[simonhch]

I am looking at adding XDelete (already have it but haven't deployed it yet) and an LSD to my 2015 435xi Msport, The car is putting down a considerable amount of extra power, and has had a lot of suspension work done too. A current list of headline mods (cutting out all the interior and aesthetic stuff):

Dinan Big Turbo
Dinan CF Performance Intake
MPPK
Dinan Stage 4
Dinan FMIC
Dinan Performance exhaust
Dinan Front and Rear Sway bars
ER Charge pipe
M Performance Brakes (orange)
xHP Stage 3 Transmission Flash

Currently running on KW Street Comfort Coilovers with mild drop but about to switch to:

Ohlins Road & Track
Vac Motorsports Upper and Lower Monoball control arms

When I do the suspension install I am also planning to replace various suspension components, depending on wear, but almost certainly Rear trailing arm bushings and tie rod assemblies.

So I have been looking at LSD options, but I could do with help navigating the best choices. I looked at diffsonline and their 435xi option with a Quaife is looking to be $3,150 after core refund at a 3.15 ratio (is this correct?). Seems a fair bit steeper than I expected.

I was also researching the M Performance LSD. Tischer's website says there is a 435 M Performance diff, which I assumed would be the correct one for my car, but the part is now discontinued and not available for sale:

https://www.getbmwparts.com/oem-part...w2LWdhcw%3D%3D

The part number is 33-10-7-555-607 (M Performance Limited Slip Differential - F3x 335i/435i Auto/Sport Auto Transmission).

They do however have the same product but for the 440i:

https://www.getbmwparts.com/oem-part...w2LWdhcw%3D%3D

The part number for this is 33-10-8-659-989.

For starters I am making the assumption that the correct LSD is the one designed for the non xdrive version of my car, but is the 440i version just an updated part? or are there actual differences.

I need help identifying the right LSD for my car.

Also, the M Performance diff is coming in at $2300, nearly a grand cheaper. Is it much worse than the Quaife? I had expected the Quaife to be around $2,700, so the $3,200 surprised me.

What are my best options and has anyone else done this? I found a few posts around the subject, but I am still a little bit confused.

Thank you for any help that is forthcoming.

[F32Fleet]

Thr M LSD is a basic 3- clutch LSD. The Quaife unit contains mire machinied parts so its slightly more expensive. Personally I'd go Wavetrac is you want an ATB.

Clutch type LSD evwntualy requires a rebuild.

[n55david]

2 things..

1. Wish you would have came here first before the mod list you have.

2. Why delete the xdrive? You aren't anywhere near axle damage power.

[simonhch]

Originally Posted by n55david

2 things..

1. Wish you would have came here first before the mod list you have.

2. Why delete the xdrive? You aren't anywhere near axle damage power.

1. How come? Curious as to what you don't like about it. I bought the car with 32K on it, and it was CPO with a further extended warranty through 95K. I went down the Dinan route (expensive!) because (a) I was looking for factory type power (the dinan is smooth and well within tolerances) and (b) I had everything installed at the dealer and I wasn't voiding my warranty, which was important to me. The car now has 52K, I have plenty of miles left on the warranty, but the car is paid off, and I am becoming slightly less risk averse to mods. I love, LOVE the way it drives now. It has gobs of power (which I am aware I could've gotten cheaper), and it is very nicely and smoothly delivered.

2. XDelete just gives you the option to switch between AWD and RWD whenever you feel like it. The idea is to make it a little more fun to drive on dry summer days, while still retaining the AWD for inclement weather. XDelete was only about $175, and I haven't even deployed it yet. I am not sold on putting in an LSD because it's another $3-4K that I can candidly use for a lot of other things. At this point, I may just leave it as is, drive it for another 2-3 years, then trade it in and move to an M3 AWD Competition sedan. The AWD is vital for me in the winter, as I live in Chicago.

[simonhch]

Originally Posted by F32Fleet

Thr M LSD is a basic 3- clutch LSD. The Quaife unit contains mire machinied parts so its slightly more expensive. Personally I'd go Wavetrac is you want an ATB.

