Announcement

Collapse
No announcement yet.

168mm LSD technical discussion and internal setup overview

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

    168mm LSD technical discussion and internal setup overview

    168mm LSD specific thread as most data is related to 188mm units.

    168mm is commonly USA found in 4 cylinder e30's
    168mm is non usa in some 6 cylinder e30's

    168mm is also interchange with older cars; e21/2002. Somewhat - More on the Old Old school later.

    E30 168mm setup:

    2 clutch discs total (1 per side)
    2 steels total (1 per side)

    Older 168mm LSD cars had factory 4 discs setups; perhaps someone with a rare setup in 2002 or e21 can chime in.


    168mm is commonly avail in these ratios stateside:

    3,45 (318ti e46)
    3,64 (some e21)
    3,91 (318i M10 e30)
    4,27 (318i m42 vert)
    4,45 (318i e36)

    some weird others must exist as well as LOW ratio 3,25 from euro e30 323i; the lower ratio 3,25 final drive has a special LSD capsule with different offset geometry not compatible with the others.

    Bolts are also M12 size instead of M10.

    LOW ratio Euro on left from early e30


    LOW ratio on right with split bell type ring gear flange



    For Internals of the 168mm there are 2 standards for clutch discs and steel discs; the center ramps are also different heights.

    Older style clutch disc (e21/2002) has different spline standard than Modern E30/e36 style



    Modern E30, E36 spider gears also are a different profile than the older units.

    168mm e30/e36 LSD spider gears are only toothed very narrow; only 1 clutch disc will fit on these teeth. (1 clutch disc per side).

    This limits lockup to 25% locking in modern e30/e36 LSD 168mm.
    The rosetta stone early e30 LOW ratio unit happens to have the Vintage style long teeth spiders so that with machine work+custom internals a 3x or 4x clutch setup could be installed.

    The older (e21/2002) units internally have longer spline teeth similar to a 188mm unit; those internal setups can be interchanged with custom internals into a newer e30 case capsule if desired; machine work and custom ground thicknesses of internals will be required.

    OBD1 M54/M52TU swap as a M50b25

    Z4 non powered steering rack fits e30



    Euro e46 2005/6 320d 6mt gearbox into E30 with M20 hardy and beck 1985 327s engine

    #2
    Some additions to your application chart.

    3.36 ratio - 2002 turbo

    3.45 - Most e21 323 (euro) and reportedly some euro 2002 tii (never seen this)

    3.64 ratio - Most 2002 and 4 speed e21

    3.91 ratio - e21 5 speed



    Also, most e21 lsd are 2 clutch 25%
    Lorin


    Originally posted by slammin.e28
    The M30 is God's engine.

    Comment


      #3
      A couple of things to add about the 168mm differentials ....

      Pumpkin Height w/topcap (in inches). The pumpkins are interchangeable between different cases as long as the heights are the same.

      2002 open: 5.7”

      2002 LSD: 5.05"

      E21 open: 5.7”

      E21 LSD: 5.05”

      E30 open: ?

      E30 LSD: 5.7”

      E36 open: ?

      E36 LSD: 5.7”

      The E21 LSD center portion is shorter and uses taller end caps. The E21 LSD on the left and the E30/E36 on the right.



      The difference is in the topcap



      Here's another picture where you can see the difference in clutch sizing and center.


      Through BMW Motorsport you could also buy higher ratio gear sets (at least until the early 90's when BMW ran out). These were never available in a production car (with the exception of the 4.44).

      4.22
      4.44
      4.75
      5.00
      ? (may have been one in between here).
      5.30

      Here's an example of the 5.30 gear set,

      ADAMS Autosport

      Comment


        #4
        Excellent info!
        Zach@Zakspeed.us

        Comment


          #5
          sub'd
          I'm looking 168mm LSD unit, with 3.64 ratio..
          Plan to put in my small case open diff (4.45)
          Is that possible anyway?

          thanks
          [ETA - E30 Adapters] 5 Lug kit with e46m3 front and e46 325/328i rear brake setup
          ---------------------------------------------------------------
          [ETA - E30 Adapters] - 5 Lug kit | DTM Shifter | DSSR
          ---------------------------------------------------------------
          Transaction Feedback

          Comment


            #6
            Originally posted by ngampleh View Post
            sub'd
            I'm looking 168mm LSD unit, with 3.64 ratio..
            Plan to put in my small case open diff (4.45)
            Is that possible anyway?

            thanks
            Yes, using the center LSD section from an E30 318 or an E36 318 (and a 3.64 ring/pinion).

            http://www.bmw2002faq.com/_/technica...tial-build-r74
            ADAMS Autosport

            Comment


              #7
              Thanks for sharing your link, Andrew
              Is that difficult to find small center LSD?


              Sent from my iPhone using Tapatalk
              Last edited by ngampleh; 09-12-2014, 09:11 AM.
              [ETA - E30 Adapters] 5 Lug kit with e46m3 front and e46 325/328i rear brake setup
              ---------------------------------------------------------------
              [ETA - E30 Adapters] - 5 Lug kit | DTM Shifter | DSSR
              ---------------------------------------------------------------
              Transaction Feedback

              Comment


                #8
                How stout are the 168mm LSD units? I'm looking for a 3.91 small case LSD for my Downing Atlanta supercharged e30 318i (M42). Should I be looking at medium case (188mm) units instead?
                sigpic
                January 2012 COTM

                Comment


                  #9
                  Yes, generically: the 168 r&p set is not all that durable at high torque.
                  It will last for a while, but the 188 will last forever.

                  Now, if you find a great deal on a 168, you can always run it until
                  it gets noisy...

                  t
                  now, sometimes I just mess with people. It's more entertaining that way. george graves

                  Comment


                    #10
                    Medium case.

                    I wouldn't recommend a small case to anybody unless its a stock car that puts around.

                    OR

                    Ok with rebuilding them as need and NEEDS the extra weight savings.
                    Zach@Zakspeed.us

                    Comment


                      #11
                      does anybody know part numbers for friction and dogear plates for this small case lsd unit?
                      for e30, as we know e36 lsd units have different number of teeth.

                      ...aaand also numbers for e36 unit :D
                      seems like I have e36 lsd element.
                      Last edited by abit; 02-15-2018, 07:38 AM.
                      http://instagram.com/mundieriss
                      my 88' m20b30 HERE!

                      Comment


                        #12
                        Good info on this thread. My car came with a factory option 168mm 4.10 LSD that I don't know what to do with. Is it possible to swap the R&P and keep the LSD center?
                        Originally posted by Melon
                        Engine work takes patience and finesse.

                        Suspension work takes anger, a big fucking hammer, and a torch.

                        Comment

                        Working...
                        X