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1983 300D Turbo
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120 Posts
Discussion Starter #1
I had a problem with severely late and painful shifts.
I noticed that the Bowden cable was adjusted all the way in yet still needed to be pulled to hook it up to the linkage.
I tried disconnecting the cable and got the opposite effect; she shifts through all gears to the point where I'm in 4th by the time I hit around 30MPH even when I step on it.
Diagnosis:
I have 2 extreme conditions and need to set the cable length between the 2 settings.
As near as I can tell the only adjustment is at the valve cover.
So I need to trace it back to its source to see if it's snagged somewhere and possibly replace the cable. (Previous owner's repair & maintenance abilities are questionable.)
My problem is I haven't been able to get info on what it's supposed to look like and what is it attached to at the other end.
 

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1983 300D Turbo!!!!
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19 Posts
Hey I have a similar issue I replaced the Transmission vacuum valve levers which attach to the Bowden cable. After doing this replacement it solved my shifting problems check out this site Transmisson Vacuum Valve Lever Replacement
The replacement is like night and day compared to the hard shifting I was experiencing in every gear . Now however it has caused a hard down shifting issue I can hear my trans clunk @ every stop light. I have adjusted the bowden cable and cannot find the sweet spot!!!! driving me crazy
To answer your question on were the bowden cable ends. My understanding is that it ends at the vaccum modulator valve but I could be wrong as Im only listening to my mechanic.
 

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1983 300D Turbo
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120 Posts
Discussion Starter #3
I did that repair to.

next I was in the process of checking if the Vaccum Control Valve might be the culprit.
is turn out it was sending a zero vaccum to the modulator as soon as I touched the pedal & that's cause the bowden cable had that whole linkage too advanced.

so now I need to either find a was to "stretch" the cable or get a new one & drop it in.

Lift-time is at a premium for me as I impose on a friend who has a shop + he's in a town about an hour away from me. That's why I want to get a mental picture of what I'll be up against.

So here's the question again to all of you who seen the inner & outer workings of our beloved 123s ... What's at the other end of that cable?
 

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300SD
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11,191 Posts
To adjust the firmness of shift, you need to play with the modulator valve. Turning it in clockwise decreases vacuum and makes the shifts firmer. Also, your vacuum source nipple on the main vacuum line that feed the transmission line can be partially blocked like mine was. This causes the vacuum to build up very slowly. As a result, you may experience clunking when downshifting when coasting to a stop at certain times.
 
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