[Nickies]

Originally Posted by Bmwhead

What you are saying seems to me to be very important information because it is objective data and there is no room for doubt, an open differential was fitted at the factory with the same final ratio but which does not officially exist for the M240i, so as you say yes If you had to change it yourself or if you had to change it, BMW under warranty would give you LSD because it is theoretically the only one that exists and with which our cars are supposed to come, although with so much information I don't even know what to think because it seems silly to stop BMW I have mounted a differential that may not have.

According to my serial number, here is what REALOEM says:

For vehicles with
Sport automatic transmission
S2TBA=Yes
01 BMW M Performance limited-slip diff I=2,81, 215W 1 33108659989

I have a LCI model with 11/18 production date and I am the original owner. I have no doubt it came like that from the factory.

The OP spoke to 4 different dealers and they all said the same thing. They cannot all get it wrong.

[XutvJet]

I just went outside and jacked up my M235 6mt that I installed the MP LSD on about 3 years ago. Sure enough, the tires spin in the same direction. I then went in my basement and tested my old open differential. Sure enough, the internal hubs spin in opposite directions.

So there you go M240 RWD 8AT owners, jack up your car in the rear and see if the wheels spin in the same direction.

[dradernh]

Originally Posted by Nickies

According to my serial number, here is what REALOEM says:

For vehicles with
Sport automatic transmission
S2TBA=Yes
01 BMW M Performance limited-slip diff I=2,81, 215W 1 33108659989

I have a LCI model with 11/18 production date and I am the original owner. I have no doubt it came like that from the factory.

The OP spoke to 4 different dealers and they all said the same thing. They cannot all get it wrong.

Below is what you're looking at then?

[spidy512]

There are two options in the above pic correct? That is what I am seeing?

The first "1" is for the open diff.
The second "1" is the optional MP.

Am I wrong?

Edit: Oh wait, I see the red brackets now. That is nuts. It actual bundles the auto with the MP.
Double edit: At least 33108659989 fits the xDrive cars.

josh

[Nickies]

Originally Posted by spidy512

There are two options in the above pic correct? That is what I am seeing?

The first "1" is for the open diff.
The second "1" is the optional MP.

Am I wrong?

Edit: Oh wait, I see the red brackets now. That is nuts. It actual bundles the auto with the MP.
Double edit: At least 33108659989 fits the xDrive cars.

josh

I don't think the Xdrive can have the MP.

Again, if you look at REALOEM, they refer to other part numbers and there is no mention of the MP as optional. Logically, this should be a package only for RWD.

[FancyDan]

Originally Posted by Nickies

The OP spoke to 4 different dealers and they all said the same thing. They cannot all get it wrong.

I spoke to 3 dealers myself and they all said my car had to have come with the LSD from the factory for the same reasons. Not knowing this, I ordered and replaced the factory unit with a brand new M Performance LSD. Turns out it wasn't in vain as I still have the factory unit and checked it, it's part number is 33107603759. RealOEM lists this as a part only for the F34, but clearly that is not the case.

It's possible RealOEM to have incomplete information every once in a while, but what's shocking is that so do the dealers. Seems whoever in Munich wrote the M240i parts catalog didn't have their coffee that morning...

[aerobod]

Searching for 33107603759 online shows plenty of used 2.81:1 open diffs that are from M240i and M140i automatics. As FancyDan says, looks like a parts catalogue omission.

[Bmwhead]

Originally Posted by spidy512

There are two options in the above pic correct? That is what I am seeing?

The first "1" is for the open diff.
The second "1" is the optional MP.

Am I wrong?

Edit: Oh wait, I see the red brackets now. That is nuts. It actual bundles the auto with the MP.
Double edit: At least 33108659989 fits the xDrive cars.

josh

Two different appear but if you look at one is 3.08 and another 2.81, the first open for 6MT and the second LSD for AUT8.

If XutvJet has checked the turning of the wheels with the LSD M Performance I think that is the maneuver that we will all have to do (even if it is difficult to lift both rear wheels at the same time outside of a workshop). Once we verify that I consider that the most likely option in this whole matter is that it is an error in the internal BMW catalog and that Realoem reproduces it since I suppose they are based on the official information of the brand, but it is something that continues to result very strange.


Edit: I have carried out a check on my car and I would like to be able to compare it with the experiences of other owners, since I have not been able to lift both wheels at the same time, I have lifted only one and the behavior is as follows: with the engine started (in N) the wheel rotates forward. When the engine is stopped, with the wheel already stopped, I can move it freely with my hands without offering any kind of resistance. These symptoms make me think clearly of an open differential but since the M Performance is a clutch system I would like to be able to make sure with those owners who have it and thus be able to unravel this strange mystery among all.

