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      12-08-2019, 01:44 PM   #1
jackstrath
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M Performance LSD

Hey all,

Just wondering what numbers can i expect to see on a M performance LSD?

Im looking at one for sale and it has 33108659989 on the bag it is in but then on the barcode sticker it has 8659989-01/EAJ8335;2,81 and 901810160019008

Now ovbs i want to make sure its a LSD and not a open diff, can anyone tell me what else i could look for to confirm its a LSD diff ?
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      12-08-2019, 02:33 PM   #2
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Originally Posted by jackstrath View Post
Hey all,

Just wondering what numbers can i expect to see on a M performance LSD?

Im looking at one for sale and it has 33108659989 on the bag it is in but then on the barcode sticker it has 8659989-01/EAJ8335;2,81 and 901810160019008

Now ovbs i want to make sure its a LSD and not a open diff, can anyone tell me what else i could look for to confirm its a LSD diff ?
Photo shows how my M Performance LSD looked when opened. The part number that I circled in the photo is the only thing that matters. My car is a 2015 335i Xdrive with an automatic transmission. There are MP LSD part numbers for various models. Make sure you have the correct part number for your car. There is a tremendous amount of LSD information on this forum. Hope this helps!
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      12-08-2019, 02:38 PM   #3
jackstrath
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yeh, it doesnt have the yellow sticker on it. i know you drop the first 4 numbers so going by that logic the numbers match up
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      12-08-2019, 03:34 PM   #4
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@johnung What's the point of having an LSD on an xdrive?
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      12-08-2019, 06:25 PM   #5
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@johnung What's the point of having an LSD on an xdrive?
That's actually a very common question, because both Xdrive and LSD are associated with improving traction. But they use different methods of obtaining traction and they even operate on opposite ends of the car! Since I've heard this question often, I will provide a detailed explanation below.

Xdrive pretty much takes a BMW rear wheel drive car and adds front drive capability by adding components to the front of the car such as a transfer case, a front differential and front half shafts. Definitely makes things tighter for space in the front end. Having all four wheels driven has obvious traction advantages in bad weather or on poor surfaces.

I've owned and driven many different all wheel drive vehicles. I believe that BMW Xdrive is one of the best systems available because of its rear wheel bias and the large range of power that it can deliver to both front wheels and to rear wheels. That translates into great road feel and control to the driver under any conditions.

Mercedes AWD which they brand "4Matic" is also a rear wheel bias system but doesn't have the same dynamic range as Xdrive. In contrast manufacturers like Honda, Toyota, VW, and I believe Audi build their AWD systems to be front wheel biases.

I had a Honda AWD. It was like driving a front wheel drive 99% of the time. Some power went to the rear wheels but only when the car's electronics sensed that there was a traction issue. It didn't have the range to transfer a lot of power to the rear wheels but it was enough to make the car safer under poor conditions than a FWD drive only car. The Honda AWD system certainly didn't make it any more enjoyable to drive, just safer.

A BMW Xdrive system has that great solid traction feel of a BMW rear wheel drive car while still providing quite a bit of power at all times to the front wheels. Xdrive really feels great from standing starts and when you accelerate on curves. It's tremendous in poor weather. I was stopped dead in traffic in a valley like section of roadway after we got a flash snowstorm of 6 inches in about 30 minutes.

Police were on the highway pushing most cars by hand off the road so plows could clear it. FWD, RWD, AWD- it didn't matter, all were going sideways instead of forward in that deep new snow. When they cars in front of me had been pushed to the side, the cops got to my car and one said "Oh, you have Xdrive. Go ahead." I just stepped on the gas and went right up the highway like the snow wasn't there.

An LSD is different. The rear end is the same whether it is a RWD car or an Xdrive. A long driveshaft comes down the center of the car and connects to the rear differential. Sometimes it's referred to as a "pumpkin" because of its size and shape. A half shaft comes out of each side that connects to distribute power to each rear wheel.

