Asking for transmission shifting advice

[mikeyfev1]

My 1986 300SDL is exhibiting the following shifting issues:

I depress the accelerator slowly from a stop. I get a hard shift at 13 mph and again at 17 mph. Then I am able to hold the RPMs at 2000 and the car will accelerate from 18 mph to 45 mph. There are no further shifts.

I inspected the Bowden cable and found an excessive amount of slack, so I turned the adjusting nut counter-clockwise several turns (at least 8-10) and now the 2 shifts occur at 17mph and 20 mph. There is still quite a bit of slack in the cable.

So I have 3 questions:

1. Doesn't this car have a 4-speed automatic transmission? Why does it only shift twice?
2. Why are the shift points so low? Is turning the Bowden cable adjustment nut the correct solution for this problem?
3. Does the fact that the car can operate from 20 to 45 mph always at 2000RPM mean that the transmission is slipping?

[SD Blue]

I was having all kinds of strange shifting problems and one of the items I found was a sticking kick-down switch. The carpet had shifted slightly and some of the fibers had got in the works. You may be able to clean it with brake cleaner and get it to function properly.

For test purposes, try disconnecting the switch connector and take it for a test drive.

[mannys9130]

It is a 4 speed auto.

With the car off, push the pedal as far as you can. Do you feel and hear a click under the pedal? That's the lockdown switch. It should click. Take the car for a drive. First, put the shifter in the lowest position and then return it to D. When you take off, you will have 3 shifts equaling 4 forward gears. Next, come to a complete stop again. Push the pedal all the way to the floor and click the kickdown switch. The car should hesitate forca split second while you feel thectrans shift into 1st gear and then take off. Again, you should count 3 shifts (after the initial kick down into 1st) for 4 forward gears. If you take off lightly, you'll only get 2 shifts due to the 2nd gear start.

Try those things and see what your results are.

[babymog]

I do not believe that the '86 SDL has a 2nd gear start, not aware of any 603 cars that do.

[Ceristimo]

There should be no slack in the bowden cable. It should be tight against the resting position.
If there's slack, that means that the transmission "thinks" you are barely pressing the fuel pedal (diesel's don't have a throttle ) and so it will shift up very early.
If the cable is too tight, it'll think you're pressing the fuel pedal far down, and so it will shift late.
It should have no slack, but also not be pulling when it's in resting position.

[tyl604]

If it was previously running well, what could have happened to affect the Bowden cable?

Perhaps we need a bit more history.

[123mike]

Wow Mannys. You know smart things! I got the clunk too. I pulled carpet , there is a switch under the pedal . I don't even know if it's hooked up. Thanks.

[sixto]

If there's slack in the Bowden cable, it will start in first from a fresh engine start but it might not downshift to first from moving. Pop the Bowden cable socket from the throttle linkage and undo the accordion boot. Does the spring back on its own like it's properly connected on the transmission end or does it stay in position when you let go?

Sixto
83 300SD