I have a '90 300D 2.5L Turbo w124. Nice car. I got it about 6 months ago.

I've been following the various suggestions on this board and performed the wastegate swap. In a posting, I think from gsxr, I also saw the removal of the vacuum amplifier, affectionately referred to as the Blue Flying Saucer (BFS).

No matter how tight I made the vacuum system, and even after adjusting the VCV and modulator pressure the shifts were to abrupt and jarring on the car.

Before doing the wastegate swap (and removing all 3 vacuum control units on the passenger side) and before removing the BFS the car has very soft shifts and some flaring.

So I have returned the BFS, adjusted it such the set screw is fully retracted, and the shifts are somewhat smoother.

So what might work well for one reader with one model engine/transmission may not do so well in another vehicle.

The BFS has returned!

harsh shifts sounds like you had a vacuum leak.

__________________
John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 190D 2.5Turbo
1987 190D 2.5-5SPEED!!!

1987 300TD
1987 300TD
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!

I know it does but when I put my vacuum gauge on the line to the transmission it's right at spec. I shut off the engine and the vacuum under the hood and at my HVAC dashpots is held for 20 minutes or so.

It use to flair or is it flare when the vacuum solenoids were present and I think when the prior owner had the trans-modulator replaced the mechanic turned the pressure up very high to stop the flaring.

I believe everything under the hood (VCV, vacuum integrity, etc) is at spec. I have misplaced one of the two green restrictors and hope that have that in place tomorrow. Reinstalling the BFS helped.

I know the Bowden cable only influences the location of the shift points but I still think I should slightly shorten the cable. After that I will try to lower the trans-mod pressure by a half turn at most.

That's as far as I can see at the moment.

Boogering by previous owners and their mechanics is the bane of this subsystem. Since this car doesn't have a carburetor, it has a BFS (to add "challenge" to "Pride of Ownership"). Both are packages of compromises held together with spit and baling wire. Like the little girl with the curl, when they work properly they're fine.

__________________

"Buster" in the '95

Our all-Diesel family
1996 E300D (W210) . .338,000 miles Wife's car
2005 E320 CDI . . 113,000 miles My car
Santa Rosa population 176,762 (2022)
Total. . . . . . . . . . . . 627,762
"Oh lord won't you buy me a Mercedes Benz."
-- Janis Joplin, October 1, 1970