How much torque?
08-07-2006, 06:42 PM
#1
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How much torque?
should a 3/8ths (16 tpi) diameter grade 8 bolt be torqued to?
I just broke two at 70lbs (with lube), is it me or the bolts? Have I just been lucky all these years?
I just broke two at 70lbs (with lube), is it me or the bolts? Have I just been lucky all these years?
08-07-2006, 06:51 PM
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08-07-2006, 06:51 PM
#3
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Re: How much torque?
2112,
I think you have been very lucky ! ARP's 3/8 fine thread rod bolts are only torqued to 50lbs. Stock Chevy 3/8 rod bolts 45 lbs, and both of those are far better than grade 8.
Here is a guide I found with a Google search:
http://www.dansmc.com/torque_chart.htm
If the bolts are specific to a particular application you should always use the manufacturers torque specs.
Hope this helps,
Bill Koustenis
Advanced Automotive Machine
Waldorf Md
I think you have been very lucky ! ARP's 3/8 fine thread rod bolts are only torqued to 50lbs. Stock Chevy 3/8 rod bolts 45 lbs, and both of those are far better than grade 8.
Here is a guide I found with a Google search:
http://www.dansmc.com/torque_chart.htm
If the bolts are specific to a particular application you should always use the manufacturers torque specs.
Hope this helps,
Bill Koustenis
Advanced Automotive Machine
Waldorf Md
08-07-2006, 10:03 PM
#5
Ginger or Mary Ann?
Charter Member
Re: How much torque?
Where did you come up with the 70 ft lbs?
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Some people are like Slinkies - Not really good for anything, but they
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Some people are like Slinkies - Not really good for anything, but they
bring a smile to your face when pushed down the stairs.
08-08-2006, 12:42 AM
#6
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Re: How much torque?
A well respected machinist. Upon reflection, I probably transposed the numbers and have been doing it for some time, luckily without a problem.
Being in a non-stressed application was probably helpful.
In a related question, is an overtorqued bolt shot?
Being in a non-stressed application was probably helpful.
In a related question, is an overtorqued bolt shot?
08-08-2006, 04:28 PM
#7
Ginger or Mary Ann?
Charter Member
Re: How much torque?
yep. Probably strecthed past its's elasticity point.
__________________
Some people are like Slinkies - Not really good for anything, but they
bring a smile to your face when pushed down the stairs.
Some people are like Slinkies - Not really good for anything, but they
bring a smile to your face when pushed down the stairs.
08-08-2006, 04:33 PM
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Re: How much torque?
Cheap insurance not to reuse a bolt your unsure of. In the offroad trucks we use to throw away every suspension bolt after a race just to be safe.
08-09-2006, 12:12 AM
#10
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Re: How much torque?
Originally Posted by Hydrolift
Torque is usually set to 75% of breaking point.
Also good information.
Had some flywheel bolts that I torqued to 95lbs with moly, reread the spec sheet, 95 with oil 75 with moly.
Tossed them to be safe though they sure looked good
