Iceman

Sorry, didn't remember reading about it.

kigerka

If I remember right, I think SMG double clutches when necessary.

SueBMW

Ok, but they say it's normal to need to double clutch every time you put it in first or 2nd. I say they are full of crap. There is no way a performance vehicle should shift the way ours does. ...especially if you read the B.S. in the BMW magazine about how smooth and seemless the new 6 speed is.

buddy

I have the same problem with my 6 speed e60, i have felt it for awhile now but seems to be getting worse, I have to take the car in next week for the headliner and left and right window surrounds to be replaced and i will have them check this stumbling problem, and check my balance on my crapinnentals. By the way i have the same car and color except i have had bbs rxII's on although i only have three now wifey hit a curb and killed on a scuffed up the other have not saved up enoughto get two more so they will sit for alittle while longer nice set - up though

Rudy

I'm not sure I believe this. Under what circumstances would it be necessary?

SueBMW

And our clutch is also slipping now. We are just VERY unhappy with this transmission.
...and I have NO idea why double clutching would be necessary in a new transmission. An old one with 100k, maybe. A new one? No way.

Blackonblackonblack

Can someone please explain what double-clutching is? I think it's what I'm doing...when I have to make two motions with my left foot for 1st gear. Although, I've come to think this is normal as it's how I've driven a 320i, 325e and a 318i in the past! (All bought new.) However, I also noticed that I only have to double-clutch, if that's what I'm doing, when I drive a normal, slower pace. When I race and floor it, I don't have to double-clutch. So back to my question...what is double-clutching?

CRRobert

Link to info belowHere is one explanation:

<<To double-clutch during a downshift, perform the following steps:


Let off the throttle, press in the clutch, and shift the "stick" to neutral.
Let out the clutch.
Bump the throttle to make the engine "blip".
Press in the clutch.
As the engine speed decreases to match the transmission speed, throw the stick into the next lower gear. Since you actively "matched the revs", it should fall right in!
Let out the clutch. The downshift should have been as smooth as butter! >>

I have only heard about double clutching on the downshift, not the upshift.

Rudy, isn't the SMG double clutching on the downshift for us??

CRRobert

Another link with Videos


Double-Clutching
Truck transmissions don't have synchromesh gears which allow you to shift even if the input and output shafts are rotating at a different speed. For a truck, you need to match speed with what the engine and wheels are doing. Shifting for truckers is a two-step process. Hit the clutch and put the transmission in neutral. You then quickly tap the accelerator to match engine revs with what the wheels are doing, hit the clutch and put it in gear. You can use this method to see how smoothly you are shifting normally, and helps you learn how to rev match. The benefits of rev matching include smoother transitions between gears, especially on downshifts as well as reducing the wear and tear on the synchromesh gears themselves.

Look around the site alittle for the videos. Done in an M5.

Rudy

Double clutching helps with transmissions that have worn syncros (or no syncros at all, like in an old truck) during both upshifts and downshifts.

What the SMG is doing is the equivalent of a "heel-toe" downshift which blips the throttle but does not engage and disengage the clutch a second time. In other words, you can perform a proper heel-toe downshift on a traditional manual by only pressing the clutch pedal in one time. (In the case of the SMG, the computer is blipping the throttle while the human is working the brake pedal.) As far as I know, the SMG never double-clutches -- there's no need to.