Fractured Connecting Rods

[Jeffrey and Jill Brueckheimer <jbrueck@domain.elided>]

Gentlemen,

The reasoning behind the fractured rods at Ford was based on both cost
and performance. Fractured rods will most generally out preform a forged
rod production rod in terms of strength and durability (often over
engineered to the point we are offering them in our SVO catalog to
racers). With that we also get the side benefits of reduced machining
costs (no dowel, no joint face machining), maintain a higher capability
on the weight variation of each rod and have a rod that weighs less than
the forging it replaced. This comes at the expense of a much higher
material cost but still at an over all cost reduction. 

The notch that is broached into the crank pin bore is there for
controlled fracture and to lower the force required to induce the
fracture. We do form the notch in the die prior to sintering when we use
the Krypsoge process as used on the new Jag and Lincoln small v-8's. 

We did a test with a laser etched line instead of the notch and reduced
the cracking force further with no detrimental effect to the fractured
surface. This process is now used in the industry (but not at ford). The
next step for the company should be to fracture precision forgings as
done by some of the European car manufactures (Rover, Daimler,
Porsche...).   
 
Regards,

Jeffrey Brueckheimer
Co-worker of Eric
(former Ford connecting rod mfg engineer)
74 GTV

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