A standard rear differential puts power to the rear wheels but if one wheel begins to slip it keeps sending more and more power to that wheel. If you recall the movie "My Cousin Vinny", Joe Pesci's RWD car was stuck completely when just one rear wheel was spinning and spinning in the mud.

Now, BMW RWD and Xdrive cars have electronic systems that work when sensors determine that one of the rear wheels is slipping by more than 30%. It can apply the brake individually to the wheel that is slipping to trick the rear differential into sending power to the other rear wheel to get the car moving correctly and under control. It can also reduce or regulate the throttle to best control the car. You know how people get frustrated and floor it when a car is slipping or stuck. Well, these electronic systems can save a driver from his own stupidity!

Okay, so now I know that the car has a great Xdrive AWD system plus these cool electronic systems that keep the car under control even despite its driver. So what is an LSD and why would I want it on top of what I already have?

Remember how the electronic systems activate only after they sense a minimum of 30% slippage at one of the rear wheels. Well, the M Performance Limited Slip Differential (LSD) is a mechanical system. An LSD is a full replacement for a standard rear differential. But besides distributing power to the rear wheels, an LSD also regulates slippage.

Remember how the BMW electronics activate when a rear wheel slippage exceeds 30%? Well, an M Performance LSD reacts immediately! From 0% to 19% slippage at a rear wheel, the MP LSD instantly increases the power to the rear wheel that is not slipping.

Driving home from LSD installation, I first noticed the difference as soon as I began to turn the steering wheel to accelerate onto an on-ramp. It felt like the steering wheel had instantly tightened as the car responded quicker than ever before and powered right through the turn. I never knew that I previously had any slippage until the LSD made it obvious by removing it.

The LSD is also an obvious improvement from standing starts. Xdrive is already known to have better traction from a standing start than RWD which tends to spin the rear wheels before moving forward. An Xdrive car with an LSD takes standing starts to another level.

BMW engineering for the M Performance LSD is brilliant for its simplicity. There is no coding at all because the LSD from 0-19% slippage and the electronics from 30%-above, don't get in each other's way at all. Seamless!

The MP LSD has a 700 mile break-in period to avoid wide open throttle and accelerate through as many smooth left and right hand turns as possible. At 1,200 miles suction and replace the 1 liter of special BMW LSD fluid. Avoid using anything else. Replace fluid every 30k miles after that.

There are several aftermarket LSDs such as Quiafe that work at a wider range such as 0-60% for racing applications.

See attached photo of the M Performance LSD being installed on my 2015 335i Xdrive Automatic. Hope this helps!
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      12-08-2019, 07:16 PM   #6
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Wow cool write up, thanks for the info. I figured the only people who would do this would be people using the xdelete software and wanting an lsd to have more red fun!
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      12-08-2019, 08:50 PM   #7
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Is there anything i need other than the diff its self? anything worth replacing ect ect
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      12-08-2019, 09:26 PM   #8
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Is there anything i need other than the diff its self? anything worth replacing ect ect
Nah, don't touch ect
As far as installation parts, the F3x rear half shafts are held on by a tiny circlip. So you need two circlips from the dealer. Same circlip part number regardless if it's the standard diff or LSD.

Also buy a liter of the special LSD fluid. The LSD is supposed to come filled from the factory but some can leak during shipment. Last step of installation is to open the fill hole to check the level. So you need a new bottle on hand in case. You'll use it anyway at 1,200 mile suction & refill. Attached is a photo of LSD fluid needed for the MP LSD shown in my previous photo
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      12-08-2019, 10:21 PM   #9
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83222365988 is the LSD oil listed for my car, same stuff that go's in the M cars by the looks of it - So there is no need to replace the 50mm nut that i have read about?
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      12-08-2019, 10:22 PM   #10
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It's a wonderful addition on xdrive. The car has much nicer turn in and you could say some oversteer when you put the power down. Very easy to break grip in the rear end but in a very controllable way. Haven't even installed xdelete yet. I'll prob only ever use xdelete for the track and snow drift fun.

