Automatic rear diff in manual 135?

RealityDesign · 06-20-2011, 05:10 PM

From what I understand, the automatic rear diff has a 3.46 final drive ring and pinion versus 3.08 on the manual. It also appears the the auto diff has a bolted ring gear, versus the welded one in the manual.

Now, I'd love to just take an auto diff and put it in my manual, but something tells me it won't be that easy. I'm assuming the driveshaft is also different. Is there anything else though? Will an auto driveshaft bolt up to the manual transmission or do I have to modify/lengthen my stock driveshaft instead?

If anyone has successfully done this swap, please chime in. I'd really appreciate it.

Also, if anyone knows of an aftermarket LSD that comes with a ring & pinion to convert to a 3.46 (or something close) final drive, that would be great too. I remember hearing something on N54 tech over a year ago about OS Giken doing this, but I don't know what ever happened to that.

RealityDesign · 06-20-2011, 05:20 PM

Found a partial answer to my question:

Quote:

You can install an auto diff into a manual as long as the auto diff is from a 08/2007 or earlier car. 09/2007 and later auto diffs are much smaller and requires a longer drie shaft.

But, assuming that I can't find an 08/2007 or earlier car, will an auto drive shaft work with a manual trans? And further, is the 335 auto diff the same as the 135 auto diff? I would assume so, but I'd like to know for sure.

BerkTechnology · 06-20-2011, 06:54 PM

All of the 135i and 335i diffs are interchangeable (auto & manual). Only the new 2011-up cars with the optional DCT trans have different diffs.

We've had two different 3.46 diffs (automatic tranny) in our 135i race car.

RealityDesign · 06-20-2011, 06:57 PM

Thanks for the info

.

xerox445 · 06-20-2011, 07:56 PM

The real question is...when is someone like PPG going to step up to the plate and build us an aftermarket soultion to FD's, so one can build a 3.46 with a quaife or wavetrac and install it in one shot without spending 5g+. Having a $1200 FD, with an install kit, paired with either diff...would FLY out the window. Halfing the current cost.

HP Autosport · 06-21-2011, 06:22 PM

Quote:

Originally Posted by xerox445

The real question is...when is someone like PPG going to step up to the plate and build us an aftermarket soultion to FD's, so one can build a 3.46 with a quaife or wavetrac and install it in one shot without spending 5g+. Having a $1200 FD, with an install kit, paired with either diff...would FLY out the window. Halfing the current cost.

There is currently a 3.46 Quiafe or Wavetrac solution for around $3600 plus freight.

RealityDesign · 06-21-2011, 06:46 PM

Quote:

Originally Posted by HP Autowerks

There is currently a 3.46 Quiafe or Wavetrac solution for around $3600 plus freight.

Can't wait for my 3.46 Quiafe.

Super stoked right now Harold! Hopefully my guy can ship the diff out to you tomorrow...

xerox445 · 06-21-2011, 07:08 PM

Quote:

Originally Posted by HP Autowerks

There is currently a 3.46 Quiafe or Wavetrac solution for around $3600 plus freight.

The diff's by themselves can be had for around $1200...lets get serious, $3600 is still redic.

HP Autosport · 06-21-2011, 07:15 PM

Quote:

Originally Posted by xerox445

The diff's by themselves can be had for around $1200...lets get serious, $3600 is still redic.

BMW 3.46 is new at around $1800 if you can still get one, plus 3-4 hours of labor and stub axle seals it's right where it should be. Still much lower than the 5k you stated above.

TJ bmw135i · 06-22-2011, 10:12 AM

Can the Speedo be easily adjusted for the new gear ratio (via the BT tool) or would you need the dealership to set the calibration?

HP Autosport · 06-22-2011, 10:36 AM

Quote:

Originally Posted by TJ bmw135i

Can the Speedo be easily adjusted for the new gear ratio (via the BT tool) or would you need the dealership to set the calibration?

BMW uses wheel speed sensor for speedo signals so no calibration is needed.

06-20-2011, 05:10 PM	#1
RealityDesign realitydesign.com 14 Rep 205 Posts Drives: 2008 Silver 135i Join Date: Feb 2010 Location: Irvine, CA iTrader: (5)	Automatic rear diff in manual 135? From what I understand, the automatic rear diff has a 3.46 final drive ring and pinion versus 3.08 on the manual. It also appears the the auto diff has a bolted ring gear, versus the welded one in the manual. Now, I'd love to just take an auto diff and put it in my manual, but something tells me it won't be that easy. I'm assuming the driveshaft is also different. Is there anything else though? Will an auto driveshaft bolt up to the manual transmission or do I have to modify/lengthen my stock driveshaft instead? If anyone has successfully done this swap, please chime in. I'd really appreciate it. Also, if anyone knows of an aftermarket LSD that comes with a ring & pinion to convert to a 3.46 (or something close) final drive, that would be great too. I remember hearing something on N54 tech over a year ago about OS Giken doing this, but I don't know what ever happened to that. __________________ 2008 135i MT - JB4 15ohm, Map 3 CM VC2 2.7gal Meth Kit \| CP-e Downpipes \| BMW Performance Exhaust \| BMS DCI \| Stett CP & Forge DV's \| ETS FMIC \| 3.46 Quaife LSD \| KW V2 Coilovers \| Breyton GTS-R's \| Dunlop Z1 Starspecs \| Complete BMW Performance Exterior & Interior Last edited by RealityDesign; 06-20-2011 at 05:20 PM..
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06-20-2011, 06:54 PM	#3
BerkTechnology Lieutenant Colonel 223 Rep 1,565 Posts Drives: Fast Join Date: May 2008 Location: Irvine, CA iTrader: (1)	All of the 135i and 335i diffs are interchangeable (auto & manual). Only the new 2011-up cars with the optional DCT trans have different diffs. We've had two different 3.46 diffs (automatic tranny) in our 135i race car.
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06-20-2011, 06:57 PM	#4
RealityDesign realitydesign.com 14 Rep 205 Posts Drives: 2008 Silver 135i Join Date: Feb 2010 Location: Irvine, CA iTrader: (5)	Thanks for the info . __________________ 2008 135i MT - JB4 15ohm, Map 3 CM VC2 2.7gal Meth Kit \| CP-e Downpipes \| BMW Performance Exhaust \| BMS DCI \| Stett CP & Forge DV's \| ETS FMIC \| 3.46 Quaife LSD \| KW V2 Coilovers \| Breyton GTS-R's \| Dunlop Z1 Starspecs \| Complete BMW Performance Exterior & Interior
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06-20-2011, 07:56 PM	#5
xerox445 Damenslip-Tropfer 23 Rep 543 Posts Drives: 2008 SGM 135i Join Date: May 2011 Location: LBI, NJ iTrader: (1)	The real question is...when is someone like PPG going to step up to the plate and build us an aftermarket soultion to FD's, so one can build a 3.46 with a quaife or wavetrac and install it in one shot without spending 5g+. Having a $1200 FD, with an install kit, paired with either diff...would FLY out the window. Halfing the current cost.
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06-22-2011, 10:12 AM	#10
TJ bmw135i Private First Class 5 Rep 145 Posts Drives: 2008 135i Convertible Join Date: May 2010 Location: Portage, MI iTrader: (2) Garage List 2008 135i Vert [0.00]	Can the Speedo be easily adjusted for the new gear ratio (via the BT tool) or would you need the dealership to set the calibration?
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