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Top speed by Wanganstyle; LSD Diff Puzzle thread; ask me to spill beans here!!!

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    #16
    Originally posted by cjdontthink View Post
    Wangan are you capable of replacing the bearings on a diff? How hard is it?
    Would you do it for some cash?
    I do FULL custom diff builds for mostly track e36/46 m's and non m's. The budget is pretty expensive for the average e30 crowd - pm me if you are serious with what you would like and I can send you a quote.

    A few locals in the 500-600rwhp range have my built units for street/track. One in the 1,000-1,100 rwhp range also.



    Setting these up is Pretty time consuming

    requires some very specific tools (or you may destroy your new races/bearings trying to install). I have had aborted projects by DIY-er's shipped to me to heal.

    Custom center section fitting with proprietary steels also really should be done with reconfigured center lsd's.

    Most e30's are running around on melted time bombs for diffs. All the 3.25 ratios are for example, almost all 3.73 units as well.
    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

    Comment


      #17
      Originally posted by e30leigh View Post
      wow this is so interesting.... how would i gain a 75% locking 4.1 for my e30? and also the 188mm is that the medium case e30 diff?
      168- small
      188- medium
      210- large.

      If you wanted 75% locking you would need to run a custom ramp angle center section with 4 clutch discs and steels.

      To compare bmw uses 4 Xlutch discs and steels for the Motorsports LSD unit but lock up is set at 40% accel and 25% deccel.

      75% both ways is very high locking, pretty extreme Setup. My guys on the king of Europe pro drift circuit run something in this range (proprietary)

      Also uping the Number of clutch disc Sets to 5 pairs with custom Case setup can make lockup in the 75% + range. .

      The centers cannot be machined, they need to be precision ground.

      Stock ramp angles are 45 degrees, with 4 disc pairs they yield 60% locking.

      Do you have enough power to power over a 60% locking high lock diff? With two way action this will understeer dramatically compared to the stock setting by bmw for the car.

      Are you setting up a drift car?
      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

      Comment


        #18
        Originally posted by Wanganstyle View Post
        168- small
        188- medium
        210- large.

        If you wanted 75% locking you would need to run a custom ramp angle center section with 4 clutch discs and steels.

        To compare bmw uses 4 Xlutch discs and steels for the Motorsports LSD unit but lock up is set at 40% accel and 25% deccel.

        75% both ways is very high locking, pretty extreme Setup. My guys on the king of Europe pro drift circuit run something in this range (proprietary)

        Also uping the Number of clutch disc Sets to 5 pairs with custom Case setup can make lockup in the 75% + range. .

        The centers cannot be machined, they need to be precision ground.

        Stock ramp angles are 45 degrees, with 4 disc pairs they yield 60% locking.

        Do you have enough power to power over a 60% locking high lock diff? With two way action this will understeer dramatically compared to the stock setting by bmw for the car.

        Are you setting up a drift car?
        basically im building a car for some fun. i want to be able to drift it shall i feel the urge. i also want it to be track driven. and the odd drag day. the car will be street driven also. so a solid all rounder. and the power will be 300-350hp. turbo m20b25

        Comment


          #19
          Do you want the car to make LSD noises when you parallel park? It will with high locking conversion- the kaaz unit I was running prior was almost un-street able, everyone would ask me what the crazy lock up noise was turning.

          Locals with 500-600rwhp are doing fine with 3 clutch discs and 40% lock up. Track /dd/ street driven and civilized. Gets sideways very easily too if setup correctly, although a e30/36 with ls7 will probably get sideways on will with drag slicks on the back.

