108 Auto Trans Down Shift workings 1968 Mercedes 250 S

[aluminum]

1968 Mercedes 250 S 89 K Miles 4 Speed Auto Trans Question
I got it Running and .....
Anyone know just what's the normal operation of these Automatic Transmission's Shifting ? I just got this one going and am not up on how the Automatics should shift ?
Transmission seems to Work in that it does not slip / leak / make strange noises or the like . Is a 4 speed Auto Trans / Floor Shifter with 2/3/4/N/R and Park.
Starting out in 4 which I assume is basily Drive ? The transmission seems to work just fine except for hanging in Gear a Tad when cold and goes through all the gears just fine .
However the Transmission does not downshift when You floor the Gas unless you slow way way down . What I mean is there seems to be no passing gear .
However if you shift into 3RD to downshift it works just fine

So MY Question ?
Is this the normal Operation of this year Transmission >
You must Manually Shift to 3RD as a Passing gear ?
I see no pressure Linkage to adjust ? But rather a Metal Vacuum Tube that runs from intake Manifold to Transmission.
I bought the Car Not running with a Cracked Head on a Very Low Mileage Rebuilt Motor and replaced the Head with a 1966 Head but used all the 1968 Valve train Guides / Cam / Cam Towers and all . Of course I rebuilt the entire head and it runs Perfect now . Just wondering about how these Things should Downshift ?
Thanks anyone knowing

[rumb]

There is a kickdown switch under the gas pedal. - and a fuse for it. Beside that there are instances where if you have the right engine load, speed and gear that it will downshift on it's own without pressing the pedal to the floor, but in my experience you seldom see that happen unless you really slow down.

There is also a vacuum modulator.

Check this thread out:
W108 transmission shifting late

If you dont know the history of your car then a trans fluid and filter change is in order.

[aluminum]

Great Info Thank You Rumb
So where is this Fuse I bet that's it ?

And the vacuum modulator is down on the Transmission ?
Is it fed vacuum by that Metal vacuum line that comes from the Intake Manifold ?

Sounds like the Switch most likely the fuse or ? Humm

Thank You I was scratching my Head thinking it must have a kick down switch
but am used to seeing pressure Linkage Type controls rather than an Electric Set up .

[aluminum]

[QUOTE=rumb;4195316]There is a kickdown switch under the gas pedal. - and a fuse for it. Beside that there are instances where if you have the right engine load, speed and gear that it will downshift on it's own without pressing the pedal to the floor, but in my experience you seldom see that happen unless you really slow down.

There is also a vacuum modulator.

Check this thread out:
W108 transmission shifting late

Checked out your link and it says Fuse is in fuse Box : humm Out of town for a week + but will check the fuse box under the dash when I get back . I know there are fuses under the hood as well and other places . I should be able to check for power at the switch ( under gas Pedal ) . Perhaps I might be able to run power to it as a test . These Cars are mostly simple but you need to know the often tricky ways of working on them.

[aluminum]

Got it Fixed
Cleaned all the fuses I could find on the Car ( none blown ) Checked for Trans Fuse in fuse box none found labeled as such > Cleaned all fuses >
Checked for power at Gas pedal Kickdown and had power in and after working the Switch several times from inside direct with a stick it started working > Test drove and it now works but needs adjustment as you must hit it Very Hard to hard so need to move it
Closer a turn or so