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1983 300 SD; 2000 E320
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Discussion Starter #1
I have seen several posts recommend leaving diesels in 3rd gear for around town use. I have tried this, but am not sure how beneficial it is. Also, I have occassionally felt a kickdown, or something like it, which should not be happening in a fixed gear?

Also, except with the lightest foot on the accelerator, the shift from 1-2 is a bit of a slam. I blamed the early turbo kick, but it might be the kickdown switch? Or, is it normal for early 300 SDs to have this "rough" shift?

Thanks
 

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1991 300 SE
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You should be starting in second, that’s why the 1 to 2 is hard. The diesels also shift differently than the gassers sometimes requiring a foot lift off of the throttle to get a sooner, smoother upshift.
 

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Discussion Starter #3
JDC,

Do you mean I should actually commence driving in 2nd and then shift into D? I thought the purpose of automatic transmissions was not to do this? I thought 2 was for hills.
 

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1984 280SEL AMG
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701 Posts
Driving that way is a preffrance thing. Reason somone tells you to drive in 3 is so you don't go into OD ( 4th gear in some 5th gear in others ) For around town in under 40 MPH traffic 3 is just fine. Since when it kicks to 4th, and you need a slight boost it has to downshift to 3rd get it to you.
As to your hard shift, Diesels have much much more torque than gas cars. So the shift feel is diffrent, try this. When you know your car is going to up shift ( from 2nd to 3rd ) lift your foot off the fuel peddal a bit. You should notice it will shift nicer.

And just because your driving in 3, doesn't mean it won't down shift into 2 and 1. It just means it won't go into 4.
 

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Instead of trying to apply strict rules to as to the gear you should troddle about in, why not just experiement? I move the gear selector around in my 126/107/116 gassers a good bit. If I'm just running around town, I typically leave it in 3rd as 4th isn't neccesary. If I'm driving in very slow traffic I'll drop the car into 2nd. Stop and go, I'll put the 560's in 1st.

Just play w/ it...you'll find patterns that suit the situation/give optimal performance with a bit of time.

Jonathan
 

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andrew_falky - 5/10/2005 6:38 AM

JDC,

Do you mean I should actually commence driving in 2nd and then shift into D? I thought the purpose of automatic transmissions was not to do this? I thought 2 was for hills.
No, I think as noted above just leave it in drive. Drive it like a stick: anticipate the upshift as you listen to the engine (not a problem with a diesel) and lift off the throttle just before, you’ll get an upshift. Gassers do it too but it’s subtler. It will make the 1 to 2 smoother if you car’s starting in first. My diesel starts in first, I think it’s an age thing. You can do the same thing as you run up the gears to 4th. Just like driving a manual except no clutch or stick.

Also, you may have noticed the tranny’s a little sluggish when cold, foot off the throttle is a good way to get an upshift and keep the RPMs down a little until the drivetrain warms. It’s almost like learning to drive again. I find it rather fun, even after all these years. [:)]
 

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1983 300 SD; 2000 E320
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Discussion Starter #7
JDC - I'm not following you 100%.

Are you saying my '83 was designed so that in D it actually starts moving in 2nd gear? or that it starts in first but other models start in 2nd and mine should be one of them?

In any case, I like your idea of easing up on the throttle. The kickdown switch is only activated when the pedal is to the metal - I wonder if the kickdown switch or throttle linkage could be playing a small part in this. Also, perhaps a small vacuum problem.

Like I said before, tranny modulator is newer. Sometimes I'm coasting at 60 on the highway and if I step on the pedal quickly and abruptly there is a little kick in the transmission - not a gear shift, but a thud as power reconnects to driveline.
 

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If you are getting small false neutrals you have a serious transmission problem.. Most likely there is a leak in the valve body and the resulting loss of pressure causes the car to fall out of gear. Stepping on the gas building pressure and the car engages said gear again. You might crank up your modulator a turn+ see if that helps your problem out.

Jonathan
 

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andrew_falky - 5/11/2005 6:30 AM

JDC - I'm not following you 100%.

Are you saying my '83 was designed so that in D it actually starts moving in 2nd gear? or that it starts in first but other models start in 2nd and mine should be one of them?
No, they’re supposed to start in second, both of my gassers do. Now, my old diesel starts in first, it’s not supposed to but I just figure it’s almost 400,000 miles on an original transmission. So the 1 to 2 is hard; lifting up on the throttle gives you a much smoother upshift.
 
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