PeachParts Mercedes-Benz Forum - View Single Post - 722.3 in '81-'85 turbodiesels W123 and W126

rcounts · #52 12-16-2009, 10:37 PM

I've seen lots of references to the tranny starting in second too, but as far as I've been able to determine, mine doesn't, and since I wouldn't want it to, I have always been happy about it NOT starting in second.

As for "caring" about how things work - sure I do. If your definition of starting in second means the transmission being in second gear to begin with, then sure, maybe it "starts out" in second gear. But if your definition of "starting" in second gear means when it begins moving the transmission is trying to move the car while it is in second gear, then it doesn't "start" (moving) in second gear. A true case of semanitcs in the sense that it depends on what you mean by "start" or "starting".

Knowing that it sits idling in second until it starts to move and then instantly shifts to first is an interesting fact, if true, but makes no functional difference in driving the car or how it accelerates or performs. I can only think of one potential benefit from having it sit in second while idling in gear and that would be if the internal pump would be turning faster and therefore providing more oil circulation and therefore better cooling and lubrication.

I just thought of another way to test it. On flat level ground, if I am idling in gear and just let off the brakes my car will attain a speed upwards of 5 mph without even touching the throttle. If it is "starting" in second gear, and I let it get up to max speed at idle - without touching the throttle - and then I drop the shift lever into first, it would have to downshift to first if it is in second, right? I'll try that tomorrow.

And I'd modify your statement that...

Quote:

If understanding automatic transmissions was critical to vehicle operation, there would be darn few cars on the road

...to say "If understanding automatic transmissions was critical to vehicle operation, there would be darn few cars with automatics on the road."

On the other hand, my dad always said that "unless you understand how one works, you can't really properly operate a clutch to make it last as long as possible"...