rear differential replacement options - PeachParts Mercedes-Benz Forum

forcefed44 · #1 12-23-2008, 12:16 PM

I'm looking for some rear differential options for my US spec. 380SE. What is there out there available that would give the car a bit more oomph..

JimFreeh · #2 12-23-2008, 12:39 PM

There are two different differential cases on the W126 cars.

The 5 & 6 cylinder cars use use a 1 liter capacity case, the V-8 cars use a 1.3.

Not sure what was used on the 380SE, but the diff for your car was used on the W116 and R107 chassis as well.

I think the lowest (numeric) ratio is 3.07 found in the 450 series of both the W116 and R107. Late V-8s used a 2.47 diff.

Ratios down to 3.69 can be found in the 1 liter case, generally used for the M110 engined cars, but this diff may not be robust enough for even a M116's torque....

Jim

forcefed44 · #3 12-23-2008, 01:15 PM

SO I attest the 3.07 would be what I would be looking for? I was made aware that the 86' and up had a deffenret mounting due to the heatsink fins ergo I would need something from 85 down (Gen 1).

pawoSD · #4 12-23-2008, 04:23 PM

A 3.07 from a 300SD would surely make it quicker, but it would run at higher rev's and use more gas.....and more engine wear.

forcefed44 · #5 12-23-2008, 06:56 PM

What would be the next step from the 3.07 since I don't want to rev like my non MB's on the highway. I just want this to keep up somehow with my euro 380SE. obviously there is a big performance differance but I figure with the rear needing to be replaced and the center support bearing on it's way out.. I'd do it together and kill 2 birds with 1 stone.

Johnhef · #6 12-23-2008, 07:56 PM

1985 SD's had a 2.88. That'd be your next option.

That said, I'm going to a 3.07 from a 2.24 for my 500SEC.

Roncallo · #7 12-23-2008, 09:26 PM

Quote:

Originally Posted by forcefed44

SO I attest the 3.07 would be what I would be looking for? I was made aware that the 86' and up had a deffenret mounting due to the heatsink fins ergo I would need something from 85 down (Gen 1).

I cant speak for the 126 series but for the 107, in 86 when the 560 came out they went to a bigger rear which forced them to move the mounting. However in the later 107's the old mounting holes are still in place in the chassi. You just need to remove the rubber plugs and put in the threaded insert plate. I believe this may because the 107 was available with a 6 cyl in Europe and probably used the smaller diff. So the 1986+ 107 is backyards compatible but I don't know if the older ones would be forward compatible. I would suspect the 126 may be the same situation.

Johnhef · #8 12-24-2008, 11:48 PM

Unfortunatly not. The subframe unit itself was changed from gen1 to gen2, and diffs wont interchange without a whole lot of modification as I found out. I originally thought all I had to do was swap the rear cover plate, but after getting a 2.47 gen2 rear end, I found it wouldn't work.

Jim B. · #9 12-25-2008, 11:25 AM

I am going from the factory 2.47 on my '91 560SEC to a 2.65 because I'd like more grunt from the lower end, and don't mind scrubbing a bit off the 152 mph I once saw on my car as it is now.

The vintage AMG Gen II catalogue, on its differential options page describes the available ones as going from the "mild" 2.65 all the way to the "neck-snapping" 3.46, (with the other available AMG diff ratios being 2.82,3.07 and 3.26)

forcefed44 · #10 12-28-2008, 08:52 PM

There for the 2.88 would be a better option combining the acceleration as well as the highway, well I understand it'll be a bit lower but I have only taken the 380 to 110mph so far. In your opinions, would you choose the 2.88 or the 3.07?

Johnhef · #11 12-28-2008, 09:09 PM

If you're driving the car a lot, I'd probably go with the 2.88

I'm opting for the 3.07 because my car sees a lot of autocross and track events.

forcefed44 · #12 12-31-2008, 10:04 AM

I'll keep an eye out for the 2.88 or the 3.07. I don't drive her much at all. She sleeps side by side with the import 380SE and 500E. Thank god they are all black...

Johnhef · #13 01-04-2009, 10:00 PM

mines already off with a US speedo in a euro car, who cares? I just use a GPS for a speedo now.

Johnhef · #14 01-07-2009, 09:59 PM

not always. my 83 has flanged axles.

why would you need to change the subframe if youre using the 3.46 housing with the 560LS? it'll be the same as whats in your 84 now.

Johnhef · #15 01-10-2009, 12:13 AM

I put the 3.07LS from a 1973 450SE in my car last night. Everything worked perfectly. Thanks to Pooka on here for saving it for all these years