Tech Tip - Radius Arm Nuts
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Cargo Master
Joined: May 2011
Posts: 2,388
Likes: 138
From: Northern California
Tech Tip - Radius Arm Nuts
In replacing my radius arm bushings I noticed someone had previously replaced the factory nuts with these ‘prevailing torque lock nuts’. Needless to say this isn’t the right nut for this application.
In an effort to do the job right, I went on a search to find the right castellated nut. I never found a part by searching the application (75 F100 4x4). Resorting to doing more of a technical search, I first identified the thread type on the radius arms as 3/4-10. From there I searched the Internet for a 3/4-10 grade 8 castellated nut. I found two different vendors. Fastenal had them for $33 each plus shipping. Grainger sold them as a pack of 5 for $11 plus $11 more for shipping. So about $22 for 5. Expensive but that is the price of doing it right. I never bothered trying the dealer but I doubt they would have them.
Thought I would share as prevailing torque nuts have a way of chewing up threads. So spend the money, save your radius arms, and cotter pin the right nut on there.
In an effort to do the job right, I went on a search to find the right castellated nut. I never found a part by searching the application (75 F100 4x4). Resorting to doing more of a technical search, I first identified the thread type on the radius arms as 3/4-10. From there I searched the Internet for a 3/4-10 grade 8 castellated nut. I found two different vendors. Fastenal had them for $33 each plus shipping. Grainger sold them as a pack of 5 for $11 plus $11 more for shipping. So about $22 for 5. Expensive but that is the price of doing it right. I never bothered trying the dealer but I doubt they would have them.
Thought I would share as prevailing torque nuts have a way of chewing up threads. So spend the money, save your radius arms, and cotter pin the right nut on there.
Lead Driver
Joined: Jul 2017
Posts: 9,606
Likes: 1,175
From: San Jose, CA
Thanks for posting up the info. But FYI even Ford used that type for at least one model year of the Early Broncos. All of them had the castellated nuts except for '77's, which as far as we've been able to tell, many (or most?) of which came with the locking nuts you describe.
Didn't even have the cotter pin holes, so they have to be drilled if you want to convert back for use with a cotter pin.
I wonder if any of the trucks around the same time came so equipped?
I agree, though, and much prefer the cotter pin. I had never even thought of the potential damage to the threads though. Glad you mentioned that aspect.
Paul
Didn't even have the cotter pin holes, so they have to be drilled if you want to convert back for use with a cotter pin.
I wonder if any of the trucks around the same time came so equipped?
I agree, though, and much prefer the cotter pin. I had never even thought of the potential damage to the threads though. Glad you mentioned that aspect.
Paul
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Cargo Master
Joined: May 2011
Posts: 2,388
Likes: 138
From: Northern California
Yeah. No.... They are worthless.
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Cargo Master
Joined: May 2011
Posts: 2,388
Likes: 138
From: Northern California
Thanks for posting up the info. But FYI even Ford used that type for at least one model year of the Early Broncos. All of them had the castellated nuts except for '77's, which as far as we've been able to tell, many (or most?) of which came with the locking nuts you describe.
Didn't even have the cotter pin holes, so they have to be drilled if you want to convert back for use with a cotter pin.
I wonder if any of the trucks around the same time came so equipped?
I agree, though, and much prefer the cotter pin. I had never even thought of the potential damage to the threads though. Glad you mentioned that aspect.
Paul
Didn't even have the cotter pin holes, so they have to be drilled if you want to convert back for use with a cotter pin.
I wonder if any of the trucks around the same time came so equipped?
I agree, though, and much prefer the cotter pin. I had never even thought of the potential damage to the threads though. Glad you mentioned that aspect.
Paul
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Cargo Master
Joined: May 2011
Posts: 2,388
Likes: 138
From: Northern California
I suppose we can’t never really be completely sure sbout anything... but what I do know is I didn’t drill the cotterpin holes and I can only assume they were meant to be used.
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Cargo Master
Joined: May 2011
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From: Northern California
Well look... Ford didn’t drill holes in the radius arms for nothing so it’s kind of hard to buy into any arguement the days otherwise. If you don’t want to use them or if maybe later models switched to a lock but fine. For anyone who has the cotterpin provisions and wants to use them, I thought I’d provide the information. In the end, we each get to decide for ourself. What isn’t necessary is jumping down my throat when I am simply trying to be helpful.
Cargo Master
Joined: Sep 2013
Posts: 3,259
Likes: 1,321
From: Pryor, OK
Well look... Ford didn’t drill holes in the radius arms for nothing so it’s kind of hard to buy into any arguement the days otherwise. If you don’t want to use them or if maybe later models switched to a lock but fine. For anyone who has the cotterpin provisions and wants to use them, I thought I’d provide the information. In the end, we each get to decide for ourself. What isn’t necessary is jumping down my throat when I am simply trying to be helpful.
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