Rear end noises

[tsmcg161]

Yes Im talking about the car! Ive got that classic groaning noise when i slow down to turn. Checked my diff fluid level and it was good. I checked it because I noticed a leak. Im in the process of replacing the output diff seals. All I was able to get done yesterday was to re grease and re boot the CV drive axles. The Lobro kits from Autohaus AZ are excellent. Are all 89 750il diffs the same? Are they LSD"s. I beleive Bently says to use 80w-90w diff oil. Do these diffs require a LSD additive. Any help would be appreciated.

[shogun]

I searched a bit for you and found:
rear end noises http://www.nmia.com/~dgnrg/page_16.htm
Here is a TI http://www.billswebspace.com/BMWOper...rive331108.pdf Approved Final Drive Oils For Front And Rear Axle Final Drives With And Without Limited Slip Or Viscous Coupling
Mineral based final drive oils are no longer recommended due to the release of synthetic final drive oils for all vehicles with or without limited slip differentials.
Limited Slip Differentials
With the introduction of the Z3 roadster a new synthetic final drive oil for all vehicles with a multi-plate limited-slip differential has been released. The new BMW final drive oil SAF-XJ will replace the old final drive oil SAF-XLS.
The SAF-XLS final drive oil is not to be used in the final drive of the Z3 roadster. Use only the SAF-XJ in the final drive of the Z3 roadster.
Note: If a non-limited slip differential oil is used in a limited slip differential a whining or chattering sound can be heard on very tight turns and will eventually result in a failure of the differential.
Description Quantity Part Number
BMW Synthetic Final Drive Oil 55 liter drum 83 22 1 470 080 (with multi-plate Limited Slip Differential) (SAF-XJ)
Non Limited Slip Differentials
BMW Synthetic Final Drive Oil 55 liter drum 83 22 9 407 768
(without multi-plate limited slip differential, (SAF-XO) or with viscous differential lock (325iX/iXA)
http://workshop-manuals.com/bmw/7_se...th_option_209/
http://blog.bavauto.com/10933/bmw-di...-applications/ says:
You can use the LS (limited slip) fluid in a non-LS differential. This makes the LS rated fluids more universal in application. You would not use a non-LS rated fluid in a limited slip differential. The LS rated fluids have modifiers that allow the clutch packs in a clutch-type limited slip differential to slip when cornering … as opposed to chattering.

Both the 75w-90 and the 75w-140 can be applicable to all BMWs. Some BMWs have been originally specified for the 75w-90, some for the 75w-140. The lighter 75w-90 is the more common weight for most vehicles in the US.
BMW applications will typically specify the differential fluids as;
* SAF-XO (75w-90)
* SAFX-LS (75w-90 Limited Slip)
* SAF-XJ (75w-140)

German Aral oil finder says: Capacity : Lubricant Capacity 1,9 litre Use : Normal Products : BS 75W-90

If it is LSD you will see on the tag on the final drive, normally they are not LSD https://www.bimmerforums.com/forum/s...iL-LSD-options

An S with any number like 3.15 or so is LSD, S stands for German Sperrdifferential

[tsmcg161]

Im going to try tomorrow to get a better understanding. I dont have a "tag". Im satisfied with the 3.15. Dimonlexx talks about "tubular" runners or "hexagonal" runners if the flaps are removed. Are these "flaps" the output flanges?

[TheStigg]

Sometimes full synthetic GL5 diff fluid is sufficient without the additive. If you have already done a fresh fluid change, then drain off enough to add an LSD friction conditioner, many brands available, usually come in 4 or 5 oz. containers. Use the whole bottle then do a few figure 8's to work it in.

[tsmcg161]

Thanks for everybodys input. We have a confirmed LSD.