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11-04-2014, 08:25 AM | #1 |
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The Differential Thread
So, I'm starting to look at the differential differential options to eventually purchase one and install in my car this upcoming spring for my STX Build.
As it stands, here are my available options. Torsen Based Clutch Based w/Set 45/45 Ramps Clutch Based w/Custom Ramps OS Giken I'm trying to evaluate what would be the best application for me. The car will be seeing less and less miles as the year goes on. So as far as noise, I'm not concerned. Torsen would be ideal because of 0 lockup when off throttle. This will help with turn in and there really is no extra service needed. Clutch, depending on ramp angles could create more push off-throttle. However depending on the ramp on-throttle lockup can be very precise and probably better over a torsen. We also have static lock here. OS Giken is probably the diff to get. However it is picky on the fluid it sees, as well as the 20 some clutch plates there is obviously going to be some extra service involved here. Also, I can go with 2 different install options: Chunk Pumpkin + Chunk Anyone have some thoughts or experience to chime in here? I want this to kind of be educational so people can relate back and see who chose what and why. |
11-04-2014, 08:44 AM | #2 |
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Garage List F15 X5 xDrive35i [8.75]
E86 Z4 M [10.00] F10 550i (Retired) [9.17] F25 X3 xDrive35i (R ... [9.43] E82 135is (Retired) [9.50] E85 Z4 M (Retired) [9.41] E90 328i xDrive (Re ... [9.25] E86 Z4 3.0si (Retired) [9.24] |
While at it you should think about possibly change to a gearing better suited for auto-x which never leaves 3rd gear (disclaimer: no clue if your current gearing works for you or not, just throwing out there).
If you don't mind the cost and maintenance I don't think anyone can argue against OSG. Clutch type is good but you should really speak to a diff specialist or a fellow auto-xer familiar with the 1 to make recommendations on rates. I have a a Torsen based and it's served me well but I know it's not the ideal solution for a road course. You're close to Brett @ KMS, I would have him do the install considering his rates are more than fair and he's as good as they get. Then you can just do the pumpkin swap yourself. Last edited by 3002 tii; 11-04-2014 at 08:50 AM.. |
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11-04-2014, 09:00 AM | #3 |
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OSG is pretty well disliked in the 911 world. The general consensus is that they are a massively overpriced clutch diff that doesn't live up to the name hype.
Torsen is definitely a street focused diff. I love them but it seems poorly matched to your application? Don't forget to get the BMW/Quaife finned diff cover when you do this.
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11-04-2014, 09:13 AM | #4 | ||
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With the increased limiter I'm at 66-67 MPH at second gear...which is pretty good. I want to check with KMS to see what they can provide. Also considered getting a diffsonline unit and doing a direct swap. Quote:
And just for another data point. The FRS/BRZ stock comes with a torsen diff. The national champion, Andrew Pallotta who drove a FRS won on a stock diff. |
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11-04-2014, 09:54 AM | #5 | |
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The e60 2004 530i/525i AT has a finned diff cover that fits our 188mm pumpkin. I strongly believe its the Quaife cover Stig mentioned. Torsen style has some cheap options - the Mfactory brand recently did a bunch of group buys and I believe the reviews here and bimmmerboost/n54boost are positive. They even have begun to cater to the n54 welded diff people, which is very nice of them. They even have Clutch diffs too.
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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 Last edited by andrey_gta; 11-04-2014 at 10:00 AM.. |
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11-04-2014, 09:56 AM | #6 |
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Some hard core lappers prefer clutch based LSD's, and recommended I go with this option.
I think the M cars are clutch based "variable lock" LSD's. The m variable unit gets clunky after continued abusive driving. This is why so many were replaced under warranty. After some research, decided to go with a Quaife (torsen) earlier this year. I wanted a low-cost, low maintenance (no clutch plates to replace), no specialty oil, and a brand with a solid reputation. I found a used large pumpkin/bolted diff at a recycler, and got the 3.08FD "chunk" converted to a Quaife 3.46FD. The torsens are probably not the best out there, but for a dual duty car, Im quite happy with the results. it really transformed how power is appllied to the ground. It removed snap oversteer, and made the car predictable at turn out. It is very noticeable even on the street, during hard accelerations, and low grip conditions. The car steers straight now, but rear-end used to twist and DSC would frequently intervene with the previous open "e-diff" ...
