Radius arm attachment

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No Quarter
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#1 Radius arm attachment

Post by No Quarter » Mon Nov 07, 2022 2:41 pm

Soon the first part of the assembly process will happen, have rebuilt rear end/cradle, and will attach. But a question, the "upside down hat" that the radius arm attaches to, how is it attached to the chassis? Just rivets? Special rivets? Welding?

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Mikael
63 E-Type, 81 XJ6, 03 X-Type, 07 XKR
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christopher storey
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#2 Re: Radius arm attachment

Post by christopher storey » Mon Nov 07, 2022 4:15 pm

It was attached at the factory with special rivets ; later, if I remember coorectly, a weld was added at the periphery . The problem with the rivets is that the rearmost ones are blind because of the vertical bulkhead in that floor area , so that I think most restorers weld them or use two bolts and weld the rear portion. If you wish to have a good guide to this, e mail Andy Rayner at Hutsons and ask him what the best solution is

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#3 Re: Radius arm attachment

Post by No Quarter » Mon Nov 07, 2022 4:41 pm

Thanks, have written to Andy, mentioning you.
Mikael
63 E-Type, 81 XJ6, 03 X-Type, 07 XKR
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#4 Re: Radius arm attachment

Post by angelw » Mon Nov 07, 2022 8:48 pm

Mikael
As Christopher states, the factory used rivets; they are a threaded rivet called a Huck Rivet, but even the early cars had these mounting domes spot welded as well.

The Huck Rivet requires a special application tool that is quite expensive to buy, but in most cases they can be hired for the occasion, at least in Australia you can.

Plug welding through the holes already in the Aftermarket parts, plus a few more to equate to the number of spot welds originally encountered, would be sufficient to hold these parts without the rivets. its quite difficult to apply Huck Rivets when the floor panel to which the Radius Arm Dome is affixed, is already part of the car. In the factory assembly of the car, these Radius Arm Domes would have been part of the floor assembly before the floor became part of the car. With a short wheel base car, its impossible to use Huck Rivets unless replacing the rear floor, where you're able to use the Huck Rivet Gun before the floor is made part of the car. Replacement rear floor sections can be purchased with the Domes already Spot Welded and Huck Riveted in place.

Although I own the correct Huck Rivet Gun, unless we are replacing the whole floor, or at least the rear floor section, we don't use Huck Rivets. To have an authentic look on completion of restoration, there needs to be a domed head on the underside of the Radius Arm Dome, similar to the Huck Rivet. For this purpose, we use a Domed Head, Unbreako screw of the same thread major diameter as the Huck Rivet. This screw actually has a greater tensile strength than the Huck Rivet. We use permanent Loctite on the thread and torque them up correctly for the size and type of threw that they are. We finish by filling the female hex socket with solder to complete the domed look.

Whether replacing the whole rear floor, or just new domes to an existing, or partial floor repair, we use a jig to ensure the correct positioning of the Domes, as shown in the following pictures:


Image


Image

Regards,

Bill

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#5 Re: Radius arm attachment

Post by No Quarter » Wed Nov 09, 2022 5:29 pm

angelw wrote:
Mon Nov 07, 2022 8:48 pm
Mikael
As Christopher states, the factory used rivets; they are a threaded rivet called a Huck Rivet, but even the early cars had these mounting domes spot welded as well.

The Huck Rivet requires a special application tool that is quite expensive to buy, but in most cases they can be hired for the occasion, at least in Australia you can.

Plug welding through the holes already in the Aftermarket parts, plus a few more to equate to the number of spot welds originally encountered, would be sufficient to hold these parts without the rivets. its quite difficult to apply Huck Rivets when the floor panel to which the Radius Arm Dome is affixed, is already part of the car. In the factory assembly of the car, these Radius Arm Domes would have been part of the floor assembly before the floor became part of the car. With a short wheel base car, its impossible to use Huck Rivets unless replacing the rear floor, where you're able to use the Huck Rivet Gun before the floor is made part of the car. Replacement rear floor sections can be purchased with the Domes already Spot Welded and Huck Riveted in place.

