Open Diff or LSD?

[razielkain7878]

2016 BMW 750ix G12

Do our cars come with LSD or some special differential?
I had both rear wheels lifted by a floor jack with the engine running and the transmission is on neutral. I rotated the driver side wheel counterclockwise and was expecting the rear passenger wheel to rotate the opposite direction as this is the case with open diff. The passenger wheel did not rotate at all!

I went to the passenger side and rotated the wheel clockwise, and the rear driver wheel did not rotate.

Do we have a special kind of electronic differential? Or did I do it wrong since the engine was running?

[Qsilver7]

Someone correct me if I'm wrong...but I don't think any BMW other than an ///M model (a true M...not an ///M sport pkg that is mainly cosmetic) has had an LSD since the introduction of the e38/e39/e46 generation onward.

When BMW debuted DSC (dynamic stability control) which includes ABS braking and ASC+T (automatic stability control + traction) with the previously mentioned chassis generation...they stopped offering LSD (limited slip differentials) except in M models (ie M3/M5/M6/etc). The e32/e34/e36 were the last of the BMW models that offered LSD as an option on standard models.

[razielkain7878]

Originally Posted by Qsilver7

Someone correct me if I'm wrong...but I don't think any BMW other than an ///M model (a true M...not an ///M sport pkg that is mainly cosmetic) has had an LSD since the introduction of the e38/e39/e46 generation onward.

That’s what I thought until I read this semi-questionable article https://jalopnik.com/bmw-7-series-th...ide-1737735061

It says “All 7 Series trims get cool features like active grille shutters, automatic 4-zone climate control, limited slip differential, active air suspension, 16-speaker Harman Kardon audio system, Gesture Control, wireless charging, WiFi, a huge head-up display and lots more. There’s tons of cool gadgetry in this big Bavarian sedan.”

So, I googled how to determine if the differential is LSD and found many videos such as this one

to jack the rear and rotate. My only mistake, I had the engine running, and I only started the engine cause I wanted to put it in neutral.

I was able to rotate the driver’s side, but then the passenger side was stand still !! My jack is not the best, but I might need to redo the test and make sure to turn off the engine. Just not sure if the other side will still rotate.

[Qsilver7]

Interesting...I haven't seen mention of an LSD on the new G11/G12 7 series...but that doesn't mean it doesn't exist.

When I look at the part database...I don't see it listed like it is with my old 1991 735iL which did have a LSD. But perhaps it is different now...and is electronically actuated or built in to the diff instead of being a separate/autonomous part. I'll keep my eyes & ears open for more info.

You can click the links below for the rear suspension for a new G12 7 series vs the diagrams for my old e32 which does show a LSD in the part database:

1991 735iL shows LSD in part database: https://www.realoem.com/bmw/enUS/par...MW-735iL&mg=33

2016 750i does NOT show an LSD in part database: https://www.realoem.com/bmw/enUS/par...BMW-750i&mg=33

[Wills2]

BMW said

"In normal driving conditions, xDrive distributes power in a 40/60 split between front and rear axles, with the rear axle getting the majority. xDrive is perpetually gathering data so it can appropriately adjust power distribution between each individual wheel using an electronically controlled gearbox and a multi-plate clutch system."

"The inside and outside wheels of a turning car will always have a different radius, so they need to travel at different speeds in order for the car to turn efficiently. When you're taking a corner in an xDrive BMW, the system reduces the power sent to the wheels on the inside of the turn."

I take from that, that no it doesn't have an LSD in xdrive form but it uses a multiplate clutch to shift the power around when it senses slip, the power can be vectored forwards/backwards and side to side.

You can on some xdrive models spec a sport LSD for the rear axle but not on the 7er but the 8 series gets one.

I believe the sdrive 7er just has an open diff and uses DSC to brake the spinning wheel.

[Sjoerd]

G11/G12 S-drive come with open diffs.

Therefore I have added an OS Giken LSD to mine. Best mod on the car.

[janea1207]

Originally Posted by Sjoerd

G11/G12 S-drive come with open diffs.

Therefore I have added an OS Giken LSD to mine. Best mod on the car.

From where did you buy it???