Hey guys I'm new here and did a bit of searching and didn't find much info on this but I have a 2004 sl55 amg. I got a complete rear lsd diff with 3.06 gears out of an sl63 and I got a tcu out of an clk55 with the same 5 speed transmission and 3.06 gears from the factory so it should go together and work together. I've been too busy to install the diff and tcu but figured I'd ask around and see if anyone here has done this and how they feel about the change. I only drive the car maybe every 2 weeks for about 50 or 60 miles so I'm not super worried about losing gas mileage at highway speeds but also don't want to be screaming at 80mph.

the car is completely stock at the moment at most I would go to a 83mm pulley with a tune.

Kind of hoping someone has done it and tells me amazing and lights a fire under me to find time haha.

 

I wouldn’t do it, it already has a 2.82 I believe. The 3.06 will be about 2700 rpm at 80 mph. In contrast the e55 turns about 2100 at that speed

 

Did you make sure your car has the updated hag215 rear end? Because some 2004s had the hag210 bolt on style still. You can see which one you have by looking at where the rear axles connect to the differential. If there are bolts that connect them it is hag210 and will require new axles and such, if not and the axles are slipped into the differential it will work P&P. Also the tcm can be recoded to work with the 3.06 rear end.

 

I would not do it either - the car is traction limited as it is, so putting in a shorter rear will just see the TC light flashing more often.

 

I do have the hag215 already and i didnt want to mess with the tcm so I could have both diffs avaliable if I want to change back for any reason.

 

The clk55 has the same transmission and 3.06 rear end ratio from the factory so it can't ve that bad on the highway.

 

if you know someone with a star computer it is a very simple menu selection, also it may have different coding because of the much less torque of the clk

 

l have an e55, cls55, c55, c32 and an sl55. The c32 and the c55 with the 3.06 gears just spin too high for driving on the highway at today’s speeds. The cls and the e are great at these speeds. It’s just unnecessary to spin this engine at 2700 rpm to drive 80mph.