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03-05-2012, 01:50 PM | #1 |
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335i and 135i Differential FAQ (No LSD, really?)
Shortly after the N54 powered 335i and 135i were released, enthusiasts and tuners wanted to ‘fix’ the lack of limited slip differential. Making easy and abundant power was simple with the twin turbo inline 6, but putting it to the ground was not.
Enter the infamous final drive. Open, LSD, welded, bolted, large body, small body, 3.08, 3.46 etc etc. We will try to make sense of everything with this blog entry. Open vs. LSD: The 335i and 135i were not offered with a limited slip differential. Yes, BMW sold a twin turbo, 6MT sporty car without a LSD. No factory option, nothing. So, owners had to rely on the aftermarket for a solution. Initially the solution was pretty simply, till BMW switched things up on us. Open: LSD – limited slip differential: Welded vs. Bolted: Very early 6MT equipped cars had a traditional ‘bolted’ setup where the ring gear was bolted to the gear carrier. Shortly after, the engineers in Munich decided to weld, not bolt the ring gear to the gear carrier. Well, that complicates matters a bit! Welded: Bolted: (we are using a bolted aftermarket diff for illustration purposes) Master Reference Chart: Does your car have a welded or bolted differential?? See chart above. As you can see, the majority of 335i and 135i owners are blessed with the welded differential. This makes adding a LSD a bit challenging, as the ring gear must be separated from the carrier carefully to ensure it can be re-used. Very few shops can do this properly and consistently, but we pioneered the what we think is the best way of performing this operation. This is how we do it. Large or small differential? There are 2 differential (housing or ‘pumpkin’) sizes. The table above shows which cars have which size. So, a Quaife ATB limited slip unit designed for the 6MT large housing will not work in your 2009 335i automatic. Fortunately, Quaife and Wavetrac have solutions for both the large and small differentials. Here are some pics so you can see the dramatic difference: Gear Ratios: See chart above. All 6MT cars were equipped with 3.08 final drive ratios. Automatic cars had 3.46 ratios. Note: we have built a few 3.46 differentials for 6MT cars and the owners were thrilled. They were willing to sacrifice top speed for an incredible power band around town :-) Lastly, DCT equipped cars have 2.56 and diesel cars have 2.81 final drive ratios. Conclusion: When you modify your N54 or N55 powered E9X or E8X, a proper differential is an essential modification if you want to put all of that power to the ground. While it is quite confusing, I hope this entry makes it a bit easier to understand.
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Brian Casella
Sales Representative, VAC Motorsports Office: 215.462.4666 | Fax: 215.462.4667 EXT 13 | Email: brian@vacmotorsports.com |
03-05-2012, 02:31 PM | #3 |
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Very informative thread! Thanks Mike@VAC.
Btw... love all your photos in your other LSD thread... VAC Motorsports - 335i, 135i Performance Built Differential - How we do it! http://www.e90post.com/forums/showthread.php?t=648271 |
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03-05-2012, 02:32 PM | #4 |
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so note for us manual guys that want an lsd...to do it on the cheap find a wrecked eearly model 07 that has the bolted gear ring!
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03-06-2012, 08:40 PM | #5 |
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Why would regearing a 6-speed effect top speed? Top speed is electronically limited to 150 mph, regardless of rear end gearing. Even if you tune out the limiter, the 1-series top speed is horsepower limited, not gear limited.
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03-06-2012, 09:34 PM | #8 | |
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Quote:
Here are my mile per hour calculations for my 6MT in each gear at 7k rpm. 1st 42 mph 2nd 75 mph 3rd 113 mph 4th 147 mph 5th 174 mph 6th 205 mph The top gears create too much spread, and are only there for fuel economy. |
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03-06-2012, 10:03 PM | #9 |
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Here are some calculations for a 6MT.
A plus is the torque at the wheels is increased by the gear ratio change. 3.48/3.08=13% added across the board Last edited by Suds; 05-31-2012 at 07:03 PM.. Reason: Added torque change |
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05-31-2012, 05:56 PM | #11 |
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You are correct on both.
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05-31-2012, 07:13 PM | #13 |
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Am I correct in assuming the smaller diff case and innards are weaker?
The sun and spider gears look cast in the pics of the smaller one, whereas the larger diff looks to have machined forged gears. I was hoping to install an LSD with the 3.46 ratio of the auto into my 135 6MT, but I don't want to sacrifice strength or reliability. |
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06-02-2012, 09:37 PM | #14 |
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Drives: 2011 135i, N55, 6MT, MPK
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I know that the 135i has an open diff, but my 135i is stock, and I can lay equal rubber trails on both rear wheels if I burn out??? I've heard some jibber jabber about e-diffs on the 135i and all that good stuff... Don't know how true it is.
