Alright, I've got an 82 240D 150k miles. The trans sifting is completely controlled by vacuum through the 3/2 valves on the valve cover, modulator, and vcv.

I have finally sorted out all the leaks in the system and adjusted the VCV to where i think i have normal shifts. Basically the 1-2 2-3 shifts are quick and firm but not harsh. 3-4 on the other hand is slow, especially when cold. I do not perceive a flare, and once the car is fully warmed up on a warm day after a 25 mile drive the shift into 4th gets firmer and quicker.

Ironically the more my foot is into the gas pedal the firmer the 3-4 shift is making me believe its getting too much vacuum on low speed shifts and sliding into 4th.

If i tweak the VCV anymore I get too hard of shifts on all other gears.

Trans fluid is very low appearing when measured when the trans is cold. Once it is at normal operating temp the fluid is right below the max line on the dip stick. I believe this is the proper way to check the fluid as per the FSM.

Anyone have any thoughts? While it doesn't flare Im worried that the shift is soft enough to wear the clutches out? I'm also thinking the best way to fine tune the vacuum system may be to get some more restrictors, perhaps the one I have is in-correct.

A guru I'm not but I did manage to get mine running and shifting quite nicely but it didn't start out that way! Included what worked for me from a previous post I made:

Hopefully you have a mityvac- without one it makes the job harder if not impossible. It sounds like you have a vacuum leak somewhere in the system. If you just check the vac line that runs to the tranny, ideally it should have 12" of vac on the mityvac guage, if its like 3-4" you get flaring, high rev shifting and a frustrating ride. When tuned right, half throttle should give you nice shifts at an easy pace. If you step on the pedal, you should get higher revs in second and third before it goes into fourth, it will noticably get up and go (as best it can) at full throttle.

Problem is, you kind of have to get vac system normalized by ensuring no leaks to then start checking vac to the modulator, 3/2 valves on the valve cover etc. Each bit of the vac system, locks, vac reservoir, ignition cut off, are consuming vacuum and if they are leaking vacuum your vac pump is working harder and stuff like the tranny is negatively affected because it isnt getting the vac it should. As much as it is a pita, you have to get familiar with the lines, where they go and what they do, the link in the prev. post has the diagrams. I started by just looking at the vac lines/hoses and replacing what was tired and crackled or spongy with new rubber hose.

Assuming you have a good 12" of vac going to the tranny, you finally have to look at the linkage on the vcv to ensure it only leaks out almost all the vac at full throttle. The cheap and cheerful method of testing that is to suck on the vcv supply line (engine off) and reach over and move the throttle linkage manually and as you just get to full throttle you can sense the leak down. On the side of the vcv you can adjust the linkage on the vcv from the throttle to achieve that effect.

Cleaned up previous post cut/paste issue, oops!