Limited Slip Differential Options For BMW E87

[Big Mexican Women]

Hi all, could someone kindly explain the differences between all these LSD options, and which one would be best? If you go under "limited slip type" there are a number of options.

Also, there is an option to install REM Ring & Pinion + Differential Bearing Polishing. What are these two options? Are they necessary?

http://diffsonline.com/bmw-135-autom...l#.WxWTuEgvxPY

Thanks!

[omgshinoda]

There's common trio

Mfactory, Quaife, wavetrac.

I went with Mfactory, and highly recommend it. It locks up to 80% which more than enough for street/autocross application imo.

If you want hardcore LSD, look into plate type LSDs.

[chris_flies]

Originally Posted by omgshinoda

There's common trio

Mfactory, Quaife, wavetrac.

I went with Mfactory, and highly recommend it. It locks up to 80% which more than enough for street/autocross application imo.

If you want hardcore LSD, look into plate type LSDs.

Would this be for the helical or clutch unit from MFactory?

To the OP: Serious drivers looking for the last tenth or hundredth will use the clutch-type LSDs for their tunability, consistency, and predictability. They come in 1-,1.5-, and 2-way flavors. 1-way only locks on acceleration, 1.5-way locks on acceleration and sorta locks on braking, 2-way locks equally both ways.

Helical diffs are most common on street cars because they don't require periodic rebuilds and the maintenance that clutch-type diffs do; they're also generally smoother, quieter and more daily-able than clutch-types are.

[omgshinoda]

Originally Posted by chris_flies

Would this be for the helical or clutch unit from MFactory?

To the OP: Serious drivers looking for the last tenth or hundredth will use the clutch-type LSDs for their tunability, consistency, and predictability. They come in 1-,1.5-, and 2-way flavors. 1-way only locks on acceleration, 1.5-way locks on acceleration and sorta locks on braking, 2-way locks equally both ways.

Helical diffs are most common on street cars because they don't require periodic rebuilds and the maintenance that clutch-type diffs do; they're also generally smoother, quieter and more daily-able than clutch-types are.

To my understanding, they are helical types. Its great for street use and occasional autocross/track.

But i totally agree with you. clutch types that use plates are much better otherwise.

[chris_flies]

Originally Posted by omgshinoda

To my understanding, they are helical types. Its great for street use and occasional autocross/track.

But i totally agree with you. clutch types that use plates are much better otherwise.

MFactory actually makes both, at least, according to ECS Tuning's website...

[Big Mexican Women]

Originally Posted by chris_flies

Would this be for the helical or clutch unit from MFactory?

To the OP: Serious drivers looking for the last tenth or hundredth will use the clutch-type LSDs for their tunability, consistency, and predictability. They come in 1-,1.5-, and 2-way flavors. 1-way only locks on acceleration, 1.5-way locks on acceleration and sorta locks on braking, 2-way locks equally both ways.

Helical diffs are most common on street cars because they don't require periodic rebuilds and the maintenance that clutch-type diffs do; they're also generally smoother, quieter and more daily-able than clutch-types are.

great, thanks for the info! do you know anything about Wavetrac VS. Quaife?

[chris_flies]

Originally Posted by Big Mexican Women

great, thanks for the info! do you know anything about Wavetrac VS. Quaife?

Not much, other than they're both reputable and reliable units, and no one has ever regretted an LSD...

[Big Mexican Women]

Originally Posted by chris_flies

Not much, other than they're both reputable and reliable units, and no one has ever regretted an LSD...

haha, i'm sure. can't really decide between the other options on this list though.

[chris_flies]

Originally Posted by Big Mexican Women

haha, i'm sure. can't really decide between the other options on this list though.

Me neither, it's hard to make a decision that costs so much money.

I've been contemplating and hmm-in and huh-ing for months about an LSD

[Big Mexican Women]

Originally Posted by chris_flies

Me neither, it's hard to make a decision that costs so much money.