          75% locking is very heavy duty and not really suggested for street cars unless you have a fetish. It will be very fun for hooning though! And induce quite a bit of understeer on deccel if it's setup for 2-way action with symmetrical ramps.

          hydrolic e brake? 2way high lock lsd +hydro e brake would be the d1 setup
          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

          Comment


            #20
            this thread is dope.

            so u said something about most 3.73's are time bombs.
            i want my lsd to just lock up nicely so what can i do to refreshen it or if it has to be opened up make it lock up more. add another clutch?
            m20 is plenty. im simply a drifter.
            build thread -- http://www.r3vlimited.com/board/showthread.php?t=206510

            Comment


              #21
              is it possible to calculate max lockup torque?
              '84 318i M10B18 | 93whp/90ftlbs | 147- Safari Beige | MS2E w/ LC, 2-Step

              Comment


                #22
                Originally posted by Wanganstyle View Post
                Most e30's are running around on melted time bombs for diffs. All the 3.25 ratios are for example, almost all 3.73 units as well.
                What exactly do you mean by this?

                Comment


                  #23
                  Originally posted by ROLLingKING View Post
                  this thread is dope.

                  so u said something about most 3.73's are time bombs.
                  i want my lsd to just lock up nicely so what can i do to refreshen it or if it has to be opened up make it lock up more. add another clutch?
                  Tear it apart and see how worn the clutch discs and steels are. Order thicker to make up for case wear. You can add extra discs/steels if you are drifting or doing other fun things with your car. the existing clutch discs and steels --->trash

                  3.73 LSD is fitted by bmw to a 5 speed 325i. Almost all of these are running original diff units from 1985-91 and the pinion bearings are close to done - most whining from diffs is this bearing angry and complaining.

                  The front pinion bearing is the first to go, its race also needs to be replaced at the same time.


                  the LSD internals are designed to wear out, its a setup of organic clutch discs and steels - most of the LSD units from manual transmisison bmw's I open up have extremely worn discs / melted organic material / smeared steels from melting. So doing burnouts, doughnuts, drag launches - all the fun things that owning an e30 allows you to do........diff hates it.

                  e36M LSD units are usually extremely worn, the steels often have heat spots and clutch discs will show signs of being worn out and just spinning.


                  Originally posted by The Dark Side of Will View Post
                  What exactly do you mean by this?

                  3.25, 3.73, 3.15/3.23 are from cars equipped with manual transmissions and a M30b34, M20b25, s52b32/s50b30. All of these are sporting engines with sporting owners; the functional materials inside are just like brake pads and rotors.

                  Fun engines = need brake pads more often. Same for diff :)


                  Originally posted by Jaxx_ View Post
                  is it possible to calculate max lockup torque?

                  you can build a jig to hold the pinion flange and a side axel flange fixed and make a fixture to measure breakaway torque. or you can block wheels in the air and jack up the rear to test it field style as they do for Spec e30
                  Last edited by Wanganstyle; 04-30-2012, 09:34 AM.
                  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

                  Comment


                    #24
                    Originally posted by Wanganstyle View Post
                    Tear it apart and see how worn the clutch discs and steels are. Order thicker to make up for case wear.
                    Oh, you were just talking about normal wear and tear.

                    Originally posted by Jaxx_ View Post
                    is it possible to calculate max lockup torque?
                    Originally posted by Wanganstyle View Post
                    you can build a jig to hold the pinion flange and a side axel flange fixed and make a fixture to measure breakaway torque. or you can block wheels in the air and jack up the rear to test it field style as they do for Spec e30
                    Well... Wouldn't that just measure the spring preload torque? The ramps allow the torque applied to the driveline to increase the torque the clutch packs can take... Meaning that as you apply more torque from the engine, the "lockup" torque increases. This leads to the rating of diffs by "% lock", meaning that the combo of ramp angle and number of clutch disks would result in the torque the clutch packs could apply being 25% of the torque applied *to* the unit. So if you end up with 2000 ftlbs at the axle in first gear (Engine torque * trans ratio * diff ratio), the unit would be capable of biasing that torque by up to 500 ftlbs difference left to right.

