All about LSD

[tuj]

wow I don't feel any smarter about the subject...

So here's what I'm hearing: OS Giken Multi-plate or the M-Factory torsen?

[MFactory]

If you want to go Plate, yes, that is my recommendation, however, do some more research on the LSD first, especially if you are making a lot of power

If you want to go Helical, then you have 3 options to choose from. All 3 are good choices, with the Quaife being the most basic, the Wavetrac offering it's patented wavelock, and the MFactory offering the most torque bias

[Kgolf31]

Originally Posted by tuj

wow I don't feel any smarter about the subject...

So here's what I'm hearing: OS Giken Multi-plate or the M-Factory torsen?

I'd do a bit more research in OSG and why they aren't on the shelf anymore selling for Non-M BMWs

[Suprgnat]

Originally Posted by Kgolf31

I'd do a bit more research in OSG and why they aren't on the shelf anymore selling for Non-M BMWs

They still have the spider gear issue or whatever it turned out to be?

[MFactory]

Until they redesign their internal layout (which they may have done? I'm not sure), the problem is not going to go away.

[Kgolf31]

Originally Posted by Suprgnat

They still have the spider gear issue or whatever it turned out to be?

The diff casing on Non-M is just too small, so you end up with some parts that are manufactured with smaller thicknesses than other OSG Diffs and thus, a failing part.

I actually wanted to get one, and a friend/person within the OSG company told me basically they will sell me the diff if I really wanted it with no attached warranty, but they didn't recommend it...and pointed me towards Dan and my now diff that has been flawless for a year and a half.

Don't know if the warranty is still true, but I'd be nervous.

[MFactory]

Originally Posted by Kgolf31

The diff casing on Non-M is just too small, so you end up with some parts that are manufactured with smaller thicknesses than other OSG Diffs and thus, a failing part.

It's not really to do with their case size (for example, most Japanese fitments are a lot smaller than the BMW fitments), but rather, their internal design i.e they designed it for maximum adjustability (more plates), sacrificing the space they have for the internal gears, thus making the gears smaller. They tried strengthening the gears, but that did not sort the issue.

Basically, unless they redesign the whole internal layout, this issue is not going to go away with any high torque application.

[chris82]

Originally Posted by MFactory

For your requirements, I would:

1) Forget about the OEM-Based LSD's. These are all washer/cone style LSD's (i.e old tech) and, although they may provide the beginner with the progressiveness/smoothness that they require, this is only because the LSD is inherently "weak" to begin with. There is a reason why the more experienced driver would prefer a "real" LSD, and not a cheap OEM-Based LSD. Disclaimer: Don't get me wrong, they work and serve their function, but if you want something more advanced and tunable as you progress in driver skill, this is not your best option
2) Forget about the washer/cone style multi-plate LSD's (again, old tech). For the most part, these are like on/off switches and will not provide you with the progressiveness/smoothness that you require
3) Look for an LSD that utilises pre-load springs (there are a few on the market). By switching out the pre-load mechanism from washer/cone to springs, this allows a much more progressive locking of the plates, and is generally smoother in operation.
4) Ramp profiles will determine how "aggressive" the LSD is, and does contribute to the overall "smoothness", but not as much as the pre-load mechanism
5) You need to differentiate between "noise" and "chatter/vibration". Less pre-load will make for a smoother feel (due to the plates slipping easier), but more noise. More pre-load will make for a rougher feel (due to plates slipping less), but less noise. However, there will be more "chatter/vibration", which most users generally translate to as noise

Specifically, which Diffs are NOT OEM-Based LSDs?

[MFactory]

Most LSD's on the market that are offered by a Manufacturer/Company (instead of a builder/tuner/shop): MFactory, Cusco, OS Giken, Kaaz, ATS/Carbonetic, Drexler, Titan, 3J etc etc

[chris82]

Originally Posted by MFactory

Most LSD's on the market that are offered by a Manufacturer/Company (instead of a builder/tuner/shop): MFactory, Cusco, OS Giken, Kaaz, ATS/Carbonetic, Drexler, Titan, 3J etc etc

So a Quaife is on that list right?

