you can shed some light on my issue too.

my car is supposed to shift at 5400 rpm at full accelerator when the bowden cable is correctly setup, The throttle linkage and bowden cable are setup perfectly like the FSM tells to do.

The trans shifts up at 4500 rpm, with a firm purposeful aggression but glides into gears at low pedal and low rpms. Ive held the transmission in 2 to wind it up to 5200 or 5400 rpm and then shifted to 3 which caused a very hard shift. vacuum issue? or linkage setup incorrect? Ive also been told that engine torque also plays a role in this, cryptic.

any ideas?

__________________
2012 BMW X5 (Beef + Granite suspension model)

1995 E300D - The original humming machine (consumed by Flood 2017)
2000 E320 - The evolution (consumed by flood 2017)

Another point to watch that affects gear changes is fuel filters ,partially blocked filters will give odd gear changes at higher rpm's.

Those of you on here who have suffered a filter that is blocking and the 'lurch' as the engine cannot rev any more past a set point will have been familiar with odd gear changes and erratic gear box behavior that occurred at the time will understand the point I am trying to get across.

This 'oddness' only occurs for a couple of days before you eventually figure out the filters are plugging up ,but it does affect shift point and slurs them etc

Hi-
This is regarding my 1983 300DT. I've done tons of research on this complex vacuum system over the years. Yes, I said vacuum since it does relate to shifting (& locking, stopping engine, climate control). There are, as I understand it, three things that affect transmission shifting that must be set correctly BEFORE Bowden cable comes into play.

1. Trans. case pressure (adjusted by modulator on side of trans.)
2. Correct amount of Vacuum pulling against that trans. pressure (controlled by Vacuum Control Valve on top of Injection Pump)
3. Correct Linkage adjustments (Throttle & Rod at rear of VCV)

As a Mercedes Tech put it: The Bowden Cable opposes the action of the governor (on the trans.) and changes the point of the shift. The basic adjustment on all these transmissions is for the cable to be attached 'free of play' at the point of initial throttle take up. In practice, the shift point can be altered to achieve some measure of control during certain flaring conditions. As such, it can affect downshifting when throttling harder on acceleration.
Above all- be sure to find the specs. for your year/model car as they are somewhat different.
Hope that helps. As I understand it!
Enjoy!
Chris

Last night I tightened up my Bowden Cable a bunch. Like 10 turns, and shift pattern was better. More interestingly, the flare was reduced on 2/3 and 1/2 was a slam. Once it was warm it became better all around. I have plugged all vaccum lines but those of absolute need, and checked pressure, all good. So, at least in my case, the cable adjustment did have an effect on hard shifts and flares.

The cable adjustment only affects the quality of the shift indirectly.

Each time you adjust the cable, you change the shift point. Depending on your driving style, your pedal position also changes as you approach the new shift points. Each time the pedal position changes, the vacuum to the modulator changes and the shift quality varies.

You are making the conclusion that the Bowden cable affected the shift quality, when, in reality, the driver's right foot is changing the shift quality.

There is no possibility of doing a proper back to back comparison due to the affect of one variable on the other.

True enough. You could play around a little bit by completing removing the vacuum line to the transmission and then messing with the bowden cable. Or, you could bypass the VCV, put full vacuum to the transmission and also mess with the bowden cable. I've tried the first but not the second.

__________________
1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

There is no switch in the 84 300SD under the pedal and the switch is unplugged in my 84 300D.
Down shifts forced by the Bowden cable are smoother than from the electric switch under the throttle pedal.
With the cable set properly and the throttle switch working I some time will get a double down shift and very high revs. Not good for the timing chain.

__________________
1984 300SD turbo 126
"My true love"

God made me an atheist and who am I to question His wisdom

There should be a switch. The kickdown should get you an extra gear compared to the cable... IE going 40 mph in 4th, press the pedal and it goes to 3rd, hit the kickdown and you get 2nd.

-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.

Not wishing to split hairs, but I want to clarify in case people take info in this thread out of context....

Unless I am mistaken, vacuum-only-control transmissions (some cars in the approx. '78 - '81 model year range) that have no bowden cable or throttle/Bowden rod going to the transmission DO rely on proper vacuum and modulator settings for shift settings.

__________________


Mac
2002 e320 4matic estate│1985 300d│1980 300td
Previous: 1979 & 1982 & 1983 300sd │ 1982 240d

“Let's take a drive into the middle of nowhere with a packet of Marlboro lights and talk about our lives.” ― Joseph Heller, Catch-22

Dropping to 2nd gear at 40 mph will really wind the the revs up and why would I want to be in 2nd gear at that speed, what circumstance.
If there is a kick down switch on an 84 SD it is very well hidden.

__________________
1984 300SD turbo 126
"My true love"

God made me an atheist and who am I to question His wisdom

I assure you there was one. It may have been removed by a prior owner.

-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.

Compu_85. You are right. I looked again for the kick down switch and the under the second floor mat is the switch, unplugged. I get my single downshift from the correct positioning of the Bowden cable.

__________________
1984 300SD turbo 126
"My true love"

God made me an atheist and who am I to question His wisdom