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Old 11-08-2014, 04:14 PM   #9 (permalink)
sandersd
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Join Date: May 2014
Location: Houston, TX, USA
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Drives: 2014 370z Nismo
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Default Notes on bolt torque values

I read in another thread to use 45 ft lbs as the torque value. The bolts provided are M10 x 40 pitch 1.25 grade 4.8 and the torque values per Nissan service manual is 21 ft lbs/28 Nm (without lubricant). I found this out after I broke one of the bolts over torquing it.

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The values in the service manual are general per bolt size and not specific to any particular assembly, nevertheless 21 ft lbs seems too low since I had originally used 45 lbs and the flanges at the front of the resonators were still leaking water. Since I had to remove the bolts several times I kept upping the torque to get compression on the gasket and when I reached 60 ft lbs one of the bolts broke. When I replaced it I used a grade 8.8 and 60 ft lbs which is still way over the recommended value of 30 ft lbs.

I'm not sure one could achieve a complete seal at only 21 ft lbs with the provided bolts but I would recommend to use that value, then start the car on the lift or stands and check for leaks and upping the torque only if necessary. If a much higher value was required it might be prudent to replace the supplied bolts with a higher grade to prevent any inconveniently timed leaks or issues with CO as a result of the bolt snapping from being overstretched/overstressed.

The manufacturer really should provide this kind of basic information with installation notes for their product.
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2014 370Z NISMO -- HKS Hi-Power Exhaust -- Swift Springs -- BC ER Coilovers -- SPL Suspension Components -- Nismo R-Tune Intake -- Seibon BD CF Hood

Last edited by sandersd; 11-09-2014 at 09:06 AM. Reason: added charts
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