# E60M5 transmission technical description?



## Kaz (Dec 21, 2001)

I've read a couple of articles, obviously cribbed from the long E60M5 introduction press info (germancarfans.com has a copy), that mention bits about the new SMGIII 7sp SMG tranny. It states that the transmission has been designed specifically to achieve optimal potential with the mechatronics involved in shifting, and that it absolutely can NOT be adapted to use a gated shifter.

I'm wondering if anyone has seen any further information on what changes in the transmission's design facilitate this. My assumption is that it's basically the same layout as other dedicated sequential MTs (F1, etc.).


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## bavarian19 (May 11, 2003)

Should answer most of your questions (hopefully)

http://www.bmwm5.com/articles/m5e60/pressrelease2/julye60m5pressrelease3.html


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## Kaz (Dec 21, 2001)

bavarian19 said:


> Should answer most of your questions (hopefully)
> 
> http://www.bmwm5.com/articles/m5e60/pressrelease2/julye60m5pressrelease3.html


Um, I said in the first sentence that I already read this...


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## bavarian19 (May 11, 2003)

Kaz said:


> Um, I said in the first sentence that I already read this...


sorry :slap:


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## avalys (Oct 14, 2003)

According to Autocar, the two cogs in the transmission that handle the greatest torque should be placed on the outside of the gearset in order to achieve the best durability, but this arrangement doesn't allow for a typical H-pattern shifter.

I would think, though, that if BMW really wanted to put a manual in the car (either six or seven speeds), they'd figure out a way to make it work. But alas...


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## Alex Baumann (Dec 19, 2001)

Actually they are using a set of stabs for the gear change and they are moving extremely fast. (very complex mechanism, according to the article I've read). And it's placed on the top of the gearbox (see pic)

I'll find the article again.


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## Jspeed (Dec 23, 2001)

One reason that this transmission can not be shifted conventionally is b/c it overlaps the disengagement of the selected gear and the engagement of the next gear.


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## Kaz (Dec 21, 2001)

Jspeed said:


> One reason that this transmission can not be shifted conventionally is b/c it overlaps the disengagement of the selected gear and the engagement of the next gear.


er, isn't that DSG?


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## Jspeed (Dec 23, 2001)

Kaz said:


> er, isn't that DSG?


DSG is able to engage the next gear (just not the clutch) even *before* releasing the current gear. I'm talking about the collar-to-gear operation.

traditional manual: collar releases a gear -> not connected to anything -> collar locks next gear

M5 SMG (SMG3?): collar engages next gear and releases the previous gear at the same time

DSG: completely separate mechanisms, both collars are engaged to the gears, the two clutches handle the change over


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## Kaz (Dec 21, 2001)

See, this is why I want to find more technical details. I'm curious to find out how it can have 2 dogs engaged exactly sequentially without a break, since there has to be a period of synchronization in a conventional design. Does it somehow have 2 layshafts (like DSG) but somehow handled by 1 clutch? I dunno.


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## Jspeed (Dec 23, 2001)

Kaz said:


> See, this is why I want to find more technical details. I'm curious to find out how it can have 2 dogs engaged exactly sequentially without a break, since there has to be a period of synchronization in a conventional design. Does it somehow have 2 layshafts (like DSG) but somehow handled by 1 clutch? I dunno.


I know what you mean. I haven't read anything that provides further detail either.

I think it still uses a single layshaft. My guess is that the spacings between the gears are much smaller, and the synchros are inherently less effective. This requires much more precise rev-matching, so engagement timing and throttle-blipping (during a downshift) must be controlled by the computer.

It's also possible that the synchronization mechanism is totally different. See this...

http://www.zeroshift.com/

I would love to see a technical drawing of the gearbox...


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