doltmo

I've got a gripe with the 7G-Tronic transmission in the '04 SL's -- related to when and how long it takes to shift gears. Curious if anyone else has similar issues. I am aware that this transmission adapts to the user, which in my case could be its downfall. Someone let me know if the issues I list below are a result of the transmission being improperly "trained".

Here are two scenarios:

1. Under hard acceleration, the transmission seems to want to stay in the current gear too long before up-shifting. This is most anoying when passing cars on 2-lane roads. In this case, flooring it at 60 MPH drops you down into 3rd. At this speed, you're running about 4300 RPM. Things go well until you get near the 6000 RPM red line (about 82 MPH), then you enter "Matrix Time" were everything seems to move in slow motion. There you sit with the engine screamming and you're not going any faster. Eventually it up-shifts into 4th, revs drop back to into the torque peak and you get a kick in the pants like someone lit the afterburner. To execute this manuver efficiently you have to back off of the gas while you're in 3rd, let the transmission up-shift into 4th and then get back on the gas (but not so hard as to force a down shift). Of course, this means that you're not getting maximum power from the engine since the throttle's not all the way open. Ideally, I'd like to downshift into 4th at 60 MPH and floor it -- without going all the way down to 3rd. Lately, I've been running the transmission in "Comfort" mode to force earlier upshifts to see if this improves the situation. Admittedly "C" mode was not an intuitively obvious solution to a performance problem.

2. Is it me, or is 1st gear pretty much useless? You get to red line at about 35 MPH and the 1-2 upshift seems slow (same issue as above). And like before, running the transmission in "C" mode fixes this problem. The car's a bit slower of the line, but you don't have to wait for the upshift into 2nd.

Comments welcome.

tiggerfink

My transmission was perfect until the SBC upgrade two days ago. Car was very fast before the upgrade. Now, it seems to stay longer in a gear. It also is a littler jerky on acceleration from a stop. I never had that problem before the SBC upgrade. My car even stall two times on acceleration from a stop after the SBC upgrade. Today, the car seems a little faster on accelerating when passing at the lower speeds. It pass great today at 70 MPH.

I wonder if my car's computer got reset from the SBC upgrade and my car is relearning me.

I never had the problems that were mention in the above post before my SBC upgrade. I never did even had to floor the gas pedal because it was always fast on the lite touch of the gas pedal, except after the SBC upgrade. I wish I never got the brake upgrade.

MBStar

I agree completely. The problem lies in its adaptive ability.
Please note my comments elswhere:
https://mbworld.org/forums/sl-class-r230/73431-2004-sl500-7g-tronic-problems.html

I could write volumes about this. It is such a shame that MB
scewed up this wonderul transmission so badly.

In the first place what is so good about the "adaptive" feature?
So that it can "learn" in stop and go city traffic? and then when I need "sport"
performance to crap out on me, just like you descibed above?
Ok, so MB won't let us turn off the adaptive feature, because
they know better, so at lest make the S mode non adaptive (as Audi did)!

AS it is, the transmission is the single biggest impediment to my enjoying this great sports car.

Bilal

Don't know if its the case with newer Mercs, but have you tried tapping the selector lever to force an upshift without taking your foot off the gas? That feature used to work on our car, but ever since complete 1st gear gearbox failure, and with the addition of a new control unit, the car won't upshift when you want it to unless you're in full manual mode and selecting gears manually.