Sheet metal formed trailing arms - WHAT THICKNESS

[jersdunz]

Hi I am getting ready to laser out the parts to build my trailing arms on my revised rear suspension setup.
I thought i'd stick my head in here and obtain some outside opinions on my design and what thickness you all might think i should go with.

I have been considering 10 ga .135" thick and 12 ga .105" thick

what are your thoughts? Here is a pdf of the arms.

[yoshi]

Originally Posted by jersdunz

Hi I am getting ready to laser out the parts to build my trailing arms on my revised rear suspension setup.
I thought i'd stick my head in here and obtain some outside opinions on my design and what thickness you all might think i should go with.

I have been considering 10 ga .135" thick and 12 ga .105" thick

what are your thoughts? Here is a pdf of the arms.

I just designed a set of boxed trailing arms as well and will be using 10 gauge for the top/bottom and 12 gauge for the sides/internal supports, material is mild steel.....

[jersdunz]

Originally Posted by yoshi

I just designed a set of boxed trailing arms as well and will be using 10 gauge for the shell and 12 gauge for all the internal supports, both mild steel.....

I wondered if they needed the internal supports and haven't put any in it
so far. I ran the properties of the assembly in inventor and it's kicking me
a figure of 38 lbs per arm at ten gauge it just seems really heavy.

I wonder if a well gusseted 14 ga unit would hold up?

[yoshi]

Originally Posted by jersdunz

I wondered if they needed the internal supports and haven't put any in it
so far. I ran the properties of the assembly in inventor and it's kicking me
a figure of 38 lbs per arm at ten gauge it just seems really heavy.

I wonder if a well gusseted 14 ga unit would hold up?

The internal bracing i'm doing will have lightning holes so they won't add much to the weight.

[Dezzrats]

Take a look at the cost of 4130 plate. It is much stronger and a dream to work with in the thin plate form and a regular Mig welds it up.

[MC@ Performance Fab]

The majority of arms are made from 12 gage.

[MC@ Performance Fab]

Having the bend close to the hub is prefered and having the pivits paralel to the hub is not.

[standfast]

Needs internal support to keep it from oil canning and as bracing at the shock mounts. .100 is sufficient if braced well internally. Doesn't look like you have any camber gain though. Try to set up your welds so they are inside corner and not outside corner by running the top and bottom pieces long. You should have a way to adjust toe as well. Heims...

[bdkw1]

I would also suggest wrapping the outer bushing/hiem housing. They have a nasty habit of ripping out.

The bottoms will see the most abuse and should be thicker, like 8 gauge. 12 gauge is fine for the sides and top. Internal ribs can be 14 gauge. And yes, you need them.

[K-fab]

Originally Posted by Dezzrats

Take a look at the cost of 4130 plate. It is much stronger and a dream to work with in the thin plate form and a regular Mig welds it up.

Boy tell me about it. I was just quoted $1,600 in materials for my trailing arms. .085 for the main structure and .125 for the two internal ribs that the shock will attach to. From what the water jet guy said, they don't make 4140 in sheet form (as in a gauge size) and they were going to have to start out with .250 plate and grind it down to thickness. WTF???

I spent the better part of a week designing and redesigning my trailing arms just to find out they'll end up being prohibitively expensive.

Needless to say I said F that. I may consider doing my arms in 1018, but I'm so totally pissed with my 10Dez (everything has been a compromise) that I'm ready to take it and throw the damn thing in the dumpster. Someone hands me $35K, comes and gets it and they can have the f'n thing.

I'll be redesigning trailing arms and be using 1.25" tubing now. Why not, it's all been a compromise and a constant kick in the balls.