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  #1  
Old 03-05-2008, 05:33 PM
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1977 W123-1030 only shifts at really high RPM

i have a 1977 300D that will only shift at really high RPM and I have to let off the accelerator to let it shift. This model doesn't have the ALDA...it is all mechanical linkge from the pedal to the valve cover to the transmission. I have a mercedes cheapo shop manual and I cannot understand the steps to adjust the shifting. Is there an easier way to adjust the shifting setting? thanks -Stephen

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  #2  
Old 03-05-2008, 06:13 PM
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sorry.....

I meant to say that it doesn't have the bowden cable. from what I understand adjusting the control pressure rod adjust the shift timing. if I were to make the rod bigger would that advance the shifting or retard it? thanks- Stephen
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  #3  
Old 03-05-2008, 06:24 PM
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sounds like your talking about wht folks generally refer to as 'flaring', you will find tons of posts regarding this on the forum
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  #4  
Old 03-05-2008, 06:35 PM
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Making the control pressure rod longer will make it shift earlier assuming its misadjusted. Did this car shift fine for years then, last week act up? By 'bigger" do you mean longer? Also I've seen bushings missing on linkages either up top or at the trans affecting shift points. Also put year and type of Mercedes in your signature profile.
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  #5  
Old 03-05-2008, 06:37 PM
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flaring

I understood flaring to be when the engine's RPM's rose BETWEEN shifts not BEFORE shifts. Is that correct?
stephen
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  #6  
Old 03-05-2008, 06:48 PM
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Quote:
Originally Posted by carnut View Post
Making the control pressure rod longer will make it shift earlier assuming its misadjusted. Did this car shift fine for years then, last week act up? By 'bigger" do you mean longer? Also I've seen bushings missing on linkages either up top or at the trans affecting shift points. Also put year and type of Mercedes in your signature profile.
No, I just got it so I dont know its' history. bigger = longer. the bushing look to be there and its not flaring from what i understand flaring to be. it just waits until it sounds like the engine is going to explode before it shifts into all gears. its 77 300D non turbo. what if its not the adjustment....it cant be vacumme because these trans dont have the vacumme adjustment right? thanks, stephen
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Old 03-05-2008, 07:02 PM
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My 77 does the same thing when its cold. Once it warms up, the shift points move down but they are still controllable by feathering the accelerator. Mine has done this for the 6 yrs I have owned it. I believe it has always behaved this way, so yours might just be behaving normally. On the other hand, it could be a stuck kickdown switch pushing the shift points up. Unplug the kickdown shift and see what happens.
I like being able to control the shift with pedal pressure.
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  #8  
Old 03-05-2008, 07:07 PM
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kickdown switch???

Quote:
Originally Posted by stephenc03 View Post
i have a 1977 300D that will only shift at really high RPM and I have to let off the accelerator to let it shift. This model doesn't have the ALDA...it is all mechanical linkge from the pedal to the valve cover to the transmission. I have a mercedes cheapo shop manual and I cannot understand the steps to adjust the shifting. Is there an easier way to adjust the shifting setting? thanks -Stephen
My 1985 300D recently suffered a stuck kickdown switch during a test drive and afterwards had the same symptons. I don't know if your model has a kickdown switch on the floorboard BEHIND the accelerator pedal, but if it does, you might trying pressing on it....with the car turned off....to see if it depresses and springs back up.
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  #9  
Old 03-05-2008, 07:16 PM
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I had a similar problem with my 1978 300D. First shift (2-3) was late in my opinion and a little harsher than I thougth it should be. Lengthened the control rod on the passenger side of the valve cover. It's the one that disappears below manifolds. Adjusted slowly, trial and error and after lengthening about 7-8 mm the shift point was earlier and less abrupt but still firm. The 3-4 shift is fine. If I can find the thread for adjustment of these non vacuum controlled transmissions I'll post.

Kevin

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  #10  
Old 03-05-2008, 07:56 PM
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Kickdown switch and control rod

I will definatley try the kickdown switch...I know this one has it. However I dont think it is normal for this transmission to behave like this. Though your mercedes might hav done this for years, it is not normal by any means. Maybe your experiening something different than me. She will not shift unless I feather the accelerator at extremly high RPMs....i am afraid to even drive it when it is like this. thanks to all i'll try to fix it tomorrow.
-Stephen
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  #11  
Old 03-05-2008, 09:05 PM
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ive understood flaring to be high rpm's before the shift, i would think high rpm's in between the shift would be a slipping kind of deal.
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  #12  
Old 03-05-2008, 09:09 PM
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Quote:
Originally Posted by johninva View Post
i
i would think high rpm's in between the shift would be a slipping kind of deal.
That's flaring.

Sounds like the high rpm's is higher than mine.
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1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
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1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13
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  #13  
Old 03-06-2008, 11:59 AM
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flaring?

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Originally Posted by johninva View Post
ive understood flaring to be high rpm's before the shift, i would think high rpm's in between the shift would be a slipping kind of deal.
I think flaring is slippage through the gears. From what I understand it is common in almost all automatic mercedes. I have experienced this my self in one of my 300SDs. I think flaring has something to do with the torque converter when it shifts gears......i dont know if im right though.
-stephen
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  #14  
Old 03-06-2008, 12:02 PM
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not the kick down switch

i tested the switch and it "switches" on and off fine when i was pushing it with my finger. I am going to try to adjust that control arm today....is the best way to get to it from underneath? I dont have jack handy so it makes it difficult to get to froom underneath. can I access it from under the hood easily? thanks, stephen
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  #15  
Old 03-06-2008, 12:34 PM
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Year and type of Mercedes in your profile signature please.

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