And you're saying the diffsonline is OEM-based?

Just trying to get my facts straight. I've found your posts very informative

[MFactory]

Quaife is a Torsen style LSD (i.e Helical). My recommendations to the OP above was concerning Plate style LSD's.

The majority of Diffsonline builds are with his OEM-based LSD's, yes. However, he does sell more advanced LSD's, but are a lot more expensive than his regular bread-n-butter builds.

OS Giken - Adjustability-wise, this is the most advanced, but as mentioned in a few posts above, they do have their issues on high torque applications
Drexler - This is the most popular LSD in Europe for BMW's, but is very expensive, especially if you want more adjustability from their units. If budget is no option, this is, in my opinion, the best choice at the present moment

We (MFactory) do have our v2 Plate LSD's currently under development, which was designed from scratch to be the most adjustable, can hold high torque and come in at an affordable price point. However, we don't have an ETA on this yet, so I am not adding it to this list.

[135]

Originally Posted by MFactory

Quaife is a Torsen style LSD (i.e Helical). My recommendations to the OP above was concerning Plate style LSD's.

The majority of Diffsonline builds are with his OEM-based LSD's, yes. However, he does sell more advanced LSD's, but are a lot more expensive than his regular bread-n-butter builds.

OS Giken - Adjustability-wise, this is the most advanced, but as mentioned in a few posts above, they do have their issues on high torque applications
Drexler - This is the most popular LSD in Europe for BMW's, but is very expensive, especially if you want more adjustability from their units. If budget is no option, this is, in my opinion, the best choice at the present moment

We (MFactory) do have our v2 Plate LSD's currently under development, which was designed from scratch to be the most adjustable, can hold high torque and come in at an affordable price point. However, we don't have an ETA on this yet, so I am not adding it to this list.

So, does that mean your MFactory v2 Plate LSD will be even better than the Drexler (and the OS Giken, excluding its gear strength issues)?
Or will the MFactory v2 Plate have some limitations, drawbacks or be missing some features compared to those two brands' offerings.

[MFactory]

Yes, we designed our new v2 to be the most adjustable (pre-load, ramp angles, lock capacity. All can be adjusted by the end-user without having to order new parts nor send back your LSD), stronger materials (to avoid the same issues that OS Giken were having), our 2nd Generation Active Friction™ Plates (originally developed for our competition Touring Cars) which reduces NVH by as much as 50% over regular steel and/or sintered plates that the competition uses, and, of course, our industry-leading globally transferable lifetime warranty

If you are in the market for a new Plate type LSD, I would suggest looking into our new option

As this is not a sales thread though, I cannot give further information with regards to pricing, so you would have to PM me for more details.

[HP Autosport]

Originally Posted by RyanDavies

Custom Diffsonline from Dan Fitzgerald. I promise you'll be better talking to him than you will "forum experts".

I would not run a Torsen / Quaife diff on an E82, given the rear roll stiffness tha is needed to make them work, you'll be running a reasonably good bit of rear bar rate to make the car neutral. And lots of rear bar can quickly turn a Torsen into an open. The diff I have behaves like an open on decel, and fairly strong lock on throttle. It's excellent, rather quiet, and has me sold on clutch diffs, after running Torsen differentials in several cars before.

I've got a friend who works for OS Giken if you're interested in going that route, but I recommend Dan at Diffsonline for sure.

The MFactory diffs are a fucking mess. I helped another competitor with some setup work, and almost all the major issues were caused by that disaster of a diff.

Most if not all Turner complete final drive are built by Dan at Diffsonline anyway so the OP should correct the listings.

