stevebfl - Upshift delay adjustments
 

For Steve Brotherton or anyone else. The car is a 1995 C280. I have determined that the vacuum element on the control cable is leaking (therfore no upshift delay and Code P1 700). In a past thread Steve Brotherton advised against a DIY replacement of the cable/vacuum element because the cable needs to be connected inside the transmission and the cable and vacuum element need to be adjusted after installation. I have three questions:

1) How is the connection inside the transmission made? I appears the valve body would have to be removed to do anything inside the transmission. If I remember correctly, the control cable (no vacuum element and earlier transmission, I know) on my '88 300TE could be connected from outside the transmission. I think the cable had some sort of hook that mated with the link from inside the transmission. Could this unit be similar? One thing is certain - there is very little room to work on the C Class.

2) In the past the basic cable adjustment used to be to set the length "free of tension". Is this similar?

3) I assume the upshift adjustment is the nylon socket head screw on the element. What is the criteria for adjustment? I assume it would be to hold the upshift to a certain RPM when cold. What direction should one turn the screw to raise or lower the adjustment?

Thanks in advance.

Thus far I have been able to find the following info:

1) From the 1994 Intro Manual, the diagnostic module looks for 2100 RPM at 26-28 mph. This is in 2nd gear, correct? Seems like a low RPM threshold for 2nd gear. And I assume the adjustment for this is the nylon socket head screw on the vacuum element. Am I correct and which way do you turn it to adjust it?

2) From the Picture Parts Manual, it looks like there is a link coming up from the bellcrank inside the transmission with a 90 degree bend on the end. This is similar to the setup on my old 300TE, if I remember correctly. The question is, does it project high enough to connect the cable from outside the transmission?

Steve, MB DOC, Gilly, Joe P, anybody?

We replace at least 2-3 cables a week at dealer.
The cable can be replaced W/O removing the valve body, just like earlier cars. Takes 2-3 HRS
On the C-class we always remove the exhaust system.
You need to disconnect the cable from the accel linkage first.

The 2-3 shift must happen between 26-30 MPH for the computer to see the correct RPM.
Adjust the allen counter-clockwise to hold the shift longer(higher RPM)

Thanks M.B. DOC! I figured I would drop the exhaust to allow me to drop down the rear of the transmission for better access. I changed the "o" ring on the cable on my old 300TE some years ago - not fun (which is how I am somewhat familiar with the connection of the cable). But the C is much tighter. I figure 2-3 hrs is probably on the lowside for me - I'll just take it easy. Thanks again!