| [ Total Views: 1530 | Total Replies: 8 | Thread Id: 91973 ] |
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 chop-chop
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 posted on August 4th, 2011 at 09:43 PM |
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Roller crank
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
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waveman1500
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| posted on August 4th, 2011 at 09:47 PM |
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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.
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HoneyAbba
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| posted on August 4th, 2011 at 11:40 PM |
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Powertune Gladesville
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 vw54
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| posted on August 5th, 2011 at 07:31 AM |
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what is it you want to build first
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HoneyAbba
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| posted on August 5th, 2011 at 08:26 AM |
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Forget Powertune,
He is not likely to help.
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vwo60
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| posted on August 9th, 2011 at 01:27 PM |
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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 "
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1303Steve
A.k.a.: Steve Carter
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| posted on August 24th, 2011 at 04:17 PM |
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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
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HoneyAbba
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| posted on August 24th, 2011 at 06:22 PM |
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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
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vlad01
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| posted on August 26th, 2011 at 07:19 PM |
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| Quote: | Originally
posted by HoneyAbba
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
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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 |
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