I agree partially on not running the gear type LSD on the E8x E9x chassis. For street/track they are fine and likely never need rebuilding with minimum maintenance. For serious track and extreme street the clutch type is preferred. This type will require more frequent maintenance and rebuilds. As for getting the car balanced, more front camber and bar works well.

[geeyore]

Originally Posted by HP Autosport

Most if not all Turner complete final drive are built by Dan at Diffsonline anyway so the OP should correct the listings.
...For serious track and extreme street the clutch type is preferred. This type will require more frequent maintenance and rebuilds.

I have a Dan-diff on the way. What do you mean by "more frequent maintenance and rebuilds"? For my use (presently track+DD) I've understood annual fluid change and rebuild 3-5 years out.

Do you have something else in mind?

By the way, in addition to Turner, I think Bimmerworld and BAVauto also source from Dan, not to mention the shop I use.

[MFactory]

Yes, all of Bimmerworlds diff's are built by Dan.

Regarding your "more frequent maintenance and rebuilds" question, you won't notice it so much on your current purchase as you purchased an oem-based build, so this very tame in terms of features/performance compared to an aftermarket Plate LSD. Not all Plate LSD's are the same.

oem-based LSD's were designed primarily for the street car, not the race car. Suffice to say, you will probably notice better performance on the street car with a Helical LSD than an oem-based LSD, as the only advantage that the oem-based LSD has over the Helical is if you un-load one wheel (which won't happen on a street car).

[HP Autosport]

Originally Posted by geeyore

I have a Dan-diff on the way. What do you mean by "more frequent maintenance and rebuilds"? For my use (presently track+DD) I've understood annual fluid change and rebuild 3-5 years out.

Do you have something else in mind?

By the way, in addition to Turner, I think Bimmerworld and BAVauto also source from Dan, not to mention the shop I use.

You will be fine as long as you change your fluid once a year.

[geeyore]

Originally Posted by MFactory

the only advantage that the oem-based LSD has over the Helical is if you un-load one wheel (which won't happen on a street car).

OK, thanks. This is mutating into track car. And I do like riding the kerbs, with unloading on the return to earth.

[MFactory]

Plate LSD is your choice then

[383backinblack]

Originally Posted by MFactory

You are correct, yes. The basic traction control is just that; basic. It is good for general street use, and is more of a "safety" feature than it is "performance". As I said though, "performance" is good for sales, so it is marketed as such.

A Helical LSD will not stop wheel-spin completely, as it can only transfer so much torque to the opposing wheel (this is what I mean with the bias ratios). Each Helical LSD has different bias ratios, but most consumers do not realise this, thus the benefits are not well known. FYI, we are the only company to allow upto 75% torque transfer; most other Helical's/Torsens are around 66%. The increased torque bias helps tremendously and is night & day difference.

For the Wavetrac, yes, they have their patented "wavelock" mechanism (which replaces the pre-load washers in a conventional Helical LSD) which, upon detecting an unloaded state, will lock the free-spinning side of the LSD and continue to bias torque as required. Traction Control serves the exact same function, but only IF you don't turn it off

I cannot go too much into the details, but suffice to say, which would you rather prefer: Increased traction during 90%+ of cornering, or increased traction during 5%+ of cornering? Of course, this scenario only applies if you are using one of the Helical/Torsen LSD's

When it comes to Plate type LSD's, then there are FAR more choices available on the market. Hint: Don't just follow blindly the "engineering talk" that "builders/mechanics/tuners" tend to spew out, as a lot of the stuff they say and advertise on their website is a complete joke, showing they have a very limited understanding of how an LSD actually works. Again, what they sell/offer/propose may do as they advertise, but so does a Honda Civic. But guess what, you chose a BMW. Why?

If you want to do thorough research, try talking to the engineers at the actual LSD manufacturers and they will tell you what's what. Don't talk to the sales people as they will have their customers best interests in mind (i.e they don't want to lose sales as these builders/mechanics/tuners also purchase their products, so they can't say their customers lack the knowledge). The difference with us is, we are both the Manufacturer & Seller, so I will always tell it as it is, regardless of these "builders/mechanics/tuners".

