My cheap eBay seats finally gave it up. After just a couple passes at the track with the new M113k powerplant, the ratcheting mechanism in the driver’s seat broke and the back would no longer stay fully upright. I took this as a sign that I should upgrade to a proper set of seats!
I decided to go with the Kirkey Series 65 seats since they are lightweight, relatively inexpensive, and would bolt right to my existing home-made brackets. They are also designed to bolt to the rear brace of the roll bar, which is an NHRA requirement.
I got the 16″ size, which fit my 5’10” 200lb body snuggly but comfortably. They fit pretty well in the car too, with plenty of room between the center console and the door armrest. The shoulder bolsters just barely touch the doors when they are closed. I may wrap a ratchet-strap around the bolsters and squeeze them in about 1/2″ for better clearance.
The total weight of each seat, with the seat covers, steel brackets and mounting hardware came in at 23.5 lb, so that’s a savings of almost 40 lb per seat over the stock units. It remains to be seen how comfortable they are on long trips, but my first few drives around town have been just fine. They are, however, quite a pain to get in and out of.
The harmonic balancer on the Mercedes 113k has a narrow key that often shears under the added stress of a larger crank pulley that produces more boost. Once that happens, repairing the crank snout can be very costly, so it’s better to keep it from happening in the first place. You do this by “pinning” the balancer to the crankshaft.
If you’ve been reading this blog for a while you know that my ultimate goal is to run a high 8-second quarter mile in the CLK. In order to do that without getting kicked out of an NHRA-sanctioned track, I plan on building the car to the rulebook and having it be 100 percent legal.
According to the NHRA Quick Reference guide, one of the things you need when you go 10.99 or quicker is an SFI 18.1 certified harmonic balancer. Not surprisingly, nobody makes one for the M113 found in the W208 CLK55. Luckily, ATI will make custom versions of their Super Damper, which is SFI 18.1 certified. I was told to expect up to a 2-year wait for a custom damper, so even though the car is currently stock, I placed the order for the damper expecting it to be ready in a couple years when the car should be running sub-11 second ETs.
After all the weight reduction, the CLK was riding high and it needed to come back down to earth. The fender gap was 3″ in the rear and 2-1/2″ in the front. I wanted it closer to zero, with the top of the tire about even with the top of the fender, or within a half inch.
There are a couple different approaches to lowering a W208 CLK. You could buy a set of lowering springs, or just cut the appropriate amount off the factory springs. I decided to take the old-school route and cut some coils out of the springs instead of spending money.
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.
I had a chance to take the CLK to the Woodburn Dragstrip over the weekend so I could get some full runs on the new PCS transmission controller and see how the weight reduction over the winter has helped.
As part of my weight saving plan I am ditching the stock seats and replacing them with a cheap set of lighter bucket seats. The factory seats weigh in at about 60lb each; the cheap eBay seats are about 30lb, plus a few pounds for the brackets I had to make to mount them.
I got the seats off the Facebook Marketplace for $200 for the pair, and spent about $50 on parts for the brackets.
I made a set of custom brackets so I can easily install and remove the seats using four bolts each in the factory threaded holes. A couple of pieces of 1/2″ square tubing and 1″ flat bar stock is all that was needed.
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.