300D/TD Diff into 1982 240D - Page 2 - PeachParts Mercedes-Benz Forum

jaysun9 · #16 03-24-2009, 01:15 PM

LutzTD, where did you get the 2.47 diff? I've got the 84CD and would be into trying that out. Thanks

t walgamuth · #17 03-24-2009, 07:29 PM

Quote:

Originally Posted by ForcedInduction

A 3.07 is not a 2.88. A 3.07 is borderline in a 240D, less so with an automatic.

Its all about the point of diminishing returns. With a 2.88 the engine RPM may be lower but a 616 will consume more fuel working harder to push the car.

You also have an extra cylinder and a turbo to increase torque.

the fellow considering the 288 has a 300 not a 240....

or did I misunderstand?

lutzTD · #18 03-24-2009, 07:48 PM

Quote:

Originally Posted by jaysun9

LutzTD, where did you get the 2.47 diff? I've got the 84CD and would be into trying that out. Thanks

I removed it from a gasser SEL. but I do not know what year. i have been told it has to be earlier than 1985 i think since there was a change in the way the diff mounts on the SEL. It bolted right in after I flipped the rear mount and all I needed to do was change the 3 bolt flange on the pinion. be sure to read up on how to remove and reinstall a pinion as I did not do it correctly and I dont want to tell you how to do it wrong.

daddi · #19 03-25-2009, 06:49 PM

Quote:

Originally Posted by holtonmusicman

I've replaced both rear half shafts on my 240D. While cleaning off the differential I noticed that the rear ratio is 3.69:1.

I know the 300 series have a "lower" ratio.

Are these a bolt in replacement? I'm not necissarily looking for better fuel mileage (but if it was even marginally better that would be a bonus) but more of a wear factor.

I drive almost 100 miles a day, most of it highway, and lowering my engine/tranny RPM (even 10%) would be beneficial to me.

I have access to a very inexpensive 300TD diff and can get a 300D diff.

Any information would be appreciated...I used to have a link to which diff would bolt in, but never thought I'd change mine out, until now. I didn't realize the ease of replacement on these units.

After Ident 108333 240D has the same ratio as the 300D so using it is ok, i have a diff from a 300D in my 240D no difference.

t walgamuth · #20 03-25-2009, 10:29 PM

That is not normal. NOrmally a 240d has a 369 diff and a 300d normally aspirated has a 346 diff. It may be different in Iceland though!

charmalu · #21 03-26-2009, 01:38 AM

Quote:

Originally Posted by jaysun9

LutzTD, where did you get the 2.47 diff? I've got the 84CD and would be into trying that out. Thanks

I pulled two 2:47 Differentials, both out of w126 gassers. one out of a 85 380SE and the other out of a 83 SEL. just start checking out the PNP for 126 gassers. the gear ratio is on the L/R corner the the Diff. stamped into the metal facing the rear.

the 86 thru 91 have a totally different way of mounting and will not adapt to the w123.

Usually you will have to change the spedo from the doner car to keep things calibrated. The W126 has an electric spedo and the W123 is mechanical. There is no W123 spedo that will calibrate to the 2:47. the closest is one out of a 85 with the 2:88 Diff.

If my math is correct there is a 14.23% difference 2:88 to a 2:47 or a 420 RPM drop. 3:07 to a 2:47 about 24%.

Charlie