Clutch type LSD evwntualy requires a rebuild.

Thank you. Let me look into the wavetrac.

[jq_f22]

Originally Posted by n55david

2 things..

1. Wish you would have came here first before the mod list you have.

2. Why delete the xdrive? You aren't anywhere near axle damage power.

Second this, xdelete is a waste of money. The xdrive system in these cars is very robust. The features the e chassis have (variable awd) were never implemented and cannot according to the devs. I had it and used it only once. If your car makes any sort of respectable power you will still spin the rears with xdrive on launch/lower gears.

[youssef123452002]

I have to disagree on the x drive delete mod being useless
At least on my 2016 435i xdrive auto
It made the whole car feel considerably better to drive.
The whole car feels lighter , fuel consumption is better as well.
I have fbo as well bootmod stage 2

I am super interested in an lsd too
I can’t find the oem m performance one at all the 607
Diffsonline is very expensive I am looking for other options so super interested in this thread. Would the 440i m performance lsd work for us ?

[n55david]

Originally Posted by youssef123452002

I have to disagree on the x drive delete mod being useless
At least on my 2016 435i xdrive auto
It made the whole car feel considerably better to drive.
The whole car feels lighter , fuel consumption is better as well.
I have fbo as well bootmod stage 2

I am super interested in an lsd too
I can’t find the oem m performance one at all the 607
Diffsonline is very expensive I am looking for other options so super interested in this thread. Would the 440i m performance lsd work for us ?

It's already been verified that mpg and performance doesn't increase. The front axles are still connected to the transfer case and things still spin there and are a drag on the car. You still have to overcome that resistance. You would need to removed the transfer case and change over to the none awd setup to see any real improvement.

Plus keis already proved its not really a power increase on his dyno

[akgambino]

Originally Posted by n55david

It's already been verified that mpg and performance doesn't increase. The front axles are still connected to the transfer case and things still spin there and are a drag on the car. You still have to overcome that resistance. You would need to removed the transfer case and change over to the none awd setup to see any real improvement.

Plus keis already proved its not really a power increase on his dyno

Cool story but the other guy didn't claim any performance gains.

I fully co-sign the fact that x delete definitely does change the steering feel noticeably in a good way and also that fuel economy is improved.

[n55david]

Originally Posted by akgambino

Cool story but the other guy didn't claim any performance gains.

I fully co-sign the fact that x delete definitely does change the steering feel noticeably in a good way and also that fuel economy is improved.

Cool story bro but no..
Steering yes

[Logicoeur]

The mperformance lsd is for rwd and xdrive. It doesn't interfere with anything. Speaking from experience.

I also life in snowy New England so I had all the same criteria as OP. I want xdrive in winter and 100% rwd in summer. Xdelete gives us that option. It absolutely transforms the way the car drives. It's even more pronounced with an LSD.

If you can find the BMW LSD snatch it up. It is indeed the cheapest of the options. Obviously a maintanence free option would be better, but how long do we actually keep these cars to justify the extra cost on that single part. I got mine right after the BMW firesale where the N55 version was 80% off. At ~$450 it was a nobrainer and they disappeared quickly. I picked one up for $700, still a wild deal. I don't regret it at all. The B58 version is not compatible with the N55 F3x (need rear axles at minimum) and is still in the $2500 range. Maybe BMW will run the same sale at some point, maybe not. At that price point the ROI is not really there for most of us.

[jq_f22]

Originally Posted by akgambino

Cool story but the other guy didn't claim any performance gains.

I fully co-sign the fact that x delete definitely does change the steering feel noticeably in a good way and also that fuel economy is improved.

Yes, he did.....

Originally Posted by youssef123452002

I have to disagree on the x drive delete mod being useless
At least on my 2016 435i xdrive auto
It made the whole car feel considerably better to drive.
The whole car feels lighter , fuel consumption is better as well.
I have fbo as well bootmod stage 2

I am super interested in an lsd too
I can’t find the oem m performance one at all the 607
Diffsonline is very expensive I am looking for other options so super interested in this thread. Would the 440i m performance lsd work for us ?

