Slow downshifting when pinning the throttle

[Quick4door]

This question is 722.3 specific, although it is in my 400 E. I have both an E420 and a 400 E, my 400 E has a delayed downshift when stabbing the throttle that the E420 does not. I did have the 400 E transmission replaced about four years ago with a rebuilt unit from Sun Valley. It’s been fine, but I noticed that driving the cars back to back, and driving my son‘s 500 SL, that the downshifts were much more immediate and crisp on the other two cars vs the 400e.

I have adjusted the tension on the shift cable that goes from the throttle linkage down to the transmission, and it really didn’t change anything, but I’m not sure I’m doing it correctly.

Does anyone have any suggestions on where I could go with this? I know there’s a ton of information on this website, but I haven’t had the right search functions to find exactly what I’m looking for.

Thank you in advance. PFA.

 

[gsxr]

If you adjust the shift cable from the throttle linkage down to the transmission, there should be a change in the upshift AND downshift RPM's at part throttle. The adjustment is pretty sensitive, you change the length of the horizontal rod at the back of the intake manifold. A few mm makes a big difference. If nothing changed, either you were adjusting the wrong item, or the cable isn't connected (unlikely).

Since the problem transmission is a Sun Valley rebuild, I'd call them up and ask if they can give you some ideas.

 

[Quick4door]

I thought it’s strange as well. My son‘s SL 500 and my other E420 just shipped like butter, this one doesn’t so I’m just trying to track down any concerns that there might be. I’ve also got some sluggish acceleration which I’ve still gotta figure out so maybe it has nothing to do with the transmission at all. Thanks for the help.

 

[maw1124]

If you adjust the shift cable from the throttle linkage down to the transmission, there should be a change in the upshift AND downshift RPM's at part throttle. The adjustment is pretty sensitive, you change the length of the horizontal rod at the back of the intake manifold. A few mm makes a big difference. If nothing changed, either you were adjusting the wrong item, or the cable isn't connected (unlikely).

Since the problem transmission is a Sun Valley rebuild, I'd call them up and ask if they can give you some ideas.

Marc at Sun Valley told me 1mm increments on this cable adjustment. Of course Rex did a little more than that, so it's affirmatively snappy if my right ankle moves too much. I've come to like it, though I might take some of the kick out of the modulator.

maw

 

[Quick4door]

Thanks. I’m certain that I adjusted the cable greatly overall in small increments but didn’t notice much of a change. This could be that the car is a daily drive and has been for 9 years and has 300k on it. May not be transmission related just trying to get it figured out.

 

[Quick4door]

Marc at Sun Valley told me 1mm increments on this cable adjustment. Of course Rex did a little more than that, so it's affirmatively snappy if my right ankle moves too much. I've come to like it, though I might take some of the kick out of the modulator.

maw

I’ll reach out to him and see if I can’t get a little more guidance on my specific situation and I’ll report back. Thanks again guys.

 

[maw1124]

Immediate = cable

Crisp = vacuum modulator... I replaced this as well with my Sun Valley box with the AMG unit which yields firmer shifts (140 part number).

I type this because you used both words in your complaint and comparison above, so maybe this helps focus the inquiry. If it's quick and not crisp, well that might explain why the cable isn't the remedy.

GL,

maw

 

[HawkerSam]

This question is 722.3 specific, although it is in my 400 E. I have both an E420 and a 400 E, my 400 E has a delayed downshift when stabbing the throttle that the E420 does not. I did have the 400 E transmission replaced about four years ago with a rebuilt unit from Sun Valley. It’s been fine, but I noticed that driving the cars back to back, and driving my son‘s 500 SL, that the downshifts were much more immediate and crisp on the other two cars vs the 400e.

I have adjusted the tension on the shift cable that goes from the throttle linkage down to the transmission, and it really didn’t change anything, but I’m not sure I’m doing it correctly.

Does anyone have any suggestions on where I could go with this? I know there’s a ton of information on this website, but I haven’t had the right search functions to find exactly what I’m looking for.

Thank you in advance. PFA.

Check the bowden cable adjustment again ,small changes matter. If that’s good, look at vacuum modulator and line pressure; a soft/delayed kickdown is often one of those.