85 300sd trans shift questions - PeachParts Mercedes-Benz Forum

blackestate · #1 12-10-2005, 07:15 PM

My 85 300SD shifts from 1st to second to third quickly, and I am in 3rd by 20MPH. And the engine is lugging to pull it. At part throttle.
IF I am at full throttle then it shifts fine, and a little hard.
This does not seem normal, because the car struggles so hard to get going.

What controlls this and how do I adjust it? I have not found a vacuum module, or a bowden cable.

thanks
Doug

Brian Carlton · #2 12-10-2005, 07:51 PM

The Bowden cable connects the throttle linkage with the transmission and delays the shifts as the pedal is pressed. You should only reach 20 mph in 4th at very light pedal. 1/2 pedal should delay the 3-4 shift until you are travelling about 35 mph.

Full pedal should delay the 3-4 shift until you are travelling about 50 mph (possibly higher on the '85).

If you are not meeting these numbers, then the cable is not tight enough. There is an adjustment for it under the hood. The cable housing sits in a bracket and the adjustment is right at the bracket. You want to tighten the cable a bit more so that more of the cable is pulled out of the housing.

Don't go crazy on the adjustment. It's fairly sensitive.

blackestate · #3 12-10-2005, 08:07 PM

Thanks. I will look again. All I am seeing on the engine is the linkage, and a switch.

doug

Brian Carlton · #4 12-10-2005, 09:48 PM

Quote:

Originally Posted by blackestate

Thanks. I will look again. All I am seeing on the engine is the linkage, and a switch.

doug

Look for a rubber boot that covers the cable. The cable is mounted at the very back of the cylinder head on the passenger side of the head. The cable runs down to the transmission. You can't miss it if you take a careful look near the rear of the engine.