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01-20-2013, 08:36 PM | #16 |
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Yes, although it has less of an impact when you have less power.
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2008 135i Montego Blue sport pkg, premium pkg, Logic 7 sound, iDrive/Nav
Mods completed: JB4+ & FBO || LSD || BMW-P suspension + F/R sway bars || 18" Breyton GTS-R || M3 front bushings || Vogtland camber plates || BMW-P rotors + Stoptech pads |||| Acquired, not installed: BMS WW Meth kit || Logic HVI intake || Mishimoto OCC |||| Shopping for: Summer tires |
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01-20-2013, 08:44 PM | #17 |
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man, I remember changing out the final drive in my ITR. It completely changed the feel of the engine. Not sure how to explain it other than it always felt anxious, but in a really good way. I'm just not sure if our engines need that, they're so torquey as it is and never really feel "out of the power band" - the DCT anyway, I know the 6MT has longer gears.
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01-21-2013, 08:09 AM | #18 |
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WOW! Awesome thread. Thanks. Very informative.
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01-21-2013, 08:34 AM | #19 |
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Hard to argue with data, thanks...
In real world driving the lower gearing will get you into the power band much quicker making it feel like the throttle is so very responsive. You will have to shift sooner (mph) because you will also run out of your gears sooner but that is a welcome trade-off.
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03-12-2013, 08:48 PM | #20 |
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great, post.
Which other cars use the "bolted small pumpkin" unit? For example, KAAZ do not list a part for the 135i automatic (which shares it's diff with the 130i), although they list a plethora of other models, now if one were to be interchangable... BMW MODEL ENGINE GRADE YEAR M/T POSITION NORMAL L.S.D. PLATES PLATE 1.5WAY REMARKS TYPE SIZE CAM 3 series E30 6-cyl 325i 85~90 MT/AT REAR OPEN BASIC 12 M DBW3010 4-cyl M3 MT/AT REAR Mechanical BASIC 12 M DBW3010 4-cyl 318is 89~90 MT/AT REAR OPEN BASIC 12 S DBW1810 E36 4-cyl 318is 93~98 MT/AT REAR OPEN BASIC 12 S DBW1810 4-cyl 318ti MT/AT REAR OPEN BASIC 12 S DBW1810 6-cyl M3(3.0) 93~95 MT/AT REAR Mechanical BASIC 12 M DBW3010 E46 6-cyl 328 MT/AT REAR OPEN BASIC 12 M DBW3020 E46 6-cyl M3 MT/AT REAR OPEN BASIC 12 M DBW3020 M1 5 series E28 6-cyl 525i、535i 81~88 MT/AT REAR OPEN BASIC 12 M DBW3010 E34 6-cyl 525i、535i 88~95 MT/AT REAR OPEN BASIC 12 M DBW3010 Z series 4-cyl Z3Roadster1.8 96~ MT/AT REAR OPEN BASIC 12 S DBW1810 4-cyl Z3Roadster1.9 MT/AT REAR OPEN BASIC 12 S DBW1810 6-cyl Z3Roadster2.8 97~ MT/AT REAR OPEN BASIC 12 M DBW3010 from http://www.kaazusa.com/lsd_bmw.html |
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02-04-2014, 03:18 PM | #22 |
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Sorry to revive an old thread ...
Would a differential and ratio from a 2009 128i manual, work on a 2011 135i manual? I found a low cost/ low mileage 128i diff, which is hopefully the bolted type. I would like to buy it and get the wavetrac LSD conversion done to it, then installed in my car ... Would this work, or do I need to continue hunting for a Diff stripped from a 135i automatic DCT?
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2011 X3 35i with M pack + 2011 135i w/6SPMT | 255 square tire setup | Quaife 3.46 LSD | Diff lock down bracket | Bilstein B8+Swift SpecR springs+H&R FSB | CDV delete | BMS Oil Tstat bypass | ER FMIC & CP | N54Tuning DP | GC Street Camber Plates | M3 FCA +guide rods+RSFB's+Tranny mounts | Manzo toe arms | Cobb Stg2 agressive tune | Hawk DTC70 brake pads | RB SS brake pistons | Goodridge SS brake lines | Custom brake cooling ducts
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