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tharber
08-27-2005, 05:56 AM
Anyone know the mechanics behind Mercedes auto/manual shifting? I just picked up my new C350 and rally like the option to shift as I need. Can the Shrifter technology be used to duplicate this but shift from the stick not the steering wheel?

FYI...the 7 speed auto is very sweet!

Thanks!

TH

Steve Chryssos
08-28-2005, 04:27 AM
There is a lot of technology there. Like a magnesium case to save weight and really sophisticated electronics. Were it not for the electronics, seven speeds might not be realistic. At first you might ask: "Why in the world do I need 7 gears?" But the box rarely uses all seven gears consecutively. Instead, the computer chooses from a wide range of gear to match the circumstances at hand. So 1st gear might be omitted at launch altogether, or a downshift from high gear might jump directly from 7th to 5th--bypassing sixth gear altogether. The computer is the key.

So can this 7 speed technology (or GM's 6 speed box) be applied directly to pro-touring? The answer is not anytime soon. You would have to adapt all of the interrelated systems at the same time.

In the meantime, the basics can be applied to available 4 speed boxes with the 4L80E being slightly more sophisticated than the 4L60E. And the Ford 4 and 5 speed boxes are even better. The basics include electronic control over shift solenoids, line pressure (PWM) solenoids, accumulator control (where applicable) and lock up clutch control.

As for your floor shifter question. You don't need a Shrifter at all. You can source any electronic "manumatic" shifter from a junkyard. You can find them in everything for a Kia to a Bentley. Any cable operated floor shifter with a "+/-" should suffice. The rest is just wiring the shifter into a manumatic capable aftermarket controller.

HOWEVER :) Let me say that nudging a floor shifter from left to right is nowhere near as stimulating as shifting from the steering wheel.
/Steevo

Steve Chryssos
08-29-2005, 08:06 AM
I found this cut-a-way of the Benz 7G on the internet. The most impressive thing I see is the stout lock up clutch (look at the front of the torque converter). From what I've read, this thing is locked up most of the time--even in 1st gear. My guess is that it "feels" like a true manual when using Touchshift. It gives that nice direct drive feel.
https://static1.pt-content.com/images/noimg.gif

And here's a nice article.
http://www.germancarfans.com/print.cfm/ID/2030903.004

Unfortunately, the only way to use this trans in your P-T car would be to cut the body off a Benz and add the skin of your favorite muscle car. From my reading, the trans computer is tied into all of the electronics--probably even the cigarette lighter. But if you can figure it out, you can boast that you have two reverse gears.
/Steevo