Kain

Why are Mercedes-Benz transmissions sometimes jerky and not smooth? I mean Mercedes-Benz goes through the trouble of making its own transmissions but they never seem as "lively" or smooth as BMW's. If I recall correctly, BMW doesn't even make its own transmissions and yet they seem to be better. Can't Mercedes-Benz source its transmissions from where BMW gets them? Anyway, any guesses whether or not the new 9G-TRONIC will be an improvement?

K-A

You really can't compare the two, IMO, which shows how differently their leagues are. The 7G tronic is not a very good transmission (and yes I know certain members here will detest and throw flame at that) in my opinion and simply isn't competitive to the ZF8 equipped in BMW's (or any of the other good implementations of in various different car makes), especially when you get the "Sport Auto Transmission" option, which is the best tranny I've ever experienced (maybe better than, or at least on par with Porsche's PDK).

M-B however is working on a 9G Tronic which will apparently debut along with the 2015 C Class on the 2015 S Class, so that will be their answer to that and we'll see how it does. It sounds very enticing and I'm eager to see how it feels (I have a feeling M-B are going to work hard on making this one really good). The 7G was never really gotten "right" to me, and although the jerks and replacement of valve body that had to happen on my 2006 (early 7G) W211 were improved, I find later iterations still suffer from the jerkiness sometimes and feel basically similar in performance and operation.

steveb9771

I have one of the first CL550s built and my transmission has always been smooth, never jerks. Are those experiencing jerky performance in the minority?

K-A

Seems mixed. My 2006 was a mess. My 2010 and 2011's had very slight jerks, just occasional. My main issue with the 7G is that the M-B powerplants have so far surpassed it that IMO it feels like it's holding them back significantly. Namely the TT V8. I'm assuming the 9G will be formatted to the newer motors.

phalen302

Mercedes, Audi, Porsche and BMW source their transmissions from Getrag and ZF with various specific manufacture only configurations. Most of the "jerks" felt in MB is related to valve body not related to transmission itself (which makes the transmission shifts; has pressure valves inside). If valve body is not addressed; wear and tear will cause the transmission to fail. MB has updated the valve body 3 times for 7G transmission only. They usually apply software update first; transmission pump runs hard in cold hard to fully engage the valve body. This info was given to me by Master AMG mechanic (20+ yrs exp with MB and multiple awards from MB).

LETO

My 2012 CLS has not had any issues with jerkyness. My 2009 CLS with the same 7 speed suffered from throttle response issues. But that was primarily due to that generation of MB's favoring the long pedal travel on the accelerator.

Quadcammer

lol, if you think the bmw sports auto gimmick is in any way in the same league as the PDK, you know less about cars than i thought.

K-A

Actually it's you lacking the merit. I've probably driven more SAT BMW's and PDK Porsche's than you have Mr. Cranky OliverK in the 10 year old S Class.

I recently drove a Panamera with a standard PDK and the first thing I noticed was how lethargic the tranny felt. Posted up a review and was pointed out that it actually was indeed a PDK (I thought it must have been a "base" slushbox of some sort) and it didn't compare to any BMW ZF8 I've driven. That said, the PDK in the 991 911 I've driven was one of my favorite tranny's, period. However, the SAT ZF8 in my BMW is also one of the, if not the best auto tranny I've ever driven (and I've driven a Ferrari F430 around a track extensively) when you factor in its multiple characters at the touch of a button (smooth as silk in Comfort and extremely aggressive in Sport, shifts rapidly without a hitch, and allows you to manually shift with no computer nannying which is something you can't do at all in an M-B).

I'd say the ZF8 implementation in the BMW namely with the Sport Auto option is as good as any PDK (or better than the one in the Base Panamera at least) that I've driven. It's that phenomenal. Not as good as a W220's 5 Speed. though.

Quadcammer

lol, what does my ownership of a w220 have anything to do with this? Did I make any claims about the automatic in my car? I'll wait for you to stumble over this.

With all your extensive (lol) drives of F430s, porsches, and BMWs, you've come to the conclusion that a torque convertor automatic in the BMW is as good as the double clutch porsche gearbox huh?

People with far more experience driving cars than you do (your little test drives are cute though) disagree...consistently remarking that the PDK is essentially the finest automated manual out there.

I know you like to imagine yourself as Jenson Button tapping the paddles in your little 5 series, but you have nothing but a snoozefest automatic gearbox.

K-A

You can "lolololol" all you want, Oliver, but the fact that you had to change your name here shows just how little your credibility is. Fact is you haven't owned a modern car and have limited exposure hence constantly resorting to ad hominem attacks to express your frustrations. I HAVE driven these cars and don't gauge it based on statistics I read in magazines. The ZF SAT in the BMW has been said many times to be so good that it feels like a double clutch, by drivers and magazine reviewers alike. Try one, you'll be surprised.

phalen302

PDK is one of the finest transmission and is considered by many a benchmark. Behavior of PDK is dependent on application (panamera, 911, caynne etc..), I am 100% sure, the mapping (software) they put on base panamera is very conservative.

Dual clutch transmission are way way better than torque converter auto's (thing of past).

BMW sport auto is nothing but a gimick as well as their sport package. They might have aggressive mapping on trans but it is not in any way in the same league as PDK.

K-A

That's enlightening about the different applications. Explains why the Panamera PDK felt awful, like a decade old slushbox. The ZF with the Sport Auto tranny will undoubtedly be the best torque converter tranny you'll find out there. Many including myself consider it *almost* imperceptible to a double clutch. It's as close as you'll get and DOES feel far better than some PDK applications I.e the V6 Panamera.

jprescott

I never understood the angry and confrontational overtones of some of the posts here....

So anyhow, as a non gear head guy who likes nice cars here is my experience. My last 2007 S550 compared to my present 2011 740Li

Mercedes: Smooth as silk and quiet
BMW: Herky jerky and if you follow the bimmerfest 7 forum you will see that many of us have that experience. I feel like my car bounces at low speed and so far there is no fix. Yes this is a sport car. No I don't think it is a luxury car in the same sense as the S. Quite a bit of road noise. And the run flats...I could go on a rampage about those(and they are a deal breaker for me).

I suppose I may be attacked for expressing my subjective OPINION but it is just that

K-A

I believe the 7 Series unfortunately didn't get the 8 Speed ZF tranny until the 2012 facelift. If I'm not mistaken your car may have the old 6 Speed which is a huge difference. The ZF8 is truly far and away superior to the Mercedes 7G but i can't speak for the previous BMW tranny that was in the first few years of the 7 Series. I agree many here have a hard time discussing cars without personal angst riddled overtones.

phalen302

Agreed. And the only BMW trans comparable (apples to apples) to PDK are the trans in M3, M6, and M5. The rest are just rest. "Sport" option on BMW is more of a cosmetic/software upgrade on non Sport models.