Just a question for all the members who own a 420SEL: What are the speeds at which the transmission shifts if you step on the accelerator all the way to the floor from a stop? I put a 1986 420SEL transmission in my '84 Euro 500SEL and when I step on the accelerator all the way to the floor from a standstill point, it starts out fast but then once it gets to around 20-25mph it shifts and lots of the power goes with that shift, then it crawls up to the higher speeds. The car thus doesn't take off as fast as I anticipated. Just checking to see if this is normal from that transmission. Thanks

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1999 Mercedes-Benz S600, 103K miles - garage queen
1988 Mercedes-Benz 560SEL, 89K miles - daily driver
2007 Hyundai Sonata Limited, 31K - daily driver

First your euro 500SEL starts in 1st gear from a stop, your 420SEL starts in 2nd, you’re missing a gear; 1st (power). From your description the transmission has stacked shifts, to soon, try adjusting the TV Bowden cable, make it tight with on slack. Do you what to sell the 500SEL Trans? make sure the gas pedal is hitting the kick down switch.

Thanks for your reply Mr. AMG :p

Let me get this straight, the Euro 500SEL starts in first gear but all US 126 cars start in 2nd gear? Why?

Secondly, you said I'm missing a gear. Does this mean that this "early shifting" that kills power will never go away? I mean, even if a transmission starts on 2nd gear, isn't it supposed to drop to first if you floor the accelerator from a stop?

Thirdly, I searched for information on the Bowden cable but all I can find are posts saying "adjust the bowden cable." How exactly do I do it and where is it located? I'll check the Service CDs as well for information on this.

Lastly, you asked me if I wanted to sell my 500SEL transmission. Do you mean the original one that came with the car?

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1999 Mercedes-Benz S600, 103K miles - garage queen
1988 Mercedes-Benz 560SEL, 89K miles - daily driver
2007 Hyundai Sonata Limited, 31K - daily driver

90% of all USA gas MB with a 722.2, 3, 4 and 5 transmission start in 2nd with the selector lever in the D posting. Diesels start in 1st, , why they have better gas mileage. Years ago I read two tech bulletins that said it was to improve gas mileage number in cars for the US market, and to avoid creeping in gear at a stop. All euros and most of the ROW cars start in 1st. If you select the ‘2’ position the transmission will start in 1st and only shift to 2nd, this is the engine braking feature as in
Cars with the ‘B’ mode.

To Command a 1st gear start from a stop at full throttle with the kick down solenoid activated there needs to be a regulation of oil pressures within the transmission. A 1st gear start is influenced by the following pressures , working pressures ( pump), modulating pressure ( modulator) , throttle valve control pressure (influenced by the TV Bowden cable ) and kick down control pressure ( kick down solenoid). There are other valve within the valve body that command 1st gear but the one mention have the most influence When the kick down solenoid is energized it drops oil pressure thereby increasing throttle pressure. The two most common problems I see are a non functional kick down system and the throttle Bowden cable out of adjustment.

The TV Bowden cable on your car is under the air cleaner on the driver’s side. Some models have a slide bar (diesels), others a pointer adjustment and others a cylindrical adjuster, a round plastic piece and some have a threaded rod with a ball socket Systems.

Adjust the engines throttle cable (gas pedal) FIRST.. Make sure you have full throttle opening on the engine. Once you do, then adjust the transmission throttle valve control pressure, Bowden cable. adjust it tight with no slack. Go for a test drive, the transmission should have late shifts. Now adjust it to your driving style, a lose cable will let transmission shift earlier. Adjust then drive.

Check the kick down solenoid system


Open the passengers’ side door with the ignition on, floor the gas pedal, you should hear the solenoid click at the rear of the transmission if not, check the fuse for the kick down solenoid, good fuse, check for 12v at the kick down switch under the gas pedal. No 12v check for a short in the wire. Check for a stuck kick down switch, check for 12v at the kick down solenoid, no voltage, check for a short in wire, 12v defective solenoid.

If you are interested in selling the original 500SEL transmission email me at

928euro@mastertechtrans.com.

Thank you for providing me with such valuable information on the workings of these things. I'll try to get my transmission cable adjusted once I get back home.
Sorry, but that part is incorrect. I have an '84 300SD (Diesel of course) and it starts in second gear. It has to be "floored" in order for the kickdown switch to engage resulting in a start from first gear.

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1999 Mercedes-Benz S600, 103K miles - garage queen
1988 Mercedes-Benz 560SEL, 89K miles - daily driver
2007 Hyundai Sonata Limited, 31K - daily driver