I replaced the trans in my 82 300D with anexcellent trans from a rusted 300SD I had. Changed the rear housing and spedo pick up along with filter and Mobile synthetic fluid.

Initial start up was good with some harsh early shifts. I drove it around the neighborhood 4-5 different times tweaking shift pionts until all was perfect.

I took it on the first road trip +/- 80 miles on turnpike with 5-10 miles around town that day starting and stopping several different places, all was well. I went to leave at the end of the day and when i started it it immediately began short shifting. 1-2 in 20 feet, in 4th in 100 feet.
I had to manual shift all the way home. Manual shifts are crisp, and in 4th on turnpike worked flawless.

Checked the following:
1) vaccum from pump 15" at idle 20"+ at throttle
2) modulator holds vacuum at least 30 min
3) proportioning valve on IP to modulator, 10" at idle, drops to 0" at throttle
4) adjusted shift cable to extremes with no change

the only thing I can think of is something changed or stuck from when I shut it off and then started again

Any ideas out there? where should I start looking?

Thanks

If your shift timing is that far off after adjustment I would guess your bowden cable needs to be replaced/repaired etc. I dont think vacuum problems can cause that type of shift timing error...

Disconnect the vacuum from the modulator temporarily, does that change anything? it will shift very hard, but does the timing change or improve?

Hopefully more qualified folk will respond.

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'85 300D, 'Lance',250k, ... winter beater (100k on franken-Frybrid 3 Valve Kit)
'82 300D, 'Tex', 228k body / 170k engine ... summer car
'83 300TD Cali Wagon 210k, wife's car

not necessarily more qualified but this is the same problem that member muleears complained of just the other day. service manual says bowden, valve body or governor.

check bowden operation first and make sure it's still attached to the actuator linkage on the valve body.

disconnecting the vacuum is a very bad idea indeed, not only will it make shifts very hard but it can ruin the transmission...I know from personal experience .

__________________
1982 300TD 210K miles ("The Replacement" aka "The Anvil") - SOLD
1979 300SD 245K miles (never ending project)
2007 Pinarello F3:13
1995 Ducati 916 (SOLD, sniff)
1999 Ducati 900SSie (SOLD)

really? i have been told by a reputable source that the transmission likes to shift hard, and that the softening of the shift is a creature comfort.

what about all the folks drvng around with vac leaks and hard shifts?

__________________
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'85 300D, 'Lance',250k, ... winter beater (100k on franken-Frybrid 3 Valve Kit)
'82 300D, 'Tex', 228k body / 170k engine ... summer car
'83 300TD Cali Wagon 210k, wife's car

The first thing I checked was the cable. Pulled it off the ball socket and made sure it was at the "0" slack point. Pulled the cable and could feel the resistance of the valve. At least it felt the exact same as when I did the inital adjustments.

What else could stick or come loose to cause it to go from shifting perfect to drastic short shifts in one shutdown to next start?

I did crawl under to make sure all of the wires and lines were tight and still connected.

I read muleears thread and the cable/valve seems to be the only thing that makes sense. I will check this further tonight.

If there is anything else you can think of I would appreciate it.

Thanks

I would guess vac leaks are better than no vac at all. When I say violent I mean REAL hard shifting. Ended up exploding the springs on the pressure plate on the main pump which resulted in no more reverse gear. This was on a 603 engine and late 722.3xx variant..maybe the older ones are more forgiving.

__________________
1982 300TD 210K miles ("The Replacement" aka "The Anvil") - SOLD
1979 300SD 245K miles (never ending project)
2007 Pinarello F3:13
1995 Ducati 916 (SOLD, sniff)
1999 Ducati 900SSie (SOLD)

OK the cable is attached and actuating the valve. I plugged the vaccum line to the modulator and it made no difference in the shifts. I stopprd on a steep hill and started out and it still shifted 1234 and lugged in 4th.

It will not kick down with the foot switch, What would be the symptoms if the kick down solenoid was stuck?

Is there any way to check anything else without dropping the pan? and even if I drop the pan what should I be lookin for?

Solenoid problems usually prevent upshifts (by continuous keeping it downshifted).

Back to the start. Warm the car up real good, park it on level ground an check the fluid level..check it for discoloration or foul smell (I doubt there will be since you haven't experience flaring AFAIK).

The only other thing I can think is the rear cover change which I believe covers the shaft and the governor linkage. as you probably saw from muleears thread a faulty governor will cause short shifting too. As I understand the hydraulics, the governor could allow too much pressure input into the valve body which will open up other "logic paths" and thus force the transmission to upshift.

There is a way to test governor pressure but no explanation that I've seen of how by a DIY'er.

As I offered muleears send me a PM with e-mail and I'll send you the better of the two diag manuals that I have.

You can remove the governor on the vehicle but it's more complicated than pulling the pan..quite honestly I don't even know what you could look for in the pan other than foreign debris.

As you've already done all the other work I have no doubt in your competence to play with the rest .

The valve body, well some have gone there, few have come back.

__________________
1982 300TD 210K miles ("The Replacement" aka "The Anvil") - SOLD
1979 300SD 245K miles (never ending project)
2007 Pinarello F3:13
1995 Ducati 916 (SOLD, sniff)
1999 Ducati 900SSie (SOLD)

I pulled the governor cover and it is engaged to the gear and the weights are free. Rocked the driveshaft back and forth and the governor move with it.

Pulled the pan, found no debris and visually observed the bowden cable actuating the valve internally.

I am out of options.

Drove it 5 miles starting in L and it shifts to second in 20 feet, I then shift manually through the rest of the gears fine. This is a good trans, what do I do?

1) buy a valve body and hope?
2) drive it and hope whatever stuck frees up or it blows up and answers my next question?
3) get a rebuilt trans because the rest of the car is cherry?

if it was me I'd go for the new valve body. if the rest of the transmission shifts fine then there's no point in throwing out a perfectly good set of gears and clutches. Not to mention that this could very well be the culprit (check valves blown out or something).

While your governor 'test' is not conclusive there's not a whole lot to go wrong there either and if it's engaged then not much more to be said..if it wasn't I reckon it would have been fried anyway.

haven't seen any VB prices but heard in the region of $200-$300..and I know a tranny is going be around $1300 so the math seems pretty simple .

__________________
1982 300TD 210K miles ("The Replacement" aka "The Anvil") - SOLD
1979 300SD 245K miles (never ending project)
2007 Pinarello F3:13
1995 Ducati 916 (SOLD, sniff)
1999 Ducati 900SSie (SOLD)

Perhaps the valve body from your bad transmission could be taken apart and cleaned for a trial substitute. Or just a straight replacement.
Might be interesting and the old body will probably go to the salvage yard otherwise. Some clue about it's general condition might be gained from a knowledge of what was wrong with that old transmission to start with. If it was the kind of problem that was not valve body related you just might prevail.

I was chasing a 2-3 falir for 100k on the old trans. I would adjust the vaccuum every six months to try and minimize. Just got tired of adjusting and finally got around to swapping this "good" trans LOL.

Just rationalizing, if I spend $300 to chase a ghost or bite the bullit and have a rebuilt trans.

Thaks for the help