Only a few hundred more miles to the drain and fill, and some powerflex inserts will go in at the same time b
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      12-08-2019, 10:58 PM   #11
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Quote:
Originally Posted by jackstrath View Post
Hey all,

Just wondering what numbers can i expect to see on a M performance LSD?

Im looking at one for sale and it has 33108659989 on the bag it is in but then on the barcode sticker it has 8659989-01/EAJ8335;2,81 and 901810160019008

Now ovbs i want to make sure its a LSD and not a open diff, can anyone tell me what else i could look for to confirm its a LSD diff ?
Just a heads up. In Oct 2016 I had my local Dealer attempt to install MP LSD pn 33108659989 into my USA Spec'd 2016 340xi with ZF auto trans. They were not able to do the install and stated "M Differential not compatible with xDrive vehicles" They also reference "internal part incompatible", I think the specific problem was with the axle shafts.
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      12-08-2019, 11:07 PM   #12
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Quote:
Originally Posted by Beek View Post
Just a heads up. In Oct 2016 I had my local Dealer attempt to install MP LSD pn 33108659989 into my USA Spec'd 2016 340xi with ZF auto trans. They were not able to do the install and stated "M Differential not compatible with xDrive vehicles" They also reference "internal part incompatible", I think the specific problem was with the axle shafts.
yeh seen alot of info about that, luckily here in the UK we only get the man option of RWD with our 340i's
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      12-09-2019, 11:14 AM   #13
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Originally Posted by jackstrath View Post
83222365988 is the LSD oil listed for my car, same stuff that go's in the M cars by the looks of it - So there is no need to replace the 50mm nut that i have read about?
NO. There is no nut to buy. It comes already on the new LSD. Only things to buy are the two circlips and the liter of special LSD fluid.
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      12-09-2019, 12:35 PM   #14
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Quote:
Originally Posted by Beek View Post
Quote:
Originally Posted by jackstrath View Post
Hey all,

Just wondering what numbers can i expect to see on a M performance LSD?

Im looking at one for sale and it has 33108659989 on the bag it is in but then on the barcode sticker it has 8659989-01/EAJ8335;2,81 and 901810160019008

Now ovbs i want to make sure its a LSD and not a open diff, can anyone tell me what else i could look for to confirm its a LSD diff ?
Just a heads up. In Oct 2016 I had my local Dealer attempt to install MP LSD pn 33108659989 into my USA Spec'd 2016 340xi with ZF auto trans. They were not able to do the install and stated "M Differential not compatible with xDrive vehicles" They also reference "internal part incompatible", I think the specific problem was with the axle shafts.
It probably is the axle shaft compatibility issue with your specific car.

FYI- I found that that same statement lingers on in BMW documentation with my car too, even though mine definitely is compatible with the MP LSD part# that I posted earlier. I have a 2015 335i Xdrive with the ZF 8-speed automatic transmission.

"M Differential not compatible with xDrive vehicles"

Through research I think that I discovered the reason, and it's not technical! It originated in marketing. When they first developed an M Performance LSD for the F30. It appears that they thought that track guys with RWD cars was their target market for an expensive dealer add-on accessory part. They didn't give Xdrive cars much thought so they never put Xdrive on the brochures. Somehow that led to someone actually writing down that statement. What they should have said back in 2011 was "Hey, we don't know if it's compatible. We never gave it any thought."

As it turns out, with the F30 335i with the automatic transmission, the rear differential, final drive ratio and half shafts are exactly the same whether it's RWD or Xdrive. So no compatibility issue in this configuration. If I recall correctly there are some configurations with a manual transmission where the half shafts are the same, only the final drive ratio differs. Lots of posts on it and guys who have done the math and say from a practical standpoint there isn't much difference. If the halfshafts aren't identical then forget about it. It definitely isn't compatible. That's the key. Lots of LSD posts you can research for more details.

Hope this helps someone!
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      12-09-2019, 01:43 PM   #15
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Quote:
Originally Posted by johnung View Post
NO. There is no nut to buy. It comes already on the new LSD. Only things to buy are the two circlips and the liter of special LSD fluid.
Yeh but this isnt a new LSD? Its used....
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