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PostPosted: March 25, 2020, 10:19 pm 
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Is there not a size of square or rectangle tubing that would be a snug fit over the LBJ? I see that it gets taller right before the bolt closest to the ball joint itself so perhaps a relief cut on the top side to allow for the change in dimension?

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PostPosted: March 25, 2020, 10:57 pm 
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Pic of one-sided mock-up.

Attachment:
IMG_0192.jpg
IMG_0192.jpg [ 200.02 KiB | Viewed 337 times ]


The ball-joint mounting is .700" wide so is not a tight fit into any tube I can find.
I also believe I will want the strength of the two halved box sections.
Not thrilled with how far the box sections hang off the tubes.
Looked at several alternative means for assembly but this seems the most practical.
With the top and bottom plates and rear gusset I think it should be plenty strong.
Using mild steel tube as I do not want to mix mild with Cro-Mo.
So will be a little heavier than ideal.

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PostPosted: March 26, 2020, 6:23 am 
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Thanks for posting a pic before making that. That is critically different from what I drew. Don't build that.

The balljoint flange width of 0.700" does not determine the size of the box section. The od of a socket that fits the hardware that fits the balljoint determines the minimum inside dimensions of the box section. Look for 1-1/4 x 4 in 11 or 12 ga.

The round tube center should point to converge at the balljoint ball center or at some point beyond the lbj.
The flanges of the box section should taper to fall on the od of the tube.

If you can't find the right size box, use flat stock.

Consider using the alfa arms and design and fabrication of less critical parts. Work your way up to the really important stuff with practice.

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PostPosted: March 26, 2020, 9:59 am 
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I will mention 2 things.

With a welder, you can make any size tube you want. Cut a sq tube across 2 opposite corners and adjust the 2 pieces as desired. Then weld back together.

By welding the nut in place, you are not constrained to a particular size based on fitting in a socket.

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PostPosted: March 26, 2020, 12:26 pm 
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Material pictured is 1.25" x .120" wall.
The only way to bring the apex of the arms further out would be to put them under or over the box sections.
That would complicate setting up the lower arms, I can play with CAD some more.
Alternately, I might be able to press the ends of the arms flat and bolt directly through them.
Then add a plate top and bottom.
But that seems potentially weak.

EDIT: OK, so now I'm thinking of compression sleeves at the ends which would eliminate the need to be concerned with sockets clearing the inside of the box tube.

More CAD and pics to follow.

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PostPosted: March 26, 2020, 5:26 pm 
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V2.

Attachment:
Alfa Dio arm v2-page0001.jpg
Alfa Dio arm v2-page0001.jpg [ 42.35 KiB | Viewed 286 times ]


To make this work I have to put compression tubes through the ball-joint end of the tubes.
It may be simpler to replace the green 1.5" tube with an assembly made from plate.
Light blue are the compression tubes, length to be adjusted for the taper of top and bottom plates.
Orange is the ball-joint mount.
Grey 1.00" tube fraction visible between the green tubes would not exist, trimmed away, but I cannot render that with BT.
And yes I did add a cross-brace.
Once welded up this should be quite strong.
My concern then becomes that if I ever need to replace the ball-joint, will I be able to remove and exchange it?

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PostPosted: March 27, 2020, 4:37 am 
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OK this MAY have gotten much simpler?
Despite a silly amount of searching I have not been able to confirm FOR CERTAIN that the ES2074R tie-rod end is 7º taper.
Lots of discussion that implies 7º, but no outright statement!
Full specs appear to be a state secret.

So is the ES2074R a 7º taper or not?

I had thought the Alfa was an odd 7.5º taper, but further research says it is actually 7º.

There is another 7º joint with a 3/4" shank that has been mentioned too.

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PostPosted: March 27, 2020, 5:21 am 
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It's math:

viewtopic.php?f=5&t=1526

Measure what you have to know what you need.

