Bowden Cable Adjustment for M104 engine
 

SteveBfl told me a few months back that I should adjust my bowden cable to optimize my shifting (already did modulator adjustment). He suggested that I 'hasten the control pressure shift point' which I believe to be the bowden cable. I would adjust it so that the car would shift earlier. This would also allow the transmission to DOWN-shift at higher speeds also.
If I floor it (kickdown) at 18 mph, it will not shift into 1st gear.

Anyway, how do I adjust the bowden cable for my 95 C280? I think I'll be making it a little tighter (shorter) and go from there.

I have no more camera, so I'll have to use some old pictures.

This is a pic of my engine....
http://www.a-p-group.com/cklasse/Engine2.JPG


And here is a closer look at the area of adjustment:
http://www.a-p-group.com/cklasse/ThrottleLinkage.JPG


Now can anyone give me specific instructions on the location?
Thanks a bunch, I appreciate it. :o :)

I asked my tech where it was when he lubed the throttle cable and he pointed to a similar looking assembly underneath the throttle linkage. It had an orange bellows type covering over the cable portion. Not sure where it would be on your car though...

Just tried to check it out.. but I can BARELY even see down in that crevice. I am thinking I must remove the Windshield washer reservoir to actually get my hands (or sight) down in there.


??? :confused: ???

Thanks JSmith!
(BTW, do you have the Mercedes-Benz repair CD for your car? I might be able to use some info you provide me ;) because we both have the M104 engine. THX)

yeah i have the cd but it's not very user friendly. it has pictures of the pages from the manual in pdf format :confused: . you can't even do a wild card search on the CD. i wish they had just made the whole thing a PDF with text so that you can at least do a decent search. instead they did this quasi-multimedia hodgepodge collection of PDF's!

BTW, i saw an old thread where Steve described it as having the "accordion" tubing over the cable, so i guess i was looking at the right thing. i'll see if i can get a shot of the thing...

John are there images of the linkage? Of Bowden adjustment? How do u adjust it anyway?! Is it a screw or something?
EIther way, I would also like to know the proper way of throttle linkage on the M104s. THANKS A BUNCH!

yup i think you're gonna have to move that reservoir. i managed to snap a pic and attached it. it will be further back than whats in your original pix if our configurations are at all alike which is probably the case. the CD is useless for stuff like this - i have yet to find any mention of the throttle actuator / bowden cable. re-read that thread where steve had a lot of answers. BTW from re-reading that old thread and another thread i think this is missing part of the answer to my kickdown / shift point puzzle.

can someone verify where the adjustment is made? i thought it was where the cable housing is attached. there is a 13mm nut that you can turn to move the cable housing in or out. i thought that moving it out would shorten the cable and make the shifts later so i gave it a half a turn out. i observed the opposite effect- now the tranny won't downshift at all and shifted 200 rpm earlier:confused:

If one turns the throttle linkage knurled knob (in the relative middle of the pic), would that get rid of slack in the throttle wire linkage?

I've turned mine all the way up and all the way down and didn't observe the slack in the linkage tighten or loosen,...

tks-fad
'94 E320 Coupe

i don't think the throttle knob is to be adjusted. i think i turned the nut the wrong way. i should have turned it in to shorten the cable (only one way to find out).

hey David, did you find it in your car yet?

knurled knob
 

I used the knurled knob to take out some slack in my cable on my M103 engine. I read somewhere that there should be a little slack, but I took most of it out, and was pleased with the results. (earlier downshifts, and quicker throttle response)

Ok,
I have the washer reservoir off and I can see the Bowden cable and now have access to it. But what do I adjust? Is it a screw or something?? I don't understand where/what this "knurled knob" is...
THX!

i think the adjustment for the bowden cable is where it is attached to the linkage as shown in the pic. i am still not sure which direction to turn although loosening it was definitely not the way to go for me as it stopped downshifting altogether and the shift points went lower. i have tightened it 1.5 turn (9 flats) and it is back to where it was before with no real improvement. maybe there was too much slack to start with. i'm giving it another half turn tomorrow morning.

george just said that he adjusted the knurled knob to get rid of the slack in the throttle linkage but i'm pretty sure that wasn't part of what steve said in the original thread.