For your requirements, I would:

1) Forget about the OEM-Based LSD's. These are all washer/cone style LSD's (i.e old tech) and, although they may provide the beginner with the progressiveness/smoothness that they require, this is only because the LSD is inherently "weak" to begin with. There is a reason why the more experienced driver would prefer a "real" LSD, and not a cheap OEM-Based LSD. Disclaimer: Don't get me wrong, they work and serve their function, but if you want something more advanced and tunable as you progress in driver skill, this is not your best option
2) Forget about the washer/cone style multi-plate LSD's (again, old tech). For the most part, these are like on/off switches and will not provide you with the progressiveness/smoothness that you require
3) Look for an LSD that utilises pre-load springs (there are a few on the market). By switching out the pre-load mechanism from washer/cone to springs, this allows a much more progressive locking of the plates, and is generally smoother in operation.
4) Ramp profiles will determine how "aggressive" the LSD is, and does contribute to the overall "smoothness", but not as much as the pre-load mechanism
5) You need to differentiate between "noise" and "chatter/vibration". Less pre-load will make for a smoother feel (due to the plates slipping easier), but more noise. More pre-load will make for a rougher feel (due to plates slipping less), but less noise. However, there will be more "chatter/vibration", which most users generally translate to as noise

Again, I just tell it how it is. Everyone has their own thoughts on how an LSD works, and how it "should" work, but be wary of those who promote their ideals as gospel. No one person is alike, especially when it comes to driving style and preferences, so at the end of the day, what works for someone else may not work for you.

Final Note: Just to show that I'm replying to you with "advice", rather than a "sales pitch", the best Plate type LSD currently available (in terms of technology and function) is the OS giken. However, make sure you do your research as they do have an inherent flaw in their design that they have not yet (AFAIK, I may be wrong) fixed, and is why most Porsche (and a lot of BMW) owners won't use their products. As mentioned, there are other Multi-Plate, spring-loaded LSD's on the market, but in their current iteration, are not as "technically advanced" as the OS Giken.

I'm new to this world, so please educate me ... in the world I come from (Drag racing) the cone/washer type of LSD is pretty standard. Is the limitation for that type of differential something that only presents itself in road racing where hard cornering and rapid changes in side-to-side relative wheel speed are an issue?

Why do the plate-type diffs require so much maintenance? To compensate for wear on the plates? There are also lots of people using those types of diffs on drag/street cars, but they're not that high mileage, so maybe that's why I haven't heard a lot of maintenance being needed on them.

I'm guessing it's not strength, as I'm putting 1000 ft/lbs through one in my race car (and driving it to meet-ups). It works gloriously well, and it locks hard enough to launch the car straight as an arrow with both front wheels off the ground.

[MFactory]

The Plates on the LSD only wear when they slip. As you are Drag Racing, the plates don't get the same sort of "workout" as they do with circuit racing. Similarly, a street car will not require as much maintenance as a dedicated race car.

You have 1000lbs? What car, and what LSD?

[383backinblack]

Originally Posted by MFactory

The Plates on the LSD only wear when they slip. As you are Drag Racing, the plates don't get the same sort of "workout" as they do with circuit racing. Similarly, a street car will not require as much maintenance as a dedicated race car.

You have 1000lbs? What car, and what LSD?

That's what I was guessing ... I can see a diff taking a severe beating winding it's way around a track.

Not BMW yet ... I'm lurking around here learning before I get a 1er for a daily driver ... This is the car, it's a blown, intercooled, alcohol injected 383 with a faceplated Tremec TKO 600 5-speed, a Spec 11" twin disc clutch, and a moser rear end with 33 spline axles and an Eaton super posi diff. I've blown the teeth off a few ring gears and the diff has survived (second picture is more recent).