purpose of part

[Jack W Drews <vinttr4@geneseo.net>]

Kinda apologetic for using so much bandwidth recently, but it's been
fun. Here's a legitimate TR question for a change:

Does anyone know the purpose of the stud that sticks out of the center
of the TR4 front plate and gets a nut on the outside, near the crank
pulley? Is it stictly a noise / vibration thing? And yes, there is a
legitimate racing reason for asking the question.

Thanks!

uncle jack --
TR4 -- in surgery
TR6 -- first drive today -- and no oil spots on the garage floor!!!!