knurled knob
 

Sorry, I had to run get a pizza.... the knob to which I am referring is approx 1 1/2 inch to the left of the "B" in Bowden in the pictures, and has the cable running through the center of it and it has 6 points/bumps on it. When I turned that knob, it visibly shortened the cable which runs through the center of it, taking up the slack going to the next piece of the linkage. I once read on another site that if you turned the knob too much, that it would start in first, and never shift into high. Don't know if that is true or not. This is all heresay, except that I felt that it helped my situation. Others may know better than I do. Hope that this may help out a little.
George

Sorry about these delays, I keep falling asleep! I'm sick :mad: :(

Ok, well I tried to adjust that black 13mm thing, and with some effort (so little room to move the wrench), I think I turned it about one full turn. Though I went to drive the car and noticed absolutely no difference at all? Should I try turning it some more?
What should I be looking for? Earlier upshifts and later (MPH)downshifts correct?

Adjusted it close to a full turn again. Still nothing?

no change for me too, although turning it the other way was definitely not good. i also noticed there was quite a bit of slack in the throttle with about 1/8" of the end of the cable protruding so i snugged that a bit too. i think maybe we need the Master Tech's to weigh in on the correct setup procedure...

Here's something I found on usenet about Bowden cable adjustment on W124. Still wish someone could verify all this as I can't find this anywhere on the CD...

<quote>

Models with adjuster on cable sheath;
1. Disconned the control pressure cable from the balljoint on the cable linkage.
2. Pull the cable forward until slight resistance is felt.
3. At the point where resistance is just felt it should be possible to fit
the cable end back onto the throttle linkage balljoint. If the cable is too
long or too short to achieve this
turn the cable sheath adjuster as necessary until the cable end can be
easily fitted to the balljoint.

Models with knurled adjuster wheel;
1. Turn the adjuster wheel sufficiently to give about 1.0mm of play between
the cable end fitting and the spacer sleeve at the end of the adjuster.
2. Turn the adjuster wheel back until the tip of the adjuster pointer is
positioned exactly above the groove in the centre of the adjuster wheel.

</quote>

Well driving around today I DEFINITLY noticed a difference! It held on to gears much longer, primarily 3rd gear. And my mpg has been reduced to about 50 miles per quarter tank (about 13 gallons); yes I drive hard, but the worst I've ever gotten is 17 mpg. Have a bottle of Techron and I'm going to check tire pressure also though.
I am going to spin it a whole bunch the other way and we'll see what happens!

(Just a note, when I was observing the shifting and driving kind of rough/hard, I really appreciate and love how tight my car feels. Someone please tell me the difference between the 230 and 280's suspension!)

well all the road testing will surely take its toll on the mpg as it did mine. with that last bit of info i found and reviewing some of the bowden threads, i realized that there was way too much slack in mine as you can even see a slight curl in the picture. all in all i've given it 5 turns and it just started taking the slack in. i gave it another full turn for tomorrow's drive in to work...

I am going to go down and make mine a bunch tighter now... since I've obviously gone the wrong way.
But I kind of like the way it drives with it loosened up some! It holds on to gears longer... and it shifts into 1st gear without going into kickdown at speeds up to 12 mph! Also throttle response does feel much quicker! I am betting this is just psychological though.. :confused:

Wish I could remove and take slack with the push of a button or the slide of a dial!

I'll keep you posted on the results.

Ok I was able to get my hand in there and I adjusted it ALL the way... I think I tightened it all the way. I took it for a test drive and DEFINITELY noticed a vast difference. It upshifted very early. But I got it to downshift into 1st gear (with kickdown) at 23 mph, instead of 18 mph like before. I got it to kickdown into 2nd gear at 58 mph instead of 55 mph like before.
Also, my 2-3 shift didn't seem right, it always seemed to take a little longer, almost like it was flaring, but that improved 50%.

So the results of a full hastening of the Bowden cable are:

Earlier upshifts.
Later Downshifts.
Improved 2-3 shifting.

I will drive with it fully adjusted tomorrow to see how I like it. I am guessing that I will probably be loosening it back up just a little so that the upshifts are SO quick. But just a little, because I LOVE the higher speed downshifting!
(Weird going from a fully loosened cable to a fully tightened one in about an hour! THe driving difference is phenomenal.)

Will keep you all updated on my final results.

that's what i observed after tightening it 6 turns. it upshifted a lot earlier and harder as a result. my downshifts are messed up now since this causes it to happen later. i will have to investigate other possible causes, maybe i have vacuum line leaks...