Can anyone out there tell me if the 3.07 ratio rear diff in the W209 CLK55 (and also in the C55) is interchangeable with the rear diff in a W208 CLK55? I have always thought my '01 CLK55 could benefit from a bit more "gear" out back, but a "custom" or aftermarket rear diff. is awfully expensive. If the W209 unit is a direct swap, that would be worth looking into, as I am sure there must be a few out there followng an unfortunate front-end total-loss collision.

 

...........why would you want to use a diff from a different chasis? you can easily get a 3.07 diff from W208 CLK320.


Ted

 

See, THAT'S why I love this board. I didn't realize that the CLK 320 came equipped with the more aggressive rear end. But that makes sense. As the 320 clearly doesn't produce as much power down low as the 430, it needs all the help it can get. After reading your post, I recalled that my wifes old ML320 spun noticably higher at freeway speeds than her new(er) ML55 at the same speed: about 250 rpms more.

Now, do you know if the 3.07 rear-end in the CLK320 is essentially the same strength and durability as the unit in the AMG model? Isn't the 2.82 in the AMG limited slip? I.E. even if it doesn't have as aggressive a lock up percentage as one might like, does it provide greater LS lock-up than the 320? The ratio is what I'm looking for as long as the "innards" are the same. Maybe that would be the advantage of using a rear from a W209 AMG car if it fits.

 

I'm not sure if they are the same strength but the AMG car are limited slip. They use ESP and BAS just like all the other cars. You will still need a tranny ECU module to run the new lower gears. I would go with a 3.27 if you are going through all this trouble. You might notice the small jump with a 3.07
Mario

 

The only AMG car that comes standard with a LSD is the SL65. Typically they use ESP to create the illusion of LSD.

 

.............Indeed the only MB that comes stock with LSD is the SL65. To modify your gear ratio, you not only need to change the ratio but you need to also change the transmission control unit or otherwise reprogram the ECU to accept the new ratio. Some older W210 and w208's have ECu's that cannot accept such programming. The easiest way is to get bothe the 3.07 diff and the control unit from a W208 CLK320. The non amg diff will be smaller and may be less durable. I do not know if the 3.06 diff from a W209 CLK 55 will fit your car.

Ted

 

Ted,

Many thanks for the valuable info. MBs are apparently more sensitive to this type of tinkering than their BMW neighbors. I swapped a 3.91 LS diff. from a 92 M5 into my auto equipped 92 850 and it was simply a matter of turning bolts. Direct fit replacement, no need to mess with the ECU. Just bolt in, add REDLINE fluid and GO! I think I may stay away from a rear diff mod on my CLK55. I get the feeling RennTech is pretty well regarded on this board and they offer a mild ECU upgrade and airbox combo that I may try instead.