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PostPosted: March 27, 2020, 10:32 am 
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What is wrong with replacing the blocks with pieces of angle iron? The control arm could even be a piece construction, bolted at the ball joint. KISS

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PostPosted: March 27, 2020, 1:06 pm 
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rx7locost wrote:
What is wrong with replacing the blocks with pieces of angle iron? The control arm could even be a piece construction, bolted at the ball joint. KISS


From above, "It may be simpler to replace the green 1.5" tube with an assembly made from plate".
Most angle iron I have seen is poor alloy with radius corners.

Spec. I found;
Suspension Ball Joint for 1972-1994 Alfa Romeo Spider Veloce 1 Piece

Specifications

Stud Thread Size: M12-1.5
Stud Type: Threaded
Small Dia. of Stud Taper: 0.639
Stud Taper Per Ft.: 1.5 in/ft
Ball Joint Attachment Type: Bolt In
Number of Bolts: 2

Going to visit a parts store to see if the ES2074R seems to fit.

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PostPosted: March 28, 2020, 12:30 am 
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Okay, now on V3 of the lower A arm.
This one assumes that either the ES2074R or ES150R tie-rod ends will fit the Alfa uprights. :?:

Since I did not spring the extra $150 for the Sheetmetal Module I cannot draw the flat plates I would tie the tube junctions together with.
The top plate also becomes the lower shock mount.
This is pretty conventional as used in several builds here so should not be an issue, right?

Attachment:
Dio A arm v3-page0001.jpg
Dio A arm v3-page0001.jpg [ 262.77 KiB | Viewed 208 times ]

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PostPosted: March 28, 2020, 7:06 am 
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It should not be an issue other than more rapid wear than a joint designed to be loaded, though it may still be less rapid than using a universal, low cost/quality rod end without seals. Like any joint, it needs to be checked for wear often enough to notice and replace before failure/separation.

Tierods, balljoints on strut suspensions, and balljoints on A arm suspension that do not have the coilover spring attached are not considered “loaded”. These "unloaded" joints may have springs inside to maintain tension/stay tight as they wear and or plastic cups inside. Some are called “low friction”.

It will last longer if used for an unloaded upper. I’d use the alfa lower joint. While they are pretty, I’ve not seen any improvement over the arm I designed a couple pages ago. It did not include the coilover mount brkt that would sit on top across the fork.

I try to avoid angle iron because it tends to crack and break rather than bend but it shouldn’t be an issue if the design and mx is good. Put angle iron in a vice and hammer it over to bend it 45 then try to straighten it. Mild/low carbon steel, no problem.

You could weld nuts or tap tubes to accept the bolts on one side without a socket and fit spacers on the other side to bring the heads out past the flanges so no socket clearance issues.

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PostPosted: March 28, 2020, 1:56 pm 
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Socket clearance is not an issue as the plate has to be 1-1/8 apart anyway.
So using 1.00" tube for the lower arms.
12 mm bolts to fit the Alfa lower joints.
No suitable rectangular tube available locally.
Need to search my shop, thought I had some plate laying around.

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PostPosted: March 28, 2020, 4:15 pm 
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Suggested box to reduce the fab and welding.

No need for box, just flat strip. Weld lbj legs to dark blue cross piece, then weld cross piece to tubes, then weld tapered strips on the outside only where they meet the other parts.

If you can't find wide enough flat strip, butt weld flat strips together.

You can order a couple feet of wide enough flat on ebay if needed.You can go to home depot or lowes for flat too.


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RICHARDSIA ALFA LCA 3.JPG
RICHARDSIA ALFA LCA 3.JPG [ 71.49 KiB | Viewed 172 times ]

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PostPosted: March 28, 2020, 10:06 pm 
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Two steps forward!
Found my flat plate steel, and the ES150R Tie-Rod end is workable for the upper A arms.
I will have to fit a spacer either under the nut, or inside the taper.
Working with plate for the lower arms does mean more welding but I will be able to get an exact fit.
Also have to remember my 9º angle which is achieved by keeping the lower edge of the BJ casting flat.

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