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  #1  
Old 11-15-2012, 03:23 PM
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Manually shifting your diesel?

Anyone else find that their diesel (sometimes) shifts to early on uphill grades?

I've turned to down shifting to keep my engine in the 2-2.5K range. It seems happier in that range and prevents "pre-shifting" into 4th.

Interested if anyone sees a down side (read:tranny health) to this?

Thanks-PK

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  #2  
Old 11-15-2012, 03:44 PM
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I often keep mine in 3 or shift down manually when coming up to a steep-ish hill, having learn to drive a manual (or stick) car, considering the narrow power-bands and that they don't mind high revs, I'd rather be in the right gear to start with than waiting for the car to do it when the car is starting to bog-down.

Shifting should be at around 2-2.5k anyway.

It's recommended in MB literature and I drove my past 300D like that for the 85,000 or so miles I had it for and the transmission still shifted perfectly when I sold it.
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Old 11-15-2012, 04:13 PM
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Quote:
Originally Posted by giff View Post
Interested if anyone sees a down side (read:tranny health) to this?
No issue but I was taught that it's preferable to ease off a bit on the throttle when you shift down.
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  #4  
Old 11-15-2012, 05:15 PM
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Climbing the passes on I-70 I routine usurp control over the transmission.
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  #5  
Old 11-15-2012, 05:30 PM
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I was just about to post this exact same question, sort of. I was questioning the 2000-2500 rpm shifting (under normal driving) and having to pull back a gear on hills.

How can you tell how much tighter your bowden cable can go before breaking it? Such a small cable, don't want to pull too hard on it and rip it out of the transmission. I would like to delay the shifting just a little bit more but I think I am out of cable.
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Old 11-15-2012, 06:28 PM
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The 85 300TD manual states:

"S" Slope.
Upshift to 3rd gear only. Suitable for meduim range up or down grades.

"L" Low.
Upshift to 2nd gear only. For driving in mountainous regions. Since Transmission will not shift up any further, this gear will make use of the engine's braking power.

I have always used S (3rd) a good bit here in West Virginia, western Maryland and western Pennsylvania.

MM
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Last edited by mozark; 11-15-2012 at 06:36 PM. Reason: spelling
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  #7  
Old 11-15-2012, 07:06 PM
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I pretty much only manually shift my 190d conversion, you need to precisely meter the power through each gear in every situation or else it leads to bogging and double shifting back down if you have to slow down slightly ....gotta be paying attention with 73hp. Stark difference from the 420...that can accelerate uphill....in 4th.....at 35mph/1500rpm....without breaking a sweat....
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  #8  
Old 11-15-2012, 07:59 PM
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Quote:
Originally Posted by giff View Post
Anyone else find that their diesel (sometimes) shifts to early on uphill grades?

I've turned to down shifting to keep my engine in the 2-2.5K range. It seems happier in that range and prevents "pre-shifting" into 4th.

Interested if anyone sees a down side (read:tranny health) to this?

Thanks-PK

If it upshifts too early, the Bowden cable needs to be tightened slightly. When properly adjusted, the upshifts are delayed based upon pedal position. If you're on a slight upgrade in third and are trying to accelerate, the transmission should never shift until you get well over 60 mph.

Absolutely no need to manually shift unless the cable is adjusted on the slack side for fuel economy purposes.
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  #9  
Old 11-15-2012, 08:08 PM
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The issue as I see it is that if you are climbing a steep grade in third and have to slow down due to traffic and you let up on the pedal, the car will upshift. Manually controlling the shifter avoids this.
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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13
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  #10  
Old 11-15-2012, 08:08 PM
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Quote:
Originally Posted by kerry View Post
The issue as I see it is that if you are climbing a steep grade in third and have to slow down due to traffic and you let up on the pedal, the car will upshift. Manually controlling the shifter avoids this.
Point.
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  #11  
Old 11-16-2012, 08:32 AM
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Brian/Kerry/ et all,

Thanks for the responses. So yeah, when climbing a hill, taking my toe out of her, it tends to shift to early and bog (having fallen out of the "happy" zone on the tach).

A turning vehicle in my path etc, where I simply get off, then back on the "gas", would causes the (early) up-shift. Getting the Tx attention seems to require putting my toe WAY back into the pedal......which may be symptomatic of the loose Bowden cable(?)

Holding the car manually in third has the desired "holding the proper gear" affect during the on/off/on of the accelerator pedal. I'll add the cable adjustment to my list of "to-dos"....

Thanks again.

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