W124 First gear start and Transmisson question - PeachParts Mercedes-Benz Forum

broken4door · #1 06-22-2010, 11:43 PM

Application

1987 Mercedes 300d with a 722.31702

Hey everybody, newbie question, from what I have researched from this very informative site, is that the K1 spring improves shifting from 2-3 gear, got that.

What modification or what parts are needed will allow a 1987 300d to automatically start in first gear from a complete stop without, manually shifting into D2?

I ask because I am going to have my transmission rebuilt in the next few days due to the neglect of the previous owner, the trans fluid came out looking darker then the motor oil.
I ordered a new transmission motor mount, Bowden cable, Modulator, transmission /torque converter drain plug from the dealer today.
So any help/ input well be very much appreciated

Thank you for your time

Jeremy5848 · #2 06-22-2010, 11:52 PM

Unless there's a problem with your transmission, it should always start in first gear.

broken4door · #3 06-23-2010, 02:10 AM

Quote:

Originally Posted by Jeremy5848

Unless there's a problem with your transmission, it should always start in first gear.

Thank for the reply Jeremy, I noticed that you sig show a 1987 300D.

Do you feel a difference in acceleration if you start in "2" VS. "D"?

From my understanding, the later (1990's) W124 built after would start off in 1st gear but the w124 built int he 1980's in second gear, unless you had the Gear selected in “2”.
There have has been information that I have seen about Valve body modifications, but I haven’t found any concert information. Perhaps my transmission isn’t functioning correctly, it was abused by the previous owner.

babymog · #4 06-23-2010, 09:12 AM

Your information is correct regarding the 300E (gas), they start in 2nd. The 300D however, starts in first.

It is possible that the transmission had problems and someone put in a gasser transmission or valve-body. it is also possible that you have low pressure in your transmission (internal leaks?) and it isn't able to downshift to 1st with the rpm at idle.

Oldwolf · #5 06-23-2010, 09:39 AM

My 93 starts in 1st gear when in Drive. When I start out in 2nd, it begins in 1st and then to 2nd but no higher.

tangofox007 · #6 06-23-2010, 10:10 AM

Quote:

Originally Posted by broken4door

What modification or what parts are needed will allow a 1987 300d to automatically start in first gear from a complete stop without, manually shifting into D2? [/FONT]

If the transmission is not downshifting 2/1 under slight load, the Bowden cable tension would be the first item to check. Throttle valve springs would be the next. From a stop, the transmission should not remain in 2nd except when under essentially no load.

Jeremy5848 · #7 06-23-2010, 12:11 PM

Quote:

Originally Posted by broken4door

Thank for the reply Jeremy, I noticed that you sig show a 1987 300D.

Do you feel a difference in acceleration if you start in "2" VS. "D"?

My daily driver is indeed a 1987 300D Turbo (W124, OM603). The transmission is a 722.317 mechanical/vacuum 4-speed. It is the car's original transmission; the serial number agrees with EPC and the correct VIN sticker is on the bell (see pictures -- the serial number is in the casting on the right side and the VIN sticker, last six digits obliterated for security, is on the left side). AFAIK the transmission works correctly and the Bowden cable and VCV are correctly adjusted.

I do not feel any difference in acceleration in starting from D" versus "2." However, if I were to use very little throttle, the transmission would almost immediately and imperceptibly shift into "2" and the car would accelerate more slowly. More throttle causes the transmission to stay in each gear longer. There is a Bowden cable in the throttle linkage that goes to the transmission; it controls the shift points -- yours may need to be tightened.

If I put the selector in "2," the transmission starts out in "1" and stays in "1." Unless I manually move the selector to "3" or "D," the transmission will not upshift. With the selector in "3," the transmission starts in "1," shifts to "2" and then "3" and stays in "3."

To get the transmission to shift to "2" and stay there, I have to start out with the selector in "2," then move the selector to "3" for just long enough to allow the transmission to shift from "1" to "2." After a second or so I move the selector back to "2." The transmission will stay in "2" until the car comes to a stop or you move the selector out of "2." This procedure is a bit of a pain but is the only way I know to keep the transmission in "2." You can also use the kick-down switch for this purpose but you will be at full throttle, not the best solution for following a slow truck up a long no-passing hill.

EDIT: Based on the 1986 "Introduction into service" manual for the 300D Turbo (W124, OM603), in position "2," the transmission should shift from 1st to 2nd and stay there until you stop, when it downshifts back to 1st. So maybe there is something wrong with my transmission.

Jeremy

Oldwolf · #8 06-23-2010, 12:16 PM

Can someone explain the effects to the shift points when you "tighten" and "loosen" the Bowden cable please?

babymog · #9 06-23-2010, 12:39 PM

Tightening or shortening the Bowden cable will raise the shift RPM. Loosening/lengthening will give you earlier shifts (lower RPM).

