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M20 Single mass flywheel material?

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    M20 Single mass flywheel material?

    Quick question I hope someone can answer. Is the M20 single mass flywheel cast iron or forged steel?

    I'd like to modify one for a project and cast iron flywheels don't take kindly to holes.

    #2
    Cast iron is quite brittle and not known for handling stress very well...so I'd say not
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      #3
      They are cast. For sure.
      sigpic

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        #4
        Just like conn rods and crankshafts, and engine blocks. All cast. Even pistons are cast, unless you pay big money. Wheels are usually cast too. The world of poured metal is large.
        sigpic

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          #5
          The ring gear is certainly not cast though, the starter would eat the teeth off if it were.
          sigpic

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            #6
            "The ring gear is certainly not cast though"

            The ring gear is integral with the flywheel as a single cast piece. The flywheel is a chilled casting with chillers installed in the casting box for the flywheel face and outer ring. The chillers regulate crystal formation conformity during the casting cooling process and result in a stronger and machinable material structure in those areas.

            The ring gear is heat treated after machining to further harden the starter ring.

            Many older cars have a separate ring gear that is heated, installed and shrinks on the flywheel as it cools. Not the case with BMW since we all have $ bills falling out of our rear ends.

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              #7
              when you get a FW machined/lightened on a lathe you get that dusty stuff rather than shavings so it would seem to be cast. the ring gear i think is a separate piece at least it looks that way
              89 E30 325is Lachs Silber - currently M20B31, M20B33 in the works, stroked to the hilt...

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                #8
                That answers my question. Thanks guys.

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                  #9
                  Originally posted by Seawolf View Post
                  "The ring gear is certainly not cast though"

                  The ring gear is integral with the flywheel as a single cast piece. The flywheel is a chilled casting with chillers installed in the casting box for the flywheel face and outer ring. The chillers regulate crystal formation conformity during the casting cooling process and result in a stronger and machinable material structure in those areas.

                  The ring gear is heat treated after machining to further harden the starter ring.

                  Many older cars have a separate ring gear that is heated, installed and shrinks on the flywheel as it cools. Not the case with BMW since we all have $ bills falling out of our rear ends.
                  This is not true, I've had the ring gear remover from several m20 and m30 single mass fw's and they all pressed off and are definitely a separate piece.

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                    #10
                    conn rods
                    these are forged. Castings suck in tension. And notch.

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

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                      #11
                      Originally posted by TobyB View Post
                      these are forged. Castings suck in tension. And notch.

                      t
                      stock rods are cast, almost always throughout all manufacturers. Break one in half and you'll see.
                      sigpic

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                        #12
                        In the ’60s and ’70s, American Motors, Cadillac, Buick, and Pontiac all used cast rods in a wide variety of engine designs
                        EnginSoft is one of the leading technology transfer companies in the field of Simulation Based Engineering Science (SBES). Since its foundation in 1984, through our expansion in the sector in the mid-Seventies, to the present day with a global presence, EnginSoft has always been at the forefront of technological innovation. With close to four decades of experience and 4,000 successfully completed projects, we are leaders in the transfer of know-how, technologies, and simulation software solutions in Italy and Europe. We have a team of more than 250 seasoned engineers who have multidisciplinary expertise across every industry sector, enabling us to offer both application and methodological consulting.


                        Development of the Connecting Rod
                        In 1206, Al Jazari described a several machines which utilized a crank-connecting
                        rod system.

                        It is unclear when the first wrought forged connecting rod was produced but the
                        wrought forged connecting rod has long been the “standard” for the automotive industry.
                        In the 1970s, the connecting rod appeared as one of the powder forged
                        technology’s target applications. The powder forging process, as can be seen in Figure 7,
                        is an extension of the conventional press and sinter powder metallurgy (P/M) process. A
                        porous preform is densified by hot forging with a single blow. The forging is performed
                        in heated, totally enclosed dies, and virtually no flash is generated.
                        Continuous-reinforcement MMC squeeze casting technology is studied to produce connecting rods for racing car engines,


                        Well, look at that. BMW rods for M10s and M20s are forged- I've looked at enough
                        pictures on the interwebs in the last few minutes to tell you that. The detailing is consistent
                        with a forging die. However, I'm edumificated about the powder casting, steel 'squeeze' casting,
                        and all the other stuff that's happened since the M20. That's cool!

                        Yes, many rods seem to be 'cast'- but it's a lot higher- tech casting process than a 2002 M10 block got.

                        Looking at the numbers, the eta rod would be a candidate for casting, even in 1985.
                        Yet I distinctly remember looking at the eta rod, and it shows all the external evidence of forging.

                        Neat!

                        I disagree that 'almost all' have been cast, historically, as the BMWs I mess with (through the E36, anyway) are forged, as were
                        the Nissan, Mitsubishi and Volvo and Toyota rods I've worked on, but it looks like the newer 'casting' technologies are
                        pretty cool, and that more and more, newer rods in newer engines are made through a process that's more like casting than forging.

                        Metals and metallurgy are improving- piston speeds are going down, for ecoreasons. Thus, more casting.

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

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                          #13
                          Originally posted by TobyB View Post
                          http://www.enginsoft.com/technologie...cting-rod.html










                          Well, look at that. BMW rods for M10s and M20s are forged- I've looked at enough
                          pictures on the interwebs in the last few minutes to tell you that. The detailing is consistent
                          with a forging die. However, I'm edumificated about the powder casting, steel 'squeeze' casting,
                          and all the other stuff that's happened since the M20. That's cool!

                          Yes, many rods seem to be 'cast'- but it's a lot higher- tech casting process than a 2002 M10 block got.

                          Looking at the numbers, the eta rod would be a candidate for casting, even in 1985.
                          Yet I distinctly remember looking at the eta rod, and it shows all the external evidence of forging.

                          Neat!

                          I disagree that 'almost all' have been cast, historically, as the BMWs I mess with (through the E36, anyway) are forged, as were
                          the Nissan, Mitsubishi and Volvo and Toyota rods I've worked on, but it looks like the newer 'casting' technologies are
                          pretty cool, and that more and more, newer rods in newer engines are made through a process that's more like casting than forging.

                          Metals and metallurgy are improving- piston speeds are going down, for ecoreasons. Thus, more casting.

                          t
                          That is neat, I didn't know BMW rods were forged. I just assumed they were cast like many others I've seen.
                          sigpic

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                            #14
                            Just remember that even something that is "forged" starts its life as a casted item.

                            Forging is just another step between casting and machining.

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                              #15
                              also there is a different between cast iron and cast steel
                              89 E30 325is Lachs Silber - currently M20B31, M20B33 in the works, stroked to the hilt...

                              new build thread http://www.r3vlimited.com/board/showthread.php?t=317505

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