I have a set of 3.73 gears I want to put in the CLK, but if you change the gear ratio you need to reprogram the Transmission Control Unit (TCU) so it knows how to perform its speed calculations. I could have a tuner modify my stock TCU, but I decided to take this opportunity to replace the factory TCU with a TCM2800 aftermarket controller by Powertrain Control Solutions. I got the controller from Sound German Automotive in Bellevue, Washington. Russell at SGA is a 722.6/NAG1 transmission guru who knows everything you could imagine about these transmissions.
I don’t know whether you would consider this an upgrade or a downgrade, but swapping the CLK55’s front rotating assemblies for a set of CLK320 brakes and wheels will definitely make the car quicker at the dragstrip.
I’ve been running the heavy 18″ Mercedes-Benz E55 wheels on all four corners of the CLK55, which look great, but they aren’t be best for drag racing. Each corner weighs-in at over 50 lb, leaving a lot of room for improvement. The factory CLK320 wheels are the hot ticket for drag radials on the rear, but they also make a good low-budget “front runner”. They only weigh about 13 lb each (because they’re forged), and at 7″ wide you can fit a fairly narrow tire on them. I bought a pair of inexpensive V rated 205-60/16 tires that can be used as daily drivers, while still saving a good amount of weight for the track.
I took the CLK to a bracket race event at the Woodburn Dragstrip on Father’s Day last weekend. The car performed flawlessly in the heat, running some pretty consistent times. Ultimately I won the class by going three rounds with good lights and good dials.
Phase I (Baseline testing) of the CLK build has been completed ahead of schedule. Yay! This is good because driving a mid-13 second “race car” is a little tedious when your daily driver is a low-11 second beast. I’m ready to get on to bigger and better things, but first let’s see how the baseline testing went.
I came up a fair bit short of my goal of running a 13.20 at full-weight, only managing a best of 13.58. A 13.20 might be possible on a really cold day, on a nearly empty fuel tank, and with the spare tire and passenger seat removed, but I haven’t got time for that! I’m ready to call this phase done and get on to the weight reduction.
The 2002 CLK55 that I recently bought came with a set of aftermarket wheels that just didn’t work for me. They were Katana GTM wheels, which look fantastic on the company’s website, but the 18×7.5 wheels didn’t have enough “dish” to look proper on the CLK. The fronts were OK, but the rear wheels had improper offset and were tucked way too far inside the fenders, giving the car an anemic look. Of course it doesn’t help that the 7.5″ wide wheels will only support a 225-40/18 tire.
I decided to solve this problem by killing two birds with one stone. I could sell the Katana wheels and recoup some of what I paid for the car, and I could clean out my garage just a little by putting my old factory E55 wheels on the CLK.
A very common place for a vacuum leak on the E55’s is that port on the rear of the supercharger with a strange multi-piece plug in it. I assume that port is used for the brake booster on cars that don’t have the SBC system, but it is beyond me why the engineers at Mercedes-Benz decided to make a three-part plug to fill it instead of using a simple rubber plug. This is especially strange since there is an existing Mercedes part that seems to work perfectly.
I was at Mercedes Benz of Portland today, trying to get a new plug for my car since the old one is leaking. For some reason the parts diagram on the computer only shows two of the pieces required. It was clear that it would not work without that third piece, so after some head-scratching the parts guy said “Hey, I’ve got an idea!” He ran into the back and two minutes later came out with a plug for the windshield washer on a CLK320 (part number 210-987-00-45) that is the perfect size for the port in the supercharger!
If you own an M113k-powered Mercedes-Benz you know that keeping the intake air charge cool is one of the biggest headaches of the platform. Any supercharged engine will have increased IATs due to the compression of the charge, but the M113K engine suffers more than others because of the size and placement of the intercooler. The intercooler is relatively small, and it sits under the supercharger, in the “V” of the engine. Heat soak is all but guaranteed after each high speed run.
Things get especially bad at the dragstrip because the car spends a lot of time in the staging lanes with no airflow over the heat exchanger, effectively rendering it useless until you start a pass. By then it’s too late and your IAT’s have likely climbed above 90 degrees, which is where the computer starts to pull timing.
There are various ways of dealing with this issue, such as a larger heat exchanger, larger circulation pumps, or methanol injection. I decided to go a different route and use my A/C to cool the intercooler water, courtesy of Kincaid Performance’s Killer Chiller.
I took the CLK to the Woodburn Dragstrip for the first time today so I could get some baseline numbers on the car while it is still full-weight and 100% stock. While not the numbers I was hoping for, I did learn a few things and started the process of getting to know this car’s personality at the track.