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Roller crank

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chop-chop Commited Dubber

56 posts · joined Aug 2010 ·

#855451
Gday, would anyone out there be able to give me some info on Roller cranks( SPG ?)? What is available and any recomendations
das boot ist meine bevorzugte mug
Warum ist es so, weil die Stimmen in meinem Kopf sagte mir

HoneyAbba Commited Dubber

66 posts · joined Aug 2011 ·

#855471
Powertune Gladesville

HoneyAbba Commited Dubber

66 posts · joined Aug 2011 ·

#855485
Forget Powertune,

He is not likely to help.

vwo60 Veteran Volks Folk

2,036 posts · joined Feb 2007 ·

#856147
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 "

1303Steve Scirocco Rare

8,650 posts · joined Aug 2002 ·

#858683
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

HoneyAbba Commited Dubber

66 posts · joined Aug 2011 ·

#858701
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

vlad01 Compulsive Aussie Vee Dubber

4,270 posts · joined Jun 2010 ·

#858955
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 😂

71 notchback,
Past owner of, 70 NB, 73 SB and 72 FB TLE