New Member Shift Transmission

[cynewan]

  Hi guys,
i'm new to this forum, and i just acquired a 1970 280 sl. I am still learning about this car. The car drives fine and idles at the recommended level. Anyway my issue is with the shifter / transmission. Anytime i move it from park into any of the gears, i feel a movement in the car (jerklike)....the shift is not very smooth at all. Is this normal, or does this have anything to do with the modulator. I inspected the drive shaft and there is no play ,the flex disc,is also in very good condition . If this has to do with a vacuum leak  can someone tell me which ones to check. Thank you in advance for your suggestions.

[ja17]

Hello,

The inputs for your automatic transmission are engine vacuum, linkage position, and engine rpms.

There is an electrical switch on the intake linkage which moves a three position solenoid on the transmission. The solenoid moves a linkage rod which changes the modulator pressure in the transmission. The solenoid and/or the linkage rod get rusted and stick.  The switch on the intake does not work properly if the linkage is not correctly adjusted. These conditions will cause the tranmission to shift poorly, harshly and irratically.

You may want to go through the "linkage tour" and then remove the cover on the inside of the car on the right side of the transmission tunnel to make sure the three position solenoid and the linkage rod are working correctly first.

Let us know what you find.

[Kayvan]

Check the "shifter linkage bushings";they wear out and create lunging or jerky engagements.

These are a few dollars and are changed in linkage assembly.

Be careful as sometimes with enought wear, these bushings prevent the shift lever form seating in PARK and the car can roll on an incline when parked.

It happened to me, even with parking brake on.