which diff is best?

[pocketmonster27]

Ok guys, first post so sorry for any ignorance. Been looking all over and cant find any information so I finally broke down and made an account. Here it goes:
87 2.7 L with getrag 260 swap from previous owner. Pretty sure it needs a new diff because it makes that grinding noise at low speeds around corners (please correct me if I'm wrong). If the diff should be replaced I figured now would be the time to upgrade. The 3.25 looks like a good option but does it bolt right up in place of the 2.93? Long story short, just looking for a good ratio without a whole lot of modification. Just trying to figure out which diffs would be most compatible. Thanks guys :)

[curtis_luu]

Sounds like you got the 2.93 LSD. The diff you get should be based on how you want your car to drive. Higher ratio diff = better acceleration, but higher RPM at cruising. Not sure whats wrong with your current diff. That "grinding" could be the LSD doing its job.

As far as I'm aware all the e30 diffs bolt up.
Good luck!

[packratbimmer]

If you find a 3.25 from a non E30, you will have to use your rear cover and likely your output flanges. Pretty easy swapping those over. Good luck!

[pocketmonster27]

Nice, thanks fellas! I put a bunch of LSD additive in and it seemed to quiet down a lot but still has a bit of LSD noise but I'm not worried about it. I'll think about that 3.25 as a possible later upgrade :D

[AndrewBird]

Could be a bad wheel bearing you are hearing.

[Wh33lhop]

If it only makes the noise at low speed and turning both left and right, it's probably not a wheel bearing. I've experienced a similar diff noise and it's not that uncommon. Are you using a fluid that's LSD approved? If you were using Redline NS or something before you dumped additive in it, that would explain a lot.

[Uber E30]

Could be a bad wheel bearing you are hearing.

I would second this. Before you go messing with the diff jack up the rear of the car, put your hand on the spring and spin the wheel. If you feel significant vibration its the bearing.

[Wanganstyle]

If it only makes the noise at low speed and turning both left and right, it's probably not a wheel bearing. I've experienced a similar diff noise and it's not that uncommon. Are you using a fluid that's LSD approved? If you were using Redline NS or something before you dumped additive in it, that would explain a lot.

honestly LSD additive in the fluid does not make a difference in sound on BMW unit; unless you got a 0 mile OEM unit or an aftermarket unit with too aggressive of internal setting and you are pretending to austin powers your car to park

aftermarket adjusted oe zf units are often noisy( too much static preload for proper circuit lap time) - ideal circuit settings across the board for OE & aftermarket units = almost no preload at static.


diff pinion bearings go first; noise sounds like a jet plane and gets worse with accel/deccel load. if MOR POWER doesnt make noise worse then it might be a wheel bearing or other item.
Take car to shop you trust & have it diagnosed