400E transmission vs. 500E Transmission

[alabbasi]

Understanding that the 400E transmission has a 1st gear start valve body. Is there any other difference between the two transmission? I have an E420 parts car and a 500SEL Engine. I'm wondering if there's any other issue with fitting the E420 Transmission with the 500SEL engine before installing it in my 500E.

Thanks

 

[gsxr]

Should be 100% plug+play using the 034 transmission in the 036. AFAIK, everything else is 100% identical besides the valve body, and you want the FGS valvebody anyway.

 

[AndyK]

Should be 100% plug+play using the 034 transmission in the 036. AFAIK, everything else is 100% identical besides the valve body, and you want the FGS valvebody anyway.

Hey. I am still dealing with the transmission switching after Engine swap (4.2 to 5.0 from SL500).

The second gear won’t engage while normal driving (without full throttle), goes from 1st to 3rd gear, pretty smooth though, no hard push

We have:
- Rebuild transmission (the reverse gear was burned on the SL500). This is actually a second transmission because original 4.2 transmission has been used with the SL 500 valve body and after 6 miles the torque converter bearing was torn.

- Rebuild valve body. I used original one from 4.2.
I replaced all necessary springs and piston rings. Shift technologies kit and genuine rings have been used.

What I tested alredy:
- I have played with the vacuum modulator on the driver side. Adding and removing pressure doesn’t provide with any improvement.
- if remove vacuum line from this modulator, the transmission won’t switch even into the third gear before 4500 RPM and shift hard
- I have played with bowden cable, if I make it too loose, it switched to the third gear anyway, and almost no kick down. If make it tight, transmission won’t switch until 5000 RPM and anyway goes into the third gear.
- I replaced kickdown switch under the acceleration pedal, no changes
- I disconnected the vacuum line from the passenger side transmission. No changes.
- I replaced the vacuum valve for this vacuum line for the passenger side, no changes

Finally, I removed single wire from the valve at the back side of the passenger side transmission, I believe this thing related to the kick-down, like kick-down solenoid AND I GOT FIRST CHANGES!!!
The transmission started shifting normally under 2000 RPM from 1st to 2nd gear, but shiftings are were. 1-2-3-4 - R - All gears are available BUT under full throttle the first gear switches to the second gear at 4000 RPM however second gear goes as it supposed to be till 6000 RPM
The first gear was available only once when you switch from Parking to drive you start driving on the first gear then switchs to the second gear and then all next stop and go goes using second gear only, which normal I guess?

I replaced that electrical solenoid and mechanical valve, I used old one from original transmission, And the issue came back, no second gear.

In my opinion, something constantly send power to that solenoid on the back side of the transmission. Any thoughts?

 

[AndyK]

I checked the power on that wire and it always under the power. If I turn on the ignition, there is no power however, once I start the engine, there is 13+ volt.

I have removed kick down switch and that wire still shows 13+ volt

 

[AndyK]

Another update:


I found a transmission wiring harness diagram for the W126. It shows that there’s another module or valve that receives a positive signal from the kick-down switch. In my opinion, this device doesn’t just act as a pickup — it functions as a signal generator that keeps the kick-down solenoid constantly engaged.

So at this point, I need to find a more detailed diagram related specifically to the kick-down system to identify what else receives that signal and what could be causing the issue.

The problem is that this device likely communicates with the ECM or EZL module to temporarily reduce engine torque for smoother downshifting.

That means I’m probably losing some engine power as well.

At the meantime I have the A/C compressor issue as well, based on the information I found when the kick down switch is pressed down the system should disconnect the AC compressor as well

 

[doolar]

Is the B-switch by the gear selector properly connected and in the correct position?