'83 MB 300Sd Seat problems

The drivers seat forward and back sliding was not working. I could hear the motor turning but no seat movement. I just assumed it was a broken cable. I
completely took the drive mechanism apart and cleaned out desiccated glue like grease and relubricated all the drives and cables and put it back together. I used a spare battery to test the job and to my amazement the forward/backward cable still was "not engaged" in the gear or motor. I pushed on the connection and then it worked but would jump out again and just "whirrr" with no seat motion. The cable is the longest of the three and the hardest to replace so before I take it all apart again I want to be sure I am not missing something or doing something wrong. The cable is basically 3 parts 1.) out plastic boot 2) 2 crimped on connector hubs 3.) inner metal cable terminated in square ends. I assume under a load of my grease glue the hubs must have stretched or moved apart somewhat and that is the root cause of the problem. I plan to replace the cable when I get some more time but wanted to know if any of you have any better solutions. I temporarily wired two of the cables together so the long cable is now more "s" curved instead of "c" curved and that seemed to help but it is not a permanent solution. Thanks for any information. Anybody know the part number for the cables ? Have not been able to find it so far. Thanks wolf
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
If you go to Mercedes and get a new cable, it will be the same length as the one you have. You need to replace the inner cable with a new one 1/4" longer. Got a speedo repair shop near you? If yes, go there and have them make you a new one out of speedo cable longer than yours. Common problem on the early 126's.

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Sorry to post on top. You mean just have a speedometer cable made that is longer ( 1/4 in.) than the one in there now? Seems like a very simple elegant solution. Are all the cable supposed to be the same length i.e..) 390mm or is the middle one longer or is mine just stretched? wolf

the
cable. I

glue
and
sure
basically
metal
the
cause
but
wired
instead
solution.
?
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
That's an easy fix... You don't need to buy anything... Just cut the outside sheething 1/4" to 1/2" shorter and put it back together... I forget the length... the answer is hot deep the slot where the cable has to go in.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

outside
Tiger I have seen that suggestion from you on my GOGGLE search and I would like to explore that with you some more if I may. The construction of the outside sheeting ends in metal that has a shoulder that buts up against the motor/gear mechanism at both ends. The shoulder and length of the terminal piece of metal hold it in the correct position. If you make it shorter will it not be able to push back more easily? It seems to me if you make that shoulder shorter you will create more room for the entire device to slip backwards i.e..) out of the socket of the gear or motor. The suggestion to get a longer inner cable seems to make more sense to me because it will force the cable to stay in place and not be able to jump out of its mooring. Let me know what you think. wolf
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Alright... let's get our terminology correct...
First, there is a drive cable... that metal inner cable that motor uses to move the seat...
Then there is outer cover sheathing...
By cutting the outer cover sheathing shorter, you are making the inner drive cable 'longer' that will insert deaper into the motor drive.
The problem with 'whirring' motor is that the inner drive cable is not catching the motor drive. So by shortening the outer sheathing, you are making it easier to keep the inner drive cable in contact with the motor.
With the motor installed and clamped in place, it is unlikely that the inner drive cable will jump out as it is pretty much held in by tension. It has been a long time since I done this... I did it right after I bought the car back in '93 and never had to touch the cable to date.
As I said before, it is pretty common occurance on W126. I think what happened is the grease somehow affected the outer sheathing... causing it to swell a bit at the connection or causing it to slip out just a bit that the inner drive cable became too 'short' even though the actual length has not changed.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

drive
inner
car
to
the
Thank you for your posting. I think we are using the same terminology. The basic concept of making the inner metal "speedometer" type cable longer relative to the black plastic sheathing sleeve (which is terminated with metal hubs) that is outside is in fact the goal. You are correct in that you can make that happen in two ways . 1.) get a slightly longer inner cable or 2.) make the sheathing cover shorter. . The problem I see with making the sheathing shorter is that it is terminated with metal bubs that are a specific length to fit into the motor or gear housing. It has a ridge (shoulder) that helps lock it in place. If you make the metal termination end shorter it will allow to and from movement of the sheathing cable. I fear that will only aggravate the problem of letting the inner cable jump out of its mooring. Thanks wolf

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
I have never had any luck trying to shorten the outer casing. That is why I recommended the speedo cable replacement. 10mm longer is fine. If yours measures 390, then get one made to 400. Any good speedo repair shop has bulk cable and the anvil to make square ends.

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

The construction of the

the
will
Hi Wolfgang
The speedo maker's cables are often of inferior quality and may not last too long if cheaply done. The cutting of the metal sleeves at the end of the outer cable is still IMO the best option - especially as you can still use your existing inners.
You are correct in assuming that the cut sleeve can slip back against the small locating shoulder in the housing but this is easily fixed by adding small worm-drive hose clamps around the outside to keep the sleeve tightly further in. In fact, if you accidentally cut too much from the sleeve, the clamp can be used to adjust the outer position for best operation.
BTW you may only need to reduce the length of one sleeve at one end. I cut mine back about 3/16" at one end, added the hose clamp and it has worked fine for 2 years now. Reducing the length at the 'working' end also left the driving end as original for location in the motor.
Don
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

too
the
cut
I am going to go with the advice of my local speedometer shop (says he sees this all the time with MB and BMW... they both use the Bosch motor and gears. This is a Bosch maldesign problem IMHO!) first and get a longer cable. If that fails then I will cut the sleeve shorter. Thanks wolf
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Got the longer cable ,put it in , worked like a charm (so far) Thanks to all who replied. wolf1
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

the
See: http://interior.articles.mbz.org/seats/126seats /
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
No need to remove the seat from car... just raise it up with the seat control as high as you can and you have full access to the motors.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Thanks for the reference. I had seen that site. My cable has been "chewed" up from being out of the socket and the motor turning. The length is supposed to be 390mm mine was down to about 285mm and the end was bent. I should have a 400mm new cable by noon today. Thanks wolf1
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Related Threads

Motorsforum.com is a website by car enthusiasts for car enthusiasts. It is not affiliated with any of the car or spare part manufacturers or car dealers discussed here. All logos and trade names are the property of their respective owners.