Don Terrill’s Speed-Talk

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 ?

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


Some info here. Might be worth asking over there.

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.

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?

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.

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

TMSJoe wrote: ↑Mon Aug 26, 2019 9:51 pm What are the chances of machining the OEM part to accept replaceable aftermarket ends?

It is impossible to make. Because there is no material on the edge of the arms. So I have to make them billet. Or Welded from 4340 maybe ? I'm looking all my options. I'm sorry I could not wrote. I could not enter the forum after the name changed. Now I have to use VNP to connect the forum.

Anyway I could not done anything to the car, because of the virus thing. everything seems impossible these days. But I'll try my best. I see wisefab arms for rallying and drifting. They seem to have less cross section. And How come they can manage the stay together on Rallying. This motor sports is abusing the car component much more worse than anything.





Please check it. Do you think this is strong enough for rallying ?

The billet arms pictured certainly look "nice", but I would have significant hesitation for any hard/street use based on just my eye. Alum has a finite fatigue life magnitudes less than steel. It's a non redundant part with catastrophic outcome in failure. 7075 costs a lot more to purchase then 6061, but in this application would be the much better choice. 2024 is also another suitable candidate. I would machine nothing that that at the least had some FEA support. Welded alum on a critical suspension part is a no no IMO. You may want to consider some post machining treatment options, like cyro for stress relieving, etc, and with alum that is not always a simple task.

j-c-c wrote: ↑Sun May 02, 2021 12:25 pm The billet arms pictured certainly look "nice", but I would have significant hesitation for any hard/street use based on just my eye. Alum has a finite fatigue life magnitudes less than steel. It's a non redundant part with catastrophic outcome in failure. 7075 costs a lot more to purchase then 6061, but in this application would be the much better choice. 2024 is also another suitable candidate. I would machine nothing that that at the least had some FEA support. Welded alum on a critical suspension part is a no no IMO. You may want to consider some post machining treatment options, like cyro for stress relieving, etc, and with alum that is not always a simple task.

I am %100 with you about welding aluminum. I won't and can't able to do it. But I can weld steel. I can cut Aluminum & steel very easily.
They have increased thickness and replaceable rod end. That kind of thing is perfect for me.
This geometry is same as my Alfa 159. And Here is a billet upper arm. This kind of photos keeps me going

Welded aluminum suspension parts are a no-no. If you used 6061-T6, it'll be T0 at the weld and will crack right in the middle of the weld. 7075-T6 (nor 2024, for that matter) should not be welded. There are a few ways to get the temper back up after welding (even using a regular oven), but for all intents and purposes, it's not practical. Just don't do it.

With what parts specifically are you having problems? The big and small bushings can be replaced with spherical bearings. Is there a racing or otherwise more durable ball joint available?

Look in a Speedway or Coleman's catalog and see if the tubular steel upper control arms can fit your needs. Lightweight and strong, and available in many sizes if you want to change your camber curve or roll center.

dannobee wrote: ↑Sun May 02, 2021 9:05 pm With what parts specifically are you having problems? The big and small bushings can be replaced with spherical bearings. Is there a racing or otherwise more durable ball joint available?

rod end of the arm is the weakest link. 10 USD part kills the whole arm. And Arm is expensive 360USD lower arm. And need to be changed 6 months - 12 months. Because of dead rod-end. I need only replaceable rod end design arm for upper and lower arms. I have harder bushings from Power Flex

racing parts are almost impossible to find in Turkey. I have to import them. But no problem to find Mercedes Benz parts in here. They are heavy and I think durable than original Alfa Romeo Parts.

OK, we call those "Ball Joints" in the US.

If you can somehow get the old ones out without damaging the control arm, it's common to replace with spherical bearings and a stud that also makes the ball joint adjustable for roll center.

http://www.colemanracing.com/Ball-Joint ... P4392.aspx

If you have access to a lathe and mill, it should not be much trouble to fabricate something.

dannobee wrote: ↑Mon May 03, 2021 7:55 am http://www.colemanracing.com/Ball-Joint ... P4392.aspx

If you have access to a lathe and mill, it should not be much trouble to fabricate something.

I have CNCs and Lathe, no problem. Only problem I don't trust my self about the strength of the finish job. Maybe ball joint area will be weaker. And would kill me in the car.

Hello, Me again after for a long time. Mean while escaping from Covid19 I did some progress in Suspension geometry and design.

3D Scan of Upper Arm


3D Scan of Lower Arm


3D Scan of Knuckle


3D Scan of Wheel Arch


Dirty Work of Solidworks Assembly


I've finished the Upper Arm CAD model. And I'm very pleased with that. I'll use FK ball joints in front and at chassis I'll use Original Design + PowerFlex Bushings.

The Problem that I have is the lower arm ball joint area. I want to use bigger diameter eye for Ball joint. "30mm Stock" vs FKS14 "Ball diameter is 33.32mm"

The Problem is the thickness of the material left outside of the arm aluminum.


Original Aluminum diameter is 46mm Circle. If I use like that All the thickness around Ball Joint is 3.16mm. But I did a trick and add material only to the side of the ARM. It does not touch the Knuckle. But I could not add more material to the front of the arm. Can you give me some review about it. I could make it steel. But it would make it very heavy. Can you guide me a little bit.

I'm sorry for my English. Maybe I use some words differently.

PS: My main goal is the make a stronger ball joint. And replaceable one if possible. Original ARM is about 3.5kg every time the ball joint fails. I have to put the arm to the junk yard.

I want to add more pictures...