[NJSPEEDER]

I am hoping to pick up my first jeep in the next week or two. Looking to pick up a mid 90's ZJ.

I was looking at a lot of the aftermarket bumpers and I like to fabricate and weld. Since most of the trucks in my price range are I6 powered, I hesitate to add all the weight of a steel bumper, would aluminum be acceptable?

I can get 1/4 or 3/8 aluminum plate and make a design similar to steel. I just wonder if there is any draw back to the lighter, softer material? I plan to incorporate a winch mount and d-rings or recovery hooks of some sort as well, recovery points would be tied into the frame mounts.

Initial design will most likely be done in steel for cost reasons, once I have a good working model I will go aluminum.

Any advice will be helpful, thanks

[Unlimited04]

the main problems with aluminum vs steel as you pointed out is the fact that its softer material. I definitely would NOT make a winch mount out of aluminum. I think you should combine the best of both worlds: create a subframe out of 3/16th and 1/4" plate steel to mount the winch and reinforce the unibody of the ZJ. then create whatever external shape you want in aluminum and bolt it to the steel with grade 8 hardware. steel has a near infinite fatigue life and will serve you much better as a winch mount than aluminum.

also note 1/4" mild steel is cheap an will hold a winch perfectly, but 6061T6 aluminum of greater would be required for stessful applications and its NOT cheap.

[NJSPEEDER]

Thanks for the advice. That is exactly what I was wondering about.

I will post up once I get started putting something together so everyone can see how it goes.

[CB3]

It's harder and stronger than regular steel. So you can use less of it, which in turn makes it lighter, yet still stronger (assuming you use an appropriate amount/thickness). You could end up with parts that are about the same weight as aluminum, but stronger and harder than steel. i.e. - the best of both worlds.

At least that's what I've read about chromoly steel.

[j0nesy]

Originally Posted by CB3

It's harder and stronger than regular steel. So you can use less of it, which in turn makes it lighter, yet still stronger (assuming you use an appropriate amount/thickness). You could end up with parts that are about the same weight as aluminum, but stronger and harder than steel. i.e. - the best of both worlds.

At least that's what I've read about chromoly steel.

depending on the grade of CrMo ... definitely. many jeeps and buggies are running CrMo cages with wall thickness in the 0.095 range (for exterior tubes, even down to 0.0625 for interior bracing).

One problem with CrMo though, is that the welds do get slightly more brittle than the welds on mild steel tubing.

Its up for debate, and really just personal preference, but some say it does need to be heat treated after finish welding.

my opinion on the subject: Even without heat treatment, its still stronger than mild steel.

But the fact is, both CrMo and mild steel can benefit from proper heat treatment after welding.

a cage built with 1.75 x 0.125 DOM mild steel will be weaker than the same cage built with 1.75 x 0.125 CrMo.

its arguable that a cage with 1.75 x 0.095 CrMo would be comparable in strength to the same cage built with 1.75 x 0.125 DOM mild steel.

regardless:

a cage built with 1.75 x 0.125 CrMo As-Welded will be weaker than the same cage built with 1.75 x 0.125 CrMo that has been Heat Treated after welding.

the same also applies for mild steel.


i tried to word that in a way to make it understandable .. .but i tend to ramble....

[mcmopar]

not sure what you are going to be doing with it, but any time you get stuck on a rock aluminum will grab the rock better not slide on it like steel would.

[CB3]

Originally Posted by mcmopar

not sure what you are going to be doing with it, but any time you get stuck on a rock aluminum will grab the rock better not slide on it like steel would.

Correct. Because aluminum is softer, it grabs obstacles it rubs against.

Since mild steel is harder than aluminum, it slips off a rock or other obstacle easier.

Cromoly steel is the hardest (as well as strongest). So Chromo should slip off a rock the easiest, IMO.