ARP etc nuts and washers
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Joined: Nov 2003
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From: Norn Iron
ARP etc nuts and washers ARP washers often have one face flat with the hole drilled.
Then on the other side, the hole is chamfered ?
Any reason for this ? Which side is up/down ?
Also, some nuts have little straight gooves cut into once face around one end of the nut on the mating surface.
Any reason for this ? Which side is up/down ?
Modern ARP sets tend to use relatively small multipoint nuts, vs older large bulky hex nuts. I assume part is for ease of installation or physical fitment...but are there any other reasons ?
I assume strength must be same or equal with the small nuts.
I'm sure in the real world it makes almost no difference either way. But they've machined them like that for some reason you'd think ?
Then on the other side, the hole is chamfered ?
Any reason for this ? Which side is up/down ?
Also, some nuts have little straight gooves cut into once face around one end of the nut on the mating surface.
Any reason for this ? Which side is up/down ?
Modern ARP sets tend to use relatively small multipoint nuts, vs older large bulky hex nuts. I assume part is for ease of installation or physical fitment...but are there any other reasons ?
I assume strength must be same or equal with the small nuts.
I'm sure in the real world it makes almost no difference either way. But they've machined them like that for some reason you'd think ?
The camfer on the washer is for the bolt fillet and then faces up towards it for no interferance
If you have studs,face it down away from the nut for better load distrobution/accurate TQ
The lines/grooves would be the nut grade rating
If you have studs,face it down away from the nut for better load distrobution/accurate TQ
The lines/grooves would be the nut grade rating
Last edited by Ari G; Oct 21, 2014 at 04:20 PM.
Its different from manufacturers and quality of the fastener being made
Its sometimes on the side of the hex nuts allso
I see many times a 10.9-12.9 fasteners with 8.8 or lower graded nuts
Its sometimes on the side of the hex nuts allso
I see many times a 10.9-12.9 fasteners with 8.8 or lower graded nuts
Staging Lane
Joined: Nov 2010
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Washers are stamped. The chamfered side is where the die enters, deforming the metal around it as it punches out the center.
It really doesn't matter which orientation you use, but it's a cleaner look having the chamfer facing out (toward the hex).
(this does not apply to belleville washers)
It really doesn't matter which orientation you use, but it's a cleaner look having the chamfer facing out (toward the hex).
(this does not apply to belleville washers)
That is not true. They may be stamped but the chamfer is not from stamping on the ARP hardware. The reason for the chamfer has already been mentioned. High grade hardware will have a radius where the head of the bolt meets the shank. This is to reduce stress. The chamfered washer is to clear this radius.
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Washers are stamped. The chamfered side is where the die enters, deforming the metal around it as it punches out the center.
It really doesn't matter which orientation you use, but it's a cleaner look having the chamfer facing out (toward the hex).
(this does not apply to belleville washers)
It really doesn't matter which orientation you use, but it's a cleaner look having the chamfer facing out (toward the hex).
(this does not apply to belleville washers)
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Joined: Nov 2010
Posts: 93
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My mistake, I was assuming the ARP washers you were referring to were the same as a standard washer. It looks like they actually do a secondary process, or have the chamfer built into their die, to create that radius. Interesting.
Is there any data on how much this actually affects torque repeatability or distribution compared to installing a standard washer, which would have a similar chamfer, in the same orientation?
Is there any data on how much this actually affects torque repeatability or distribution compared to installing a standard washer, which would have a similar chamfer, in the same orientation?
My mistake, I was assuming the ARP washers you were referring to were the same as a standard washer. It looks like they actually do a secondary process, or have the chamfer built into their die, to create that radius. Interesting.
Is there any data on how much this actually affects torque repeatability or distribution compared to installing a standard washer, which would have a similar chamfer, in the same orientation?
Is there any data on how much this actually affects torque repeatability or distribution compared to installing a standard washer, which would have a similar chamfer, in the same orientation?
The chamfer on the ARP washer allows them to run an ID that is tight to the fastener to keep it centered, and still have the necessary clearance for the radius between the head/shank of the fastener.
If you hold an ARP bolt in your hand and slide the washer on the wrong way, you'll see it won't clear the radius, and will have some wiggle as a result of not landing flat on the underside of the head...flip the washer over and the problem goes away.
The side of the nut having little divets around the perimeter of the mating surface is designed to trap the ARP moly lube, or some prefer E.P.L., to prevent nut to washer galling while torquing.