You are probably not pushing enough power to those rear wheels to miss xdrive, ots 91,93 is pretty slow. The awd f chassis use a smaller pumpkin than the rwd models. Look for a awd specific unit.

Originally Posted by n55david

Cool story bro but no..
Steering yes

People think that hitting off in the app magically makes their car a RWD monster lol.
It is still carrying all the handicaps of an AWD model. MPG and performance advantages are in fact nonexistent, my car returned the same 30 mpg highway at 65,70mph with it on or off. I thoroughly tested 60-130 with it on and off and no advantage. The advantage would be if you actually converted it to RWD because.....weight.

The lighter steering that xdelete produces is not necessarily a benefit, the car feels unbalanced at higher speeds, xdrive is an anchor that keeps it in line, go triple digits you'll see what I mean. Some of you need to go and drive a well-sorted e36 m3 or any other RWD M. All these excuses for spending $150 just to burn tires. People can't admit that's all it's really good for.
I was excited for xdelete for completely different reasons when it was announced, the possibility of altering the awd bias is where the app would have shined in my opinion.

[jq_f22]

Originally Posted by Logicoeur

The mperformance lsd is for rwd and xdrive. It doesn't interfere with anything. Speaking from experience.

I also life in snowy New England so I had all the same criteria as OP. I want xdrive in winter and 100% rwd in summer. Xdelete gives us that option. It absolutely transforms the way the car drives. It's even more pronounced with an LSD.

If you can find the BMW LSD snatch it up. It is indeed the cheapest of the options. Obviously a maintanence free option would be better, but how long do we actually keep these cars to justify the extra cost on that single part. I got mine right after the BMW firesale where the N55 version was 80% off. At ~$450 it was a nobrainer and they disappeared quickly. I picked one up for $700, still a wild deal. I don't regret it at all. The B58 version is not compatible with the N55 F3x (need rear axles at minimum) and is still in the $2500 range. Maybe BMW will run the same sale at some point, maybe not. At that price point the ROI is not really there for most of us.

It is a different unit for RWD vs AWD, did you install yours already?

[Logicoeur]

Originally Posted by jq955

It is a different unit for RWD vs AWD, did you install yours already?

It is not a different unit. It's the same part number. I have installed the same part number op lists for his car. It's been in my car for almost 3yrs now. Xdrive on for winter. Xdrive off for summer and autox.

The advantage of rwd is not weight. It's 100% power to the rear. Push sensation all the time. The car understeers far less because no power is sent to the front tires. They're just focused on turning and not powering. Xdrive only hits this while cruising in a straight line. There is nothing different than an xdrive car in rwd with lsd and another rwd lsd car of the same weight and power. Physics is physics.

[jq_f22]

Originally Posted by Logicoeur

It is not a different unit. It's the same part number. I have installed the same part number op lists for his car. It's been in my car for almost 3yrs now. Xdrive on for winter. Xdrive off for summer and autox.

The advantage of rwd is not weight. It's 100% power to the rear. Push sensation all the time. The car understeers far less because no power is sent to the front tires. They're just focused on turning and not powering. Xdrive only hits this while cruising in a straight line. There is nothing different than an xdrive car in rwd with lsd and another rwd lsd car of the same weight and power. Physics is physics.

If it does fit that's great news because the understanding for the longest is there were different units even the braces in the aftermarket are different. Did you notice a size difference between the two?

If they were the same weight there would be still a difference in how they handle because you would still have 150lbs more hanging over the front axle and behind the trans resulting in a different front and rear weight bias and that's besides the fact that they will never be the same weight apples to apples. You will always be carrying a weight penalty of 150lbs or whatever the total isk. So yes, physics are physics.

[Logicoeur]

Originally Posted by jq955

If it does fit that's great news because the understanding for the longest is there were different units even the braces in the aftermarket are different. Did you notice a size difference between the two?

