3 replies to this topic

[haz]

does grinding the 1275 crank (mine is a GT crank) to suite 'S' rods change the stroke?

I hadnt really thought about it till now, but making the big ends smaller would increase the stroke wouldnt it? But do the rods differ in length from the standard 1275 ones.. i dunno

someone must know?

cheers

[Boomboy77]

depends if you offset the regrind, if its on the same centre point then the stroke will remain the same, offset it one way for longer and t'other for shorter.

[dklawson]

No, crank grinding does not automatically change the stroke. You CAN take a large rod journal crank and ask that it be ground to smaller journals WITH increased stroke... but the stroke doesn't change automatically... you have to plan for it and ask for it.

This is strictly a geometry thing. With a normal regrind what you're looking at is the distance between the center of a main journal and the center of a rod journal. When the machine shop puts the crank on a grinder they program it to regrind the rod journals around the same center point they were originally. So... the distance to the crank main journals remains unchanged.

[haz]

ahh yea, never thought about it like that. makes sense

I'll try and measure it up when i get home