Although I own the correct Huck Rivet Gun, unless we are replacing the whole floor, or at least the rear floor section, we don't use Huck Rivets. To have an authentic look on completion of restoration, there needs to be a domed head on the underside of the Radius Arm Dome, similar to the Huck Rivet. For this purpose, we use a Domed Head, Unbreako screw of the same thread major diameter as the Huck Rivet. This screw actually has a greater tensile strength than the Huck Rivet. We use permanent Loctite on the thread and torque them up correctly for the size and type of threw that they are. We finish by filling the female hex socket with solder to complete the domed look.

Whether replacing the whole rear floor, or just new domes to an existing, or partial floor repair, we use a jig to ensure the correct positioning of the Domes, as shown in the following pictures:


Image


Image

Regards,

Bill
You're right, the tool is (ridiculessly) expensive. Thinking about normal rivets and welding, I weld well. But have already bought the C6Ls...
Mikael
63 E-Type, 81 XJ6, 03 X-Type, 07 XKR
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Author of "Tuning Made Easy"
https://www.amazon.com/Tuning-Made-Easy ... 373&sr=8-1

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#6 Re: Radius arm attachment

Post by angelw » Wed Nov 09, 2022 7:36 pm

Mikael Wrote:
You're right, the tool is (ridiculessly) expensive. Thinking about normal rivets and welding, I weld well. But have already bought the C6Ls...
Hello Mikael,
I see your car is a FHC. In that case, unless you're going to replace the superstructure that the Domes will attach to, you wont be able to use the Huck Rivet tool or the Huck Rivets. Even with a long wheelbase car, not all, proper Huck Rivets can be installed without cutting part of the surrounding material inside the car away.

Regards,

Bill

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#7 Re: Radius arm attachment

Post by Dal » Fri Nov 11, 2022 3:58 pm

The radius arm cup should not be welded to the floor. Please see a post by Chuck Hadley from Monocoque Metalworks. https://www.monocoque-metalworks.com/ma ... works-way/. There is an equivalent rivet that can be used that is easier to install. I'll see if I can find the details.
1958 triumph tr3, 1968 mgb, 1965 etype coupe

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#8 Re: Radius arm attachment

Post by Dal » Fri Nov 11, 2022 4:17 pm

Please see Hi-Lok protruding shear head alloy steel, Cad II plated HL18PB-4 aluminum shear type HL70-6 collar.
Installation guidelines can be found on manufacturer's website. I agree that is just easier to purchase the replacement floor section with the cups already installed and cut it down to the size needed if not using the whole half floor. Its best to plug weld the patch to the nearest floor flanges of the rear bulkhead, transmission tunnel and middle cross member as appropriate. Good luck Dave
1958 triumph tr3, 1968 mgb, 1965 etype coupe

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#9 Re: Radius arm attachment

Post by angelw » Sat Nov 12, 2022 8:53 am

Dal Wrote:
The radius arm cup should not be welded to the floor. Please see a post by Chuck Hadley from Monocoque Metalworks.
There is not viable engineering, or metallurgical argument to support Chuck's comment that welding these parts will lead to cracking. If that were the case, there are other stressed components on an E Type that are attached via welding and therefore, they would also be prone to the failure Chuck is predicting.

My apologies for the poor picture quality; the flash made the spot welds not to stand out as they do in real life.
The following pictures are of a Radius Arm Attachment Dome of an S2 OTS. This car is totally unmolested, except for being stripped to bare metal and primed. The Radius Arm Attachment Domes are the originals for this car and clearly, have never been tampered with.


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#10 Re: Radius arm attachment

Post by No Quarter » Sat Nov 12, 2022 10:16 am

Thanks all. I've decided what I'll do. I bought the Huck rivets, but since I welded new floors in before this (this is my first E-Type), I can't really use them and refuse to pay €€€ for the tool.

So I found normal rivets that just fit in the holes, sturdy, will use them. Then I'll put a weld line on three sides. And I'll keep an eye on it. In any other car I would consider this very very robust. We'll see.

