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jdamm

Factory 02 LSD info/specs and help needed

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Hi FAQers,

i have a factory 3.64 lsd in my tii, i have spent a few hours searching the FAQ and reading through the blue book(which was the most help) but i still haven't found the answer.

using the picture below (of my diff) the numbers in the blue book state its a 3.64 ratio with "s" for LSD, however in the blue book it references "S40" and "S75" stampings for 40% and 75% lock up, it also has "SP" for steel on steel disc LSD.

is there any way to work out what i have from the casing stamps? i also looked at the exploded views for the bmw schematics(realOEM) and it looks like the 75% diff has 2 moly coated inner discs each side, the 40%(assumption) diff has one moly disc each side.

so that leads to my next question, does a "SP" diff have no moly discs and if so how much is it's lock up %?

the diff is about to be rebuilt as the input seal and bearing are toast and i want to give the bloke rebuilding it as much info as possible, as he's never rebuilt one of these before i'd hate to steer him wrong.

any and all info is appreciated, even on part availability too ( to help me should i need some parts, guessing there NLA)

thanks in advance 

jules.

IMG_20190107_124153.jpg

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Measure the lockup percentage you have now before rebuilding. Also remove the rear cover and look at the LSD pumpkin for the original % lockup. Should say S40 if it's an original 2002 LSD. Most E21 LSDs were 25% so you'd see S25.

 

When replacing the worn input shaft bearings your rebuilder should be able to just remove the pinion, press off the one bearing that is fitted to the shaft and reassemble without needing to change the pinion spacing which impacts the gear lash. Pinion spacers are available from BMW or the aftermarket. When BMW had trouble delivering I went to a local trans/diff shop and bought a shim package for a GM product. The diff will never know there is a non BMW component in it's midst. 

 

As far as parts go the bearings and seals should all be available as are the LSD wear discs. I'd tear your diff down and see what shape they are in before buying replacements. One word of caution regarding a 40 plus year old part, specifically your diff as pictured above. What's inside may not be what the case indicates in terms of ratio or LSD. Someone may have played with it at some point in the last 4 decades.

 

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Thanks RussTii,

Ok, he said he'd check the lock up % as you mentioned but he was unsure if it would reach it's lock up % if really worn (you may know more about that?).

 

That explains the 25% diff i'd read about in posts but found no solid info on, going off the amount of random bmw parts from E12's/E21's i've found while restoring my tii, there is quite a chance the diff internals could be made up of E21 parts.

 

I'll drop off the blue book for him, while i'm there i'll look at the pumpkin to see the lsd stamp and also check for the correct codings for klingelnberg or gleison are matching codes on the crown and pinion, that'll be a dead give away if its been messed with.

do you know anything about the "SP" steel on steel disc version of the LSD?

 

I'll report back for others if this thread becomes useful.

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The reason for checking the breakaway torque before disassembly is to determine how well your clutches in the LSD are working. I have seen LSD's that have no resistance at all and others as much as 40 LBS breakaway. As far as I know all the LSD clutches are moly coated and the wear on the coating basically determines how effective the LSD unit will be. Worn Discs = not much breakaway torque. More discs can be fitted to up the % and of course new discs are available from various sources. Don't really know what "SP" signifies as I was under the impression that all friction discs were created equal. 

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(edited)

Here is the S40 stamping on the 3.64 LSD I have in my 69.

image.png.d0b9aeee176a73723596da7be24e979c.png

20170730_172329_zpssc3ycq5k.jpg

"H9" designation on the ring gear is the Gleason contact pattern (in the 3.64:1 ratio). Could also be stamped "H1, F1 or F9".

20170730_172237_zps3csioofc.jpg

 

A "K" stamping is the Klingelnberg contact pattern.

 

Other stampings are for special versions (refer to Blue book page 33-0/3 specifications). 

Edited by jgerock
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ok so i've had the diff rebuilt, turns out i have a S40 with stampings similar to JGEROCK, however i have a klingelnberg contact pattern.

my guy did the before mentioned break away test and got nothing not worthy, once he pulled it apart the reason appeared to be very worn friction discs on either side (see pics), once i referenced new part thickness i worked out id lost 2mm of (total) thickness on either side.

i purchased new inner and outer discs, bearings etc.

filling it up with oil tomorrow and road testing sunday, it will be interesting to see how noticable the difference is.

 

01-25%2f02%2f17.zip

IMG_20190109_111044.jpg

IMG_20190118_164900.jpg

IMG_20190118_164905.jpg

IMG_20190118_164908.jpg

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Curious on the outcome - thank you for posting the details!

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(edited)

Just adding another datapoint to this thread, my factory original LSD has case markings identical to those shown above and internal markings very similar.

IMG_20200612_094934_copy_1587x2355.jpg

Its a Gleason 'H9' at 3.64:1 with the LSD carrier marked S40. Casing is marked 11    S    40  and then directly below the S there's a 1 and below that 3 (but the 3 is rotated 90 degree clockwise)

IMG_20200612_095022_copy_1587x997.jpg

I removed it because of no LSD action after 100kmiles, i noticed it loosing action at about a year ago. Seems that it had never been removed before, with the factory yellow paint on various fasteners under 45yrs of crud.

IMG_20200612_094958_copy_1587x1190.jpg

I bought the clutch pack from racing diffs:

https://racingdiffs.com/collections/lsd-clutch-plate/products/bmw-168-mm-lsd-clutch-packs

The old friction disc thicknesses were 1.93mm and 1.92mm, the old 'eared plates' were 1.98 and 2.0 mm, the new parts were exactly 2.10 - so the diff had lost 0.57mm of thickness over the years. The ramps and spacers were in excellent condition, no significant scoring.

Edited by dlacey

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(edited)


Dave,

 

The “1” below the “S” indicates January and the sideways “3” indicates 1973, the manufacturing date. There is perhaps a casting date on the top of the housing. This can help confirm the differential’s date as it, when present, uses a two-digit indication of year, in contrast to the possibly-ambiguous single-digit year stamped into the left front panel of the housing. (For example, could an ‘02 replacement differential have been manufactured in January 1983? Before you say “no”, check the dates on many quick ratio steering boxes and replacement E12 heads!)

 

I have an ‘02 LSD in my tii: the casting date on its housing is February 23, 1972 (“23B  72”), as shown below in the first and second photos. It came out of a 1972 tii which was being parted. The car’s mileage was, perhaps, 150,000 miles. The third photo illustrates the “as found” condition. Neither the seller nor I realized it was an LSD until Korman opened it: it’s limited slip capabilities had been reduced to nothing, as in nada, zilch.

 

Best regards,

 

Steve

 

 

 

 

 

 

 

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0163B02A-AF2A-4302-A1D4-17D1DD4AF40C.jpeg

C3F6446E-BDC7-4933-9E99-2203A7B76A18.jpeg

Edited by Conserv

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(edited)
7 hours ago, Conserv said:

There is perhaps a casting date on the top of the housing. This can help confirm the differential’s date as it, when present, uses a two-digit indication of year.

Nothing on-top, but on the base is 'FF6' ..? Correction ...but on the base it says HH6

Edited by dlacey
  • Confused 1

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