Control arm/coil-over brackets...

[wellis77]

Designing the brackets to mount my control arms and coil-overs. Is 1/8" okay or is 1/4" needed? I am running cross-shaft UCA's and figure a 1/4" plate will probably be needed for that but I'm not sure. I "thought" I've seen 1/8" used for most tabs or brackets and just want to confirm. I'll be running a tube through the front cross member that the inner LCA mounts will meet and will bring an outbound mount down from the frame rail for the outbound portion of the mount. What about coil-over mounts? Is 1/8" okay if it's boxed? Thanks guys.

[Bryce]

1/8" boxed should be fine. But minimize the moments you put on the brackets.

[wellis77]

Not sure what you mean by "minimize the moments", can you clarify that?

[Bryce]

Basically, minimize the distance between the bracket attach point on the frame and contol arm attach point.

I hope that makes sense, leaving now to a new year party with my wife.

Also I got your PM. I will answer tomorrow. But I can help.

[wellis77]

Thanks for clarifying Bryce and thanks for the help. I did figure a few things out on the software and I'm going to try and post what I have to get some feedback. Thanks again.

[parsonsj]

Most tabs and brackets designed for suspension usage are 3/16". I'd consider that the minimum for control arm and c/o brackets.

jp

[wellis77]

Thanks John. I'll run with the 3/16" then.

[Bryce]

If you box in an 1/8" it will be fine. I look at everything as trying to make it as light as possible. I wrote an excel program that calculates the forces on the front suspension in a 1G turn with a given body roll and a 1G bump at the same time. I will try to find it on my old laptop.

3/16 if you dont box it in.

[wellis77]

Good to know. Thanks Bryce. I'm definitely planning to box (the top anyway) of the control arm mounts. That leads me tow onder about the other thread I started about using 2x3 tube, if it's 3/16" vs. 1/8", what is the difference in strength compared to the 2x4x1/8?

[Motorcitydak]

I like to use 1/8 plate and laminate em. That gives you a total of 1/4 inch thickness and 4 flat sides of steel that resist bending better. They are easy to make and usually lighter as well since you can reinforce only as needed. 1/8 plate is also a lot easier to work with compared to 3/16 or 1/4. You can bend it easier if you need something other than flat pieces. Im sure Will has seen some of the pieces Ive made but here are the axle link brackets I made using 1/8









See what I mean about 1/8 being easy to work with? I bent one single piece over the brackets making them very strong. I also have another bent piece on the inside of the brackets

[JRouche]

Im not an engineer so I dont know. I tend to copy what products are out there. And I do go on the heavy side of building.

Now with that bit of excuses aside here is what I like.

For the upper control arm mount on the front of the car I dont see a need for 1/4" steel. The lateral forces on the upper control arm is all that it sees, no real vehicle weight, all the weight of the car is on the lower arms. But sometimes you cant make an upper arm mounting plate stiff enough with 3/16" steel. And I think 3/16" steel is common. And works great where there is some included design strength. I didnt have any design strength included so I used 1/4" plate for the upper arms.



But you were asking about upper coilover mounts. My front uses the mustang II upper mounts. So I cant show a fabricated mount for the front coilovers. I could have trimmed off all the extra metal when I swapped the coil springs out for coilover springs. But I chose not to. The extra metal thats not needed is more weight. But its also adding some stiffness to the entire front mounts. And it wasnt out of laziness. My plasma cutter could remove the mustang II coil spring mounts in a minute. Then I would have a clean slate to work with. But really, I like the added stiffness the coil spring mounts provide. They got to stay.

But... I did have to make mounts for the rear coilovers, shockwave air springs actually, but its the same loading on the mounts. And I used 1/4" plate for those. Why?

Couple of reasons. One, the 1/4" welds up really nice to the heavy walled frame I have. The other point is the diff between 3/16" and 1/4" for weight is small, because the mounts are small. And I wanted a strong upper spring mount, it wont flex, break or do anything, its really solid, but not supper heavy. Might be less than a pound more for both sides compared to 3/16" And I would never make the mount I made from 1/8" sheet, its too simple and there's no design strength.

But you can do some work with 1/8" sheet, as some have shown. I just prefer 1/4" plate for simple mounts and 3/16" plate for standard mounts. Major boxed mounts can be done with 1/8" sheet but the bearing, or loaded part, like where the bolt for the top of the coilover mounts to should be beefed up with a heavy walled tube so the 1/8" "box" is the structural member and you have some heavy (3/16") walled tubing welded into the box structure so the 1/8" sheet isnt taking the loads directly. The 3/16" tube distributes the loads to the box weldment, but the weldment isnt taking the load directly, its acting as a full frame type of load handler, the impact loads are handled by the heavy tube and distributed throughout the entire surface of the 1/8" box structure. But NO. I wont make any suspension pieces from 1/8" steel. IMO it tears too easily and flexes. Id rather make simple mounting pieces out of 3/16" steel and call it a day.

I like to use simple structures and stronger pieces, its simpler and not all that much of a sacrifice IMO.

Some pics of my 1/4" coilover mounts.

1/4" plates to start out with.


Cut to the shapes I needed.


Drilled and prepped for welding.


Bench welded and cleaned up.


Mock shocks made up to weld them to the frame.


Welded up to the frame.


Fully welded up to the frame.


Lil paint.


The spacers cause I have a four link, the coilovers will move fore and aft during 4-link adjustment.


The final look. The coilovers are all the way forward cause my 4-link arms are all the way short. If I adjust them I will turn another spacer for the front and rear to center the coilover mount.


Thats all, really. There are more pics here if interested with bottom mounts. JR

[wellis77]

That's great stuff JR, thank you. I'll be using some of those ideas when I'm back in 6 weeks.