I have no proof of this theory except on my own cars, but I really think this simple vacuum upgrade can help even out many of the erratic shifting issues on the 722.3 and 722.4 (perhaps others).

This is what you need: (courtesy Locry)



The Vacuum Amplifier (BFD, vacamp) started showing up in '84 models but was supposed to be on everything beginning '85. My '84 190d did not come with one, but I changed that. The improvements were amazing, softer downshifts and better timed upshifts that were evenly applied.

They can be added to both turbo and non-turbo models pretty effortlessly and are easily adjusted for vacuum range. (thanks BC!) They come in black and blue and I do not know the difference b/w colors.

This device will even out the vacuum signal as well as increase it, or decrease it with the proper vacuum signal curve that your trans so desperately wants.

This is not a band-aid fix for a vacuum system that is not up to snuff or a trans that is too far gone or ill-maintained. But it could help if none of those things are attainable in the near future.

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