Yoshi's Differential Rebuild/mod (pre)write up

From the tranny down to wheel bearings.
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Yoshi's Differential Rebuild/mod (pre)write up

Postby Yoshi » Tue Dec 15, 2009 3:24 pm

The factory LSD is a fairly nice 2-way locking differential (accel and decel). From time to time, they either die or just start clunking. My attempt is to make a 1 stop thread for your diff rebuilding needs. This means, if you do everything below, your diff will either be race prepped or factory fresh!

I will post pix as I actually do these. For now this is all theoretical.

AFAIK none of these things require setting lash or preload. I could be wrong!

Table of Contents:
#1 - Seals
#2 - Bearings
#3 - LSD rebuild
#4 - LSD modification (more lock up)
#5 - Further reading



---------------------------------------------------------------------------------------

#1 Seals

Seals are fairly simple. Outside of the cover gasket, there are 3 main seals to the diff. The two axle seals and the drive flange seal. I've personally never taken off the drive flange seal but it seems fairly simple as long as you can keep the diff from rotating. Seal replacement is straight forward.

Parts:
Flange seal
http://www.pelicanparts.com/cgi-bin/kse ... 4-099-M204
Axle seals (buy 2)
http://www.pelicanparts.com/cgi-bin/kse ... 5-602-M213
Axle cup O rings (buy 2)
http://www.pelicanparts.com/cgi-bin/kse ... 4-144-M213

Sources:
http://www.realoem.com/bmw/showparts.do ... g=33&fg=10
http://www.realoem.com/bmw/showparts.do ... g=33&fg=10

Cost: $25.75

---------------------------------------------------------------------------------------

#2 Bearings

I'm not really sure how hard it is to replace bearings yourself. So for now, I recommend professional installation until I figure out how to do it.

Parts:
Axle bearings (buy 2)
http://www.pelicanparts.com/cgi-bin/kse ... 13-893-M34
flange front bearing
http://www.pelicanparts.com/cgi-bin/kse ... -468-892-M (-892 m = -976 yd)92
flange rear bearing
http://www.pelicanparts.com/cgi-bin/kse ... -468-893-M (-893 m = -977 yd)92

Sources:
http://www.realoem.com/bmw/showparts.do ... g=33&fg=10
http://www.realoem.com/bmw/showparts.do ... g=33&fg=10

Cost:
$77.25


---------------------------------------------------------------------------------------

LSD Rebuild

The rebuild can be fairly simple. You replace the clutches and reverse the dog ears. Tada!

Parts:
Clutches
http://store.bimmerworld.com/shared/Sto ... rworl&All=
(Optional) new dog ear plates (buy 2)
part number 91733255212
http://www.pelicanparts.com/cgi-bin/sma ... SC%202.1MM (202 mm = 0'7-31/32")
Bolts that hold the capsule together if you strip one or kill one 33-14-7-740-005-BOE

Price:
$75 - 168

---------------------------------------------------------------------------------------

LSD upgrade

LSDs have 3 upgrades (afaik), more clutches, thicker clutches, and/or modified ramp angle. Adding clutches involves machining the inside of the LSD to accept more.

From what I know, only 1 extra clutch can be added without major trouble. I'm not sure of pros/cons of this.

Modified ramp angle requires a machinist to change your ramp angles. This gives you full control over lock up percentage on accel and decel. The down side is that it is costly. http://icpcitation.com/variloc_theory.htm for more info.

The last option is to simply get thicker clutches (the dog ear, not the clutch itself). Porsche 944 disks fit into the E30 differential without modification. Stock thickness is 2mm (2 mm = 0'0-3/32") and porsche sells 2.1mm (2.1 mm = 0'0-3/32") thickness disks. This raises lock up a hair and is not very expensive to do.
The parts are available here (buy 2) http://www.pelicanparts.com/cgi-bin/kse ... ILTER_911M (911 m = 996 yd)=ON&FILTER_911L (911 L = 241 gal)=ON&FILTER_996J=ON&FILTER_997M (997 m = 1,090 yd)=ON&FILTER_986M (986 m = 1,078 yd)=ON&FILTER_987M (987 m = 1,079 yd)=ON&FILTER_987C (987 °C = 1,809 °F)=ON&FILTER_356M (356 m = 389 yd)=ON&FILTER_9144=ON&FILTER_944M (944 m = 1,032 yd)=ON&FILTER_928M (928 m = 1,015 yd)=ON