I've been contemplating and hmm-in and huh-ing for months about an LSD

It's a fantastic upgrade if you enjoy to corner spirited, no doubt. if you like to attack apex's and throttle-out like a madman driving above the speed limit around a bend, this mod is the one for you. also super helpful in rain and snow. i'd select a slightly higher final-drive ratio if you do lots of city driving.

some other good upgrades worth noting would be camber plates, coilovers (or Bilstein B12 kit, Ohlins which is pricey but excellent kit) along with some sway bars + your LSD and that little 128i is going to be a monster around corners.

[xQx]

Hey!

LSD owner with regrets here

First and foremost: Get a LSD. Do it before you do anything else to the suspension or handling of the car. It's a lot of money, but it's a lot of worth it. I've got 100% stock standard spongy suspension but the combination of good tires and a LSD changes a 135i from an unpredictable little beast into something you can throw around corners with confidence. It changes traction control to something you despise to something that works perfectly 95% of the time. (The other 5% is when you _want_ to drift).

Your first choice is: Traditional or Helical.

Helical uses gears to put power to the wheel with most grip. Traditional locks both wheel together under power.

Helical

A Helical diff can be installed then ignored for its lifetime. From what I've heard/seen/read (never driven one), you don't really know it's there. It just gives you traction you never had.

It has two downsides.

First, If you have a pure helical (Mfactory or Quaife), you're driving around a track _fast_ and you lift a wheel off the ground under power, the LSD stops putting power to the wheel with most grip and starts putting it to the free wheel. When that free wheel hits the ground again, the sudden shock can shatter your diff. I'm honestly not sure if this has ever happened, or if it's pure Wavetrac sales spin. ... A wavetrac fixes this "problem" by having an additional clutch that engages in this specific scenario and locks your back wheels together. Quaife is expensive. If I were doing my car again, I'd get a MFactory or Wavetrac helical.

Second: Say you're in a drift, a helical doesn't put the power down evenly on your two back wheels. It puts the power to the wheel with the most grip - and being gears, not clutches, it can instantly transfer that power from one side of your car to the other. The net result is if you're driving on or above the limit of traction, a helical diff can be unpredictable.

Traditional

A traditional diff is what I have. It's a pain in a daily driver, but its an absolute delight when you're driving on or over the limit.

A traditional diff has more adjustability, but to adjust it you need to take it off the car, disassemble it, re-assemble it, and put it back on the car. ... suffice to say, unless you're in competition sport, you guess the settings you want then you're stuck with `em.

The clutches wear out over time, which is a major selling point of helicals. However, as long as you're changing the diff fluid often (every 3k miles), and you're not using it for competition sport, you can expect to get 60k miles out of the diff before having it rebuilt.

Now, unless you ease off the diff settings drastically (like in a M3 stock diff), you'll instantly know you're driving a car with a LSD on the street. When you drive out of your driveway and turn onto the street, it'll go "clunk clunk clunk shudder". When you hit the gas hard then lift off hard, you'll feel it "clunk" as it disengages the engine from the wheels (1/way & 1.5/way diffs only). If you accelerate into a corner then lift off the gas halfway through when you've got the suspension loaded-up on the outside; you'll experience the feeling of snap-oversteer on the chassis. (If this turns into _actual_ snap over-steer depends on conditions)

BUT, there's a good reason why traditional diffs are preferred for racing, and this is it:

A traditional diff is 100% predictable. When you're balls to the wall, you wouldn't want anything else.

The back wheels are either locked together, or they're free. And whenever you're on the power, they're locked together. The back of your car is always pushing you in one, and only one direction. When you loose grip, you loose it at both wheels, then when you regain grip, you retain it at both wheels. It's never pushing one way or the other, it's never squirrelly, and its behavior doesn't change on different roads/conditions.

It's much harder to drive a traditional LSD well, but once you've learnt how to, you wouldn't want anything else.

