Roller crank

Gday, would anyone out there be able to give me some info on Roller cranks( SPG ?)? What is available and any recomendations

Why would you need one? Plain bearings are fine. The more important thing to look for if you're changing cranks in a VW is counter-weights and stroke.

Powertune Gladesville

what is it you want to build first

Forget Powertune,

He is not likely to help.

I read a great artical where they compaired a roller bearing and plain bearing crank for frictional loss, the plain bearing crank came out ahead, also the roller bearing cranks are prown to twisting if you produce enough horse power, they used to tig weld around the big end pins to stop this, i do not think they are available new but i have seen them on " thesamba "

Hi

Its most likely forgotten in time unless your an old bloke like me, the common 8 dowel flywheel attachment with the offset dowel was called the SPG pattern, SPG made the roller cranks.

I've driven the same size motors with same stroke etc, the roller did feel smoother probably because of the weight in the full circle counterweights.

Steve

I don't like em, they twist , also fullcircle counterweights defeat the purpose of the counterweight.


The counterweight is to compensate for the piston /rod assemby in the boxer engine 180degrees

HoneyAbba wrote:I don't like em, they twist , also fullcircle counterweights defeat the purpose of the counterweight.


The counterweight is to compensate for the piston /rod assemby in the boxer engine 180degrees

Thats bang on!

full circle cranks are worse than non counter-weighed ones in most cases.

Why add weight and centrifugal forces to a crank and unbalance it at the same time. That is just asking for trouble 😂