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Race Car Fabrication There is a lot of cool fabriaction going on the race car industry, show us what you got.


Race Car Fabrication There is a lot of cool fabriaction going on the race car industry, show us what you got.

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  #1  
Old 03-25-2020, 10:00 PM
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Lightbulb BT Pro, lower A arm pic.

OK, here is a lower A arm drawn in Bend Tech.
Not a conventional CAD program so I bent it's arm a bit, as you might say, to get it to do what I wanted.
No way to trim the box sections in BT (Could in true CAD) but this is close to the final plan.
BJ to chassis end of tube is 13.5", leaving some room for trimming as needed.
I wanted the chassis ends strait for easy fitment of rod-ends or other adjustable attachments.

The dark blue piece is a 1.25" tube cut away to be added as a gusset.
In addition there will be flat plates added top and bottom.
The welding may be a bit tricky to do.

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Old 03-26-2020, 11:02 AM
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Maxx Levell Maxx Levell is offline
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What vehicle is the A-Arm going on/in? Just curious more than anything lol...
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Old 03-26-2020, 12:45 PM
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Now being revised for more strength.
Not really happy with the way the box hangs from the arms.
Car is a Dio Tipo sports-racer / street car.
Dry-sumped Alfa Romeo 2.0 twin-cam four, five speed with lightened gears, target weight of around 1300 Lb's.

Here is one another guy built.

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Old 03-26-2020, 01:56 PM
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Do you have room to bring the tubes all the way out to the balljoint to replace the green and orange pieces? Will a coilover mount to the arm and if so where?

That looks like a really cool project. At 1300lbs, it should really fly! Do you plan to do some road racing with it? NASA?

There is some good info here the construction and testing of arms:
https://www.joesracing.com/a-arm-science/
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Ongoing 70 Nova build: http://www.offroadfabnet.com/forums/...ead.php?t=8160
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Old 03-26-2020, 03:13 PM
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The orange section represents the ball-joint mounting area.
I'm revising the design to bring the arms closer to the ball.

Wish I could just find a conventional ball-joint but I need a 7.5 degree taper.
There are some Ford truck tie-rod ends with the correct taper but the shank is way over-size.

Only racing planned is "Test & Tune" track days, Virginia City Hill-Climb, and Silver State Challenge.
Might do some Autocross if I can finds a local event.

EDIT: Found out that the taper is actually 7?.
So I should be able to adapt a more common BJ for the upper A arms.
Still stuck with OEM for the lower.

Last edited by R3Fab.; 03-29-2020 at 11:49 PM.
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Old 03-26-2020, 06:31 PM
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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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Old 03-29-2020, 11:46 PM
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Revised again, much simpler now.
Need to buy some more tube as I want to post an actual finished part.
Tired of fighting these so the upper is going to be a roundy-rounder part from Speedway.
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a arm, alfa romeo, bend tech pro, dio tipo


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