[ggggbmw]

Originally Posted by XutvJet

A simple test to determine if you have the LSD or not is to jack up the car by the differential and spin a wheel. If the opposite wheel spins in the same direction, then you have the LSD. If it spins backwards, then you have an open differential.

I have the MP LSD installed, and this is NOT true. On my car spinning one rear wheel by hand, the other goes in the opposite direction, just like a regular open diff. I believe the reason for this is that when you are just turning it by hand the clutch packs are not spinning fast enough to lock up and do the same direction spin.

dradernh you have a Wavetrac on your car. So your experience may be different. But on a clutch-pack style diff like the BMW MP LSD, this is not a reliable test.

The exterior of the standard 'open' diff, and the LSD, are identical. (Which kind of bugs me.) The ONLY way to be completely sure is read the part number off the diff. And they make that really hard by putting the label on top. You can't see it without a mirror or sticking your phone up there and taking a picture.

--- EDIT ------
Well, it may be true or not, but definitely not the whole story. Please see the update below in post #55.

[Nickies]

Originally Posted by aerobod

Searching for 33107603759 online shows plenty of used 2.81:1 open diffs that are from M240i and M140i automatics. As FancyDan says, looks like a parts catalogue omission.

The REALOEM parts catalog doesn't cover 2020 and up. I would rather say that there is no update but not an omission at this point in time.

[aerobod]

Originally Posted by ggggbmw

I have the MP LSD installed, and this is NOT true. On my car spinning one rear wheel by hand, the other goes in the opposite direction, just like a regular open diff. I believe the reason for this is that when you are just turning it by hand the clutch packs are not spinning fast enough to lock up and do the same direction spin.

Mechanical clutch based LSDs (may not apply to electronically or hydraulically controlled ones) have preload that keeps the plates engaged at a lower torque level to prevent the ramps from banging backwards and forward due to lack of pressure on them. 30Nm / 20lbft is about the minimum torque required to overcome the preload, anything less usually indicates time for a rebuild to replace worn plates, broken preload springs or incorrect shimming. This preload should be enough to overcome any friction in the differential and driveshafts.

When testing the LSD on an RWD car to see if it is an open or clutch based one, the transmission has to be in neutral, parking brake off with no brake drag at all and both back wheels off the ground, to ensure minimum resistance through the driveline and the driveshafts are all able to rotate freely.

[XutvJet]

Originally Posted by ggggbmw

I have the MP LSD installed, and this is NOT true. On my car spinning one rear wheel by hand, the other goes in the opposite direction, just like a regular open diff. I believe the reason for this is that when you are just turning it by hand the clutch packs are not spinning fast enough to lock up and do the same direction spin

Would posting a video of this prove it to you?

[XutvJet]

Originally Posted by aerobod

When testing the LSD on an RWD car to see if it is an open or clutch based one, the transmission has to be in neutral, parking brake off with no brake drag at all and both back wheels off the ground, to ensure minimum resistance through the driveline and the driveshafts are all able to rotate freely.

YEP!

[Bmwhead]

It would be very interesting if those of you who had the LSD M Performance installed could do the tests, with one or two wheels raised, so that those of us who have doubts could check it.

[morphomeman]

This is the most heated exchange that I have seen on this forum in a very long time.
The big dogs have really come out to play!
Luckily, I own a 235X, so I can simply enjoy it all from the sidelines.

[msej449]

The only definitive way to tell what differential is fitted is to check the label on the casing*:





And then ring up a BMW Parts/Service department and get them to check the part number on the unit itself. It's little use ringing up a dealer without this part number because they can't tell you definitively - they can only go on what they think, based on experience across the whole range of BMW vehicles, models, years and geographies. It doesn't help that the BMW M Performance LSD part number has changed with both time and model as well. From other threads and forums, it's clear dealers often get confused between the standard-fit LSD on the M2 and the retro-fit LSD on the M Performance models.

Apart from being tricky to do, jacking up the car and rotating the wheels doesn't seem to be a very reliable indicator, from all the discussions I've read. It often seems to produce ambiguous result.

If the official BMW service record says it's fitted with an LSD, then it'll be fitted with a retro-fit BMW M Performance unit. But if the service record doesn't say it has an LSD it could still have one: just that it's been fitted by an independent garage.

From feedback on UK and US sites, the 2 Series was never factory-fitted with an LSD. There are various scenarious where the documentation seems to say it is but that's turned out to be misleading, and the only definitive way is to check the label.

Yes, it's awkward to get to the label, but some owners with access to a jacking lift have used that to get the wheels to drop, making access to read the label with a mobile easier.

