[StuyMac]

Ive just got my F31 335i back from a having a little tuning, and its instantly apparent that the OEM diff is not up to the job at all - especially in the wet! (spinning rear wheels easily in 5th at 90mph!)

Im therefore in the process of deciding which Limited Slip Differential to fit to help remedy this.

Question is, which one to go for...?

The M Performance diff is a plated unit, and can be had for £1750, bought outright! (Still have original diff to sell)

The other option is a Quaife ATB, which is £2600 (with £750 surcharge on my original diff). so that is £1850 with no diff to sell after the swap.

Is the Quaife really worth about £500 more - once you take in to consideration the price I could sell my old diff for after the M Performance diff had been fitted?

[sspade]

I would definitely give the AC Schnitzer unit some thought.

[zinner]

Mperformance Diff, it's cheaper, it's an OEM option so it's quality and reliable.

[IK6SPEED]

Originally Posted by StuyMac

Ive just got my F31 335i back from a having a little tuning, and its instantly apparent that the OEM diff is not up to the job at all - especially in the wet! (spinning rear wheels easily in 5th at 90mph!)

Im therefore in the process of deciding which Limited Slip Differential to fit to help remedy this.

Question is, which one to go for...?

The M Performance diff is a plated unit, and can be had for £1750, bought outright! (Still have original diff to sell)

The other option is a Quaife ATB, which is £2600 (with £750 surcharge on my original diff). so that is £1850 with no diff to sell after the swap.

Is the Quaife really worth about £500 more - once you take in to consideration the price I could sell my old diff for after the M Performance diff had been fitted?

https://f30.bimmerpost.com/forums/sh....php?t=1534335

Of course people who have NOT ponied up the money for their own car are quick to give your their opinion.

[Polo08816]

Originally Posted by StuyMac

Ive just got my F31 335i back from a having a little tuning, and its instantly apparent that the OEM diff is not up to the job at all - especially in the wet! (spinning rear wheels easily in 5th at 90mph!)

Im therefore in the process of deciding which Limited Slip Differential to fit to help remedy this.

Question is, which one to go for...?

The M Performance diff is a plated unit, and can be had for £1750, bought outright! (Still have original diff to sell)

The other option is a Quaife ATB, which is £2600 (with £750 surcharge on my original diff). so that is £1850 with no diff to sell after the swap.

Is the Quaife really worth about £500 more - once you take in to consideration the price I could sell my old diff for after the M Performance diff had been fitted?

I bought the M Performance LSD for my car and it's been fine for HPDE use. Far less expensive and time consuming than the other aftermarket options which require you to send them a core.

[XutvJet]

M Performance LSD for sure. Readily available, cheaper, and a very high-quality unit built by Drexler to BMW specs. The 2 way clutch setup is agruably the best for street and light track track use. Here's my detailed review of the M Performance LSD:

https://www.2addicts.com/forums/show....php?t=1493261

[ChrisFulton]

I have the M and happy. Still getting used to it as it changes the way the car tracks/handles. Had a track day soon after install and cut my lap times.

[zinner]

Last Black Friday there was a 1000 dollar rebate on the M-LSD. I would wait to see if they do it again this year.

[IK6SPEED]

Originally Posted by zinner

Last Black Friday there was a 1000 dollar rebate on the M-LSD. I would wait to see if they do it again this year.

I am going to make an educated guess BMW UK does not coordinate sales with BMWNA.

[enjoythemusic]

BMW M here and loving it.

[Munchi435i]

Originally Posted by zinner

Last Black Friday there was a 1000 dollar rebate on the M-LSD. I would wait to see if they do it again this year.

If they offer that deal this year, im all over it!!

[IK6SPEED]

It would appear many do not understand the difference in a Quaife ATB and a BMW MPerformance plated LSD.

Once an ATB LSD is fitted, that’s essentially it. No need to deal with it again for the life of the car. They are also strong, not just strong, but really strong because of the amount of gears used.

Up to 80% of the torque can be sent to one wheel with an ATB LSD.

The negative of an geared LSD is that if you lift a wheel it will just spin up as if you have an open differential fitted. As I have faith in my suspension and hybrid batteries in the rear keeping the wheels on the ground, I do not view that as an issue.

A plated differential has friction plates in the casing. There are ‘ramps’ on each, with cross pins within the casing that try to ride up the ramps and lock the plates together. The steepness of the angles determine the conditions under which it’ll lock and unlock.

The plate differentials are referred to as one-way, 1.5 way or two way, and that’s all about the ramp angles. A two-way has 45 degree angles for both the locking and unlocking phase allowing it to apply locking force under deceleration, a one-way is 45/90 degrees and only locks up under power, while a 1.5 way is 45/60 and doesn’t lock as aggressively on the deceleration phase.