A "funny" thing an E-Type rookie also learned yesterday. I had it on jack stands. The front ones on the front frames, the rear ones on the frame rails just ahead of the rear axle cavity, since I found no place behind the rear axle cavity to place them. When we got the rear axle assembly up and attached, the whole car tilted backwards! :shock: :scratchheadyellow:
It was heavier behind the the rear axle stands than in front, due to the rear axle assembly. Thankfully I had as a precaution my engine hoist attached to an eye in the trunk, so nothing happened, but if I hadn't, things could have gone really bad.
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#11 Re: Radius arm attachment

Post by angelw » Sat Nov 12, 2022 9:19 pm

Mikael Wrote:
Thanks all. I've decided what I'll do. I bought the Huck rivets, but since I welded new floors in before this (this is my first E-Type), I can't really use them and refuse to pay €€€ for the tool.

So I found normal rivets that just fit in the holes, sturdy, will use them. Then I'll put a weld line on three sides. And I'll keep an eye on it. In any other car I would consider this very very robust. We'll see.
Hello Mikael,
Had you bought the Huck Rivet Application Tool, as I've mentioned in previous Posts, you wouldn't be able to use it on your car.

When you say "Normal Rivets", what do you mean by that? Most solid rivets you have to have access to both sides to be able to use them; with your short wheelbase car, you won't. The material the rivet is made from is also important in the application of securing the Radius Arm Dome to the car, as the rivets will be subjected to cyclic, both tensile and shear forces.

With the appropriate rivet, welding the edges of the Dome component is an overkill, will lead to substantial shrinkage and localized stress, which maybe what Chuck was referring to in his article, plus it detracts from the originality appearance for the purist.

Our last adapted method (for long wheel base cars) is as shown in the pictures attached to my first Post, where larger holes have been drilled in the four corners, plus another two closer to the Dome (not yet drilled when that picture was taken) for the purpose of substantial Plug Welding. Unbrako, domed, socket head bolts, of the same thread diameter as Huck Rivets, where used in place of the Huck Rivet. On a Shear and Tensile strength test, bolts were stronger than the Huck Rivet.

On Short Wheelbase cars, we replace the infrastructure that the Radius Arm Dome is attached to. In the area where the Dome is attached, its three layers of metal plus the Dome component, so, its a case of replacing the whole section at least to the chassis rails.

Regards,

Bill

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#12 Re: Radius arm attachment

Post by No Quarter » Fri Nov 25, 2022 9:14 pm

Got my radius arms on now. I've read about them not lining up and needed force on IRS to fit, but amazingly, even with new floors, they aligned perfectly.

Question here is, the safety wiring for the big bolt, where should the other end of the wiring go?
Mikael
63 E-Type, 81 XJ6, 03 X-Type, 07 XKR
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#13 Re: Radius arm attachment

Post by Gfhug » Fri Nov 25, 2022 9:23 pm

Mikael, you may need to drill a small hole in the arm to thread the other end of the safety wire through.
Geoff
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#14 Re: Radius arm attachment

Post by abowie » Fri Nov 25, 2022 9:32 pm

No Quarter wrote:
Fri Nov 25, 2022 9:14 pm
Got my radius arms on now. I've read about them not lining up and needed force on IRS to fit, but amazingly, even with new floors, they aligned perfectly.

Question here is, the safety wiring for the big bolt, where should the other end of the wiring go?
We usually just wrap it around the safety strap in a figure eight and then tighten it.
Andrew.
881824, 1E21538. 889457. 1961 4.3l Mk2. 1975 XJS. 1962 MGB
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#15 Re: Radius arm attachment

Post by 44DHR » Sun Nov 27, 2022 9:22 am

Or like this :-

Image

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Dave
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#16 Re: Radius arm attachment

Post by No Quarter » Sun Nov 27, 2022 10:02 am

Beautiful
Mikael
63 E-Type, 81 XJ6, 03 X-Type, 07 XKR
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