1966 230SL Shifting Characteristics

[Harry]

My 230SL drives so well that I think maybe I'm being picky by asking but I was wondering if others with this car and the automatic transmission could weigh in on the shifting behavior.  My recollection from many years ago with Mercedes automatics (old models, not newer ones) was that the transmission shifts somewhat rough, ie it sort of snaps into the next gear.  Its not smooth and "seamless".  The downshifting behavior is the same.  Coming from 4th to 3rd is relatively seamless.  Coming from 3rd to 2nd usually occurs as you almost come to a stop and is much rougher with a distinctive harder downshift. Maybe it's fine and if so, I have no desire to fix something that isn't broken.  Thoughts?
Harry

[twistedtree]

Compared to American cars of the time, yes, the shifts are much harsher.  But a lot of cars have gotten even harsher over time because the automatics are out of adjustment and/or some of the controls are no longer working.  For example, the 3-position solenoid, which is essentially a gear shifter for the hydraulics that control the transmission, gives three pressure ranges, each of which yields progressively harder and faster shifts. If that solenoid isn't in the right position at the right time, shifts will be harder or softer than intended.

[Via Manci]

I remember asking a similar question a few years ago about feeling as if I was being kicked in the butt every time the 230 shifted.  Don't remember if I got an answer.  But, I had the transmission completely flushed (a bit pricey) but it is now as smooth as my Lexus.

Mike

[Harry]

Only flushed and got those results?  My father was a Mercedes nut growing up and my memory for these cars (automatics) in the 60's was that they were distinctly different than their American counterparts.  The latter always shifted very smoothly whereas the Mercedes' had a characteristic rougher shift.  I even recalled Dad getting a 280SE with the V8 (automatic) and I was so impressed with how much smoother it shifted than the earlier cars.  So I'm really surprised that your 230 shifts as smoothly as a Lexus.  I did recently change the fluid and filter in the 230 but only because the car is new to me and it was part of the fluids change I went through to freshen everything up.  It didn't really affect the shifting behavior - that I could tell.  Who did the flushing for you?  A Mercedes dealer?  (Thanks)

[Via Manci]

The flushing was done by a local garage.  It must have been pretty thorough because it cost $250.00. It worked.  Just think of all the things that must have accumulated over 40 years in that system.

[glenn]

Harry, Twistedtree refers to the solenoid on top of the tranny.  This is tied into the throttle micro s/w, vacuum, modulator, etc.  We (The Forum, etc) have yet to define how this is wired and how it's s'posed to work.   But, you're on the right track......
If your's shifts smoothly, be happy....

[stickandrudderman]

The solenoid on the transmission, via a mechanical rod, reduces modulating pressure in the transmission when the throttle is closed and drive or reverse is selected. This enables a relatively soft shift when engaging either forward or reverse from the nuetral position. As soon as you touch the accelerator the throttle switch is opened and circuit to solenoid is broken. Modulating pressure is switched from "basic" to "control" pressure which is much higher (around 7 bar IIRC).

[twistedtree]

The solenoid on the transmission, via a mechanical rod, reduces modulating pressure in the transmission when the throttle is closed and drive or reverse is selected. This enables a relatively soft shift when engaging either forward or reverse from the nuetral position. As soon as you touch the accelerator the throttle switch is opened and circuit to solenoid is broken. Modulating pressure is switched from "basic" to "control" pressure which is much higher (around 7 bar IIRC).

Right, and when you put the peddle to the metal and the kick-down switch closes, the solenoid changes position once again (the third position) and modulator pressure goes up to around 60 PSI.  These different pressure ranges (about 10, 30, and 60 PSI if memory serves me) control how fast and hard the shifts are, and are the "gears shifter for the hydraulics" I was referring to in my earlier post.

[glenn]

Ah, yes.  Let's get this in the form of a good 'German' exact description and wiring diagram document with pictures, etc.  I've a 230SL tranny to install and want it 'right' the first time(operation, wiring, etc).