1981 300SD starts in which gear?

[tyl604]

Sorry guys, this is an old question that has been answered. I just cannot find the answer again.

I thought the SD shifted to second at a full stop (no idea why) and downshifted to start off in first (low) from a standstill when you hit the accelerator.

Looked and looked on this forum and my lousy CDs (very hard to use) and just could not locate the info.

[Diseasel300]

If you have the 722.3 (which you should), it should take off in 1st gear. Resting in 2nd gear is a 722.1 thing. V8 cars are programmed to start in 2nd, but can downshift to 1st if the kickdown switch is held or the shifter moved to "B" position. 6 cylinder gas cars in the US market have 1st gear disabled for some goofy reason.

[tyl604]

D300 - thanks, was confused. Is the 722.1 for an earlier SD? I seem to remember someone talking about his diesel (not sure) stopping in second and downshifting quickly to get going again.

Now that I think about it my 6.3 started from second unless I really goosed it.

[jsb357]

if it shifts twice under normal acceleration it started off in second

[Diseasel300]

Originally Posted by tyl604

D300 - thanks, was confused. Is the 722.1 for an earlier SD? I seem to remember someone talking about his diesel (not sure) stopping in second and downshifting quickly to get going again.

Now that I think about it my 6.3 started from second unless I really goosed it.

W116 300SD's had the 722.1 transmission and did idle in 2nd gear. The W123 cars with 722.1's do the same thing. The W126 300SD came with the 722.3 from Day 1.

[CantComplain]

I have an '81 300SD and it takes off in 2nd. Part of the cause of it being so sluggish in a thread that's active now. It's an early build (2/81) and I'm not sure if it's 722.3 or not, but going to L is the only way to get it to go at all off the line.

Would love to hear if there's a way to work around it, actually.

[Alec300SD]

For troubleshooting, and testing purposes on my W116's, I made a handheld bypass for the foot operated kickdown switch.
Used a couple of spare MB male and female plug connectors, a spare length of wire harness to reach to driver, and a spare MB courtesy lamp rocker switch.

Tested the concept beforehand by unplugging the kickdown switch, adding test leads to the kickdown harness, and touching the other end of the leads together while seated in the driver's seat.

If you hear the click of the kickdown solenoid on the transmision when testing, this setup should work for you.
Allows operation of the kickdown switch, at will, without flooring the accelerator.

[Frank Reiner]

Originally Posted by Alec300SD

For troubleshooting, and testing purposes on my W116's, I made a handheld bypass for the foot operated kickdown switch.
Used a couple of spare MB male and female plug connectors, a spare length of wire harness to reach to driver, and a spare MB courtesy lamp rocker switch.

Tested the concept beforehand by unplugging the kickdown switch, adding test leads to the kickdown harness, and touching the other end of the leads together while seated in the driver's seat.

If you hear the click of the kickdown solenoid on the transmision when testing, this setup should work for you.
Allows operation of the kickdown switch, at will, without flooring the accelerator.

See the prolonged, and somewhat tortured discussion of this approach in this thread:
http://www.peachparts.com/shopforum/tech-help/411859-test-troubleshoot-kickdown-switch.html

[H-townbenzoboy]

Originally Posted by tyl604

Sorry guys, this is an old question that has been answered. I just cannot find the answer again.

I thought the SD shifted to second at a full stop (no idea why) and downshifted to start off in first (low) from a standstill when you hit the accelerator.

Looked and looked on this forum and my lousy CDs (very hard to use) and just could not locate the info.

My 7/81 build 300SD rolls in 2nd when in D, but if you even slightly press the accelerator pedal, it downshifts into 1st.

[cmac2012]

Originally Posted by CantComplain

I have an '81 300SD and it takes off in 2nd. Part of the cause of it being so sluggish in a thread that's active now. It's an early build (2/81) and I'm not sure if it's 722.3 or not, but going to L is the only way to get it to go at all off the line.

Would love to hear if there's a way to work around it, actually.

My '84 300D rarely goes into first. If I'm going up a steep grade and push the pedal partially through the floor, it somehow finds a first gear it didn't know it had. I gather the W126 SDs have differences from the W123 617s and trannies though I don't know much about them. My '81 300SD seemed more peppy off the line than does my 300D but then I did an amateur jail break on the alda and it had noticably more power immediately after. May have contributed to its premature end, not sure. A painful chapter for me. The body was cherry and the front end was sweet.

[vwnate1]

@ TYL ;

How is it now ? .

The 1981 300SD is supposed to start off in first gear, it doesn't rest in second like the early OM617 W123's did .

My bother has a 1981 300SD and it has always started off in second gear, didn't subtly down shift .

My January 1982 240D with 722.117 slush box was the same until I had it rebuilt, then it would rest in second gear an down shift into first when I accellerated from a dead stop .

To fix this I had to make up a modulator pressure test rig and test and adjust the modulator pressure, it was off and once I had it close to spec the shifting was dramatically better, final fine tuning followed by test drives got it back to where it's supposed to be ~ it should take off in first gear and shift to second so quickly it seems wrong but isn't .

Once that is done 9the correct modulator pressure, tested when warm with the engine running at idle and vacuum line disconnected you can move on to touching the VCV and this will help you get the RPM's where it shifts at where you like them .

Before doing any of this it's important to drain the tranny and torque converter (there's a handy 5MM drain plug on the T.C. making this easy) and replacing the tranny's filter as it's a true paper element filter, not the metal mesh screen American and Japanese slush boxes use so any dirt in it will cause restriction and wrong internal pressures no matter how much you tweak the modulator .

This isn't rocket science nor difficult but it takes time and patience, a thing few have .

You'll need to either jack up and safely block the car on jack stands or find a tall curb and driveway opening and drive to tires up on the curb so you can scrootch underneath the car with the tranny in park, the park brake firmly set and chocks in blocking the tires from rolling .


You're going to get rally filthy doing this but the rewards are great .

YOU can likely do a better job where that any shop because you care and won't rush the job .

[tyl604]

Nate - it shifts fine. I asked the question because someone in another thread talked about his starting off in second gear. I did not think that was right.

Yep, I get three normal shifts.

Thx.

[vwnate1]

Welcome .

It seems to have changed during the 1981 model year .