A plated differential will lock, but only to 50/50. It will also lock if both wheels are not on the ground.

Hiwever, it’s a wearing differential that requires maintenance of having the plates shimmed and eventually replaced. Now unless you are living under a rock, you will note more and more threads about not being able to replace BMW Parts but needing to replace the entire part. So lots of luck with the constant maintenance of plates being shimmed and eventually replaced.

Plated LSD are also a much more aggressive diff due to the way it locks up - there’s no progressive transfer between the unlocked and locked state. It’s noisier due to using straight-cut gears as opposed to helical, and low-speed maneuvering can be clunky and unpleasant. With the aggressive way it operates and its main benefits being related to motorsport applications, that’s why I (and others forum members) went towards a Quaife ATB instead of plated M Performance.

In my opinion, when it comes to modifying a road car, geared is probably going to be the right way to go, unless you have a very specific set of circumstances that warrant opting for plated.

Besides, look at the photo and which looks more rugged and sturdier to you?

[XutvJet]

The MP LSD isn't a crap and cheap viscous LSD like you find in a lot of Japanese cars that can wear out quickly. Sure, the MP LSD will eventually wear out, but we're talking 80K+ miles of generally harder than normal driving. The MP LSD is built by Drexler. Not exactly a crap drivetrain company. Get on their website compare and take note of the quality the LSDs they make for the OEM and race teams. Just because a clutch LSD is compact doesn't means it's weak. Most any professional racer would tell you a clutch-based LSD is the way to go for the best performance and control, especially when hitting bumps and dips.

Curious, have you even driven a late model BMW with the MP LSD? It's quite kick to react, quite aggressive on lock up, and totally changes the dynamics of the car assuming you drove the car without the LSD for a while prior. It's quiet, but you can most certainly feel it working often.

I get that you love the Quaife, but for the money, the quality, an OEM part, ease of purchase, no need to find someone modify the gear set and install the Quaife, etc., the MP LSD is really hard to beat for $2,300-2,500 installed.

[ChrisFulton]

I understand the differences and that's why I chose the M LSD.
I track the car and believe it to be superior for that application.
I also don't mind a couple of fluid changes while I own it, and I will wear the car out and move on before I wear out the M LSD.

[XutvJet]

Originally Posted by ChrisFulton

I understand the differences and that's why I chose the M LSD.
I track the car and believe it to be superior for that application.
I also don't mind a couple of fluid changes while I own it, and I will wear the car out and move on before I wear out the M LSD.

Same boat. BMW says you technically can't service the LSD fluid without dropping the diff which makes no sense. Guys change out the fluid all the time. You just need to buy an angled tube to suck out the fluid from the filler hole. The fluid is about $80.

[upsidedownfunnel]

Originally Posted by XutvJet

The MP LSD isn't a crap and cheap viscous LSD like you find in a lot of Japanese cars that can wear out quickly. Sure, the MP LSD will eventually wear out, but we're talking 80K+ miles of generally harder than normal driving. The MP LSD is built by Drexler. Not exactly a crap drivetrain company. Get on their website compare and take note of the quality the LSDs they make for the OEM and race teams. Just because a clutch LSD is compact doesn't means it's weak. Most any professional racer would tell you a clutch-based LSD is the way to go for the best performance and control, especially when hitting bumps and dips.

Curious, have you even driven a late model BMW with the MP LSD? It's quite kick to react, quite aggressive on lock up, and totally changes the dynamics of the car assuming you drove the car without the LSD for a while prior. It's quiet, but you can most certainly feel it working often.

I get that you love the Quaife, but for the money, the quality, an OEM part, ease of purchase, no need to find someone modify the gear set and install the Quaife, etc., the MP LSD is really hard to beat for $2,300-2,500 installed.

I'd rather have a vLSD over an open diff. it's pretty ridiculous to have an open diff on a sport sedan with over 300 hp without a factory option of an LSD of some sort. The track handling package should definitely have come with one. And it shouldn't have to cost $3000+ to acquire and install the M Performance version. Given all that, it's not quite fair to blame the Japanese manufacturers of using "crap and cheap" parts when those are still a ton better than no LSD at all. Especially when BMW made the user-hostile decision to weld the diff to make them nigh impossible to upgrade without complete replacement.

I actually admire IK6SPEED for not giving in and just getting the "easier" M Performance LSD. I know he did it for performance, but I think it was a good decision to not give BMW more money for an expensive solution to a problem they created.

