Just bought an LSD

[Poon]

I just bought an LSD off someone from the bimmerforums. It's from an e21. It hasn't arrived yet, but I was just curious what type of oil I should use in it. In the 2002 restoration guide it says not to use hypoid gear oil? Please help me!

-Andrew Poon

[752dbl02]

i use regular old gear oil in mine. I have a 3.91 lsd as well and dont seem to have any problems, aside from the tired little car not having quite enough power to keep them both spinning!

what reasoning does the guide give?

[Emyers]

Andrew,

You DO need a hypoid gear lube in the differential...GL-4 80W gear lube non hypoid in the transmission. So hypoid in the diff, non hypoid in the trans.

Earl

74 02Lux

02 M Roadster

72 Volvo 1800ES

[Poon]

Here is a direct quote from the book.

"It is imperative that limited-slip differentials are filled with the right type of oil. Normal SAE 90 Hypoid gear oil is not suitable for the ZF limited-slip units.

Doesn't really give a reason why, but Mike Mcartney knows his stuff. Anyone care to chime in?

-Andrew Poon

[Emyers]

Andrew,

They are referring to a hypoid that is designed for use in LSD units. Usually have friction modifiers to keep the clutch packs from chattering. Someone chime in if this is bad poop....You still need a hypoid but one specified for use in a LSD.

Earl

[752dbl02]

Andrew,

They are referring to a hypoid that is designed for use in LSD units. Usually have friction modifiers to keep the clutch packs from chattering. Someone chime in if this is bad poop....You still need a hypoid but one specified for use in a LSD.

Earl

ahh yeah thats right. the friction modifiers increase the life of the clutch packs as well, and improve lockup? someone correct me if i am mistaken.

[aa/fd]

SAE 85-90 and GM EOS or Ford friction modifier work great for LSD.

Hypoid tooth profile means the gear set is off center, the pinion is lower than the center-line of the ring (crown for Europeans) gear. The ZF is similar to the Eaton/Dana Series in pinion location. The Ford 9 inch has one of the most pronounced drops (about an inch lower than the Dana 60), is one of the most durable designs ever. Introduced in 1957, it is utilized in 90% of all North American race cars competing in NASCAR, NHRA, and larger road race cars with V8 power. Flexibility, strength, and economy are it's forte. Just some meaningless information I thought I'd share.

[Guest Anonymous]

Here is a direct quote from the book. "It is imperative that limited-slip differentials are filled with the right type of oil. Normal SAE 90 Hypoid gear oil is not suitable for the ZF limited-slip units. Doesn't really give a reason why, but Mike Mcartney knows his stuff. Anyone care to chime in? -Andrew Poon

Hypoid lube typically involves extreme pressure additives. If you do a little research you will find that the reason hypoid is not recommended for the manual transmissions in our cars is because it tends to have a corrosive effect on the syncros. This is not true of all transmissions, and in particular, the manual transmissions offered from Detroit.

Last I checked, there are no syncros or other parts that might suffer the same malady in the differentials in our cars. For what its worth, I had an original LSD that came with my 02. For 29 years it managed to get along with Castol's hypoid lube. I would not pretend to speak for Mr. Mcartney but what he means by normal SAE 90 weight might be something entirely different than what is typically offered by today's auto lubricant purveyors. This may also involve different oil weights. conventional versus synthetic, and friction modifiers as mentioned by others. If you search the forum for "hypoid" you will find collective agreement that hypoid is recommended for all rear ends.

If the LSD was obtained from an E21 (320i), look at an E21 manual and see what BMW recommended. I do not believe the Manf distinguished between normal and special hypoid lubes other than using well known, branded offerings.

HTH

[74tiiGolf]

Redline 75-90. I just bought a LSD diff also and checked with my (dare I say brilliant) mechanic and that's what he recommended. he's been doing this for a LONG time so I trust him.

Matthew

[Mike87]

I have to agree with Matthew on Redline. It is the only oil that I use!

[Poon]

Alright guys, red line it is!

Thanks to all who posted.

-Andrew Poon

[TobyB]

And there are a variety of Red Line products-

it says right on the bottle if it's good for a friction- type

Limited Slip...

So just read the bottle!

(it's what I use, too- in everything)

t