Bowden cable... - PeachParts Mercedes-Benz Forum

190D22 · #1 07-06-2002, 05:10 PM

I keep seeing people mention the bowden cable on their transmission and it smooths up shifting. My car has pretty tough shifts, feels like it's a manual. The thing pulls forward when it shifts. Is it supposed to shift like this? Would my 190 have a bowden cable and where is it? What's a good starting point for the ammount of adjustment?

I was just beginning to accept that that is how the car shifts... maybe not?

psfred · #2 07-06-2002, 07:15 PM

Your bowden cable connects to the accelerator linkage at the IP. It is held out with a large coiled spring, and should be all the way out with no slack at idle -- it retracts into the transmission with accelerator travel.

However, your problem is most likely a vacuum issue rather than the bowden cable. The cable really controls shift point, the vacuum system controls harshness. If you have high rpm slamming hard shifts (bangs the diff on the floor in back) the vacuum system is out of whack.

You should shift into 4th at around 30 mph at light throttle, very smooth shifts.

There are several vacuum lines on the IP -- there is a little aluminum box connected to the throttle linkage. The black one is a vent, the white one is vac supply, the the other one goes to the tranny.

I'd gues that the rubber connectors for the hard plastic lines are shot and there isn't enough vacuum. You could also have a bad vacuum pump, or something else in the vac system (the EGR vacuum acuator, for instance) leaking. There is also a restriction in the servo supply that can get clogged, resulting in low vac.

Does you AC work properly, or does it blow conditioned air up the windshield? If it does , you have low vac.

Peter

84300DT · #3 07-06-2002, 08:28 PM

190D22,
yes i always thought my 'hard' shifts were normal, until today that
is!! i took 3 clockwise turns on the bowden cable and my shifts are now exactly like psfred described- soft and shifing into 4th about 30mph. i could not believe the difference - feels like a 'new' car

190D22 · #4 07-07-2002, 12:08 AM

yeah, she shifts nice and easy when I'm not gunning it. It gets into 4th gear around 30 mph. But when I floor it from a stop it shifts really hard. Much more solid shift than the jeep! I guess that's normal?

psfred · #5 07-07-2002, 05:59 PM

Full throttle upshifts are quite firm, but they shouldn't bang as if something was loose. If you hear and feel a very hard thump from the rear, you are shifting too hard. This is usually a vacuum problem, although it can also be a cable problem. There is a long plastic nut used to adjust the bowden cable, and it can break. Vac lines can leak, too, causing hard shifts.

That said, there is no comparison between an american sloppo tranny (excpet old torqueflights) and the one in the MB. Much, much more positive at all speeds.

Peter

pawoSD · #6 01-18-2005, 12:46 AM

What does it mean if mine shifts into 4th around 21-23mph with a light throttle?? Is there an adjustment I can make to tend to this? Mine goes....1st to about 6mph (estimate) 2nd to about 14mph, 3rd to around 22mph with maybe 1/5 throttle. If I use maybe 1/3 to 1/2 throttle it shifts to 4th around 30-35. I think the bowden cable has a bit of slack at idle position, would getting rid of the slack solve the problem? Also, mine tends to flare in the 2-3 shift about half the time, especially when warm, and acclerating from standstill or from when its in second. Then the 4th gear is slippery to engage under heavy throttle unless I let off a little bit. I wouldn't mind making the shifts just a little bit harder to tighten up the slipping. What adjustment would I make to do that? Or do I have other problems....I'd like it to shift a little later on partial throttle, and to harden those flares and slipping a little bit. Our 83SD has much firmer shifts than mine does, but not firm in a bad way, just firm in a "I'm shifting now, locks right in" kind of way, no flaring or slipping, ever. Help?

Also, under full throttle none of the shifts are very firm, its actually quite a soft shift, especially to 4th, I am guessing this causes excess wear, which I would very much like to prevent.

Cateaux · #7 01-18-2005, 08:31 AM

Taking the slack out of the Bowden cable will make the trans shift later, but won't help the soft shifts. Try turning the modulator valve on the driver's side of the transmission clockwise. A search will tell you more about the modulator valve than you ever wanted to know

. If you're having trouble finding it, it's next to the neutral safety switch and has a vacuum line (should be black) going to it.

wayne2970 · #8 04-12-2008, 01:03 PM

1992 300D

I see 2 cables ...

1 cable on passenger side of valve cover is connected to throttle linkage. It has a red/orange covering the cable. I do not see and way to adjust this cable except by adjusting the linkage.

The other appears to be the throttle cable as it passes through the firewall on the drivers side. It has a large white adjustment wheel and looks to be adjusted all the way out. This cable has alot of slack betweeh the adjustment wheel and the end of the cable.

any pictures would be helpful