Usually, with AWD, you want at least two limited slip differentials, or if you only have one it should be in the middle -- if you don't, you can still get a one-tire fire on the axle that doesn't have the LSD. Or worse, if you put the LSD on the back axle and get stuck such that a front wheel is in the air, you will be stranded more or less the same as if you had three open diffs.



It's better than three open diffs, but still is susceptible to some of the same problems.

Also, I have been very disappointed to find that after replacing the pads & rotors together on the front of the car (with OE hardware), I have developed a pretty solid brake squeal. Whereas when I opted to put new pads on old rotors on the back of the car last fall, they are nice and quiet.

I fought brake squealing and other unnatural noises (usually coming to a dead stop) for 20 years in my X5. I never put anything special on the car though in terms of pads or rotors, just whatever OEM stuff was on sale at FCP or Pelican…cheap organic pads. No amount of anti squeal seemed to help. To be fair though, my experience could definitely be related to the guy doing the installation work!

Despite the issue, now hopefully solved, with steering wheel shudder/rusted rotor, I will say the ceramic brakes are much quieter. Zero squeal or groaning coming to a stop. They’ve only been on a month or so, but so far I think there may be less dust. I suspect my issues were related to improper break-in perhaps. I followed the directions in as much as I could get the car going fast and stomp on the brakes where I live. I will say I couldn’t get all the way to 60 mph as many times as needed, so maybe 40 just doesn’t cut it and the pads/rotors didn’t seat properly the first time. I don’t notice any difference in stopping power from the organic OEM stuff to the TRW ceramic pads and Zimmerman rotors. The lack of noise though is nice.

Regarding my differential questions, thanks for the feedback. I was thinking that the fact that my 2002 X5 sends a fixed torque to the front diff via the non xdrive transfer case would be an advantage when putting an LSD in the rear diff. Wouldn’t 62% of the engines torque be going aft, regardless of what the front wheels are doing?

I wonder also how an LSD would play with the DSC as it ties to simulate an LSD. I suppose one could just turn DSC off, but then the front (open diff) wouldn’t have the advantage of the system. I also don’t understand how an LSD would affect the final drive of the car, if at all. Obviously the front and rear ratios need to remain the same.

Not too much at all!

It will but the torque applied by the engine has to be resisted by the wheels. The center differential is still an open differential and if one front wheel has no resistance (because it is spinning or in the air) then that is all the torque that can be applied to the other wheels as well. In our case the problem might be slightly alleviated by the slight bias to the rear, but I doubt it would keep a car with a front wheel in the air from getting stuck. We are still talking about multiples of zero, more or less.

Yes, the early X5 transfer case works the same way that the E30 iX transfer case works when the viscous coupling has failed. You won't get any torque to the axle that has zero grip.

Also, quaifes suck. If you're driving in conditions that are bad enough that you need an LSD, the quaife is probably going to go open anyway. Quaifes are good for front diffs because they don't screw with the steering.

Jurid? Textars are quiet, Jurids are loud on the X5 in my experience. Both are OE suppliers to BMW, although I don't believe that the aftermarket pads are the same compound.

Good info, thanks gents. The juice may not be worth the squeeze then. Although even an incremental increase in traction might be good, for the right price. Quaifes are expensive, but I’ve found others that are not as expensive.

Is that because Quaife’s are a helical gear design? I came across another company called Blackline that makes an e53 LSD, but it’s helical as well. It’s about half the price of a quaife.

Obviously any LSD has to “match” the final drive ratios, correct? Mine are the 3.64 of the 4.4i.

Yes, quaife, torsen, helical... All the same shit.

I should note that helical diffs do have one real and meaningful advantage: They don't really wear out. Clutch diffs and viscous diffs absolutely do.

Edit: And no, the LSD doesn't match the drive ratios per se. The LSD coupler is bolted to the ring gear. You would almost certainly reuse the existing ring gear.

Thanks Nick, I appreciate the info. If I could get a used diff for cheap (not a problem generally) and rebuild it with an LSD for not too much money, I’d consider it. I could always swap my old diff back in if it sucks.