'81 300sd - Rear Sag Question
 

Question is simple. I am new to this car and am slowly falling in love with it and want to fix the small issues I have with it. 1st is that rear sag. The car doesn't bottom out and feels smooth so I dont really feel I need to change shocks so what can I do to lose the sag?
Also, while I'm here, does anyone know much about fixing the vacuum issues with the door locks? I also have some transmission gear change smoothness issues. It isn't rough but when she's cold, I need to either be real gentle with her or decrease the amount of fuel she's getting before a shift change so it doesn't seem so sudden or noticeable. Anything I can do about that?
Any help you can give will be greatly appreciated.

Mario

I just redid all the rubber lines vacuum lines on my 81 300sd and made sure they were in the right place. which they werent. It took about an hour to find and fix all the little spots since i was new to it. A mighty vac will help you more than anything. It solved all of my problems... the worst hoses for me was the egr hoses (which i will soon delete my egr) I am pretty sure you can delete the vacuum hoses on top of the valve covers because in 81 these only control the EGR. I did not delete mine just made sure the 3/2 valves flaps were replaced and working.

and the hose that connects the hard vacuum tube from the pump to the transmission. Make sure you get hose that is a direct fit which i believe is in metric size... the stuff at my local auto store was a tad too lose and would not work...

I also dropped the pan and changed the filter which was pretty nasty. all of my issues are now gone... when you are done closing all the leaks you can then adjust the vacuum pump and then the transmission module and bowden cable for a perfect shift.... just read up on the forum of all these issues there are a ton of stuff....

click on the word replies at the main diesel discussion page, and the top or close to the top of the reorganized list will be the thread "transmission vacuum critical" or similar... it's a VERY VERY VERY long thread full of great information...

as for the sag, the dealership has spring pads in varying thicknesses and you can put thinner ones in the front, and thicker ones in the rear... or you can change the springs for stiffer ones. this is assuming you don't have 10 bags of sand in your trunk...

The shocks don't affect the height of the car. The springs do.

Also an aging/dying differential mount can cause the rear end to sag as well.