Yidney

Last weekend I changed my own transmission fluid. I was pleasantly surprised that the fluid, although brown, still had a pinkish cast when spread in a thin layer, and the pan magnets were not very fuzzy.

For the last year or so the tranny was "sticky" at the first shift from a stop. Not a noise or clunk, but the feeling of a valve sticking for a second longer than it should and then opening. But it always went away after a mile or so as the tranny just started to warm and was smooth after that.

But what made me scratch my head was that the sticky shift was always in the same place whether I was in S or C mode.

So I changed the fluid and as soon as I it took off the jack stands and drove it I could tell it felt different. I made the following observations:

1. The first shift from a start was now smooth.

2. The sticky shift had moved to the second shift from start. That really made me scratch my head, until I observed:

3. The sticky shift moved back to the first shift if I put it in C mode.

4. For the first time since I can remember, when I press the button to go from C to S and back I can actually feel something happening inside the transmission.

So the obvious conclusion is that I have been driving this car with no first gear whatsoever for who knows how long. Probably since I bought it at 28k two years ago. Just changing the fluid brought it back. Now hopefully the sticky shift will smooth out.

CLK550 $wagger

Wow... first gear is where all the fun is at!I wonder what caused that to happen. Well, have fun with the extra gear and hopefully the stickiness smoothes out!

Yidney

Yeah, kinda makes me feel dumb. But when you assume a gear is there you don't really do anything to confirm it is there, especially on my slow 3.5 mile commute, and the car was still plenty peppy even starting in 2nd. I always had it in S, but on the couple of occasions I did put it in C just to see what it was like, I do recall thinking "that doesn't seem that much different." Duh. So basically my C/S button was a placebo, and I was perpetually in C mode. So now I can look forward to buying more gas.

Rudeney

Interesting. And it's good that your fluid and magnets were in good shape - mine were horrible.

LAZARU5

I think this is because "C" mode by definition starts off in second gear. Also, I think the tranny is programmed to shift at higher revs when starting from a cold start. This heats up the engine faster to reduce pollution. So, that behavior may be what you have diagnosed as a sticky first gear in "C" mode.

Yidney

Yeah, I know it starts in second, but this stickiness is not just a higher rev before shifting. It makes the car lurch sort of, and for a period of two or three months it went away and then came back. But I can live with it if it does not reslolve itself with the new fluid because it goes away after a mile or so each morning.

Yidney

I think I may be in the running for the first annual "Stump Rodney" award. But on the theory that no problem is isolated to only one car, I'll bet others with the 722.9 are driving around with no first gear.

Rudeney

I definitely had 1st gear. After I had the balance shaft (in my case, crankshaft timing gear) replaced, I had a bad shift when cold with it slipping and slamming on the 1-2 shift. I suspected low fluid due to the transmission cooling lines being disconnected from the radiator for the work. The dealer checked and said the fluid was "a little" low, and then they reflashed the TCU. Now, I have a very smooth shifting transmission - its almost like a CVT when I drive it gently. In fact, I'd like to have it hold 1st gear just a little longer without having to stay on the accelerator, but I guess it's better this way for MPG.

If you aren't happy with your shifts, I'd recommend having the dealer update the TCU code. It will probably cost on hour or so of shop time, but it may be worth it. Like I said, mine is very smooth now.

Yidney

It's sort of funny when I think back on it now. There were threads here from Kev and others about how hard it was to launch these cars from a stop because of all the low end torque causing the rear tires to tear loose, and I thought "I don't have that problem." I could only manage a small squeal and then the car would just squat down and go. No wonder. Today I took it out to an empty country road to, as my kids would say, blow the stink out of its pants, and I darn near fishtailed into a ditch.

Frank Rizzo

I have so much low end grunt, I think my ESC warning triangle light will burn out soon...

interesting. How many miles are on your car?
Did you consider synthetic fluid?

Yidney

41,000 miles, so I was a little past the 39,000 recommended level, but no big deal. I didn't consider any fluid that didn't meet the MB spec. I used Shell ATF 134.

Rudeney

The approved fluids (which includes Shell ATF 134) are synthetic.

Yidney, you must have had a problem because even if you are in "C" mode, and you hammer it, it will still downshift to 1st and spin the wheels. One of the ironic things about the CLK550 is how its specs don't really tell the whole story. For example, 0-60 is listed at 5.1 (5.2 for the cabriolet). But, if you have really good tires and disable ESP (fully) you can go into the 4.8 range.