Quote:
Originally Posted by Lemans_Blue_M
Well the first part is pretty hilarious... 
It's very strange that you bought a DCT equipped car...without even knowing how it's supposed to work. 
What exactly did you think DCT was anyway? (before you bought the car) 
It can operate in either mode MANUAL or AUTOMATIC (where you don't have to shift). Are you saying the dealer or salesman never told you this? That is very odd indeed since this transmission is one of the key selling points of the M3. The fact that no one explained how your transmission works is a little troubling. I wonder what else they forget to tell you... 
Anyway, the DCT can work in either the S or D modes, and it won't hurt the motor if you switch back and forth between the two modes. 
As for the second item (highlighted in bold text), my opinion is that you should use a $20,000 state of the art motorsport derived engine to actually save your brakes. If you are making a normal downshift, then fine, but I'm not going to put additional stress on the my engine,my DCT transmission, my driveshaft, and my differential to save a little wear and tear on my brake pads and rotors. That's not a very smart trade-off in my opinion. Now will it damage your engine? Not likely, but it will increase the wear and stress on the drive-train components so personally, I wouldn't use that method of slowing my car down. The M3 comes with pretty decent brakes from the factory so I'll just uses those to slow down or stop the car when needed.
I just don't see a good reason to use "engine braking" on a regular basis (that may cause a problem down the line) to slow the car down.
In the interest of full disclosure...I actually experimented with the engine braking technique in my E36 & E46 M3's (briefly), but in both cases, I decided this method was simply not worth the potential risk the drive-train components over time. 
So I have more or less abandoned any desire to employ this with any of my cars going forward. I would advise you to do the same, especially if you intend to keep this car for several years. (including after the warranty expires) |
I guess a better term here would be "unhealthy" instead of harmful.
My main concern was the engine braking part, in which you weren't too sure if it's "healthy or not" also, so I wouldn't conclude my post being ridiculous or anything.
I actually know how to operate the DCT, I was just asking if it would be harmful or, in this case, "unhealthy" to frequently engine braking instead of stepping on the brakes.
The reason why I'm not sure is the manual actually encourages engine braking, but in my traditional way of think, it's somehow unhealthy to the tranny or the engine in the long term, and I thought I would get someone who knows the answer to answer this thread.
My thought was it's similar to the launch control function, where it's totally safe to perform such actions, but when you do it frequently it becomes a problem.
Either I was unclear about my question or anything, further help is appreciated...