35iS diff options

[techathy]

I'm seriously considering some sort of LSD/ATB diff. There are 2 ATB options but I'm struggling to find any plate LSD option, are there any on the market at all?

[Machine monkey]

I dont know what options you have available for your car. But putting a M factory diff in my car is the best mod i have done.

[PerryGunn]

I've got a Quaife ATB diff, which is essentially the same as ///MM's MFactory unit - and it's great

there's a version available for the 35is as well

[Mister T]

OS Giken probably do a plated diff that will fit

[Mister T]

I dont know what options you have available for your car. But putting a M factory diff in my car is the best mod i have done.

I'd guess that it would be like fitting the E92 M3 diff in the 1 series and you'd need a custom propshaft.

[Machine monkey]

No sorry M factory are a brand not associated with BMW nothing to do with ///M

Give grinspeed a call see if they have an option for your car. https://www.google.co.uk/url?sa=t&rct=j ... 6267,d.ZGU

They are the UK distributors of M factory.

[Mister T]

Ah... They look proper

[Zed Five]

Don't Birds do one?

[techathy]

The problem I keep hitting is getting the correct final drive ratio DCT box, if I don't mind running at 2'900rpm then there are plenty about


Zed Five, Birds don't do an LSD per-se they are the UK Quaife ATB supplier. ATBs also go by the names Helical LSD & Torsen. They push torque to the wheel which is moving more slowly, however they don't function when one wheel has little to no grip. Wavetrac do a variant which has a secondary locking plate which engages when there is a high wheel speed difference in the half axles to add extra load to the low load side of the diff. What I want is a proper locking LSD which basically is a clutch between the two output sides of the diff & the bigger the difference between the two output shaft speeds the harder the clutch is pushed together

[Machine monkey]

Ah... They look proper

I love mine the machining work is second to none. A proper well made bit of kit and a very good price. I wouldn't want to try and make one for the price i paid.

[MFactory]

Our new 215 Plate type LSD is undergoing testing just now, and is expected to be ready sometime late Nov.

Your only other option at present is the OS Giken or Drexler, both of which will severely dent your wallet (if you must buy now though, go for the Drexler. I would stay away from the OS Giken units)

[PerryGunn]

Zed Five, Birds don't do an LSD per-se they are the UK Quaife ATB supplier. ATBs also go by the names Helical LSD & Torsen. They push torque to the wheel which is moving more slowly, however they don't function when one wheel has little to no grip.

Apparently that's a misconception about Quaife LSDs - it was raised when I had my Quaife fitted and GuidoK (who seems to know quite a lot about the mechanics of LSDs) provided an explanation

See: viewtopic.php?f=2&t=74954&start=75#p1105648

[GuidoK]

They push torque to the wheel which is moving more slowly,

An atb doesnt push torque to the wheel which moves more slowly, it pushes torque to the wheel that has more grip. It acts before there is any slip/loss of traction, as lockup occurs when there is a difference in torque between the wheels instead of when there is a difference in speed. The bmw m diff (since e46 m3) is a diff that acts on difference in speed as it uses a gerotor system. So that needs loss of traction (or a difference in speed) before it can act.
And a normal clutch diff locks up when force is applied and the ramp slope and style sets the amount of lock (so it is a pre-set system which is accellerated and decellerated controlled).
But there are many ways to control the clutch mechanically; there have even been lsd's with centrifugal velocity controlled clutch actuation etc.

When you want lots of straightline stability (like for instance drag racing) the classic clutch type is probably the way to go as it mimics a solid axle.
But for high maneuverability the ATB type is more suitable. There is a reason why FWD cars never have a clutch style lsd and always have an ATB style lsd (or computer controlled ones). You don't want to loose the ability to steer in a corner when applying power (my guess is that a clutch type lsd in a fwd car would create really massive amouts of understeer)

[MFactory]

By nature of its design, a Torque Biasing differential does NOT lock; it is in a constant state of Torque Biasing (hence the name) between the left/right wheels, depending on which has more traction. The internal cone washers are used for pre-loading the gears against the housing, but in real world terms, only serve as noise control.

All current torque biasing differentials on the market are based off the Torsen (Torque Sensing) design, invented by Gleason.

This applies to the 3 major torque biasing differentials on the market today for the BMW: MFactory, Wavetrac, Quaife

Quaife: Back when they released their ATB (Automatic Torque Biasing. Just another name for Torque Sensing), there was no such thing as the internet, and searching patents wasn't something most people would do. The result? They took out a useless patent (which has long expired) to give the "impression" that they invented the thing. Of course, those who know better knew this was a load of BS, especially those in the US domestic muscle car market who were using the Torsen design when Quaife was still in diapers. To give Quaife credit, their marketing plan worked, and most Europeans think they invented the LSD. Until recently, they refused to call their differential an "LSD", but this has changed when they started losing major market share in North America (which, back then, accounted for over 50% of their consumer-based sales). Quaife will deny all of this, of course, but everything can be confirmed with upper management at Autotech. Most components are made in-house by Quaife at their own manufacturing facilities.

