Here is what I think,
the reason why change from 1 piece construction to 2 pieces construction is to reduce the cost of production. Compare the time and metal use and waste to "machine" a solid rod to actual a piston to just thread the piston shaft and machines the piston head , joins them together and seal it with glue, I believe the later method safes a lot of cost on machine.
if you look at the first version of the Composite Piston @ yearJan 2000 on MK20, it don't have the small O ring , instead they have a silicon ring to seal between the shaft and the piston head. The silicon ring also stop water contact with the piston shaft ( it is very cold there when HP to LP [is it call joules thomson effect effect?] ) so less chance to freeze up
I suspect there is some problem with this design and the second version of Piston @ May 2002 is launched with the new O ring to seal between the shaft and the piston head...,
after that, a few new "improvement" has been done on the piston and I believe now is the final version .....
the reason why change from 1 piece construction to 2 pieces construction is to reduce the cost of production. Compare the time and metal use and waste to "machine" a solid rod to actual a piston to just thread the piston shaft and machines the piston head , joins them together and seal it with glue, I believe the later method safes a lot of cost on machine.
if you look at the first version of the Composite Piston @ yearJan 2000 on MK20, it don't have the small O ring , instead they have a silicon ring to seal between the shaft and the piston head. The silicon ring also stop water contact with the piston shaft ( it is very cold there when HP to LP [is it call joules thomson effect effect?] ) so less chance to freeze up
I suspect there is some problem with this design and the second version of Piston @ May 2002 is launched with the new O ring to seal between the shaft and the piston head...,
after that, a few new "improvement" has been done on the piston and I believe now is the final version .....
