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Re-use Connecting Rod Bolts?

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    Originally posted by SkiFree View Post
    I'd go buy a lottery ticket.

    I have reused rod bolts in a pinch but always accompanied with a bolt stretch gauge. If the bolt stretches in spec at the required torque it can safely be reused.

    However, i never do this if it can be avoided.The consequences are severe if it goes pear shaped.

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


      Originally posted by bmwstudent View Post
      I've banged dirty chicks with no rubber before. Just because i've done that doesn't make it okay or safe.

      haha... yea guilty on both accounts!

      You have to weigh up the intended use and invested value of the engine, i wouldn't hesitate reusing them on a dayly driver or mild build for the odd track day

      I have reused them on many occasions even engines that have seen a LOT of track use and never had a problem, but in an all out high rpm race engine i would only use ARP's and custom rods etc. I guess its just piece of mind but in my opinion its not an area of weakness, MOST bottom end failures in M20's come as a result of oil surge not rod bolts

      i think it comes down to rpm if you want to go over 7000 then you need to start paying a lot more attention to the bottom end.

      I sell ITB's and performance parts

      e21 race car m20 power! 293Whp atmo 2.9
      details here

      drive by video
      incar race
      incar video
      drag racing


        Huh. This thread has some value, it looks like, because I just dug through the BMW
        PDFs, and it sure looks like the rod bolts are torque to yield on an M20.

        Enough that I'd NEVER reuse them.

        M10- sure, for a utility engine that won't go over 6k.

        M20- only for something that I wanted to use to oil down the track spectacularly.

        ...and here I thought they weren't tty. Thanks, all.

        now, sometimes I just mess with people. It's more entertaining that way. george graves


          Thread Update Number 2

          Two years, more hard street miles and 10+ track days later, motor is still running superbly and connecting rods are still safely inside the engine block.

          aside: Whodwho's MSPNP is fucking *awesome*

          edit: skifree: can you point me to those failed M20's with reused rodbolts? Genuinely interested.


            My motor has reused crank bolts, has a couple thousand on them already after rebuild. I beat on it and has been fine.


              Crank bolts are not tty.
              Build thread



                THREAD UPDATE #3 - 2 more years

                2 more years, 8 more track days, lots of redlining and hard street miles.

                Motor holding up like a beast


                  The rod bolts are tty that's one reason why they have the necked down section. The sky won't immediately fall down if you reuse them but you probably don't get the same clamp that was intended. high tensile bolts dont have a huge amount of plasticity before they start to neck/fracture so reusing them they can snap or start to neck, you could test a bolt and see how many times you can do it before they break might be a decent margin built in. The consequences of failure are pretty severe so it's up to the individual what risks they are willing to take ...
                  Last edited by digger; 06-27-2016, 06:47 PM.
                  89 E30 325is Lachs Silber - currently M20B31, M20B33 in the works, stroked to the hilt...

                  new build thread


                    lol I'm building an M10 for my 2002 and ran across this thread again.. (going to reuse rod bolts in that too)

                    THREAD UPDATE #4 - 3 more years
                    7 years total since reusing M20 rod bolts.

                    3 more years, 6+ more track days including Laguna Seca and getting my NASA race license. Lots of redlining, not a lot of street miles though.

                    Motor is running great oil pressure is superb, but rings/pistons are going bad and it's burning a lot of oil. Gonna build a stroker M20 with S50 crank (and ARP rod bolts).