Long shift

[Chsmadden]

I drive a 1973 450 SL and it takes a long time to shift. It takes forever to get out of 1st and then when does it kicks you in the seat of your pants(really hard).
Now I love that car but the shift is a real shocker.

[Skippy]

Sounds like lack of vacuum to the modulator, or a problem with the modulator itself. The modulator is on the right side of the tranny, toward the back. It should have a line attached to it, running up to the intake manifold. Check to see if this line is disconnected or broken. If that checks out, it's a good idea to check the vacuum signal at the modulator end using a gauge.

A search will turn up LOTS of further information.

[250 Coupe]

There is a link to the transmission at the rear of the engine. It lets the transmission know the throttle position. It needs to be correctly adjusted or it will shift at odd times. There was a rather good discussion about it sometime in the last month, either here or on w116.org

Try here,
or here,

Michael

[berfinroy]

Assuming you have the proper degree of vacuum delivered to the shift modulator, the modulator itself is adjustable, and will affect shift timing and "quality," which means how sharply the upshift takes place. If you look down the throat of the transmission side of the modulator you will see an allen head screw. That's how the modulator is adjusted. It's a "trial and error" thing, but as I recall counter clockwise will sharpen and extend the shift points, and vica versa. Do not turn more than one full turn for each "trial."

There is also a small and fairly accessible gasket inside the transmission that is prone to failure over time and messes up the hydraulic pressure signals to the shifting mechanism. I had this happen on a 6.9 I owned (same basic design), and a savy mechanic made the proper diagnosis and repair.