I have 12.9 grade bolts uprated version of oem ones how much torque should I go for...
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If its not a torque-to-yield around 10-15% more than a 10.9 fastener. I assume you mean the main cap bolts? The big crank sprocket bolt is already supposed to be a 12.9
Be aware that you can distort the main tunnels by applying more torque to the main cap bolts meaning you might need to get the main tunnels honed. Measure once they are torqued down
Panthero Coupé quattro 20vt
Indigo ABY coupé
Imola B6 S4 Avant -
Spec for stock 10.9 main bolts is 65Nm, and for ARP studs 81Nm. I torqued my 12.9 bolts to 76Nm. As Alex says you really should mesure the cap roundness, but it can be difficult without proper tools. I just did go by the feeling, crank turned over light and easy without binding, have been working fine. Of course I can't recommend this style of checking.
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I read about the caps being distorted on arp if you go by their torque spec. I will go 76nm and check for roundness.
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The main caps distort about 0.025mm with ARP main studs in my experience. I expect a minor distortion with higher torque on 12.9s, at a guess perhaps 0.01mm?Panthero Coupé quattro 20vt
Indigo ABY coupé
Imola B6 S4 AvantComment
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I have a set here is you want Steve, I decided to use OEM in the end for the above reasons.
Panthero Coupé quattro 20vt
Indigo ABY coupé
Imola B6 S4 AvantComment
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I bought it from ebay.de I will try to find it for you he was saying is the substitute for expensive apr bolts
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