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  #1  
Old 08-19-2006, 03:31 PM
EZ
 
Join Date: Jul 2006
Location: Sacramento, California
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what does a second gear start mean exactly?

I have a '88 300 SEL. In doing a lot of reading on this site I have noticed 1) my car has a 2nd gear start and 2) everyone seems to hate the 2nd gear start. What does it mean to start in second? Do you ever end up using first on these cars? Why is it so bad? Finally, if it is so bad, why did MB do it; they usually make fairly responsible engineering decisions? I am having no trouble with the trans (knock on wood) but I am curious. Thanks for your input.

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  #2  
Old 08-19-2006, 03:55 PM
sixto's Avatar
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My guess is it allows smoother take-offs, provides better traction on slippery ground and helps mpg.

First gear should come right along with enough pedal travel.

If it was such a good idea, why do MB 5-speed ATs have first gear start? Other manufacturers copy MB ideas. Why didn't anyone copy second gear start?

Sixto
93 300SD
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  #3  
Old 08-19-2006, 04:08 PM
EZ
 
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Oh, I never said it was a good idea, just curious to know if anyone was aware of the logic behind the decision to make a second gear start. So, when I start my car, I start in 2nd, and then as I build speed I just go straight into third? What about when I leave my garage: I start in second, put it in reverse and then when I am out on the road put it into Drive. At that point would it be in first or second gear?
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  #4  
Old 08-19-2006, 04:45 PM
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It all depends on how hard you push the gas pedal. Put it to the floor and you will find first gear. It's there if you need it.
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  #5  
Old 08-19-2006, 04:48 PM
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smoke gets in your eyes
 
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It will never go into first from a dead stop unless you put the shift lever in 2. You pull the lever down to 2 at a full stop and feel the transmission shift down to first. You'll get wall-climbing torque for a few feet then an abrupt shift to second.

It can go into first automatically if it senses a heavy load as you get moving, even if you don't hit the kickdown switch.

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93 300SD
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  #6  
Old 08-19-2006, 04:50 PM
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I think a 2.88:1 would be an ideal ratio for a 300SEL with first gear start.

Low gear ratio would be about 10.9:1 (with ~3.8:1 first + 2.88:1) versus the ~3.47:1 + ~2.3:1 (second) making about a 7.9:1 only.

So you'd be quicker and probably have better economy as the motor won't be lugged badly getting from a dead stop not to mention drop about 500rpm on the freeway... about 2900 @ 70mph versus closer to 3500rpm @ 70mph.

Problem is 2.88:1 was only in the SDLs for the W126 (as I understand) and it'll cost a bit to get a VB converted for the ~6400rpm shift point. I have a few first gear start VBs but I need them, I see them at times. Next time I have a spare I can take it apart to compare with a second gear start to see what's up.

2.47:1 seems like it'd be too low of a cruise RPM for an M103 in a W126... not enough power to keep it going at 24-2600rpm @ 70mph. But hell, it very well could for all I know.
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  #7  
Old 08-19-2006, 04:54 PM
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All European cars (of this era at least) must pass a test for certification in Switzerland whereby they must be able to pull a house trailer from a standing start on a significant grade.

Therefore, they have a first gear not really suited for anything else.

Kind of like the old "granny" gear in pickups that you never used unless you were a teenager that didn't know any better.
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  #8  
Old 08-19-2006, 09:59 PM
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The second gear start in the Mercedes of the 80's was done for two reasons. The main reason was fuel mileage (and IIRC there might have been a fractional benefit for emissions), and the other reason was that first is a true stump-puller (for the reasons cited above) and in slick conditions can be tricky; starting in second allows easier control of power and less likelihood of wheelspin. As others have mentioned, first is available through the shift lever, through the kickdown switch if you floor it from rest, and on demand if there's an unusual load sensed.
To the best of my knowledge, it was only done on the larger V8s, due to their exceptional thirst and exceptional torque.
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  #9  
Old 08-19-2006, 10:48 PM
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Quote:
Originally Posted by ericzacha View Post
So, when I start my car, I start in 2nd, and then as I build speed I just go straight into third?
Just in case....there is a 4th too.
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  #10  
Old 08-20-2006, 12:51 AM
Moneypit SEL's Avatar
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Quote:
Originally Posted by cbdo View Post
To the best of my knowledge, it was only done on the larger V8s, due to their exceptional thirst and exceptional torque.
Nope. It's on the I6 300, too.
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  #11  
Old 08-20-2006, 03:25 AM
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I had my '91 changed to the 1st gear start (with a Bergwerks module), as the 2nd gear start while smooth, didn't give me the instant torque I hoped to get with the 1st gear start. The pedal throw is real long so you have to mash it all the way to the floor to get a full bore 1st gear start, but it's satisfying.

It took me a month to get used to the difference, but now I usually start out slowly and smoothly from a start, and works well too. But it was nice to have the quick response if I'd like it.

The 2nd gear start was offered by Mercedes for economy and smoothness.
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  #12  
Old 08-20-2006, 08:54 PM
EZ
 
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well thanks everyone, I guess that answers that question. I have a nice smooth start and enough power for me, so I guess I have no problems with the 2nd gear start.
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  #13  
Old 08-21-2006, 08:46 AM
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It allows less torque to be put to the ground in adverse weather conditions as well. Newer MB's just have a switch now that allows either 1st or 2nd gear start, they also have a 2nd reverse gear as well. This is for smoother starts as well as less torque to the ground in rain and snow. Like starting in second on a standard shift so you do not spin the tires and lose traction. Of course this was more helpful before Traction Control and ESP/ASR were introduced.
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  #14  
Old 08-21-2006, 09:05 AM
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my 74 240d had second gear start.

first was a real stump puller.

that car had so little power pulling the slushbox it always seemed like a wash whether to take off in first or second. the higher rpm seemed to mainly result in more noise!

tom w
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  #15  
Old 08-25-2006, 05:38 AM
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hiya folks

i just bought a 190e 2.3-16 with an auto box. this auto box doesnt have a s/e switch however which i thought was strange, i thought they all had it.

mine too starts in second gear. i have buried the accelerator to try and get it to start in first but it just refuses to do it.

I dont really mind the second gear start though, its very smooth and it doesnt take all that long to reach 60mph in second gear.

If i wanted to, is it possible to adjust the box so that it starts in first?

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