Is coding needed with a diff ratio swap on an AT?

rothwem · 05-02-2016, 08:57 AM

If diff ratios are swapped, is coding required to let the car's electronics and transmission know about the change? My only other experiences are with Toyota trucks, where putting on larger tires effectively changes the final drive, meaning the shift points get all screwed up. A speedo re-calibration fixes the problem on the Toyota Tacoma, but is the system different/better/more complex on the E9x chassis?

andrey_gta · 05-02-2016, 09:49 AM

I swapped my rwd ratio, no coding needed. All the safety features kick in like they used to...

rothwem · 05-02-2016, 11:09 AM

Quote:

Originally Posted by andrey_gta

I swapped my rwd ratio, no coding needed. All the safety features kick in like they used to...

But you're in a manual transmission car. I'm wondering if the shifting gets messed up in an automatic when the diff ratio is changed.

matteblue3er · 05-03-2016, 08:40 AM

Quote:

Originally Posted by andrey_gta

I swapped my rwd ratio, no coding needed. All the safety features kick in like they used to...

I have a none related question for you....in your sig you say you converted to euro 130i spec.....did you swap on the euro directed injected N53 head?

hassmaschine · 05-03-2016, 09:42 AM

it will "work" without changing it, but it would be better to change the diff ratio. It uses the diff ratio & tire rolling diameter to determine what gear you're in.

technically, it's not coding - coding only changes which options are selected that the computer already has flashed into it. On the DME you have to flash it - there are only 2 options, one for AT and one for MT.

rothwem · 05-03-2016, 10:11 AM

Quote:

Originally Posted by hassmaschine

it will "work" without changing it, but it would be better to change the diff ratio. It uses the diff ratio & tire rolling diameter to determine what gear you're in.

technically, it's not coding - coding only changes which options are selected that the computer already has flashed into it. On the DME you have to flash it - there are only 2 options, one for AT and one for MT.

Good to know.

What is impacted by changing the diff ratio in the DME?

hassmaschine · 05-03-2016, 10:45 AM

everything that relies on knowing what gear you are in.

I haven't mapped it all out, but there's more on an AT for sure.

rothwem · 05-03-2016, 11:19 AM

Quote:

Originally Posted by hassmaschine

everything that relies on knowing what gear you are in.

I haven't mapped it all out, but there's more on an AT for sure.

Ha, right on. This is a bit in the future, but is a DME flash possible with winkfp? I've got it installed on my dedicated laptop along with NCSexpert and INPA

hassmaschine · 05-03-2016, 12:17 PM

not without BMW's private RSA key..

rothwem · 05-03-2016, 01:31 PM

Quote:

Originally Posted by hassmaschine

not without BMW's private RSA key..

Hmm. Now you've got me really confused.

It would seem that changing the diff ratio and flashing the DME are similar to what is being done with the 3 Stage Intakes--basically tricking the car into thinking that its a different one.

So with that in mind, I guess something like a custom Active Autowerkes flash with the diff ratio change would be required?

hassmaschine · 05-03-2016, 02:41 PM

you can flash it, just not with WinKFP. WinKFP files have an RSA hash that lets you flash them, but in order to recalculate the hash after changing the file you would need the private BMW RSA key. Otherwise, it throws an error for invalid RSA checksum and stops the flash.

This is the reason why transmission flashes for the automatics have been stuck for so long. It could be done just not without building a separate tool.

05-02-2016, 08:57 AM	#1
rothwem Major 476 Rep 1,191 Posts Drives: 2009 BMW 328i Wagon Join Date: Apr 2009 Location: Asheville, NC iTrader: (0) Garage List 2009 BMW 328i [0.00]	Is coding needed with a diff ratio swap on an AT? If diff ratios are swapped, is coding required to let the car's electronics and transmission know about the change? My only other experiences are with Toyota trucks, where putting on larger tires effectively changes the final drive, meaning the shift points get all screwed up. A speedo re-calibration fixes the problem on the Toyota Tacoma, but is the system different/better/more complex on the E9x chassis?
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05-02-2016, 09:49 AM	#2
andrey_gta Brigadier General 300 Rep 4,040 Posts Drives: 130i coupé ;) Join Date: Nov 2011 Location: Bimmerpost iTrader: (1) Garage List 2008 BMW 128i [10.00]	I swapped my rwd ratio, no coding needed. All the safety features kick in like they used to... __________________ 128i Sport 6MT converted to Euro 130i spec, 3.73 diff, tuned by evolve ~220 whp 207 wtq(ft-lb) SAE In-progress: //M front arm, M3 rack, e36M lip Wishlist: Coils, n55 mnts, headers, LSD, e60 finn diff "The 1-series is the last car that BMW engineered before the Germans, as a car-making culture, fell out of love with driving." - R&T 2013 135is
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05-03-2016, 09:42 AM	#5
hassmaschine Major General 3973 Rep 7,215 Posts Drives: "NBO" 330i Join Date: Jun 2014 Location: earth iTrader: (0)	it will "work" without changing it, but it would be better to change the diff ratio. It uses the diff ratio & tire rolling diameter to determine what gear you're in. technically, it's not coding - coding only changes which options are selected that the computer already has flashed into it. On the DME you have to flash it - there are only 2 options, one for AT and one for MT.
	Appreciate 0 Quote

05-03-2016, 10:45 AM	#7
hassmaschine Major General 3973 Rep 7,215 Posts Drives: "NBO" 330i Join Date: Jun 2014 Location: earth iTrader: (0)	everything that relies on knowing what gear you are in. I haven't mapped it all out, but there's more on an AT for sure.
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05-03-2016, 12:17 PM	#9
hassmaschine Major General 3973 Rep 7,215 Posts Drives: "NBO" 330i Join Date: Jun 2014 Location: earth iTrader: (0)	not without BMW's private RSA key..
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05-03-2016, 02:41 PM	#11
hassmaschine Major General 3973 Rep 7,215 Posts Drives: "NBO" 330i Join Date: Jun 2014 Location: earth iTrader: (0)	you can flash it, just not with WinKFP. WinKFP files have an RSA hash that lets you flash them, but in order to recalculate the hash after changing the file you would need the private BMW RSA key. Otherwise, it throws an error for invalid RSA checksum and stops the flash. This is the reason why transmission flashes for the automatics have been stuck for so long. It could be done just not without building a separate tool.
	Appreciate 0 Quote