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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
Last edited by dcaron9999; 11-04-2014 at 10:15 AM.. |
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11-04-2014, 09:58 AM | #7 |
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Don't get me wrong, I think they are wonderful(I have a Quaife in the closet I need to get around to installing). But there is a reason they aren't found on top spec performance cars.
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11-04-2014, 11:11 AM | #9 |
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Aside from this Part of me think one can use the 2 Series M Sport/M perfromance units
it would be like using a 135i diff- changing the half shafts etc... Unless they make it for the 228i which still should have the 188mm pumpkin yes the 128i has 3.23 MT 3.73AT the 135i has lesser final gears, obviously a different transmission gearing too so net effect is still probably in 135i favour
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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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11-04-2014, 11:23 AM | #10 |
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You probably can, but that is a half assed diff designed to be worse than the M units and costs a ton. No thanks.
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11-04-2014, 11:28 AM | #11 |
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Lol. I guess, makes sense that its not very dedicated diff
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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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11-04-2014, 11:34 AM | #12 |
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I think it has somewhere in the neighborhood of 15%-20% lockup?
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11-04-2014, 12:17 PM | #14 |
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I imagine that for your use you want the clutch type. Personally i plan on going with wavetrac, mfactory, or quaife. I've only began researching each option but they're all gear driven so its essentially the same thing.
Are you planning on changing all the associated bushings when you're in there? I plan on doing LSD, diff bushings and the subframe bushings while i have it apart. I'm inclined to say i'll be starting this next summer.
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11-04-2014, 12:21 PM | #15 | |
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11-04-2014, 12:23 PM | #16 | |
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OP have you considered Wavetrac? Aren't they a combination of Torsen and clutch style diffs? |
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11-04-2014, 12:30 PM | #17 |
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I see. I forgot you're mostly prepped already. I'm undecided if i want to change to a higher final drive or not. I think it'd be beneficial but it mostly depends on highway drivability.
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11-04-2014, 12:31 PM | #18 |
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911s come with the shittiest clutch diffs in the world. One good track blows out most of them, including the units on the GT3. Seriously the cheapest part of the car. Most serious owners upgrade to a Guard unit.
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11-05-2014, 02:02 AM | #19 |
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I have a Quaife in my 130i, it's a nice traction aid for a street car.
Note: I live on a mountain, frequent 100km/h (62mph) winding roads both sealed and unsealed. Low maintenance was also a factor in this decision. In the past I have owned a Cusco 2way clutch LSD in a RWD JDM car, for a weekender and track car, a clutch 1.5way LSD would be my preference. If you would consider a 1way clutch LSD, get a Torsen and save money. Else, if you would make use of a real diff and/or can hold a slide and/or can deal with the service costs/time, buy a 1.5way. Speak to Jesse Streeter, an Australian living in Japan who is pretty good with sourcing parts. He did the research with me, the OSG part number for the BMWs isn't on par with the JDM equiv- apparently made and sold under licence. A KAAZ is cheap and reliable for a track hack, a Drexler is arguably superior but will cost 250% ! |
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11-05-2014, 07:49 AM | #20 |
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Yea, the most I would do is a 3.46. That's about a 7% increase. I don't know what I'm talking about but wouldn't that increase your RPMs at a given speed by 7% too?
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11-05-2014, 08:54 AM | #21 | |
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@justpete swapped in a 3.73, I wish he would comment on the new shift points and daily life. That is a 15% increase and its very tempting because of numerous junker 3.73 parts for sub $500 For a 128i to get 3.36 or 3.46 we have to either get a custom small pumpkin or think about drive shaft mating to large one and half shaft fitments. I have no idea what is a direct swap
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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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11-05-2014, 09:04 AM | #22 | |
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