@Bmwhead It can save a lot of confusion if your signature says at least what country and state you are in. Sometimes things that apply in one greography are different in another.

[*7599411 is the part no for this, my original ex-factory standard differential, which my dealer repaced with an M Performance LSD. This for a UK 2016 M235i Convertible]

[Bmwhead]

In any case, it would be strange for them to equate LSD without BMW saying so, in no press release and no technical specification sheet BMW reports the incorporation of an LSD, therefore with the information we are collecting I think it is an internal error from BMW (which is transferred to Realoem). Anyway, I think it would be very interesting if we could check it on our cars, since here we are quite a few owners with M240i but if the test of turning the wheels is not considered reliable we will have to find a way to access that sticker.

[Bmwhead]

Originally Posted by msej449

The only definitive way to tell what differential is fitted is to check the label on the casing*:





And then ring up a BMW Parts/Service department and get them to check the part number on the unit itself. It's little use ringing up a dealer without this part number because they can't tell you definitively - they can only go on what they think, based on experience across the whole range of BMW vehicles, models, years and geographies. It doesn't help that the BMW M Performance LSD part number has changed with both time and model as well. From other threads and forums, it's clear dealers often get confused between the standard-fit LSD on the M2 and the retro-fit LSD on the M Performance models.

Apart from being tricky to do, jacking up the car and rotating the wheels doesn't seem to be a very reliable indicator, from all the discussions I've read. It often seems to produce ambiguous result.

If the official BMW service record says it's fitted with an LSD, then it'll be fitted with a retro-fit BMW M Performance unit. But if the service record doesn't say it has an LSD it could still have one: just that it's been fitted by an independent garage.

From feedback on UK and US sites, the 2 Series was never factory-fitted with an LSD. There are various scenarious where the documentation seems to say it is but that's turned out to be misleading, and the only definitive way is to check the label.

Yes, it's awkward to get to the label, but some owners with access to a jacking lift have used that to get the wheels to drop, making access to read the label with a mobile easier.

@Bmwhead It can save a lot of confusion if your signature says at least what country and state you are in. Sometimes things that apply in one greography are different in another.

[*7599411 is the part no for this, my original ex-factory standard differential, which my dealer repaced with an M Performance LSD. This for a UK 2016 M235i Convertible]

msej449 excuse me but I wrote the message before your edit, I am a resident of Italy therefore my vehicle has European specifications and it is a 2J51 unit. I called several official BMW workshops in the country and made the query with my VIN number, therefore it was not a generic query about M240i if it does not specify about my specific unit, Nickies carried out a similar procedure with identical results to mine, and I believe that none of we are both sure of having it mounted or not.

[aerobod]

Originally Posted by Bmwhead

...but if the test of turning the wheels is not considered reliable we will have to find a way to access that sticker.

The test is reliable if performed correctly. Another test is to check the preload: Transmission in neutral, right rear wheel removed and left rear on the ground and blocked. Put a torque wrench on the axle nut and rotate clockwise, adjusting the torque wrench setting upwards in small increments (if a click type) until it no longer turns, then note the torque value, or note the torque if a beam type.

Most plate type diffs should have a minimum preload breakaway torque of 30Nm, but typical for a road car is 50Nm or so and track cars can be 100Nm or higher. In foot pounds, 20/40/80 are the approximate equivalent values. I know some Drexler units for BMWs have been built with 80 foot pounds preload, not sure what the MP one is from the factory.

If the diff doesn't have preload and you think it is a plate LSD, it needs to come out for inspection and rebuild anyway, so you can then confirm that it really is open or a failed LSD!

[msej449]

@Bmwhead Yes, this is a difficult issue and why forums like this are very useful. Dealers do not always know the fine detail of a specific model, year, country version and standard vs retro-fit parts and this is often confused when BMW change the part numbers and options.

As @aerobod says, there are tests you can do, but the feedback from similar topics is that for someone who isn't mechanically adept (like me) the results can be ambiguous. So I think the consensus is to try and read the label if at all possible.

On other threads, people have reported that they were able to slide their mobile phone into the space between the top of the differential and the body of the car. Others have said they used a selfie-stick with the phone on a timer on the end, and others a mirror. And as I mentioned, if you know someone with a lift that suspends the car on its jacking points, then that may drop the wheels enough to get to the space above the differential.

Really, once you have the differential part number off the label, your situation should be much clearer.

[dradernh]

Looking at this another way, why would BMW put an LSD in a non-M 2 Series car?

[KennyFSU]

Would doing a burnout and seeing if both tires leave marks be a good way of telling if it has LSD or not?