[W126 Coupe] Getting my 560SC to shift gears earlier?

[Dick Spellman]

Hi David,

You need to adjust the control linkage between the throttle cable and 
the transmission.  The control linkage for the transmission shift point 
is a steel rod running vertically down your firewall.  It connects on 
one end to the throttle linkage on the intake manifold and on the other 
end to the transmission.  When you depress the gas pedal this linkage 
moves the throttle and this rod to precisely control your rpms while 
holding the shift points on the transmission.

Based on your description, there is too much slack in the rod.  If you 
locate the rod, you will note a nut of either 10 or 13mm that permits 
the rod to be lengthened or shortened.  In your case, you want to 
shorten the rod.  The correct adjustment is outlined in the service 
manual.  There is no harm in your loosening the nut and making an 
incremental adjustment where you make it shorter.  This will get you to 
the correct shift point with one or two tweaks.

Regards,
Dick

On 1/8/2011 9:16 AM, Dawid Loubser wrote:

> Hi All,

>

> After some pretty major work done to my 1990 560SEC (Euro,ASR) 

> including an engine replacement

> (which I am very happy with, as per an earlier message to this list) 

> my only remaining complaint

> is that my car shifts gears too late, making gentle driving 

> uncomfortable.

>

> In "E" mode, under gentle (fuel-efficient!) acceleration, my car used 

> to change gears

> around 2,500RPM or even less, depending on throttle pressure. Of 

> course, in "S" mode,

> it held on for longer, like it's supposed to.

>

> Now, in "E" mode, it changes at 3,000, even 3,500 RPM during gentle 

> driving, which I

> find unfavourable for my daily driving.

>

> Surely there is a reasonably simple adjustment I can make myself to 

> rectify this?

> This behaviour is consistent across all gears, so basically I would 

> like to drop the

> RPM of gear changes by about 1000. Could this be related to the 

> throttle position

> sensor? I say this, because, at about 2,500RPM, if I almost completely 

> release the

> throttle, it does change. I would like this behaviour with moderate 

> throttle applied in

> "E" mode, like it was.

>

> For performance driving, the car is a beast (great). In "S" mode - and 

> flooring it -

> changes are very positive and close to the RPM limit.

>

> Any help appreciated to restore what used to be a wonderfully balanced 

> character to

> my gear changes! I don't feel like taking it back to the shop unless I 

> can help it,

> I'd rather understand the mechanism myself.

>

> I adjusted my throttle linkage to remove quite a bit of play (in an 

> attempt to cure

> this problem) but, despite being *much* happier with the lack of play 

> now, shifting

> characteristics have not changed at all.

>

> kind regards,

> Dawid

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