---------------------------------------------------------------------------------------

#5 Further reading:

Porsche and E30 LSD similarities: http://r3vlimited.com/board/showthread.php?t=156816
LSD innards: http://www.e30tech.com/forum/showthread.php?t=44131
Seal replacement: http://www.e30tech.com/forum/showthread.php?t=39599
LSD rebuild pdf: http://www.factory3performance.com/prod ... cement.pdf
Porsche parts break down: http://www.autoatlanta.com/porsche-part ... 305-05.php
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Re: Yoshi's Differential Rebuild/mod (pre)write up

Postby M20_fever » Tue Dec 15, 2009 5:35 pm

nice thread, I'll be using this eventually. Would this information also apply to an mz3 diff?
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Re: Yoshi's Differential Rebuild/mod (pre)write up

Postby bataangpinoy » Thu Jan 07, 2010 4:13 am

mz3 is torsen i thought?
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Re: Yoshi's Differential Rebuild/mod (pre)write up

Postby Yoshi » Thu Jan 07, 2010 3:43 pm

I have not a clue!

I didn't think bmw made torsens.
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Re: Yoshi's Differential Rebuild/mod (pre)write up

Postby ten2doyle102 » Thu Jan 07, 2010 7:03 pm

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Re: Yoshi's Differential Rebuild/mod (pre)write up

Postby Yoshi » Thu Jan 07, 2010 7:04 pm

ah... interesting. boooo on bmw
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Re: Yoshi's Differential Rebuild/mod (pre)write up

Postby M20_fever » Thu Jan 07, 2010 7:09 pm

so this write up would apply to MZ3 diffs, good to know.
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Re: Yoshi's Differential Rebuild/mod (pre)write up

Postby Yoshi » Mon Mar 15, 2010 2:53 pm

killed my diff yesterday. might be doing this soon. Also found out it's $75 per clutch. so thats $150 for clutches and $90 for new dog ear plates.
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Re: Yoshi's Differential Rebuild/mod (pre)write up

Postby Yoshi » Mon Mar 15, 2010 3:01 pm

from http://forums.bimmerforums.com/forum/sh ... p?t=931518

Part # Description Qty

23 21 1 490 120 securing plate 1 1.5 $1.50
33 10 1 214 099 shaft seal (pinion) 1 $9.75 $9.75
33-12-1-468-892 tapered roller bearing (pinion, superceded?) 1 $18.75 $18.75
33-12-1-468-893 tapered roller bearing (pinion) 1 $25.00 $25.00
33 12 1 744 368 clamping bush 1 $11.25 $11.25
33 10 7 505 602 shaft seal (output) 2 $7.50 $15.00
33 13 1 213 893 tapered roller bearing (output) 2 $17.25 $34.50
33 11 1 214 144 o-ring 2 $2.25 $4.50
33 13 1 207 280 lock ring 2 0.5 $1.00
33 11 1 210 405 diff cover gasket 1 $4.00 $4.00


bimmerworld

LSD clutch 2 $65 $130.00



TOTAL: $255.25
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Re: Yoshi's Differential Rebuild/mod (pre)write up

Postby Yoshi » Mon Mar 15, 2010 9:34 pm

parts ordered!
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Re: Yoshi's Differential Rebuild/mod (pre)write up

Postby M20_fever » Tue Mar 16, 2010 12:17 am

do another video!
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Re: Yoshi's Differential Rebuild/mod (pre)write up

Postby Yoshi » Tue Mar 16, 2010 12:22 am

haha really?

BTW total was about $350.
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Re: Yoshi's Differential Rebuild/mod (pre)write up

Postby M20_fever » Tue Mar 16, 2010 3:50 pm

yeah really, just use the suggestions we gave you last time. I really like the idea, just needed a little refining.
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Re: Yoshi's Differential Rebuild/mod (pre)write up

Postby Yoshi » Tue Mar 16, 2010 5:09 pm

true. I think lash and pinion depth should be the same. 90% of what I read says shims are more to make up for diffs in the housing than the internals. I do have to set pinion drag torque or something like that. Needs to be 15-20 in oz of force. inch OUNCE!
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Re: Yoshi's Differential Rebuild/mod (pre)write up

Postby M20_fever » Tue Mar 16, 2010 6:58 pm

if thats like setting preload on the diff from a muscle car it's not that hard.
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