What donor car is compatible and what years/engines should I be looking for??? So far, everything I have looked at has a 3.07:1 ratio.

Thanks...Robert

2.88 is an 85. Don't know what the ratio is in my 79SD but it seems a little better for mountain driving than my 85TD. 85 is a better cruiser at high speeds on flat roads.

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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

Hello Dr Bert how are things going in Visalia?
My (stock) 85 runs great on the 2.88 - highway or hills (and I drive plenty of mountain roads). I replaced the 3.07 in the '83 300D (now sold) and it ran like it should have from the start. Wow I can't begin to tell you how much of an improvement that made!
If you run a turbo with the ALDA setting mod (I used a copper crush washer under it instead of removing the seal) and the boost lines are not plugged up and (very important!) you have set IP timing to spec THEN the 2.88 differential will really be a very worthwhile swap, better top speed and lower fuel consumption all at the same time. Realizing that Dr Bert has certainly got everything listed (and then some!) perfect, better than spec, I mention those factors because they are important, if you slap a 2.88 into a poorly running (ie. sluggish) turbodiesel you are NOT going to gain anything in fact you may wind up lugging an engine or wearing out the tranny as it down shifts too much, as well as polluting more than it would otherwise.
Oh, yes (personal need) I am interested in finding a low mileage 3.07 for my 220 Gasser. I put the 3.07 out of my '83 300D in it, even though it was a whiner (that was one reason for wanting to upgrade to the taller gears, it was a 3.46 I believe) I really wanted to try it out.
I was told the gasser would bog down with such a tall gearing but as its a strong little puppy with a stick shift it actually works great! Now I want to find a quiet 3.07 diff for it. So if you do find a 2.88 for your W116 please let me know if the old diff becomes available! I can fit a 116 diff in to a 115 or a 123 for that matter. But you need the right spacer rings to fit the half shafts.
DDH in San Mateo

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'95 E320 Wagon my favorite road car. '99 E300D wolf in sheeps body, '87 300D Sportline suspension, '79 300TD w/ 617.952 engine at 367,750 and counting!

^^^ I got a good 3.07 that I like to get out of my storage. Make me an offer!





The 2.47 ratio can be found on the gasser W126 (380se, etc.) up to 1985. If you hadn't already, do a search there is a lot of info of the 2.47 swap.

__________________
1983 123.133 California
- GreaseCar Veg System

Should have a very quiet W116 3.07:1 out of the car next week.

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Did you just pass my 740 at 200 kmh in a 300SD?????

1978 300SD 'Phil' - 1,315,853 Miles And Counting - 1, 317,885 as of 12/27/2012 - 1,333,000 as of 05/10/2013, 1,337,850 as of July 15, 2013, 1,339,000 as of August 13, 2013



100,000 miles since June 2005 Overhaul - Sold January 25th, 2014 After 1,344,246 Miles & 20 Years of Ownership

But that's a 123 chassis, No????

DDH,

Thanks for the informative post. So, you say I can put a 123 diff in my 116.120??? What exactly must I change, other than the speedo????

Robert, you've got to be a bit careful here. All of the previous responses are related to the W123 and early W126. I don't think anyone has addressed the issue of the W116.

I'm not sure of the diff in the W116 and whether it's compatible with the W123/W126.

I'd wait until you got confirmation of that.

They are compatible.

107, 114, 115, 116, 123 and 126 should interchange up to 9/85 with maybe a yoke swap and of course need to possibly correct the speedo.




As far as an actual person doing the swap with pics. Johnhef, put a w116 differential in his w126 in this THREAD.





.

__________________
1983 123.133 California
- GreaseCar Veg System

Thanks........good info for the future.

Donor car???

Thanks, Brian...

I already have the speedo, but since I am starting to drive this car again (daily) any swaps I make must be well-planned out in advance.

DDH,

A bit more on the spacer rings????

OK, back now, yes the spacer rings are also called shim rings, they are different thickness to make up for slight differences in the housings, I found this out the hard way after buying a diff off an SD to put in my 123 300D. I had to get some rings from a friend in another shop to fit the half shafts otherwise they wouldn't lock the clip inside because they were too thick. I was told that MB used to sell a kit of these spacers, you will find one on each side on the outside of the housing where the axles go in. They probably throw them out at wrecking yards.

__________________
'95 E320 Wagon my favorite road car. '99 E300D wolf in sheeps body, '87 300D Sportline suspension, '79 300TD w/ 617.952 engine at 367,750 and counting!

Could you post some photos????? Are the seals/axle shafts the same??? I'm looking at doing this swap to a 2.88:1 soon...Robert

I drove the car this weekend for the first time since my son's April 21, 2006 traffic accident. Originally, I thought going away from the 3.07:1 axle would be a mistake, but after driving the car, I have changed my mind. This thing has so much torque, right off idle, especially with the 2-1 downshift as you release the foot brake, that the higher gear shouldn't be detrimental at all.

I'm still looking for a 2.88:1 but everything so far has a 3.07;1 axle under it. Guess I will start looking at the 126's chassis cars now...Robert

DDH,

Is any one donor car preferred over another????