In summary: A Helical is something you'll put on your car and it'll make the car better in every way. A Clutch/Plate (Traditional) LSD is something you'll put on your car and it'll make your car awesome in some ways and shitty in others. You'll have no problem selling your car with a helical, but nobody will come near your car after a test-drive with a traditional diff. ... but if you want an uncompromising sports car - skip the helical and learn how to drive with a _real_ diff.

... Your second choice is brand. Helical will be a choice of Mfactory/Wavetrac/Quaife (going from cheapest to most expensive). I don't think Quaife is worth the extra money. Traditional is generally a choice of MFactory/M3 OEM/OS-Giken (going from cheapest to most expensive & best).

What I got is in my signature. I love it, but I do wish I'd got a helical instead.

[chris_flies]

Originally Posted by xQx

Hey!

LSD owner with regrets here

First and foremost: Get a LSD. Do it before you do anything else to the suspension or handling of the car. It's a lot of money, but it's a lot of worth it. I've got 100% stock standard spongy suspension but the combination of good tires and a LSD changes a 135i from an unpredictable little beast into something you can throw around corners with confidence. It changes traction control to something you despise to something that works perfectly 95% of the time. (The other 5% is when you _want_ to drift).

Your first choice is: Traditional or Helical.

Helical uses gears to put power to the wheel with most grip. Traditional locks both wheel together under power.

Helical

A Helical diff can be installed then ignored for its lifetime. From what I've heard/seen/read (never driven one), you don't really know it's there. It just gives you traction you never had.

It has two downsides.

First, If you have a pure helical (Mfactory or Quaife), you're driving around a track _fast_ and you lift a wheel off the ground under power, the LSD stops putting power to the wheel with most grip and starts putting it to the free wheel. When that free wheel hits the ground again, the sudden shock can shatter your diff. I'm honestly not sure if this has ever happened, or if it's pure Wavetrac sales spin. ... A wavetrac fixes this "problem" by having an additional clutch that engages in this specific scenario and locks your back wheels together. Quaife is expensive. If I were doing my car again, I'd get a MFactory or Wavetrac helical.

Second: Say you're in a drift, a helical doesn't put the power down evenly on your two back wheels. It puts the power to the wheel with the most grip - and being gears, not clutches, it can instantly transfer that power from one side of your car to the other. The net result is if you're driving on or above the limit of traction, a helical diff can be unpredictable.

Traditional

A traditional diff is what I have. It's a pain in a daily driver, but its an absolute delight when you're driving on or over the limit.

A traditional diff has more adjustability, but to adjust it you need to take it off the car, disassemble it, re-assemble it, and put it back on the car. ... suffice to say, unless you're in competition sport, you guess the settings you want then you're stuck with `em.

The clutches wear out over time, which is a major selling point of helicals. However, as long as you're changing the diff fluid often (every 3k miles), and you're not using it for competition sport, you can expect to get 60k miles out of the diff before having it rebuilt.

Now, unless you ease off the diff settings drastically (like in a M3 stock diff), you'll instantly know you're driving a car with a LSD on the street. When you drive out of your driveway and turn onto the street, it'll go "clunk clunk clunk shudder". When you hit the gas hard then lift off hard, you'll feel it "clunk" as it disengages the engine from the wheels (1/way & 1.5/way diffs only). If you accelerate into a corner then lift off the gas halfway through when you've got the suspension loaded-up on the outside; you'll experience the feeling of snap-oversteer on the chassis. (If this turns into _actual_ snap over-steer depends on conditions)

BUT, there's a good reason why traditional diffs are preferred for racing, and this is it:

A traditional diff is 100% predictable. When you're balls to the wall, you wouldn't want anything else.

The back wheels are either locked together, or they're free. And whenever you're on the power, they're locked together. The back of your car is always pushing you in one, and only one direction. When you loose grip, you loose it at both wheels, then when you regain grip, you retain it at both wheels. It's never pushing one way or the other, it's never squirrelly, and its behavior doesn't change on different roads/conditions.