The '87 300D/300TD NEVER starts in 2nd gear, contrary to a couple of the posts above. If it does, there's something wrong or something has been changed.

tangofox007 · #10 06-23-2010, 12:56 PM

Quote:

Originally Posted by babymog

The '87 300D/300TD NEVER starts in 2nd gear, contrary to a couple of the posts above. If it does, there's something wrong or something has been changed.

The MB operating manual for the 722.3 transmission suggests otherwise. Have you seen it?

Jeremy5848 · #11 06-23-2010, 01:46 PM

Quote:

Originally Posted by tangofox007

The MB operating manual for the 722.3 transmission suggests otherwise. Have you seen it?

Tango, you are right up to a point. Various models of MB have 1st or 2nd gear start based on type and power/torque of engine, weight of vehicle, etc. The transmission is set up by the factory to be a compromise that they hope will appeal to most drivers. In particular, the 722.3 and 722.4 transmissions can be set up to start in either 1st or 2nd gear, hence the notes that you have found in the transmission manual.

As specifically regards the 1987 300D Turbo, I first want to point out that the 1986-1995 W124 models were preceded by the 1984-19?? W201 models (the 190D/E, etc.) and many of the features that are found on the 124s were first introduced on the 201s. The 1986 "Introduction into service" manual for the 124 is full of comments like "similar to Model 201."

So, in the 1984 "Introduction into service" manual, Model 201, Section 27, page 11, the factory notes that "On vehicles with engine 601, the transmission [722.4] starts in 1st gear in all forward driving positions . . ." The manual goes on to note that the gasser version, which has the same transmission, starts in 2nd gear. [Model 201 used the 722.4 transmission, which is similar to 722.3 but handles less power.] In this version of the transmission, 2nd gear remains engaged at idle "to prevent creeping." The transmission immediately downshifts to 1st when you "step on the gas."

The 1985 "Introduction into service" manual repeats this information, specifically noting one change, that the 722.4 now downshifts to 1st gear "when coasting to a stop." [Models 107, 123, 126, 201, Section 27, page 97.]

The 1986 "Introduction into service" manual introduces the W124 chassis and, in the table of shift points for the 722.3 transmission [Section 27, page 185] footnotes the Model 124.030 [gasser] "starts in 2nd." This same 722.3 transmission, depending on whether the car is diesel or gasser, is "wired" to start in 1st or 2nd. Thus, although the the OP's car is probably just maladjusted, it could have had a gasser transmission installed at some point in the past. The OP can check the serial number of his transmission against EPC to see if his is the original.

This is also a warning to all of us to be careful when we replace transmissions. I have no idea what parts are changed to make a 1st gear start into a 2nd gear start or vice-versa. Perhaps another forum member might explain.

Jeremy

broken4door · #12 06-23-2010, 03:23 PM

Wow!! you guy a amazing!!

babymog: thank you for explaining the difference between the gas and diesel transmissions/valve body's

Jeremy5848: thank you for explaining in detail the shift patterns of your 1987 300d and for the pictures.

You guys are an encyclopedias of information!! My car was purchased as a "walking wounded" it would shift, it only stayed in 2nd gear, so i completely changed all the transmission fluid with very cheap surplus ATF. The fluid went from completely dark like the motor oil, to a lovely shade of cherry Kool-Aid.

So as babmog mentioned there might be "internal leaks" that is highly possible, the prevoius owner drove the car untill the transmmison stayed in 2 gear. The transmssion matches the Vin on the car, so its should be orgnal. My parts arivied from the dealer: "transmission motor mount, Bowden cable, Modulator, transmission /torque converter drain plug" So the next stop the the transmmsion rebuild facility.

Guy thank you very much for you help! With out you help and this website, this wounded car would have been first in line at "Pick-A-Parts"

camshaft190 · #13 10-04-2010, 10:15 AM

I came accross these in a different forum. I have not tried the spring position swap on the gov boost valve yet. My W201 starts in 2nd (rebuilt trans) which I do not like and will be trying this once I get the K1 kit too. Has anyone here tried this yet?

camshaft190 · #14 10-05-2010, 04:43 PM

W124 First gear start and Transmisson question-cimg8292.jpg

Sorry if the images weren't working (i was getting little red x boxes), now they seem to work. Anyone know if this spring swap on the gov. pressure boost valve would result in a 1st or 2nd gear start depending on position?

Looks too good to be true, I'd really like 1st gear starts, any ideas?

If nobody knows, I'll take a stab this weekend while I do the K1 spring kit and report back.

booker_noe · #15 01-21-2011, 06:19 PM

Hey camshaft190,
did the spring swap work for you?
do you now get 1st gear starts ?
Cheers,
Booker.