If they were the same weight there would be still a difference in how they handle because you would still have 150lbs more hanging over the front axle and behind the trans resulting in a different front and rear weight bias and that's besides the fact that they will never be the same weight apples to apples. You will always be carrying a weight penalty of 150lbs or whatever the total isk. So yes, physics are physics.

Yeah no difference between rwd and awd lsd. The oe open diff is the very same as well. You must be thinking of the sniffs between 35i and 40i cars.

And the weight is irrelevant. You can still get 50:50 on both those cars even though the xdrive will weight a bit more up front. They will drive the same. The push sensation of 100% to the rear is absolutely the same.

[jq_f22]

Originally Posted by Logicoeur

Yeah no difference between rwd and awd lsd. The oe open diff is the very same as well. You must be thinking of the sniffs between 35i and 40i cars.

And the weight is irrelevant. You can still get 50:50 on both those cars even though the xdrive will weight a bit more up front. They will drive the same. The push sensation of 100% to the rear is absolutely the same.

I would have to dig through the threads but someone went real in depth with the f chassis n55 powered cars. Did you have any photos of back when you did the swap?

But that's the thing where the additional weight is placed from the factory affects the weight distribution, a m235 xdrive for example is 54/46, while a RWD model is 50/50, so you are claiming a phone app changes that?

Yeah you'll feel the push instead of push and pull of xdrive but the handling will not be the same, weight and weight distribution means your xdrive car will never handle the same as a RWD equalivant.

[n55david]

Originally Posted by jq955

I would have to dig through the threads but someone went real in depth with the f chassis n55 powered cars. Did you have any photos of back when you did the swap?

But that's the thing where the additional weight is placed from the factory affects the weight distribution, a m235 xdrive for example is 54/46, while a RWD model is 50/50, so you are claiming a phone app changes that?

Yeah you'll feel the push instead of push and pull of xdrive but the handling will not be the same, weight and weight distribution means your xdrive car will never handle the same as a RWD equalivant.

Just let it go man.. the bmw scene here is very very odd. Suddenly everyone becomes an automotive engineer etc. Having done this for 25 years myself I can tell you that even if you had solid undeniable proof in person people would still not want to believe you. Had this happen in the bike industry often. Harley guys were terrible about spouting facts that weren't really truths. Then the old school muscle car guys, and so on.

[simonhch]

Thank you for all the helpful responses. I watched the debate unfold here with interest. Just for clarity, as the OP, I am fully aware that XDelete plus and LSD will not make my car drive like an equivalent RWD 435 with an LSD. I am aware of the additional weight of the AWD system, and the weight distribution being different. This is my first Xdrive BMW, prior to this I had an e92 335 (RWD), and an e46 330 (RWD). I went with the XDrive because the winters in Chicago are terrible and I really needed the vehicle to be practical year round.

With all that said, being able to turn off the AWD and go RWD only will produce a more fun summer driving experience when compared with AWD only. It won't be as good as a native RWD F32 in that regard, but my understanding is that it won't be too far off. I am very happy with my AWD 435 in all conditions, but this seems like a way to add some added fun to the experience.

[Logicoeur]

Originally Posted by jq955

I would have to dig through the threads but someone went real in depth with the f chassis n55 powered cars. Did you have any photos of back when you did the swap?

But that's the thing where the additional weight is placed from the factory affects the weight distribution, a m235 xdrive for example is 54/46, while a RWD model is 50/50, so you are claiming a phone app changes that?

Yeah you'll feel the push instead of push and pull of xdrive but the handling will not be the same, weight and weight distribution means your xdrive car will never handle the same as a RWD equalivant.

Woah I am not at all saying that a phone application is changing the weight distribution of the car. That's insane.

I am comparing the way you would experience a fully rwd car to a quasi-awd car, around a corner, when I say they "handle the same". For example my car feels different with xdrive on vs off around the same roundabout at 20mph. The push sensation with xdrive off would feel effectively the same as taking that turn in say someone else's 335i that is rwd from factory. The front end steering of a factory rwd car may feel lighter by comparison, but the experience through the corner would not be discernable from the latter.