Radius Arm Cup Base

e-bygum · Post by **e-bygum** » Thu Jul 05, 2012 12:03 pm

The radius arm cup bases are originally fastened on with a special type of rivet. My parts manual shows them fastened on with nuts & bolts/set screws, part number BD20958/3 - bolts, BD20959 - nuts. I have not been able to find these fasteners listed in the "usuals" lists. The decoder I have to convert Jag fastener part nos. to generic sizes does not work on these part nos.
Does anyone know the size & spec. of these fasteners?

Pete Grice

christopher storey · Post by **christopher storey** » Thu Jul 05, 2012 6:25 pm

I cannot tell you the dimensions, but they were hook bolts of the type used in manufacturing containers and for certain aerospace applications. The problem is that they need the appropriate, and expensive, tool to fit them . The object of using them, as I understand it, was to provide a low tensile fastening that would shear in a gross overload e.g. accident , rather than distorting the floor and rear bulkhead . The same effect can be obtained, albeit not very scientifically, by using small ( e.g 1/4 UNF or m4 ) low tensile bolts and nuts instead . Most restorers now seem in any event to weld one edge , which may or may not be a good idea !

vee12eman · Post by **vee12eman** » Thu Jul 05, 2012 9:30 pm

Hi Christopher,

Just a question for you - by "Hook Bolts", do you actually mean "Huck Bolts"? Certainly that's what I thought they were and a quick internet search shows the two to be somewhat different.

Regards,

Simon

christopher storey · Post by **christopher storey** » Fri Jul 06, 2012 8:40 am

Simon : You are quite correct - I meant huck bolts , which are similar to avdel fasteners

e-bygum · Post by **e-bygum** » Fri Jul 06, 2012 10:21 am

Thanks Peeps
Looks like it's going to be 3/16 or 1/4 nuts and bolts depending on the size of the hole when the cup bases are removed. Hopefully the bolt heads will not interfere with the bush housing. I dont like putting bolts in from underneath with nuts on top, I prefer to go down onto my nuts from above.

christopher storey · Post by **christopher storey** » Fri Jul 06, 2012 3:59 pm

e-bygum wrote:I prefer to go down onto my nuts from above.

Sounds very uncomfortable

e-bygum · Post by **e-bygum** » Fri Jul 06, 2012 9:14 pm

It's even more uncomfortable if you arms fall off.

vrracing · Post by **vrracing** » Thu May 30, 2013 10:10 pm

So is the consensus is to use normal (Grade 5 in the US) nuts and bolts? Ignoring the orientation of ones nuts obviously!

My floors have some rust where water would puddle inside; like the cutouts in the sound deadening around the seat nuts. It's a CA car so salt free and rust is limited to the interior floor from the leaky top.

The "plate for radius arm mounts" are quite pitted and cheap at $49 each. I was thinking of replacing them and the sheet metal under them as I would speculate that capillary action would draw water between the two sheets of metal.

I saw references to "cold rivets" which seemed rather involved and for which I could find little support on the internet. It's odd because I've never seen a rebuild blog that covers that task.

Thanks,

Jim

vrracing · Post by **vrracing** » Thu May 30, 2013 10:16 pm

btw, I searched for "huck bolts" and that's like saying "IBM". Huck fasteners makes a lot of different bolts and rivets.

http://huckfastening.com/

None of the ones pictured look appropriate

johnney · Post by **johnney** » Wed Jul 31, 2013 4:05 am

For your reference
http://www.afshuck.net/en/Products/Fast ... s/C6L.html

abowie · Post by **abowie** » Wed Jul 31, 2013 8:42 am

Why not contact Robey's or Hutson's who make replacement panels and ask them what they use?

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