Wavetrac: Autotech, the parent company, used to be the North American distributors for Quaife. Around 2006, Quaife were working on a workaround to this "no-load" issue (i.e when one wheel goes into the air), but deemed it unnecessary as most cars post-2000 came with Traction Control, which basically makes it a non-issue (i.e if one wheel goes in the air, the traction control kicks in, providing load again to the spinning wheel via light braking. Before, the driver would have to left-foot brake to achieve this. Most experienced race drivers know how to do this, but if we only sold to race car drivers, we would only be worth less than 5% of our company value). Realising the "marketing advantage" this would offer, Autotech basically took the abandoned idea from Quaife, discontinued being their distributor and started offering their own Differential i.e Wavetrac (although to give them credit, this wasn't their only reason for doing so. As Quaifes North American distributor, they were fed up of being given the runaround by Quaife as Quaife were still selling to other companies in North America). Basically, it's all "marketing", as it is not a required function for cars with Traction Control. You're basically paying for technology designed for a 20 year old VW, not your modern day BMW. Autotech/Wavetrac will deny all of this, of course, but everything can be confirmed with upper management at Quaife. Like Quaife of yesteryear, they refuse to call their differential an "LSD". All of their components are outsourced to other manufacturing facilities, as they do not have the capability to manufacture their own components (Autotech are a trading company, not a manufacturer)

MFactory: Released in 2008 (same time as Wavetrac) and marketed as a "Helical LSD". We didn't invent the term, but we were the ones to put this term on the map. Like those before us, our Helical LSD was based on the original Torsen design, but improved metallurgically to handle the high power produced in modern day cars (our LSD was the only one that did NOT have to be revised to handle high power, as it was specifically designed for this function i.e 1000whp drag cars). Unlike the others though, we were not limited by patriotic marketing (i.e Made in USA, or Made in UK), so this allowed us to produce an LSD that was metallurgically stronger, lighter and better machined, yet at a much lower cost per unit (due to being made from Forged Blanks, and not pieces of Billet). Our LSD was marketed towards the general consumer market (i.e 80% of sales), and we are proud to be "Engineered in the USA", but "Made in Taiwan" (all in-house, as like Quaife, we own our own manufacturing facilities thus control our own QC). For the Honda/Mazda market in North America, we have over 90% market share, and are very quickly taking over the BMW market also. So much so, that Quaife resorted to taking design cues (NOT copying. I hate the word copy, and hate anything to do with copying. However, there is nothing wrong with "improving" existing products using design ideas from your competitors) from our product (Again, Quaife will deny this, and say we copied them! lol) and started marketing their ATB as a Helical LSD

I realise that there are die-hard fans/loyal supporters in each camp, so you can take what I say with a grain of salt if you so wish. However, for those not blinded by marketing, I'm sure the above is an interesting "twist" on the various stories out there.

This is not me trying to say that all other LSD's on the market are inferior (although I am a little biased, which is to be expected knowing what I know) as both Quaife and Wavetrac are high quality LSD's that perform as advertised. For most consumers, they would not be able to tell the difference between them when installed and used on a daily driver.

So it basically comes down to 4 things when choosing a Torque Biasing LSD:

1) Brand loyalty (all three have their own loyal supporters)
2) Bragging rights at the pub (if this is most important, buy a Quaife)
3) Value for money (Stronger, lighter, machined better, better warranty, money back guarantee, higher torque bias, lower cost. Do I need to say more? I can't, or I will be flamed for advertising)
4) You own a car without traction control, and will be very regularly taking it to the track (i.e putting yourself in a position to lift a wheel) but don't know how to left-foot brake. If this is the case, buy a Wavetrac

If you have a daily driver with only occasional track day use, the Torque Biasing LSD is your best choice as it is noise-free, maintenance-free and drives no different from an open-diff under normal use (e.g getting the groceries)

If you have an all-out race car, then a Plate type LSD is by far your best choice as it offers a night-and-day difference in terms of cornering performance and most (not all) are customisable to your driving style (this is the main reason for buying one in the first place. If you are not going to play around with the settings on your Plate type LSD and just run it at manufacturers default, then why even bother getting one? You're better of with a Torque Biasing Differential). There are even more choices/brands available, but going into that will most definitely get me warned/banned from this forum for perceived advertising (feel free to PM me though if you want more advice)

[Machine monkey]

Well that was an interesting read.

I am most defiantly not on M factory pay roll. I love my diff others who have driven it really like it too. In fact it has performed really well at track days. One local guy at the track i go too who has a 330. Had a go and was really impressed with the extra mechanical grip. And at the drifting days the diff is still performing well. Its very versatile and predictable. And the improved front end grip was a surprise!! Well not really if you think about it!! But turn in is sharp and crisp.

I would 100% recommend a M factory diff to anyone. And i would buy another no doubt if i needed too. Grinspeed who i brought mine from where very helpful as well. Always at the end of a phone as i was fitting mine myself that was a god send.