126 seats bottom frames and seat rail widths are wider that those on a W116 and will not fit without  modification.

The W126 seats are electrically controlled by 4 motors (fore-aft, seat angle, seat height, and headrest height) with the controls in the doors.
So you would need to install a harness to power the seats, and have a place to mount the control switches.

The W126 seat back has better side bolster support that the W116 seat back.
I started to convert the W126 seat back to manual seat angle control by swapping in a set of W116 seat hinges.
I lost interest and eventually scrapped the modified W126 seat back, after I realized the headrest adjustment would be lost.
The hinges would also be exposed, as neither the W116 nor the W126 plastic hinge trim covers would fit properly.
With just a spring box swap you retain the original look and controls.

W126 seat back frame

W126 seat hinge removed - rivets drilled out

Paint prep for installing W116 hinge with manual adjustment mechanism

W126 seat back with W116 seat hinge

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

UTn_boy

The actual spring box frame is the same between the W116 and W126.  The motors and all of the electric things can be removed from the W126 seats.  Since it's only the spring box you need there is no need to install electric seats.  The only difference is that the early W116 cars had actual coil springs in the frame, whereas after 1975 they all started using ribbon springs.  The seat rails from your W116 will bolt right up to a W126 seat spring frame after the W126 rails are removed.
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

orientrot

I think that Kent's kit works but that you can do a lot better.

I didn't take any pictures unfortunately but have recently done the seat spring swap on 123 seats while also dismantling a set of 116 seats out of a parts car that luckily had had the seat pads replaced at some point with new genuine Mercedes pads. I agree that trying to integrate 126 seat motors/rails because it's a lot of work and if your seat rails aren't piles of rust in the shape of seat rails, you can clean and lubricate them such that they work incredibly well. I should get pictures and type up everything when I do the 123 passenger seat in the future, or when I refurb one of my 116 seats.


Things to note:

  • Bottom seat spring frames are compatible between W116, W123, and W126
    • They revised the spring frame in the late 126 by adding coil springs to the front, you can transfer the coil spring piece into a 116/123 set of springs or swap the entire spring frame
    • Pool noodles will work for a time, but there are actual Mercedes inserts for the coils springs (1269142215) that will last much longer than a pool noodle, or you can get this kit that includes some foam support for the rest of the springs
  • I believe the back seat frames are largely the same between the 116 and wide shoulder 123 seats (through 1982 I think). Some websites list them as being the same but I'm not 100% sure. I think the pads are almost the same except maybe that the 116 has some different foam pieces glued onto it. I'll investigate this further.
75 450SEL
80 300SD- ZF8 OM606 superturbo
83 300D- 6-speed M111 Kompressor
84 300D- 5-speed OM617
92 300D- 722.6 OM603 3.5
93 190E 2.6 Sportline LE x2- 6-speed M111 turbo, 3.0 M103
02 C320 Wagon
03 Sprinter 2500
06 E500 4Matic Wagon

raueda1

Many thanks to all, very helpful.  If I can't find a decent 126 then I guess I'll try the kit.  Obviously I'll report on the results...   Cheers,
-Dave
Now:  1976 6.9 Euro, 2015 GL550
Before that:  1966 230S, 1964 220SE coupe, 1977 Carrera 3.0

orientrot

#8
Quote from: raueda1 on 19 April 2022, 08:48 AMMany thanks to all, very helpful.  If I can't find a decent 126 then I guess I'll try the kit.  Obviously I'll report on the results...   Cheers,

I probably have a couple spare coil springs and some of the regular flat springs I could send you just for cost of shipping, I think I also have a regular 116 spring box that was a replacement from Mercedes probably 15 years ago if you would prefer that, but obviously that will be a bit more to ship.

Edit: I don't actually have the 116 spring boxes anymore, I remembered that I tried to save them but that the rusty rails had become a permanent part of them due to corrosion and stripped screws
75 450SEL
80 300SD- ZF8 OM606 superturbo
83 300D- 6-speed M111 Kompressor
84 300D- 5-speed OM617
92 300D- 722.6 OM603 3.5
93 190E 2.6 Sportline LE x2- 6-speed M111 turbo, 3.0 M103
02 C320 Wagon
03 Sprinter 2500
06 E500 4Matic Wagon

Jenno1981

For what it's worth I went with the MercedesSource kit. Took 15mins to work out how it worked, 15mins to install and stuck some of his foam in as well. Time will tell...

Also, when I took the driver seat out it became evident the previous owner had the seat in for repair of the outer springs. Some heavy duty springs put in on the outer side. They were so heavy duty it caused the driver to lean to the inside and.... collapsed the springs on the inside 😔
1978 450SEL - Green
1999 ML430 - Also green 🤷�♂️