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.
If you are looking for better traction for your E55 you have come to the right place! The hot ticket for cutting your 60′ times is a set of Hoosier DOT Drag Radials mounted to OEM Mercedes CLK320 wheels.
The rearward bushings in the front lower control arms of the W208 CLK are known to wear out rather quickly. They are “loose” by design, having an air gap around more than half the perimeter of the bushing, meaning there is only about 2″ of rubber holding the outer shell to the inner sleeve. This not only leads to premature failure, but often leads to vibrations in the car, even when the bushings are new. I’m sure the Mercedes engineers had good intentions, but in practice these bushings have been a sore spot for many CLK owners. You can replace the factory units with aftermarket polyurethane bushings from Powerflex if you want a performance and reliability upgrade.
This typically happens under hard acceleration and can cause a lot of expensive damage to the car. The rear subframe is held in by four bolts, and it always seems to be the rear two that have the problem, never the front two. This makes sense, since under acceleration the rear end is trying to squat while the front end rises due to the torque imparted on the chassis by the drive axles. The front half of the subframe, ahead of the axles, is pushing up into the body, while the rear part, behind the drive axles, is pulling down on the body. With 516 ft-lb of torque available from even the stock engine, those two rear mounting points tend to fatigue and fail when you least expect it.
Adding the large-diameter washers is the key to this fix.
The fix is pretty straight forward, especially if you do it before it becomes a problem. It’s a simple matter of replacing the factory rear subframe bolts with a pair of new bolts with nuts and large washers on them, creating a “sandwich” that is much stronger than the original setup. Adding the large-diameter washers is the key to this fix. They spread the load out over a much larger surface area than the original mounting bosses, thereby making it nearly impossible to tear them out of the body. My car has over 180 dragstrip passes on it, all on sticky Hoosier drag radials, and the bolts have held strong. Continue reading “E55 Subframe Bolt Replacement”→
How can you tell if your Mercedes needs new motor mounts? Well…
I did this simple test by opening the hood, starting the car and putting it in drive. While holding the brake, give it a little gas until the engine starts to torque over. If your driver’s side mount is completely separated like mine, it will be obvious. I thought the engine was going to jump right out of the car!
The M113 and M113K motors in the AMG Mercedes are notorious for destroying engine mounts because they make a lot of torque. Replacing CLK engine mounts is not hard, but it does take a lot of patience, and one special tool. My car happens to be a CLK55 AMG, but this DIY is applicable to the 1998-2002 CLK320 or CLK430 as well. Read-on if you want to learn how to do this job and save yourself about $500 compared to what the dealer would charge you. Continue reading “CLK55 Engine Mount Install”→
I’ve been racing my 2004 E55 for the past three years and now that it’s running in the low 11’s I risk getting kicked out of the track at every event because it lacks a rollbar. Since it’s my daily driver I don’t want to cut into it so I decided to retire it from race duty and buy another car to use exclusively for drag racing. This will allow me to be aggressive on the weight-reduction and tuning fronts, as well as add any safety gear necessary as my ETs drop and the MPHs go up.
…it’s a running, driving car and I only paid $850 for it!
I decided to go with a W208 CLK chassis because they seem to be the lightest cars that came with the M113, and I definitely plan on doing an M113k powerplant. After a few months of trolling the various car-selling websites, I came across this beauty:
She’s a 2002 CLK55 with 219k miles on the clock, but the best part is that it’s a running, driving car and I only paid $850 for it! Even with shipping from LA to Portland the total cost was only around $1500. Of course for that kind of money it does have some issues, but they are typical stuff for any MB of this era: needs a battery, motor mounts, rear main seal, front LCA bushings, new tires all around and a good cleaning. It’s got some other issues with the electronics, but for a racecar, I don’t really care about those too much.