Automatic Transmission Slipping

[Joel Podkaminer]

Not sure how to post on this forum because this is my first day at it
My 69 280sl is slipping regularly at this point.
Thought of draining some fluid and putting in some treatment as a first step.
Any better suggestions....also is it a common transmission that is repairable in the US?

[ja17]

There is a three position solenoid on the top of the transmission which operates linkage to change the modulator pressure. It changes the pressure depending on the position of the engine accelerator linkage. You need to make sure this is working. If the linkage is stuck in the rearmost position the modulator pressure will remain low causing slipping. Check the fuse to the "Automatic Transmission" also. You can remove an access cover on the interior tunnel (right side) to view the transmission linkage. Make sure it can be moved rearward, and forward with the ignition off. With the ignition on and the accelerator at rest, the linkage should move to the rear position. Once the accelerator is slightly depressed the linkage should move to the middle position. Forward position only happens when the accelerator is fully depressed and the kick-down switch on the floor is activated (passing gear).

[Joel Podkaminer]

Joe,
thanks for the reply and info.....
Car is still in my basement behind my TR6  waiting for spring, and the salt to be washed off the roads.
I will check these things when I can drive it a bit. Last fall I was able to get it to go thru the gears when just warmin up, then would find it slipping even once out on the road, so I don't suspect the fuse, though I'll check. What do you think of lucas transmission treatment draining it down a bit.... as an option if I am not successful with solenoid....just asking your point of view.
It's a great car otherwise. Papyrus white with only pagoda top.Blue interior.  I have no ragtop nor frame for it, though at my age, and before all our savings are eaten up by the market, I'd like to get my hands on one....any ideas in the North east or Central USA 
thanks again

[ja17]

Hello Joel,

I don't think I would use any additives. I would check all the mechanicals (fuses, solenoids and linkages). Next I would do a full fluid change (including draining the converter). Change the filter also and check and torque the bolts on the transmission valve body while the filter is out. Afterwards, if you are still having trouble, try to do a pressure check on the transmission modulator pressure. Pay attention to any significant debris or parts in the transmission pan when it is off.

Soft top frames are a premium. Some originals frames have been badly damaged. Many owners with factory coupes have sourced most of the spare frames over the years. Good used ones are scarce. Occasionally one will appear on this forum. If yours was a factory coupe you may be missing a lot of other parts and sheet metal work. Some cars had the "soft top delete" option and are just missing the frame and canvass. In this case the metal hatch cover, the top well and all the hardware are present.