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Crankshaft runout how much is Ok
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PedalWerks
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Joined: January 16, 2005
Posts: 219
Location: San Bernardino SoCalif
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PostPosted: Sat Dec 17, 2005 6:49 pm    Post subject: Crankshaft runout how much is Ok Reply with quote

Hello, I recently Purchased a 78.8mm Volkstroker Crankshaft and my machine shop found it has .0012 runout. ( I started with a less expensive "import" crank. it had the same Amount of runout/problem so I decided to take it back and buy the best I could afford).

I know .000 runout is preferable, but I cannot find any Runout tolerance for the VW crank's.

I'm told chevy allows .002 and my machine shop likes to stay under .001 for a V8.

if this is true .0012 would be a lot for a short VW crank.

Question: How much Runout is Allowed? /Ok to use?

Question: should I exchange this for another volkstroker? or will I not find a scat/other crank with less than .001 runout?

Question: will the Cast Volkstroker 3 have less runout?

Question: Should I give up and have this Crank straightened? and If so who should I trust?

I am here in Southern California. I am building a 2025 street engine and will probably not go over 5,000 RPM.

But I am looking to get the Most miles possible for this combination.

Thank's, Scott.
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GjMan
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Location: Grand Junction, CO
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PostPosted: Sun Dec 18, 2005 9:12 pm    Post subject: Reply with quote

How are you measuring runout? Bill Fisher (How to Hotrod VW Engines) says to lay the crank in the bearings in a case half, put a dial indicator on the center main, and rotate. Should not defect more than .001". This is for a performance engine. Fisher notes that many new stock VW cranks (he was talking about the German forgings, not the cast mexican stuff or aftermarket cranks available now) show more runout than this, and implied that they were acceptable for a stock rebuild.

If you can, do what Fisher recommends: take the case half and dial indicator to the crank dealer's shop and keep measuring new cranks until you get a straight one. If the shop won't allow it, take your business elsewhere.

As a reference, my early 90s Pauter Machine welded stroker 78mm crank with 60k miles on it has runout of less than .0005" with negligible wear on the journals.
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PedalWerks
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Joined: January 16, 2005
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Location: San Bernardino SoCalif
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PostPosted: Sun Dec 18, 2005 10:03 pm    Post subject: Reply with quote

I measured it the same way, in the case @ the center main. the machine shop used V Blocks @ the center main.
I will take the case and a lunch back to the part's house. Thank's.
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PedalWerks
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PostPosted: Sat Jan 28, 2006 9:52 pm    Post subject: Reply with quote

DPR offered to Straighten any crank I brought them. Next time I'll use one of their's

Scat offered to find me a straight one or straighten mine if I took it to them.

I found a straight CB forged on the second try.

Thank's
_________________
Nothing Exceeds Like Excess!!!

www.pedalwerks.com
@pedalwerksdotcom
909-289-9655
12' Golf 2.5
07' Rabbit 2.5
59' Single Cab
57' Oval hard top
55' Oval hardtop
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