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  #1  
Old 04-25-2006, 07:57 PM
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Really confused - Auto Transmission 1978 300D

I looked at trying to make some adjustments to my transmission today because of late shifts, especially when cold. Sometimes, to get the car to shift into the next gear, I have to let off the accelerator, otherwise it really shifts late.

Anyway, I have the 722.118 transmission, serial number ending with 050484 (see link below where the listed modulator is for AT's with the last 6 digits of the transmission serial number FROM 086899). So, I'm confused - no vacuum control and no bowden cable??? I can find neither - no vacuum lines running to the transmission, so can you make adjustments? Is there vacuum somewhere that I am overlooking?

http://catalog.eautopartscatalog.com/mercedesshop/sophio/wizard.jsp?partner=mercedesshop&clientid=catalog.mercedesshop&baseurl=http://catalog.peachparts.com/&cookieid=1QE0XP3HK1SD14BNVC&year=1978&make=MB&model=300-D-002&category=J&part=AT+Modulator+Valve


ryan

1978 300D
1972 250
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1984 300D
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1986 560SL
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  #2  
Old 04-26-2006, 02:45 AM
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Ryan... see my http link for 722.0 / 722.1 / 722.2 series modulators

I have a 1980 300D with a 722.118 tranny with 098161 S/N so that explains why mine has a vacuum modulator... but yours !?

Take a look at the following link that seems to me is implying that all 722.0 / 722.1 / and 722.2 series M-B trannies should have a modulator.
Note that this listing does not make any reference to S/N(s) !??

http://www.bulkpart.com/Merchant2/merchant.mvc?Screen=PROD&Store_Code=2&Product_Code=58160D

And you say your tranny has NOTHING... no vacuum... no mechanical interconnection to tell the tranny how much you are pressing down on the throttle??

Something is missing from your story... that is unless you have one of those rare Claire Voyant trannies that M-B experimented with years ago… is this possibly a stick shift in disguise?!

Sam
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  #3  
Old 04-26-2006, 02:49 AM
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Hmmm, I'll try and remember to go crawl under the '77 tomorrow and look for a modulator, since it is an earlier model than yours. I can't imagine yours not having a modulator. But then again, I'm not that smart either....
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  #4  
Old 04-26-2006, 08:10 AM
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I am not sure of this , but I THINK some of the 722.1xx trannys had an internal mechanical modulator and no bowden cable or crank from the throttle. Seems to me I remember running across some of these critters in the boneyard. My 722.1xx in my 77 240D and my 722.120 in my 80 300SD have vacuum and throttle inputs, FWIW.

I wouldn't go by the catalogs- MB did a lot of tinkering with those 4-bolt trannys. You might want to check with someone like Steve Brotherton or Jaggie (jie.com , I think), one of the rebuilders, for specifics.

Rick
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  #5  
Old 04-26-2006, 10:20 AM
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I played around with my Trans on the 77 300D a bit. You have a "TV" Rod no Vac-Mod. The TV rod connects to a turn buckle on the right side of the engine along with the "throttle" (Accellerator pedal) linkage. If you shorten the length of it will allow the trans to build less presure and shift earlier. If you lengthen it, it will shift latter but may slip or flare. You need to find the right combination. There is also a bolt that can be removed from the right rear of the trans that allows access to a sort of K1 type spring. You can tighten it to reduce slipping. But I heard that if it is to tight it can lock up trans, I haven't adjusted my spring yet. I'll search for a post I had that contained some very usful info on these Trannys, and post it for you.
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  #6  
Old 04-26-2006, 11:18 AM
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I found what the last post discussed (by 97E300D) - if anyone can find info on how to adjust this linkage, I would appreciate it. I'll look for the post....

thanks.

ryan
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Old 04-26-2006, 11:25 AM
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You lengthen the rod by scewing in or out the end of the rod which is a ball link.
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  #8  
Old 04-26-2006, 11:56 AM
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Just to be sure - where exactly do I turn the rod and will it turn by hand?

ryan
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  #9  
Old 04-26-2006, 12:17 PM
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The Rod runs from a lever on the right side of the transmission to the turn-buckle on the side of the engine. You can unsnap one end of the rod from above if you reach through the engine bay or or the other end from bellow from the transmission. I think you'll need to back off the locking bolt with a wrench and turn the Ball joint end. (see Picture) http://img.eautopartscatalog.com/live/J407011930LEM.JPG you have one of these on each end of the TV rod. When I boought my 77300D it ran great but would just shift quick 2nd 3rd 4th. The day after I got it home I noticed the TV rod was disconnected. Boy was I happy when I drove it and it actually shiffted, It took a little adjusting to get it right. Mine still shifts a little late but thats better then slipping.
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  #10  
Old 04-26-2006, 12:25 PM
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Actually if I remenber correctly only one side can be adjusted, thats the side nearest the engine on the turn-buckle. The turn buckle again, is on the right side of the engine and connects three rods: 1) TV Rod running to the transmission, 2) Accelerator rod running to a the linkage from the foot pedel, 3) a rod running to the linkage on the valve cover that leads to the Injector pump.
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  #11  
Old 04-26-2006, 09:03 PM
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It looks like you are in good hands and on track Ryan...

Ryan [ rgnprof ],
I'm glad that others who recognized what your 300D has under the bonnet has picked up on your thread. Actually your tranny's shifting sounds like its all mechanical and actually much simplier than the later models [ many different versions too ] that used vacuum and many different "gizmos" to simulate load/demand and communicate this to the tranny. In a way I wish I had your older mechanical system.

Sidebar Q? - What does yours have for "kickdown" to send a "kick it in the axx" message to the tranny so it will drop back at least one gear?

I'm glad you are in better, more knowledgable hands now... all the luck with your beastie!
Sam // Novato, CA
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  #12  
Old 04-27-2006, 09:48 AM
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There is still a kickdown that works off the button on the floor under the accelerator pedel as well as the pressure from the tv rod input.
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  #13  
Old 04-27-2006, 09:57 AM
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Tranmission

The MB manuals spells out how to do this, each linkage should be a certain lenght in MMs, Haynes manual aslo gives details on this. I am planing to do it on my 79 300D as soon as i am finished with the engine.
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  #14  
Old 04-27-2006, 11:21 AM
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Thanks for all of the help -my kickdown switch works fine, just like described - but I don't have any FM, or Haynes information on this car - how many mm's etc? All of the online manuals do not have any transmission information. Anyone have another source? I keep looking to purchase a Haynes - see them on eBay.

ryan
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1972 250
1986 560SL
1991 300CE
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  #15  
Old 04-27-2006, 12:13 PM
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78 300sd

Does my tranny have the tv rod and not the vac mod?
Thanks!
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