It's much harder to drive a traditional LSD well, but once you've learnt how to, you wouldn't want anything else.

In summary: A Helical is something you'll put on your car and it'll make the car better in every way. A Clutch/Plate (Traditional) LSD is something you'll put on your car and it'll make your car awesome in some ways and shitty in others. You'll have no problem selling your car with a helical, but nobody will come near your car after a test-drive with a traditional diff. ... but if you want an uncompromising sports car - skip the helical and learn how to drive with a _real_ diff.

... Your second choice is brand. Helical will be a choice of Mfactory/Wavetrac/Quaife (going from cheapest to most expensive). I don't think Quaife is worth the extra money. Traditional is generally a choice of MFactory/M3 OEM/OS-Giken (going from cheapest to most expensive & best).

What I got is in my signature. I love it, but I do wish I'd got a helical instead.

Say, do you feel like you could maintain a nice slide on a rained-on surface of you were to put your mind to it? In less words, can you do mad skids in the rain?

I'm looking for predictability and control, and I want to have the same when I'm on my favorite empty road and there's a tight corner, so it sounds like I'll do a traditional diff!

I really appreciate the info, you kinda made my decision for me!

[Big Mexican Women]

Originally Posted by xQx

Hey!

LSD owner with regrets here

First and foremost: Get a LSD. Do it before you do anything else to the suspension or handling of the car. It's a lot of money, but it's a lot of worth it. I've got 100% stock standard spongy suspension but the combination of good tires and a LSD changes a 135i from an unpredictable little beast into something you can throw around corners with confidence. It changes traction control to something you despise to something that works perfectly 95% of the time. (The other 5% is when you _want_ to drift).

Your first choice is: Traditional or Helical.

Helical uses gears to put power to the wheel with most grip. Traditional locks both wheel together under power.

Helical

A Helical diff can be installed then ignored for its lifetime. From what I've heard/seen/read (never driven one), you don't really know it's there. It just gives you traction you never had.

It has two downsides.

First, If you have a pure helical (Mfactory or Quaife), you're driving around a track _fast_ and you lift a wheel off the ground under power, the LSD stops putting power to the wheel with most grip and starts putting it to the free wheel. When that free wheel hits the ground again, the sudden shock can shatter your diff. I'm honestly not sure if this has ever happened, or if it's pure Wavetrac sales spin. ... A wavetrac fixes this "problem" by having an additional clutch that engages in this specific scenario and locks your back wheels together. Quaife is expensive. If I were doing my car again, I'd get a MFactory or Wavetrac helical.

Second: Say you're in a drift, a helical doesn't put the power down evenly on your two back wheels. It puts the power to the wheel with the most grip - and being gears, not clutches, it can instantly transfer that power from one side of your car to the other. The net result is if you're driving on or above the limit of traction, a helical diff can be unpredictable.

Traditional

A traditional diff is what I have. It's a pain in a daily driver, but its an absolute delight when you're driving on or over the limit.

A traditional diff has more adjustability, but to adjust it you need to take it off the car, disassemble it, re-assemble it, and put it back on the car. ... suffice to say, unless you're in competition sport, you guess the settings you want then you're stuck with `em.

The clutches wear out over time, which is a major selling point of helicals. However, as long as you're changing the diff fluid often (every 3k miles), and you're not using it for competition sport, you can expect to get 60k miles out of the diff before having it rebuilt.

