[yarokanyuka]

Hey everyone,

I have a 2015 BMW M235i without the optional limited slip diff. Is it an electronically locking or semi-limited slip diff or is it completely open like on all other cars

[Rich.Wolfson]

Originally Posted by yarokanyuka

Hey everyone,

I have a 2015 BMW M235i with the open diff. Is it an electronically locking or semi-limited slip diff or is it completely open like on all other cars

I am not sure what you have but if it's an open diff as you say, it is not electronically locking or semi-anything.

///Rich

[msej449]

All the M235i/M240i cars came out of the factory with a standard mechanical, open differential fitted.

If you wanted a 2 Series BMW LSD the standard diff’ had to be discarded and the car retro-fitted with the MPerformane one. In the USA there was an option to retro-fit the BMW MPerformance LSD at the port before delivery of a new vehicle, as well as the option for a dealer to fit the MP LSD at a later date. If you did either of these, then it would be included in the new car warranty. If you take out BMW Extended Warranty, then the BMW LSD is also covered as long as it was a genuine part supplied and fitted by a dealer(plus the usual requirement to only have servicing undertaken by a BMW garage and for the car to be unmodified).

Drexler are the manufacturers of the 2 Series BMW MP LSD. This is not the same as that fitted to the M2 and is a mechanical plate design. The only reliable and certain way to tell if you have a standard or BMW MP LSD fitted is to check the part number on the top of the diff’. There are no other external differences or cast labels to indicate which.

If you wanted a different, non-BMW LSD product or an LSD supplied directly by Drexler, then fitting it would usually invalidate any drivetrain/engine warranty from BMW. However, quite a lot of US owners go the 3rd-party route for various reasons, while in the UK, the stricter warranty conditions tend to push owners towards the BMW MP LSD. This forum has lots of threads discussing the pros and cons of the various different LSD products available.

The consensus is that after choosing the optimal tires (usually not those fitted as original equipment on the M235i) retro-fitting an LSD is one of the most effective mods you can make to a 2 Series, especially the more powerful models like your M235i. Many think that the 230i and M235i should have exited the factory fitted with one as standard. But that BMW choose to fit a standard open diff’ in order to justify the price premium of the M2 i.e. with an LSD fitted as standard, an M235i would have been too close in handling to an (early version) M2 to make it worth paying the extra, unless you perhaps did a lot of track racing.

Of course, the problem for many owners is that retro-fitting an LSD is expensive, especially as it involves discarding a perfectly sound standard diff’ and then forking out around $2K for the new LSD. Some insurers will then charge you extra because they class it as a modification. Thus, many people are hesitant to spend the money for an uncertain advantage, however much those who have done so extol it’s merits and cost-effectiveness. If this describes you then take a look through the various discussions on this forum and it may help you decide.

If you do retro-fit an LSD then another consensus view is that you should do an oil change after run in sometime between 800~1200 miles, and most manufacturers recommend another at ~50K miles. BMW say their unit oil is ‘lifetime’ but that is not true: for exactly the same unit, Drexler recommends an oil change at 50K-60K miles. Run-in for the BMW MP LSD involves taking the car to a large empty space and doing multiple figures-of-eight: 8x (full-left-lock circle then full-right-lock circle) and then taking it easy for 300 miles or so, before any aggressive usage.

The BMW MP LSD does not require any re-coding or similar after installation. It works in tandem with the various electronic stability aids like DSC and DTC. In effect, it significantly defers the point at which they will need to intervene, but they are still active as your ‘last line of defence’. You may read some posts suggesting an LSD requires these to be coded off (they aren’t disabled fully even in Sport+), but these tend to refer to cars which do competition track racing, where it may be desirable to code them off because the car spends so much time at the limits of traction that the constant intervention of stability software is actively destabilising.

[Kernel Kurtz]

It is a completely open diff, but so far as I know all modern BMWs use ABD-X, or Automatic Differential Brake, to brake the wheels (and/or cut power when DSC is on) with less traction and maintain power to the wheels with most traction. Not a substitute for an actual locking diff, but better than an ordinary open diff with no additional assistance. Some previous discussions here;

https://www.2addicts.com/forums/show...1214851&page=2

https://www.1addicts.com/forums/showthread.php?t=719012