GS7 Identification Inconsistencies

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phunk

New Member
Nov 10, 2019
4
I recently acquired a GS7D36?G. But I am having issues identifying the transmission due to a lack of consistency in information.

The seller tells me it is from a early 2014 M4, allegedly a sort of demo car that was wrecked on a road course. He is attempting to locate the VIN number for me, but might not be able to. None the less, based on the following screen shots (attached) from documentation I located on this forum, I was expecting this transmission to be a BG...

Now that I have picked up the transmission, there is clearly a BMW sticker on it that says GS7D36SG. So now I start wondering, is the seller wrong about where it came from?

So I look around on realoem.com, and it says the M4 has the SG as well.

The part number on my transmission is 28007853530, Code AOM. This comes up dry on a google search and realoem.

While the trans remains a mystery to me, its going to be difficult to determine which gear set it has, what its original torque capacity is rated to, and it may also have an influence on my options for TCM/control strategies.

If anyone has any information or theories that could help, its greatly appreciated. Thanks.
 

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doublespaces

Administrator
Oct 18, 2016
8,009
AZ
That documentation with the chart is wrong. You have the M4 DCT (Or some other 6 cylinder DCT).

EDIT: It is possible the SG/BG etc has nothing to do with the bellhousing shape or gear sets. It might just be the electronics, regardless of software.

Maybe being an early demo car it got the old version and not the updated version for the production car?
The F80 DCT has the same gearing as a 6AT N54, so that would be quite a big change. I find it unlikely they would matched a 3.46 final drive in the F80's electronic diff with the E9x M3's gearing which expects a 3.15 on an 8400 redline.
 
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phunk

New Member
Nov 10, 2019
4
I wont be able to check the TCU software version since it wont be going into a vehicle capable of doing that. The seller was able to reference the part number in some dealer software and sent me a screenshot. So its clear that the M4 did come with a SG trans, despite them calling it the BG in several tech data articles.

So now I have to figure out what separates it from the SG in the E9x. I would want to think it has the gear ratios and clutches from the BG. Its unfortunate that BMW has all their own data conflicting since this is going to make this transmission very hard to work with. I am considering buying an older SG from a E9X to use for the time being, and holding on to this M4 SG until its mysteries are uncovered.
 

doublespaces

Administrator
Oct 18, 2016
8,009
AZ
I wont be able to check the TCU software version since it wont be going into a vehicle capable of doing that. The seller was able to reference the part number in some dealer software and sent me a screenshot. So its clear that the M4 did come with a SG trans, despite them calling it the BG in several tech data articles.

So now I have to figure out what separates it from the SG in the E9x. I would want to think it has the gear ratios and clutches from the BG. Its unfortunate that BMW has all their own data conflicting since this is going to make this transmission very hard to work with. I am considering buying an older SG from a E9X to use for the time being, and holding on to this M4 SG until its mysteries are uncovered.
Do you have the option of opening the transmission? I bet a few measurements should be able to solve that problem?
 
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phunk

New Member
Nov 10, 2019
4
Do you have the option of opening the transmission? I bet a few measurements should be able to solve that problem?
I wouldnt mind pulling the clutches out since that appears to be relatively simple based on your thread about that (thank you for sharing). Although I will have to ask someone who knows how to tell which clutch pack between the 520nm vs the 700nm types.
 

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