Now, unless you ease off the diff settings drastically (like in a M3 stock diff), you'll instantly know you're driving a car with a LSD on the street. When you drive out of your driveway and turn onto the street, it'll go "clunk clunk clunk shudder". When you hit the gas hard then lift off hard, you'll feel it "clunk" as it disengages the engine from the wheels (1/way & 1.5/way diffs only). If you accelerate into a corner then lift off the gas halfway through when you've got the suspension loaded-up on the outside; you'll experience the feeling of snap-oversteer on the chassis. (If this turns into _actual_ snap over-steer depends on conditions)

BUT, there's a good reason why traditional diffs are preferred for racing, and this is it:

A traditional diff is 100% predictable. When you're balls to the wall, you wouldn't want anything else.

The back wheels are either locked together, or they're free. And whenever you're on the power, they're locked together. The back of your car is always pushing you in one, and only one direction. When you loose grip, you loose it at both wheels, then when you regain grip, you retain it at both wheels. It's never pushing one way or the other, it's never squirrelly, and its behavior doesn't change on different roads/conditions.

It's much harder to drive a traditional LSD well, but once you've learnt how to, you wouldn't want anything else.

In summary: A Helical is something you'll put on your car and it'll make the car better in every way. A Clutch/Plate (Traditional) LSD is something you'll put on your car and it'll make your car awesome in some ways and shitty in others. You'll have no problem selling your car with a helical, but nobody will come near your car after a test-drive with a traditional diff. ... but if you want an uncompromising sports car - skip the helical and learn how to drive with a _real_ diff.

... Your second choice is brand. Helical will be a choice of Mfactory/Wavetrac/Quaife (going from cheapest to most expensive). I don't think Quaife is worth the extra money. Traditional is generally a choice of MFactory/M3 OEM/OS-Giken (going from cheapest to most expensive & best).

What I got is in my signature. I love it, but I do wish I'd got a helical instead.

what a fantastic write-up! thanks a lot bud. this was very, very helpful.

here is a list of the options I have.



Would you mind describing what is the difference between having 2, 3, or 4 clutches within the differential and what 30/90 or 35/60 means? I am currently leaning towards the OS Giken differential, but all together this is going to cost me almost $3000. I have not found anything else that's cheaper for my specific car. is it worth it?

Thanks again!

[xQx]

Okay, you're going to want to go down the rabbit hole and read as much as you can I just went on the advice of a very experienced diffbuilder (There's really only one guy in all of Australia who does aftermarket diffs for BMW's, so I did what he told me )

I'd start here: http://www.blueskymotorsports.com/in...id=20&Itemid=6
and here: http://support.teammfactory.com/supp...fferential-faq

From what I understand, the preload is how much power you put down before it locks up, the ramps angles and clutch pack configuration determines how quickly/progressively it locks up and what wheel slip it will allow when completely locked up.

On the street, you don't want 100% lockup because when you turn a tight corner you want the inside wheel to be able to spin a little.

It's important to know when it's 75% locked up, it's not putting 75% of the power to one wheel, and it's not letting one wheel spin 25% more than another - it's locked up to 75% of the full force of the clutches.

The number of clutches is proportional to the number of friction surfaces and 30/90, 35/60 is the ramp angles ... When it comes to clutches, I think more is better, because it's more adjustable - but it seems it might be more complicated than that. (I have 6 out of 10 friction surfaces engaged and that's plenty for a street car ... but I don't know what the percentage is, the ramp angles are or if that directly translates to any other brand).

With your list above, I'd be either buying the Wavetrac Helical or the OS Giken Clutch pack.


Is it worth it? Yes. Hands down the most fulfilling modification you can make to our cars.

Mad skids in the rain? Yes. I have yaw control on my car. Especially on our cars having an aggressive clutch diff really teaches you to trail-brake into a corner then power out. If you plant the throttle right before the apex, it's very easy to step the back out. Amazingly, having traction control set to the DCT setting (DCT off, DSC on) it works very well at kicking in just after the back has let go - meaning I can quite confidently kick the back out around a corner and catch it again before it gets scary

[tock172]

OS Giken is a legit company that has been manufacturing some of highest quality aftermarket parts on the market for decades. Couldn't resist when I saw the name. Fascinating company.