Hi, my SD is fun - PeachParts Mercedes-Benz Forum

shane83SD · #1 10-05-2003, 11:46 PM

I was trying to tune up the auto transmission. The shift point is usually not one would like if one can operate in "manual". This is true especially for in-town driving. Most often, the transmission will shift to 4th gear too soon and the car struggles. What I did is drop the gear selector to "3" for in-town driving. This totally transformed the car. The big body is surprisingly agile, and the suspension is superb once some speed is attained. I've owned many Beemers, this car is even better in some ways...

BoostnBenz · #2 10-06-2003, 12:01 AM

Yea I use 'S' every now and then to make it drop right into 3rd gear, makes it easier for passing and such because you know it'll shift the instant you tell it to (as long are you're on the accelerator). What speed does yours shift into 4th with normal driving? I set mine to shift there at about 43mph under normal driving unless I let off and let it shift in as low as 25mph.

shane83SD · #3 10-06-2003, 12:32 AM

I have to admit that I don't know how to set the shift at a specific speed. I may have to leave it to an expert. Would you share some of your experience?

However, given the torqy engine, 3rd gear for in town driving will put a big smile in my face.

BoostnBenz · #4 10-06-2003, 12:55 AM

Well on my 300D there is a cable which starts on top of the valve cover (with the throttle linkage) and goes down with the automatic dranny fluid tube. This cable is going to the tranny, it is called the bowden cable. If you unscrew the nylon bolt it will change the shift point to a higher speed, screwing it in will lower the shift point. There are other tradeoffs with the adjustment like a harder 1-2 shift or harder kick going into gear, you just have to find the spot that seems to work the best for you overall.

shane83SD · #5 10-06-2003, 01:03 AM

Thanks, I'll experiment with the Bowden cable adjustment. By the way, my pedal linkage maybe loose, and has some initial "dead" spot. Is this normal, or should it be tout ?

BoostnBenz · #6 10-06-2003, 01:09 AM

It depends on how it works out with on the adjustment under the hood. It should be tight there and leaning against the left side (facing motor). I'd recommend adjusting this or figuring out what to do with this before adjusting the bowden cable as it may affect the bowden cable as well. If you'd like I may be able to send you the factory manual pdf for the 300d linkage the 300sd should be similiar.

shane83SD · #7 10-06-2003, 01:17 AM

I'll appreciate the pdf instruction. Thanks in advance.

The Warden · #8 10-06-2003, 02:07 AM

BTW, I leave the gear selector in "S" at any speed below 40 or so...I think it also changes the 1-2 and 2-3 shift points. Really makes the car more responsive in city driving. MPG hasn't really changed, either.

I also found that I wasn't getting full throttle...with the pedal all the way down, the lever on the injector pump had another 1/8" of travel before hitting its stop. I adjusted the linkage to the pump to compensate for this, and it felt like I was driving a completely different car afterwards.

Also, welcome aboard!!

shane83SD · #9 10-06-2003, 10:51 PM

As the "der Dieseling Doktor" , in this thread: 85 Mercedes 300D Automatic Transmission Lifespan... pointed out that most transmission wear when shifting. I think my trany is original (185K miles) and probably well worn (sometimes will flare on 3-4 shift). Minimizing in-town shifts by selecting "S" will be beneficial to my old trany. I also want to have some fun while figuring this trany system out. What do you guys think?