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Old 11-22-2004, 10:17 AM   #1
cib101abn
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can Gd 8 bolt replace crossmember rivet?

I have a 79 Chevy P/U that previous owner had collision in, the front cross member is slightly twisted and popped a rivet on the cab side letting it lift up about 1 inch in the twist...thought about bending it back down and replacing rivet with a grade 8 bolt, will this work or does it have to be welded? thanks, bob
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Old 11-22-2004, 11:07 AM   #2
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i know quiet a few people who use grade 8 bolts on suspension mounts. Dont see why you couldnt use them on the crossmember as well. just double check the torque on it occasionally and might be beneficial to use a thread lock compound.
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Old 11-22-2004, 09:55 PM   #3
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use grade 5 bolts..that would be equal to the rivet. Grade 8 bolts would be too brittle for that application. A grade 8 bolt would just shear off whereas a grade 5 bolt would bend before it popped...like the factory rivet.
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Old 11-23-2004, 01:29 AM   #4
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I dont know where the thread is , but there was an article showing fatigue strenghts in both compression & tension......the grade 8 , while a bit overkill for the app, is stronger than a grade 5. The article went on to say that the rockwell hardness of the grade 8 was not high enough to make it brittle. when a grade 8 fails, it fails catostrophiclly......but it is still far beyond the point where the same sized grade 5 bolt would fail (that is in tension, or compression) ! I have used many grade 8 fasteners on the chassis & suspension on my longhorn, & not had a bit of problem A grade 5 would be plenty strong for that app.....but IMO, an 8 would be better(even tho a bit overkill)..... crazyL
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Old 11-23-2004, 07:48 AM   #5
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There have been several colorful discussions here about the grade 5 versus grade 8 bolts. Like Longhorn said, the grade 5 will be long gone before the grade 8 will break. Besides, there are plenty of grade 8 bolts in suspensions, stock from the factory. That tells me something.

Also, back in the day when I was in A&P (airplane mechanic) school, they taught us that the FAA requires using at least a grade 8 bolt, when replacing a rivet with a bolt. The FAA is the authority on every craft that leaves the ground in the US.
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Old 11-23-2004, 09:59 AM   #6
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Back in the day when I worked at the dealership, the factory recommended replacing bad or removed rivits with grade 8 hardware. If its good enough for the manufacturer, it's good enough for me! Brian
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Old 11-23-2004, 10:30 AM   #7
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Not to make things more confusing there is the issue of fine thread and corse thread. Fine thread is stronger then corse thread.
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Old 11-25-2004, 04:00 AM   #8
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Ya, someone make those last two threads a sticky please? Or we'll just have to make it a semi annual arguement.
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Old 11-25-2004, 06:07 AM   #9
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Here's the last thread and here's a link to the grade 5/8 write up.
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Old 11-29-2004, 01:25 PM   #10
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How about using Titainium bolts?
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Old 11-29-2004, 02:55 PM   #11
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Quote:
Originally Posted by Truckhead
How about using Titainium bolts?
Why? Regular grade 8 steel bolts are more than enough.
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