Graded bolts
Cruiser
Joined: Jul 2019
Posts: 130
Likes: 80
From: NV
Mattbastard had the same issue with his rocker cover bolts. I seem to remember there was a good discussion on various possible causes:
https://www.hdforums.com/forum/engin...-8-my-***.html
https://www.hdforums.com/forum/engin...-8-my-***.html
Seasoned HDF Member
Joined: Nov 2009
Posts: 15,705
Likes: 22,720
From: Farmington ,MS
Maybe when talking about hardware store ss hardware...ARP stainless bolts are 180,000lbs... stronger than grade 8 which is 150,000 lbs...
https://arp-bolts.com/kits/bulk-list...=*&Set1_page=1
https://arp-bolts.com/kits/bulk-list...=*&Set1_page=1
Seasoned HDF Member
Joined: Aug 2007
Posts: 8,201
Likes: 3,089
From: NW AR
The factory bolts for the rocker box are not grade 8. Just a plain grade 5. I know, I snapped one on the Sportster once. Had to pull the head. Last time I've used a torque wrench on a Harley outside of a head bolt.
The stainless bolt for the adjuster would be just fine, in my opinion.
The stainless bolt for the adjuster would be just fine, in my opinion.
Thread Starter
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Road Warrior
Joined: Apr 2018
Posts: 1,347
Likes: 820
From: Moneta, Virginia
Originally Posted by Tom84FXST;[url=tel:19807318
19807318[/url]]Maybe when talking about hardware store ss hardware...ARP stainless bolts are 180,000lbs... stronger than grade 8 which is 150,000 lbs...
https://arp-bolts.com/kits/bulk-list...=*&Set1_page=1
https://arp-bolts.com/kits/bulk-list...=*&Set1_page=1
They are also very pricey, compared to grade eight they cost 4 or 5 times more.
Seasoned HDF Member
Joined: Sep 2017
Posts: 12,271
Likes: 4,952
From: England
When I originally removed the rocker boxes two of the three 1/4-20’s were loose.
Grand HDF Member
Joined: Nov 2009
Posts: 4,315
Likes: 1,663
From: Tampa
Mattbastard had the same issue with his rocker cover bolts. I seem to remember there was a good discussion on various possible causes:
https://www.hdforums.com/forum/engin...-8-my-***.html
https://www.hdforums.com/forum/engin...-8-my-***.html
Cruiser
Joined: Jul 2019
Posts: 130
Likes: 80
From: NV
Timely discussion, this is something else to add to the list of things to improve when my engine goes back together.
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Cruiser
Joined: May 2010
Posts: 218
Likes: 38
From: NE Illinois
As the grade goes up the tensile strength is supposed to go up. As many have experienced the higher grades are also more brittle and may fail by breaking. AN (Army Navy) mil-spec fasteners are designing to bend, not break. The military doesn't want parts falling off of airplanes and tanks.
Seasoned HDF Member
Joined: Oct 2007
Posts: 8,852
Likes: 2,494
From: Decatur, Alabama
Make sure you're torquing the bolt to the correct spec. Grade 8, grade 5, grade godzilla, doesn't matter if you have enough muscle and leverage. Most guys could break any 1/4" bolt alive with a decent breaker bar.
carl
carl