1986 190d, w201, OM602.911 NA

I looked at my mercedes cd, can't find any information on the transmission and it calls the throttle cable a Bowden cable. No mention of the transmission cable adjustment. Searched the forum. Found two contradicting answers. Apparently I need my cable both looser and tighter.

I want my trans to rev out longer between shifts and downshift sooner when the throttle is pressed. As it is now, the cable to the transmission is taught at WOT, no slack, any tighter and you could strike a tune on it. (it is not under tension, but any tighter and it would be)

I am understanding the cable is adjusted at the transmission? What does the adjustment on the linkage over the valve cover accomplish? Does it change the geometry of the whole setup and therefor how responsive / touchy it is? or is this just a quick way to adjust the bowden cable?

If I hit a hill, I have to manually pull the transmission back a gear, same when accelerating. for the most part, I can only get a downshift with the kickdown switch on the floor but by that time I am at full throttle and then need to back off because I don't need that much acceleration.

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1982 300sd, new project car to restore

It doesn't matter if you know what you're doing, as long as you look like you know what you're doing.

I can't help much with your transmission problem - but I can say that Bowden cable is just a name for a type of cable - it is used in many applications including an accelerator linkage and brakes on a bicycle.

See:-

http://en.wikipedia.org/wiki/Bowden_cable

Anyway back to the transmission:-

I thought that if a Bowden cable is fitted to a transmission it is used to change the severity of the shifting - and vacuum control is used for when to shift. I'm not sure if this is relevant for your car though. It is for my older W123.

Have you gone through the obvious? Have you:-

Checked fluid level - an art in itself for a MB gearbox

How is the engine running? Is it healthy?


EDIT - I think my comments about the severity of shifts and when the gears shift with reference to the bowden cable and the vacuum control are the wrong way round! See subsequent posts! SORRY...

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1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!

Weird,
I will try & remember in the morning to take a pic of the adjustment on my 602 n/a. If you tighten the cable it shifts later. If too tight it will rev out to the limit & just stay there without changing up. Its a little slide adjustment with a lock bolt on top at the back of the motor.

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Grumpy Old Diesel Owners Club group

I no longer question authority, I annoy authority. More effect, less effort....

1967 230-6 auto parts car. rust bucket.
1980 300D now parts car 800k miles
1984 300D 500k miles
1987 250td 160k miles English import
2001 jeep turbo diesel 130k miles
1998 jeep tdi ~ followed me home. Needs a turbo.
1968 Ford F750 truck. 6-354 diesel conversion.
Other toys ~J.D.,Cat & GM ~ mainly earth moving

the baseline adjustment for the cable is to have no free play at the point where the throttle linkage picks up. it's important to find the pick up point of the linkage because on the diesel there is lots of linkage and lots of movement in the end of the throttle cable before the arm on the injection pump starts to move. so you find the point where the injection pump arm just starts to move and this is the pick up point. at this pick up point is where the thrust cable AKA bowden tube cable should have zero free play. once you find this baseline spot you can fine tune the adjustment from there. it is quite sensitive, like 1/2 turn either direction will yield noticeable changes in the way the transmission shifts.

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punkinfair

My understanding is that the bowden (US calls it a Detent Cable) is used to decide WHEN to shift and the vacuum modulator controls how "hard or soft" the shift is. It is more complex than that....I would ask a tranny guy to give us the down low on exactly the differences and how it works. lots of people are scared of transmissions.

Only adjust one at a time. and have test drives in between. Preferably several days. when adjusting the modulator it will effect each shift at differing severities. meaning that you might get 1-2 perfect, 2-3 soft, and then it takes forever for it to shift from 3-4. These trannys shift different warm and cold so be aware of tranny temp. Be very gentle and count how many turns so that you know where you are.

start with the bowden/detent cable and only adjust it half to a whole turn at a time. Get a feel for how much a full turn effects when the trans shifts.

write down the shift points and the number of turns. Once you get it shifting when you want, then begin to adjust the modulator....one turn then test drive.

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The way it is adjusted now it seems like there is no cable left at full throttle. Does that mean I have all I can get or is this where the actual pull on the cable is starting? does the cable moove more when the engine is running?

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1982 300sd, new project car to restore

It doesn't matter if you know what you're doing, as long as you look like you know what you're doing.

weird,
This is the thing that adjusts it. The little bolt is loosened & you can move the slide. Making its length shorter (this makes the cable tighter) will raise the change points. The higher rpm the change point, the smoother it appears, but if it changes at lower rpm, with a slow take off it may change hard. The whole set up is just a compromise.
If you have got to the end of the adjustment on the slide, the cable may have stretched. Have some one put their foot to the floor on the throttle & see if there is any slack left in the cable going to the trans (pull the cable inner side ways near the little crank arm; the cable is in the red rubber bit in the pic).

Hope that helps.

Good luck weird, I cant blame it on WVO this time !!

Attached Thumbnails

 

__________________
Grumpy Old Diesel Owners Club group

I no longer question authority, I annoy authority. More effect, less effort....

1967 230-6 auto parts car. rust bucket.
1980 300D now parts car 800k miles
1984 300D 500k miles
1987 250td 160k miles English import
2001 jeep turbo diesel 130k miles
1998 jeep tdi ~ followed me home. Needs a turbo.
1968 Ford F750 truck. 6-354 diesel conversion.
Other toys ~J.D.,Cat & GM ~ mainly earth moving

got it sorted, advanced the cable as far as it would go. It seemed like there was no more cable to be had because I was checking it while holding the throttle lever at full travel, which is a bit further than the cable will make it go. Shifts quite nice now!

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1982 300sd, new project car to restore

It doesn't matter if you know what you're doing, as long as you look like you know what you're doing.

This is very critical. For the longest time I have been setting 'zero free play' based on the where the bowden cable connects, which left me about 5 turns out, when I based 'zero free play' on the throttle rod.... Thanks a million Scott.

1982 300sd.
My Bowden Cable's rubber sheath is gone, and the PO repaired the clip with duct tape. I purchased a new cable from the dealership to replace it, but chickened out when I saw where the reverse end got connected.

The details in this thread give great directions on adjusting the throttle end, but nothing on the transmission end. Can anyone help me out on the transmission end? Flawless

Check out this video I made, it might be helpful.

http://www.youtube.com/watch?v=z2tLAwJbpYg

-J

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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.

Great Video, and quite informative. My car (1982 300sd / w126) is set up quite different than the vehicle in your video. Any chance you have one showing similiar steps in a w126? Or, do you have one that focus's on the connection at the transmission? Bill

Ya your early W126 is set up differently then my late W126, but the bowden cable is adjusted the same. It's just in a different place in the engine bay.

Compu_85,
You are the man. Thank you very much for the video, it's very helpful.
Jon

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1987 300D Turbo
140K on vehicle
Seattle, WA