85 300TD 3-4 transmission flaring

[tomas_maly]

I replaced both the K1 and K2 spring kit recently on my 300TD and 95% of the 2-3 shift flaring is gone but the 3-4 shift flaring is NOT. It's actually gotten worse.

I notice that when there is less overall transmission pressure (from holding the pedal down less and thus the bowden cable not pulled as much), the flaring is not as severe, but still really awful (spikes probably 500+ rpm more before coming back down). It seems in the last few days to have gotten worse, even to the point where it would stay flared until I let off the pedal. I adjusted the bowden cable all the way closed (screwed in, toward the valve cover) and it helped a little bit, but not much.

I tried adjusting the vacuum modulator and wasn't sure if I did that right, because with 1/4 turn counterclockwise I didn't notice any changes (except perhaps a slight firmness to 1-2 shifting, which may have been my imagination). What I did was remove the cover from the modulator and then turned the T-key 1/4 counterclockwise. I felt it clicking as I was moving it, so I figured it was doing something. Is this right? I'm not sure if I was supposed to push the T in or pull it out before turning, but I tried it with it fully in place.

I then yanked out the vacuum line to the modulator, entirely, and drove the car around, noticing that it shifted probably 50% better in 3-4. But still noticeable flaring.

I put in 1/2 quart of Trans-X and didn't really notice anything. I've read that it may take 2 quarts to show any results.

I was also wondering if having the transmission overfilled (maybe 1 inch on the dipstick) would cause any of these problems and if I should lower the level.

The vacuum isn't even a part of the shifting at this point and it still flares. Are there any other external adjustments? Or are we looking at a transmission overhaul/replacement? I have noticed that when I've changed the transmission fluid (even when within 5-10,000 miles of each other) that it smells quite burned.

What are my next steps? At this point, the vacuum is not part of the equation anymore.

Are there any transmission troubleshooting/repair manuals for this particular transmission? I think it's a 722.315 or 722.355 . I've seen manuals for later models, but not the 80's diesels.