[zinner]

Originally Posted by XutvJet

Same boat. BMW says you technically can't service the LSD fluid without dropping the diff which makes no sense. Guys change out the fluid all the time. You just need to buy an angled tube to suck out the fluid from the filler hole. The fluid is about $80.

You can pump up the fluid out easily. Redline diff oil has the modifiers in all their diff oil so regardless of the internals (open, quaife, clutch) it's the same oil. I changed the oil around 1500 miles after a break in. It's very easy it's just messy.

[afranke]

Originally Posted by upsidedownfunnel

I actually admire IK6SPEED for not giving in and just getting the "easier" M Performance LSD. I know he did it for performance, but I think it was a good decision to not give BMW more money for an expensive solution to a problem they created.

I admire him doing it as well, since now I know I can do it too, but he didn't choose it for the performance specifically. We have the AH3, and our final ratio is different, so the MP LSD would mess that up.

The N55 F30s run 2.81 (d and AH3), 3.15 Sports/Automatic and 3.23 Manual

[upsidedownfunnel]

Originally Posted by afranke

I admire him doing it as well, since now I know I can do it too, but he didn't choose it for the performance specifically. We have the AH3, and our final ratio is different, so the MP LSD would mess that up.

The N55 F30s run 2.81 (d and AH3), 3.15 Sports/Automatic and 3.23 Manual

From the other thread, I think he said you could use the 340i M Perf LSD since that has the same final drive? I might be mistaken though.

[afranke]

Originally Posted by upsidedownfunnel

From the other thread, I think he said you could use the 340i M Perf LSD since that has the same final drive? I might be mistaken though.

Oh hey yeah, look at that, I missed that detail:

BMW changed the final drive from the 3.15 used in the 335i Automatics to 2.85 in the 340i Automatics which matches the AH3 (and 330d). The donor dif I purchased came from a 2017 340i with under 10k miles.

Now RealOEM list the difs of the 340i and the AH3 as the same part number.

There is a $2560 Mperformance LSD for the 340i with a 2.85 final (part 33108659989)

[XutvJet]

Originally Posted by upsidedownfunnel

I actually admire IK6SPEED for not giving in and just getting the "easier" M Performance LSD. I know he did it for performance, but I think it was a good decision to not give BMW more money for an expensive solution to a problem they created.

If you're doing it for performance, a quality clutch-based LSD is the way to go. Baring the AH3 setup, he did the Quaife because of long term life. Apparently he intends to keep his car a very long time.

It sucks that BMW doesn't make the LSD standard, but their thinking is:

1) The brake-based electronic LSD (eLSD) is good enough for most drivers and even I admit it's pretty dang good. Prior cars to the F series didn't have it. Most don't realize that the eLSD only works in Traction and DSC Off though.

2) It saves BMW money.

3) Giving enthusiasts the option to buy it makes us think we've got something special. At least they're selling us a high quality LSD already assembled in a OEM pumpkin for $1,900-2,000.

[IK6SPEED]

Originally Posted by XutvJet

The MP LSD isn't a crap and cheap viscous LSD like you find in a lot of Japanese cars that can wear out quickly. Sure, the MP LSD will eventually wear out, but we're talking 80K+ miles of generally harder than normal driving. The MP LSD is built by Drexler. Not exactly a crap drivetrain company. Get on their website compare and take note of the quality the LSDs they make for the OEM and race teams. Just because a clutch LSD is compact doesn't means it's weak. Most any professional racer would tell you a clutch-based LSD is the way to go for the best performance and control, especially when hitting bumps and dips.

Curious, have you even driven a late model BMW with the MP LSD? It's quite kick to react, quite aggressive on lock up, and totally changes the dynamics of the car assuming you drove the car without the LSD for a while prior. It's quiet, but you can most certainly feel it working often.

I get that you love the Quaife, but for the money, the quality, an OEM part, ease of purchase, no need to find someone modify the gear set and install the Quaife, etc., the MP LSD is really hard to beat for $2,300-2,500 installed.

The BMW Performance LSD is not Drexel’s top quality model. It one of Drexel’s lower quality LSD.

Originally Posted by afranke

Oh hey yeah, look at that, I missed that detail:

Still interesting to note BMW does not list that as compatiable with AH3 (even though the 340i now share same diff). I wonder if Dealer would even install?

Originally Posted by XutvJet

If you're doing it for performance, a quality clutch-based LSD is the way to go. Baring the AH3 setup, he did the Quaife because of long term life. Apparently he intends to keep his car a very long time.

No, I see it as

1) Better for Road use as I do not car about motorcross

2) literally impossible to break the gears.

3) non-ATB should constantly have the plates shimmed for proper usage before replacement.

4) smoother when working