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Can Billet CNC Cut Suspension arm, replace factory cold formed arm?

Shocks, Springs, Brakes, Frame, Body Work, etc

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emre2blue
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Can Billet CNC Cut Suspension arm, replace factory cold formed arm?

Post by emre2blue » Fri Jul 12, 2019 3:17 pm

Hi

I'm using Alfa Romeo 159, it's relatively heavy car. Front Wheel Drive and Front has double wishbone suspension.

As you can see, it is cold formed forged aluminium, and it is very tough. But bushings and rod end is pain in the ass. Every time there is a problem, we need to buy whole assembly. And it costs too much. Rod End has life time of 15.000km :(

I have a CNC, and I can make it from billet aluminium with replaceable bushings and with motor sports rod ends But I don't know if it will have good life . I saw some aftermarket billet arms. If they can make it. I can make it too. Can you give me hints. Or direct me, suggest me a material. Or I can go welding tubes ?
Arm.jpg
18085AP.jpg
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BenE64
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Re: Can Billet CNC Cut Suspension arm, replace factory cold formed arm?

Post by BenE64 » Fri Jul 12, 2019 4:38 pm

http://corner-carvers.com/forums/showth ... ontrol+arm


Some info here. Might be worth asking over there.

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Rick!
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Re: Can Billet CNC Cut Suspension arm, replace factory cold formed arm?

Post by Rick! » Fri Jul 12, 2019 6:28 pm

Forged 6061T6 aluminum will be about 10% stronger than billet 6061T6 aluminum in yield strength.
Unless someone actually witnessed the forging process, I'm doubtful that it is "cold-forged."
Material needs to displace during the forging process and heated material displaces and leaves a mostly smooth surface finish.
Otherwise, it takes a press of enormous tonnage which is like killing a fly with a sledgehammer.
If you can find good billet 6061T6, and you can match the cross-sections at most every location, then you should be fine.
If you make cross-sections even 5% smaller, then you may encounter durability issues.
YMMV.

emre2blue
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Re: Can Billet CNC Cut Suspension arm, replace factory cold formed arm?

Post by emre2blue » Sat Jul 13, 2019 3:21 am

Rick! wrote:
Fri Jul 12, 2019 6:28 pm
Forged 6061T6 aluminum will be about 10% stronger than billet 6061T6 aluminum in yield strength.
Unless someone actually witnessed the forging process, I'm doubtful that it is "cold-forged."
Material needs to displace during the forging process and heated material displaces and leaves a mostly smooth surface finish.
Otherwise, it takes a press of enormous tonnage which is like killing a fly with a sledgehammer.
If you can find good billet 6061T6, and you can match the cross-sections at most every location, then you should be fine.
If you make cross-sections even 5% smaller, then you may encounter durability issues.
YMMV.
I can find 7075-T6, It does not have much cost differences. For the cross-sections, do you mean I have to make the part exactly same thickness in every where. I should or must not make a smaller part even with %5 smaller in same material can cost me some strength?

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Rick!
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Re: Can Billet CNC Cut Suspension arm, replace factory cold formed arm?

Post by Rick! » Sat Jul 13, 2019 8:23 am

emre2blue wrote:
Sat Jul 13, 2019 3:21 am
Rick! wrote:
Fri Jul 12, 2019 6:28 pm
Forged 6061T6 aluminum will be about 10% stronger than billet 6061T6 aluminum in yield strength.
Unless someone actually witnessed the forging process, I'm doubtful that it is "cold-forged."
Material needs to displace during the forging process and heated material displaces and leaves a mostly smooth surface finish.
Otherwise, it takes a press of enormous tonnage which is like killing a fly with a sledgehammer.
If you can find good billet 6061T6, and you can match the cross-sections at most every location, then you should be fine.
If you make cross-sections even 5% smaller, then you may encounter durability issues.
YMMV.
I can find 7075-T6, It does not have much cost differences. For the cross-sections, do you mean I have to make the part exactly same thickness in every where. I should or must not make a smaller part even with %5 smaller in same material can cost me some strength?
Between the top picture and the bottom picture, the lower arm changed shape with the added rib coming out of the inside radius between the ball joint and the rear bushing. They added that for extra bending strength for braking forces and for slight frontal impacts like potholes. With the combinations of measurements and eyeballing the geometry you can mimic the cross sections pretty close and making the arm a little larger in cross section won't cost much in weight while staying strong. For aluminum, 1 ounce is about 1 cubic inch of material so trying to save weight would remove considerable cross section while adding an ounce makes for peace of mind and a stronger part (if the ounce is added in the right place.)

7075T6 will be crazy stronger but you need to make the surface finish pretty smooth. 7075 compared to 6061, has a higher "notch" sensitivity which means that a micro crack turns into a macro crack easier than 6061 with the wrong input force. One way to alleviate this is to tumble-deburr the part after cutting it to take all the little rough edges off and dull the edges between cutter passes. If you make the final cutter passes so that the steps movement of the bit is short to minimize and then tumble deburr, the arm should have good strength, maybe even better than the original part.

TMSJoe
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Re: Can Billet CNC Cut Suspension arm, replace factory cold formed arm?

Post by TMSJoe » Mon Aug 26, 2019 9:51 pm

What are the chances of machining the OEM part to accept replaceable aftermarket ends?

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