                    Comment


                      #25
                      its simple and just measures the preloaded torque + static Mu yes.

                      the internal "locking" is more of a characteristic of the center section than anything else. - the stock e30 units are ramped to do the same thing both accel and deccel. The ramp angle can aid the clutches in locking up or prevent them from contacting (i.e. you have a 90 degree angle on deccel and the diff is = open when off throttle.

                      the sider gears slide on these ramps, the stub axels are mated into the spiders with splines.


                      the stock e30 ramp angles are 45deg. This is setup with a sideload spring and one clutch disc+steel each side.

                      the motorsports LSD has 4 clutch discs inside, no sideload springs.
                      its ramp angles are 45deg on accel and 55 deg on deccel. The stock diff setting will allow coasting and minimal to no lock up when in neutral - its unsprung.

                      if playing the spec e30 loading test game it would perhaps register nothing on breakaway, it can basically act as an open diff.

                      ZF differentials are setup this way in other cars; alfa, ferrari, porsche.

                      as far as how to rate/specify a diff, what kind of data are you trying to capture?

                      more clutch disc sets = grabbier feeling item like a KAAZ or cusco unit.

                      if one really wants a mathematical data point wouldnt a gear type or torsen be the best?
                      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

                      Comment


                        #26
                        Originally posted by Wanganstyle View Post
                        the sider gears slide on these ramps, the stub axels are mated into the spiders with splines.
                        Referencing the diagrams in your TIS link:
                        http://tis.spaghetticoder.org/s/view.pl?2/08/69

                        The square lugs on the sides of #9 components are driven by channels on the inside of #12. As they are driven, they push on the cross-shafts which cause the spider gears to push on the side gears... the same way an open diff works.
                        However, because of that power path, the torque through the unit controls how hard the #9 components are squeezing the clutch packs. Since the normal force on the clutch pack is proportional to the torque applied to the unit, the "lockup torque" of the unit is a fixed fraction of the torque being put through the unit.
                        If you all the coefficients of friction, you can calculate what this fraction is.
                        But a rating like "max lockup torque of 500 ftlbs" can not be applied because that torque varies with how much torque is applied to the unit.

                        A Torsen is a bit different in that the max torque in can bias to the wheel with more grip is a fixed ratio times the torque that the wheel with less grip can deal with.

                        Comment


                          #27
                          Still rocking your diff! I do need new ratio though lol :)
                          Mtech1 v8 build thread - https://www.r3vlimited.com/board/sho...d.php?t=413205



                          OEM v8 manual chip or dme - https://www.r3vlimited.com/board/sho....php?p=4938827

                          Comment


                            #28
                            Originally posted by The Dark Side of Will View Post
                            Referencing the diagrams in your TIS link:
                            http://tis.spaghetticoder.org/s/view.pl?2/08/69

                            The square lugs on the sides of #9 components are driven by channels on the inside of #12. As they are driven, they push on the cross-shafts which cause the spider gears to push on the side gears... the same way an open diff works.
                            However, because of that power path, the torque through the unit controls how hard the #9 components are squeezing the clutch packs. Since the normal force on the clutch pack is proportional to the torque applied to the unit, the "lockup torque" of the unit is a fixed fraction of the torque being put through the unit.
                            If you all the coefficients of friction, you can calculate what this fraction is.
                            But a rating like "max lockup torque of 500 ftlbs" can not be applied because that torque varies with how much torque is applied to the unit.

                            A Torsen is a bit different in that the max torque in can bias to the wheel with more grip is a fixed ratio times the torque that the wheel with less grip can deal with.
                            Yes, it's measured vi a bias. quaife has good tech on this.

                            Anyone with an engineering back ground able to more explain how to measure the ramping lock up? And also the difference between sprung and unsprung?
                            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

                            Comment


                              #29
                              You have an amazing mind I wish to pick in the future, when I've got more money to rebuild my differential...until then, keep being awesome.

                              Comment


                                #30
                                I just came back from watkins glen and running pilot sport cups my 140k 3.94 LSD was failing hard in tighter turns.

                                what's the best value home rebuilding that will refresh and upgrade while keeping costs down?

                                It's basically a drive once a week for fun + track day car.
                                1997 BMW 328ic 5spd sport Moreagrun Metallic
                                1989 BMW 325is 5spd with a M50 swap
                                2006 Audi A3 6spd DSG sport with APR stg 2

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