When I first bought the CLK back in 2017, I knew the rear end was going to be the weak link. As luck would have it, I found a guy who was selling exactly what I would eventually need in order to make the back half of the car bulletproof.
Those two guys figured out how to mount an E55 differential, with its larger, stronger 215mm ring gear, into the CLK subframe, along with heavy duty Driveshaft Shop axles, rated to 1000 hp. Ahmad currently holds the 1/4 mile record for the CLK with his pass of 9.65s @ 146 mph. Alex is upgrading to a full tube chassis, and just happened to be selling his rear end setup when I was doing my research. I went ahead and bought it from him, even though I knew it would sit in a crate in my garage for over a year. I have finished Phase II of my build (weight reduction), so the time has finally come to put that sucker in!
The giant box sitting in my garage like an unopened Christmas present contains a complete rear subframe with many upgrades. The differential is out of a W211 E55 and it contains a heavy-duty Quaife limited slip diff and Richmond 3.55:1 gears. The axles are from the Driveshaft Shop, and are rated to 1000 hp. The toe and camber arms are on heim joints and are completely adjustable. The other front arms are custom boxed units, which are much stronger than the flimsy factory ones. The diff is mounted on solid aluminum bushings fore and aft. The only thing left to be upgraded are the four main bushings that mount the frame to the body.
Installation was pretty simple. It was just a matter of dropping the muffler, disconnecting the driveshaft, shocks, sway bar, brake lines, and cables, then removing the four bolts that hold the subframe in. The whole thing lowered balanced on my floor jack.
The most difficult part of installing the new one was deconstructing the crate from around the rear end while it was balanced on my jack. Then I just jacked it up into place and put everything back in the reverse order.
I finished it off by installing new CLK320 rotors to save another few pounds of rotating mass.
Once I got the car back on the road, I made it to a Late Night Drags event at Portland International Raceway to get in a few test passes. My first impression is “Damn that thing is loud!” With the Richmond gears, which are known to be noisy, no rear seat or sound deadening material, and solid diff mounts, the whine from the gears is very noticeable. I’m still fighting a 3-4 shift issue, so my 1/4 mile ET did not improve with the gears, but I was able to lower my best 60′ time by about a tenth of a second from my previous best. I hope to do some more testing soon so we’ll see how well the new gears wake up the car on the low end.