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#1
02-17-2011, 08:49 PM
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722.3 722.4 Mercedes W123 and earlier Diesel Transmission Shifting Upgrade
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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#2
02-17-2011, 09:02 PM
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Heh, I removed that unit from my car and it made the shifting a lot more predictable.
-J
__________________
1991 350SDL. 230,000 miles (new motor @ 150,000). Blown head gasket  Tesla Model 3. 205,000 miles. Been to 48 states! Past: A fleet of VW TDIs.... including a V10,a Dieselgate Passat, and 2 ECOdiesels. 2014 Cadillac ELR 2013 Fiat 500E.
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#4
02-17-2011, 09:17 PM
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Miles? Unknown. Trans supposedly only had 60k on it, but has lost reverse. 200k on the odometer. The Bowden cable and valve on the injection pump were set up per the service manual.
-J
__________________
1991 350SDL. 230,000 miles (new motor @ 150,000). Blown head gasket Tesla Model 3. 205,000 miles. Been to 48 states! Past: A fleet of VW TDIs.... including a V10,a Dieselgate Passat, and 2 ECOdiesels. 2014 Cadillac ELR 2013 Fiat 500E.
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#5
02-18-2011, 07:36 PM
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I am not familiar with the settings described in the fsm.... what did they say?
Tv / Bowden cable should not make tension until throttle / acceleration begins. Steve Brotherton's article says vacuum range is often lowered to improve shifting in old transmissions. If you lost reverse, do you really think it was decent rebuild or had 60k on it?
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