Hello gentlemen,
Could anyone please help clarify what the lowest differential ratios found in the US are, which are bolt-in into a W201 or W124?
Even better if it is a somewhat common model as a opposed to a rare low-volume application. Also, I am only interested in open differentials.

The 190D 2.0 5-speed and 190E 2.6 5-speed came with 3.92 and 3.91 differentials, but those were only available in Europe. The US-spec 2.6 5-speed is very rare and did not receive the 3.92 differential.
The only other cars with these ratios are various W201 and W124 taxi cab models in Europe, I believe.

The 190D 2.5 5-speed, 190E 1.8 5-speed, and 250D came with 3.67 and 3.64 differentials, but once again the 1.8 was only available in Europe, while I am not sure if the 2.5 diesels came with that ratio in the US, not to mention the manual model is quite a rare find nowadays.
Did any cars in the US come with a 3.6x (or higher) differential?

The next step up (down) seems to be a 3.46 differential. Since I am doubtful any of the lower ratios can be readily found in the US, I would really like to at least find this size. It supposedly came in various W201 manual models, though I believe those models received 3.27 and 3.07 ratios in the US.
However, it is also listed as the ratio for 300D NA models.
Can anyone confirm if the OM603 W124 received this differential in the US?

Are there any other low ratio options or models I missed?
For example, I believe R129 differentials are also interchangeable with the W201 and W124, but I have not been able to find much information on their ratios.

Any input is welcome.
Thank you.

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Irony.cc

You need to determine ring gear diameter / case volume or the diff you have in the car. Once you do that you can search other cars. Some common ring gear diameters are 185 mm 196 ( 195? ) 210 . There are various case volumes ( this is the amount of oil used ) and sometimes a reinforced case.

Next you need to figure out what axle length will work with your track width and diff. There is a 124 performance site that has a few pages of diff numbers and interchanges but it isn't complete.

The OM603 turbo ('87 300D & TD) in the U.S. have a 2.65:1 final drive. You're definately going the wrong direction looking at diesel-automatic cars. The highest ratio 201/124 cars in '87 were the 190E 2.3, 190E 2.6, 190E 2.3-16v, and 260E (all transmissions same on these cars) at 3.27:1.

__________________

Gone to the dark side

- Jeff

Early US 300Es have a 3.07 axle ratio, but 2.87 in later years. I don't recall the first year of the change, and I believe both autos and manuals (in the years manuals were available in the US) use the same ratio.

The early 260E and 190E 2.6 are 3.27, auto or manual, but I'm not sure about later years; 190E 2.3 16 has a 3.27 limited slip.

The 300SE got a 3.46.

I believe the carriers for all the above models are essentially the same and interchangeable.

Duke

I pulled a 3.46 from a 300SE and it won't fit the w124. I parted out a 92 300SL with a 3.69 210 mm that'll fit the W124 with the right axles from a W124

Ive got a 3.69 in a 94 124 cabriolet in our shop right now, car is grey market
5 speed automatic

Dave (sixto) has some interesting information in this PDF: http://www.w124performance.com/docs/mb/W124/ASD_Differential_Retrofit.pdf

__________________

Gone to the dark side

- Jeff

Just researched the R129 diffs a bit more and it seems that the 300SL's with the M103 came with a 3.92 differential.
Can anyone confirm whether this is the case for US models as well? And will they fit into a W201?
I know that the larger pumpkin cases in the W124 have 129 numbers stamped into them, so if W201 and W124 differentials can interchange, I would think the R129 would fit as well. Unless it is physically too big to fit the 190E subframe.

I do not mind swapping axles or the input shaft, as long as I know what needs to be swapped.

Thanks for the input so far.


Great information, thank you.

According this, I am guessing an R129 differential will not fit into a W201, because there is no four-bolt cover that will swap onto it. However, I would assume it is possible to put an R129 differential into a W124.

__________________
Irony.cc

info on axle ratios

http://www.w124performance.com/service/w124CD2/Program/Chassis/rearaxle/function185.pdf

http://www.w124performance.com/service/w124CD2/Program/Chassis/rearaxle/function210.pdf

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07 E350 4Matic wagon, 06 S430 4Matic, 99 SLK 230
retired W210 (x3), W124, W126

The 300SL never came to the USA with a M103 it might be possible to fit a 210mm differential into a 190