Keep in mind that these little engines have really nice torque so no problem what so ever from a standing start, I actually feel like its faster. Before 1st was a throw away gear, basically you came out at 5 or 10mph, now you can stay in it up to 20mph. I'm using standard wheels and tires. It's a completely different animal from before and I couldn't be more pleased. Mercedes just had it geared way too low.
No fuel consumption data yet but expect a nice bump up.
The 85 SD is a w126 and this chart shows it's probably not compatible:

differentials, gear-ratios and compatibility | Mercedes-Benz turbo

Actually, 1st-gen W126 1.1L rear ends fit into the W123.

The 300SD 81 - 84 3:07 and 85 2:88 Diff will fit in a w123. The spedo`s will not.
They are electric. The w1123 are mechanical. And the shape is different.

I have an 80 240D as a DD, and do not see how you get to 4th gear at 25mph.
When I drop to 40 mph I grab 3rd gear to keep the eng at a proper RPM range w/o lugging.

I swapped in a 3:58 Diff from a 280E so I could have the 150mph spedo.
That small of difference did not make any difference from a start.
But going to a 2:88, I would say you are on the edge of lugging the engine and slipping some on the clutch.
We are talking about 67 HP here.

I swapped in a 4-spd in our 85 300D, and it has the 2:88 Differential. For the most part it is ok.
But try starting on a steep hill, and you are going to be reving the engine and working the clutch just to get her going. Most highway grades are ok, but I was on a friends
very steep driveway. I needed a couple gears lower than 1s gear.

There is a guy with a 240D some place in Kansas that installed a 3:07 in his 240D, and has good luck with it.
But Kansas is pretty flat.



Charlie


sent from my pos computer

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there were three HP ratings on the OM616...

1) Not much power
2) Even less power
3) Not nearly enough power!! 240D w/auto

Anyone that thinks a 240D is slow drives too fast.

80 240D Naturally Exasperated, 4-Spd 388k DD 150mph spedo 3:58 Diff

We are advised to NOT judge ALL Muslims by the actions of a few lunatics, but we are encouraged to judge ALL gun owners by the actions of a few lunatics. Funny how that works

I don't agree that Mercedes had it geared way to low. I think it probably just needed the the 5th gear that you could get in Europe.

I'm also having a hard time wrapping my head around crawling around at 25 in 4th. With mine I'm flat to the floor in 3rd before I get around to shifting up to 4th at around 40 to 45 depending on traffic conditions.

- Peter.

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2021 Chevrolet Spark
Formerly...
2000 GMC Sonoma
1981 240D 4spd stick. 347000 miles. Deceased Feb 14 2021
2002 Kia Rio. Worst crap on four wheels
1981 240D 4spd stick. 389000 miles.
1984 123 200
1979 116 280S
1972 Cadillac Sedan DeVille
1971 108 280S

Exactly. 4th is of no use below 40mph in a 240D. At 25 in 4th some SERIOUS lugging would be going on and that's very bad for the engine.

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'84 190D 2.2 5MT (Red/Palomino) Current car. Love it!
'85 190D 2.2 Auto *Cali* (Blue/Blue) *sold*
http://badges.fuelly.com/images/sig-us/302601.png
http://i959.photobucket.com/albums/a...0/sideview.png

Most of the "5th geared" vehicles have a lower geared differential to remove the benefit!

I think on the whole the W123 was built for a different time where road speeds were slower.

If in the US of A the old fashioned 55mph maximum was forcibly regulated the gearing wouldn't seem too slow!

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1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!