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  #1  
Old 09-26-2009, 04:05 PM
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1980 300sd skipping 3rd gear

Newly acquired 1980 300sd with 105,000 miles on it. The main problem is that the car will shift into second and then straight into fourth. This only occurs when I am at around 3000 rpm or higher. At lower rpms the car will shift into third just fine. I checked the transmission fluid level at operating temp and is seems high to me. Definitely above second mark on the dipstick. I then checked the vacuum system. I have a reading of 20 going into the vacuum control modulator on the injection pump and 14 going down to the modulator on the transmission at idle. I adjusted the modulator one notch clockwise and it seemed to help overall shift quality, however the problem with skipping third at higher rpms continues. Do you guys think the fluid level may have something to do with this? possibly more adjustment to my modulator or something more serious like an internal transmission problem.

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  #2  
Old 09-26-2009, 06:40 PM
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Originally Posted by KJenkins View Post
Newly acquired 1980 300sd with 105,000 miles on it. The main problem is that the car will shift into second and then straight into fourth. This only occurs when I am at around 3000 rpm or higher. At lower rpms the car will shift into third just fine. I checked the transmission fluid level at operating temp and is seems high to me. Definitely above second mark on the dipstick. I then checked the vacuum system. I have a reading of 20 going into the vacuum control modulator on the injection pump and 14 going down to the modulator on the transmission at idle. I adjusted the modulator one notch clockwise and it seemed to help overall shift quality, however the problem with skipping third at higher rpms continues. Do you guys think the fluid level may have something to do with this? possibly more adjustment to my modulator or something more serious like an internal transmission problem.
Too much fluid is just as bad as too little. It could be your problem if its so high it is not going where it should be in the valve body - drain a bit of the fluid and try again.
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  #3  
Old 09-26-2009, 07:30 PM
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No. I don't think it has anything to do with fluid level. It probably has something to do with the bowden cable. My W116 SD had really close spaced shifts from 3-4. I adjusted the bowden cable and it pushed them further apart. It's still a little too close for my liking.
Vacuum controls the harshness/softness of the shift but has nothing to do with shift points.
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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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Old 09-26-2009, 07:44 PM
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Well how is the 1-2 shift? How high do the RPMs get before it'll go to 4th? These cars do not shift down into 1st unless they come to a 100% complete stop.
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  #5  
Old 09-26-2009, 10:14 PM
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1-2 shift isn't bad, especially after I adjusted the modulator. How high the rpms get going into fourth depends on how much throttle I am giving it. I'll try adjusting the bowden cable or control rod as kerry suggested and see if that helps any. Thanks for the responses.
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  #6  
Old 09-27-2009, 10:07 AM
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Originally Posted by KJenkins View Post
1-2 shift isn't bad, especially after I adjusted the modulator. How high the rpms get going into fourth depends on how much throttle I am giving it. I'll try adjusting the bowden cable or control rod as kerry suggested and see if that helps any. Thanks for the responses.
Firstly, I'm doubtful that it shifts from second to fourth. More likely shifts from second to third with a quick 3-4 right behind it.

The correct terminology is a "stacked shift".

The problem is typically fixed by replacing some of the springs in the valve body using the Superior Shift kit.

The Bowden cable adjustment might improve it slightly, but don't expect any miracles on that front.
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  #7  
Old 09-27-2009, 02:45 PM
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Ok, just a quick question. I noticed that most of these kits say they are for a 722.3 and a 722.4 tranny. Will these kits also work on my 722.120 transmission?
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  #8  
Old 09-27-2009, 03:10 PM
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Drove my W116 today for the first time in a while. (My wife usually drives it). The 3-4 shifts are nicely separated now.
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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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  #9  
Old 09-27-2009, 05:14 PM
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Quote:
Originally Posted by KJenkins View Post
Ok, just a quick question. I noticed that most of these kits say they are for a 722.3 and a 722.4 tranny. Will these kits also work on my 722.120 transmission?
From memory, the kit won't work on the 722.1 but, you might check with them.
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  #10  
Old 10-02-2009, 09:22 PM
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What tranny is on the w116 300sd? is it the 722.1 or 722.2?
I have a 80 sd with a slight shifting problem wouldnt mind trying superior kit, but that valve body doesnt look like there is much to do there, just had the pan down for tranny service see if things got any better.
Four bolts.
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  #11  
Old 10-02-2009, 11:01 PM
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The 116sd has the 722.120 transmission.
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  #12  
Old 10-02-2009, 11:10 PM
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Dear tbomachines when you say "These cars do not shift down into 1st unless they come to a 100% complete stop."
Are you certain of this? reason i ask is 1st you have a w126 sd it says, i may be wrong,
2nd when i asked the diesels specialist tech(who also happens to be the manager) at the local dealer in my area mechanic why my car downshifts into either 2nd or 1st when i slow down to 25mph and hit throttle again, im not super sure which one it is yet, that it is because in europe there were not design to drive at our speeds such as 25mph, the car will shift into 2nd at just about 27mph, so when i am say going 60 then slow down to a 25mph area and then hit throttle again even lightly at any speed below 27 the car downshifts, im confused now, car only has 100k miles since new and foes thru all gears powerfully and beautifully i just dont understand this well.
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  #13  
Old 03-31-2011, 02:33 PM
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The 4-bolt (722.1) transmissions have the springs up a few layers. I found a diagram once that showed the difference between the 722.1 and later models with six bolts, and it turned out the 4-bolt models are really complex... HERE is a nice diagram for you 722.1 people. It made me abort the fix.

The real question is whether or not we can put 722.x transmissions in place of our 722.1's. I have an 81 300D (non-turbo) with a 722.1 and wonder if I could replace it with either a 116 (300SD) 722.1 or a later 300TD's 722.2 or 3.

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